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Article

Identification and Expression Analysis of Two allene oxide cyclase (AOC) Genes in Watermelon

by
Jingwen Li
1,2,
Yelan Guang
1,2,
Youxin Yang
1,2,* and
Yong Zhou
2,3,*
1
Jiangxi Key Laboratory for Postharvest Technology and Nondestructive Testing of Fruits & Vegetables, Collaborative Innovation Center of Post-Harvest Key Technology and Quality Safety of Fruits and Vegetables, College of Agronomy, Jiangxi Agricultural University, Nanchang 330045, China
2
Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, Jiangxi Agricultural University, Nanchang 330045, China
3
Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, China
*
Authors to whom correspondence should be addressed.
Agriculture 2019, 9(10), 225; https://doi.org/10.3390/agriculture9100225
Submission received: 2 August 2019 / Revised: 30 September 2019 / Accepted: 14 October 2019 / Published: 17 October 2019
(This article belongs to the Special Issue Vegetable Crops Breeding)
Browse Figures
Versions Notes

Abstract

:
Allene oxide cyclase (AOC, EC 5.3.99.6) catalyzes the most important step in the jasmonic acid (JA) biosynthetic pathway and mediates plant defense response to a wide range of biotic and abiotic stresses. In this study, two AOC genes were identified from watermelon. Sequence analysis revealed that each of ClAOC1 and ClAOC2 contained an allene oxide cyclase domain and comprised eight highly conserved β-strands, which are the typical characteristics of AOC proteins. Phylogenetic analysis showed that ClAOC1 and ClAOC2 were clustered together with AOCs from dicotyledon, with the closest relationships with JcAOC from Jatropha curcas and Ljaoc1 from Lotus japonicus. Different intron numbers were observed in ClAOC1 and ClAOC2, which may result in their functional divergence. qRT-PCR analysis revealed that ClAOC1 and ClAOC2 have specific and complex expression patterns in multiple organs and under hormone treatments. Both ClAOC1 and ClAOC2 displayed the highest transcriptional levels in stem apex and fruit and exhibited relatively lower expression in stem. JA, salicylic acid (SA), and ethylene (ET) could enhance the expression of ClAOC1 and ClAOC2, particularly that of ClAOC2. Red light could induce the expression of ClAOC2 in root-knot nematode infected leaf and root of watermelon, indicating that ClAOC2 might play a primary role in red light-induced resistance against root-knot nematodes through JA signal pathway. These findings provide important information for further research on AOC genes in watermelon.

1. Introduction

Jasmonates, including jasmonic acid (JA) and its related compounds, play vital roles in plant developmental processes and responses to various biotic and abiotic stresses [1,2]. Jasmonate is biosynthesized from α-linolenic acid through a canonical pathway, and allene oxide cyclase (AOC, EC 5.3.99.6) is one of the most important enzymes, which produces 12-oxo-phytodienoic acid (OPDA) with 12,13(S)-epoxy-octadecatrienoic acid (12,13-EOT), and establishes the stereochemical configuration of naturally occurring JA [3,4,5,6].
Several studies have shown that AOC genes compose a small gene family, and the numbers of AOC genes are different across plants. For example, there are six AOC genes in soybean [7], five in upland cotton (Gossypium hirsutum) [8], four in Arabidopsis thaliana [9], three in Lotus japonicas [10], two in Physcomitrella patens [11], while only one AOC gene in rice and tomato [6,12], respectively. In addition, AOC genes were found to have specific and complicated tissue expression patterns in different plants. In barley, HvAOC mRNA accumulation is abundant in root tip, scutellar node, and leaf base [13]. Soybean GmAOC1 and GmAOC2 also exhibited abundant mRNA transcripts in roots, while GmAOC3 and GmAOC4 showed relatively higher expression in leaves and stems, respectively [7]. Camptotheca acuminata CaAOC is constitutively expressed in various organs, with the highest expression level in leaves [14]. In Arabidopsis, AtAOC1, AtAOC2, and AtAOC3 promoters exhibit high activities in the leaves, while only AtAOC3 and AtAOC4 show promoter activity in roots [15]. These results suggest that AOC genes are involved in the regulation of multiple plant developmental processes.
The expression of jasmonate biosynthetic pathway genes, including AOCs, is regulated by JA, and overexpression or suppression of these genes can greatly affect the JA levels in plants. For example, a severe deficiency of jasmonate was found in two AOC mutants (cpm2 and hebiba) of rice [12], and partial suppression of MtAOC1 in hairy roots of Medicago truncatula also resulted in lower JA levels in mycorrhizal roots [16]. In addition, elevated JA levels were found in transgenic plants overexpressing AOC genes from different plants, such as AaAOC from Artemisia annua [5], TaAOC1 from wheat [17], and GmAOC3 from soybean [18]. JA and its related compounds are involved in plant defense reactions against biotic and abiotic stresses, and the expression of some AOC genes can also be regulated by various stresses, implying that they may play regulatory roles in response to abiotic and biotic stresses. For example, overexpression of GmAOC1 and GmAOC5 in transgenic tobacco plants contributed to significantly increased resistance to salinity and oxidative stress, respectively [7], whereas GmAOC3 confers resistance to common cutworm (CCW) in transgenic tobacco plants [18]. Rice AOC mutants were less sensitive to salt stress but susceptible to Magnaporthe oryzae, and exogenous application of JA restored the resistance to M. oryzae in these mutants [12,19], while overexpression of OsAOC in rice significantly increased the resistance to chewing and piercing-sucking insect pests through AOC-mediated increases of OPDA and JA, respectively [20]. Overexpression of peanut AhAOC in rice resulted in increases of root elongation and plant height and improved salt tolerance with increased expression of stress-responsive genes [21]. Overexpression of Cymbidium faberi CfAOC gene in tomato also resulted in significantly enhanced drought tolerance with increased expression levels of genes related to MeJA biosynthesis [22].
Watermelon is an important agricultural crop and can be invaded by root-knot nematode (RKN) Meloidogyne incognita, which finally causes substantial losses of crop production [23]. Various hormones, such as JA, salicylic acid (SA), and ethylene (ET), are key components in plant defense against nematode infection, and red light (RL) could potentially activate systemic defense against RKN by modulating hormone pathways [23,24,25,26]. A previous study has shown that loss-of-function of AtAOC3 rendered plants are more susceptible to nematode infection [27], suggesting that AOC genes may be involved in plant defense against RKN. However, less information is available about the AOC genes in watermelon. In the present study, two AOC genes were identified from watermelon, and their phylogenetic relationships, gene structures, expression profiles in response to JA, SA, ET, red light, and RKN were also examined. The findings provide further insights into the role of AOC genes in watermelon.

2. Materials and Methods

2.1. Identification and Sequence Analysis of the AOC Genes in Watermelon

To identify the AOC members in watermelon and other plants, watermelon genomic database (http://cucurbitgenomics.org/search/genome/1) and plant genomic resource Phytozome (https://phytozome.jgi.doe.gov/pz/portal.html) were screened using AOC protein sequences of in tomato, rice, and Arabidopsis as queries. The possible AOC proteins were confirmed with NCBI CDD program (https://www.ncbi.nlm.nih.gov/Structure/cdd/wrpsb.cgi). The physicochemical properties including isoelectric point (pI), molecular weight (MW), and grand average of hydropathy index (GRAVY) of the AOC proteins were analyzed by using the ProtParam tool (http://web.expasy.org/protparam/). GSDS (Gene Structure Display Server) tool was employed to analyze the gene structures of AOC family genes from different plant species by comparing the coding sequences (CDSs) and the genomic DNA (gDNA) sequences.

2.2. Alignment of Amino Acid Sequences and Phylogenetic Analysis

For multiple sequence alignment, the full-length AOC protein sequences from watermelon and other plant species in literature were aligned using Clustal Omega with default settings and visualized with GeneDoc [28]. To investigate the evolutionary relationships of AOC genes among different plant species, a phylogenetic tree was created with the MEGA 7.0 software program by using the neighbor-joining (NJ) method with bootstrap analysis of 1000 replicates.

2.3. Expression Pattern Analysis of the AOC Genes in Different Tissues

For analysis of the expression of watermelon AOC genes during the fruit development, the transcriptome data of both the rind and flesh at different stages of fruit development were obtained based on a previous study [29]. The transcriptome data were analyzed and the expression was picked out and displayed as fragments per kilobase of exon model per million mapped (FPKM) values as previously described [24,28].

2.4. Plant Materials and Growth Conditions

Watermelon (Citrullus lanatus L. cv. Xinong 8) seeds were germinated and sown in pots containing nutritional soil, placed in greenhouse under the conditions of 25 °C/19 °C (12 h/12 h), and light intensity of 200 µmol·m−2·s−1. Seedlings at 2-month-old stage were harvested for tissues including the leaves, stems, stem apexes, fruits, flowers, and roots. For hormonal stresses, the leaves or roots of the four-leaf stage watermelon seedlings were used to test the expression levels of ClAOC1 and ClAOC2 using qRT-PCR at different time points (0, 1, 3, 9, and 24 h) with 100 µM methyl jasmonate (MeJA), 1 mM salicylic acid (SA), and 500 μM ethylene (ET) spraying on watermelon leaves, respectively. For analysis of the expression of watermelon AOC genes in response to red light induction of watermelon against root-knot nematode infection, the experiment was conducted according to our previous study [23], and the samples of leaves and roots from control (mock, white light, and water solution), RL (red light treatment and water solution), RKN (white light and root knot nematode M. incognita infection), and RR (red light treatment and root knot nematode M. incognita infection) treatments were collected. All samples were immediately frozen in liquid nitrogen and stored at −80 °C for RNA exaction.

2.5. RNA Isolation, cDNA Synthesis, and Quantitative Real-Time PCR of the AOC Genes in Watermelon

Total RNA was extracted with the total RNA Miniprep Kit (Axygen Biosciences, Union City, CA, USA), and reverse transcribed using the ReverTra Ace qPCR-RT Kit (Toyobo, Japan) according to the manufacturers’ protocols. qRT-PCR was carried out using the iCycler iQTM Real-time PCR Detection System (Bio-Rad, Hercules, CA, USA) in three replicates with the procedure as follows: 3 min at 95 °C, followed by 40 cycles of 30 s at 95 °C, 30 s at 58 °C and 1 min at 72 °C. Watermelon β-actin gene (Cla007792) was used as an internal control, and qRT-PCR data were compared with those of 0 h and the relative expression values were calculated using the method described previously [30]. Significant differences (p < 0.05) were determined with Tukey’s test in the SPSS software, and the differences were indicated by different letters.

3. Results and Discussion

3.1. Identification and Sequence Analysis of the AOC Genes in Watermelon

Two AOC genes, Cla016453 and Cla003512, were identified in watermelon genome and were named as ClAOC1 and ClAOC2, respectively. The ClAOC1 coding sequence (CDS) consisted of 741 nucleotides and encoded a putative protein of 246 amino acids, with a predicted isoelectric point (pI) of 8.74 and a molecular weight (MW) of 28.86 kDa (Table 1). The ClAOC2 gene contained a 1005-bp CDS, which encoded a putative protein of 334 amino acids, with a predicted pI of 9.62 and a MW of 36.67 kDa. The predicted GRAVY values of ClAOC1 and ClAOC2 were −0.268 and −0.309, respectively (Table 1), suggesting that both of them are hydrophilic. Domain analyses by CDD showed that each of ClAOC1 and ClAOC2 contained an allene oxide cyclase domain (Figure 1), which was located on their C-terminus, indicating that they are members of the AOC gene family.

3.2. Characterization of ClAOC1 and ClAOC2

To characterize ClAOC1 and ClAOC2, a multiple sequence alignment was performed for their full-length amino acid sequences, as well as other published AOC proteins, such as SlAOC from Solanum lycopersicum [6], HvAOC from Hordeum vulgare [13], HnAOC from Hyoscyamus niger [31], JcAOC from Jatropha curcas [32], AaAOC from Artemisia annua [33], OsAOC from Oryza sativa [12], LmAOC from Leymus mollis [34], TaAOC1 from Triticum aestivum [17], GhAOC1 from Gossypium hirsutum [8], GmAOC3 from Glycine max [18], CsAOC from Camellia sinensis [35], and Ljaoc1 from Lotus japonicus [10]. The results showed that the identity between ClAOC1 and ClAOC2 was 62.13%, and the amino acid sequences of ClAOC1 and ClAOC2 shared 58.05% to 69.08% identity with other AOC proteins (Figure 2). It should be noted that all of these AOC proteins comprised eight highly conserved β-strands (Figure 2), which might play vital roles in determining the biological function of the AOC enzymes [7,36,37]. Therefore, ClAOC1 and ClAOC2 might have similar functions with their homologs in other plant species.

3.3. Phylogenetic and Structural Analyses of AOC Genes from Different Plant Species

To investigate the evolutionary relationships of AOC genes within multiple plant species, a phylogenetic tree was created by MEGA 7.0 with the NJ method by using the full-length amino acid sequences of AOC proteins from different plant species. As a result, these AOC proteins were found to originate from a common ancestor and could be divided into three groups (Figure 3). ClAOC1 and ClAOC2 clustered together with AOCs from dicotyledon in Group I, which is in accordance with the category of watermelon. Amongst them, ClAOC1 and ClAOC2 showed the closest relationships with JcAOC and Ljaoc1, respectively (Figure 3). In addition, the monocotyledonous AOCs from rice, L. mollis, wheat, barley, maize, and sorghum were clustered together in Group II. Four AtAOC proteins together with GhAOC1 were clustered in Group III and diverged earlier than other species (Figure 3), which is consistent with the previous reports [9,33].
The gene structures can provide important information to reveal the evolutionary relationships among gene families [30]. We then performed the structural analyses of AOC family genes from watermelon and other plant species such as Arabidopsis, rice, tomato, maize, and sorghum. It should be noted that tomato, sorghum, and rice contain a single AOC gene. Most AOC genes contained two exons and one intron, while SlAOC and ClAOC1 possessed three exons and two introns (Figure 4). The members with close phylogenetic relationships shared similar gene structures, including intron numbers and CDS lengths, revealing the conserved features during the evolution of AOC genes. It is noteworthy that ClAOC1 and ClAOC2 harbored different numbers of introns, which may result in their functional divergence. Similarly, four soybean AOC genes (GmAOC3-6) have two introns, and other two AOC genes (GmAOC1 and GmAOC2) contain only one intron [7].

3.4. Expression Patterns of ClAOC1 and ClAOC2 in Different Tissues

The expression patterns of ClAOC1 and ClAOC2 in different tissues were determined by qRT-PCR. Both ClAOC1 and ClAOC2 displayed the high transcriptional levels in stem apex and the lowest expression levels in stem (Figure 5). In addition, their expression was also detected in flower and fruit at relatively high levels. It is noteworthy that ClAOC1 displayed higher transcriptional levels in fruit than in flower, while ClAOC2 exhibited higher transcriptional levels in flower than in fruit (Figure 5). In Arabidopsis, AtAOC1 and AtAOC4 promoters were found to be active in flower development [15]. To further access the functions of the ClAOC1 and ClAOC2 in the developmental regulation, their expression during the development of flesh and rind at different stages was examined. According to the transcriptome data, ClAOC1 showed much higher expression during fruit development than ClAOC2 (Figure 6). Both ClAOC1 and ClAOC2 displayed gradually declining expression during the earlier development of flesh, while their expression increased at 34 DAP. During the rind development, the expression of ClAOC1 increased gradually, while that of ClAOC2 exhibited a down-regulated trend (Figure 6). These results suggested that ClAOC1 and ClAOC2 play different roles in the fruit development of watermelon.

3.5. Expression Patterns of ClAOC1 and ClAOC2 in Response to Hormones

Previous studies have revealed that the expression of AOC genes could be induced by treatments of different hormones, such as JA and SA [8,35,37]. To determine whether ClAOC1 and ClAOC2 are responsive to hormones, their expression patterns under treatments of different hormones (JA, SA, and ET) were examined by qRT-PCR. The results showed that the two genes displayed markedly up-regulated expression in response to these hormones. Upon JA treatment, the transcription levels of ClAOC1 and ClAOC2 were significantly up-regulated at 1 h and 3 h both in leaf and root, and their expression levels showed a decline trend at 9 h and 24 h (Figure 7A,B). The expression pattern was similar to that of AOC genes in Salvia miltiorrhiza [37] and G. hirsutum [8]. However, the expression of ClAOC1 and ClAOC2 was increased to different degrees in leaf and root. In leaf, the rising trend of ClAOC1 was more rapid than in root, while that of ClAOC2 was just the opposite (Figure 7A,B), implying that these two genes have different roles for JA signaling in leaf and root. For SA and ET treatments, the transcription levels of ClAOC1 and ClAOC2 increased gradually at the earlier stage but showed significant decreases at the later stage (Figure 7C,D). The expression of ClAOC1 peaked at 9 h and 3 h under SA and ET treatment, respectively. However, the expression of ClAOC2 reached the maximum at 1 h and then gradually decreased under SA and ET treatments (Figure 7C,D). Similarly, the expression of CsAOC also increased rapidly at the earlier time points after SA treatment and then decreased gradually [35]. In particular, the highest mRNA accumulation of ClAOC2 was observed after 3 h of JA treatment in root, which was significantly higher than that of control and under treatments with other hormones (Figure 7). The results indicated that ClAOC1 and ClAOC2 might play vital and diverse roles in hormone responses.

3.6. Expression Patterns of ClAOC1 and ClAOC2 in Response to Root-Knot Nematode Infection

Previous studies have revealed that red light (RL) could stimulate JA and SA biosynthesis and signaling pathway genes to activate plant defense against RKN [23,24]. Considering that ClAOC1 and ClAOC2 were induced by JA and SA, they may play a role in watermelon defense against RKN. To verify this speculation, we examined the expression of ClAOC1 and ClAOC2 in the leaves and roots under the treatments of CK, RKN, RL, and RR by qRT-PCR based on the experiment procedures in our previous study [23]. There was no significant difference in the expression of ClAOC1 and ClAOC2 under RKN treatment compared with the control (CK) in leaf (Figure 8A). However, the expression levels of ClAOC1 and ClAOC2 were obviously increased not only under RL treatment compared with CK but also under RR treatment compared with RKN treatment (Figure 8A). In root, only ClAOC2 was observably up-regulated not only by RL treatment compared with CK but also by RR treatment compared with RKN treatment (Figure 8B). In addition, the unequal rises of ClAOC1 and ClAOC2 in response to the treatments of CK, RKN, RL, and RR suggested that ClAOC2 might play a primary role in red light-induced resistance against root-knot nematodes. AOC plays a vital role in JA biosynthesis, and this phytohormone can regulate plant defense against RKN [23,24,38]. Light can regulate plant defense by modifying multiple hormonal pathways including JA signaling and homeostasis [23,39,40]. After the induction of the generation of JA, it can be long-distance transported in plants through the vascular system [41,42,43]. Therefore, exposure of watermelon leaves to RL could influence the expression of ClAOC1 and ClAOC2 to produce JA in leaves, which can be transported to root and thus induce the expression of jasmonate biosynthetic genes to increase the JA content in root and finally induce watermelon resistance against RKN infection.

4. Conclusions

In this study, a systematic analysis of the AOC genes in watermelon was carried out through analysis of the protein structure, phylogenetic relationship, gene structure, and the expression profiles. Each of ClAOC1 and ClAOC2 contained an allene oxide cyclase domain and eight highly conserved β-strands, but ClAOC1 and ClAOC2 harbored different numbers of introns. In addition, the expression analysis revealed that ClAOC1 and ClAOC2 have distinct expression patterns in different tissues and in responses to hormones, implying that they may have different roles in the developmental regulation. Moreover, both of ClAOC1 and ClAOC2 were obviously induced not only under RL treatment compared with CK but also under RR treatment compared with RKN treatment in leaf. However, only ClAOC2 was observably up-regulated not only by RL treatment compared with CK but also by RR treatment compared with RKN treatment in root. The different expression profiles of ClAOC1 and ClAOC2 indicate their diverse roles in the growth and development of watermelon.

Supplementary Materials

The following are available online at https://www.mdpi.com/2077-0472/9/10/225/s1, Table S1: Primers sequences used in qRT-PCR, Table S2: AOC proteins from different plant species used for phylogenetic analysis.

Author Contributions

Data curation, J.L., Y.G., Y.Y., and Y.Z.; formal analysis, J.L.; funding acquisition, Y.Y. and Y.Z.; methodology, Y.Y. and Y.Z.; resources, J.L., Y.G., and Y.Y.; software, Y.G. and Y.Z.; writing—original draft, Y.Z.; writing—review and editing, Y.Y. and Y.Z.

Funding

This research was funded by the Foundation of Jiangxi Educational Committee (GJJ160393 and GJJ180172), the National Natural Science Foundation of China (31560572), and the Natural Science Foundation of Jiangxi Province, China (20171BAB214030).

Conflicts of Interest

The authors declare that they have no conflict of interest.

References

  1. Lyons, R.; Manners, J.M.; Kazan, K. Jasmonate biosynthesis and signaling in monocots: A comparative overview. Plant Cell Rep. 2013, 32, 815–827. [Google Scholar] [CrossRef] [PubMed]
  2. Per, T.S.; Khan, M.I.R.; Anjum, N.A.; Masood, A.; Hussain, S.J.; Khan, N.A. Jasmonates in plants under abiotic stresses: Crosstalk with other phytohormones matters. Environ. Exp. Bot. 2018, 145, 104–120. [Google Scholar] [CrossRef]
  3. Stumpe, M.; Feussner, I. Formation of oxylipins by CYP74 enzymes. Phytochem. Rev. 2006, 5, 347–357. [Google Scholar] [CrossRef]
  4. Hamberg, M.; Fahlstadius, P. Allene oxide cyclase: A new enzyme in plant lipid metabolism. Arch. Biochem. Biophys. 1990, 276, 518–526. [Google Scholar] [CrossRef]
  5. Lu, X.; Zhang, F.; Shen, Q.; Jiang, W.; Pan, Q.; Lv, Z.; Yan, T.; Fu, X.; Wang, Y.; Qian, H.; et al. Overexpression of allene oxide cyclase improves the biosynthesis of artemisinin in Artemisia annua L. PLoS ONE 2014, 9, e91741. [Google Scholar] [CrossRef]
  6. Ziegler, J.; Stenzel, I.; Hause, B.; Maucher, H.; Hamberg, M.; Grimm, R.; Ganal, M.; Wasternack, C. Molecular cloning of allene oxide cyclase: The enzyme establishing the stereochemistry of octadecanoids and jasmonates. J. Boil. Chem. 2000, 275, 19132–19138. [Google Scholar] [CrossRef]
  7. Wu, Q.; Wu, J.; Sun, H.; Zhang, D.; Yu, D. Sequence and expression divergence of the AOC gene family in soybean: Insights into functional diversity for stress responses. Biotechnol. Lett. 2011, 33, 1351–1359. [Google Scholar] [CrossRef]
  8. Wang, Y.; Liu, H.; Xin, Q. Improvement of copper tolerance of Arabidopsis by transgenic expression of an allene oxide cyclase gene, GhAOC1, in upland cotton (Gossypium hirsutum L.). Crop J. 2015, 3, 343–352. [Google Scholar] [CrossRef]
  9. Stenzel, I.; Hause, B.; Miersch, O.; Kurz, T.; Maucher, H.; Weichert, H.; Ziegler, J.; Feussner, I.; Wasternack, C. Jasmonate biosynthesis and the allene oxide cyclase family of Arabidopsis thaliana. Plant Mol. Boil. 2003, 51, 895–911. [Google Scholar] [CrossRef]
  10. Zdyb, A.; Salgado, M.G.; Demchenko, K.N.; Brenner, W.G.; Płaszczyca, M.; Stumpe, M.; Herrfurth, C.; Feussner, I.; Pawlowski, K. Allene oxide synthase, allene oxide cyclase and jasmonic acid levels in Lotus japonicus nodules. PLoS ONE 2018, 13, e0190884. [Google Scholar] [CrossRef]
  11. Neumann, P.; Brodhun, F.; Sauer, K.; Herrfurth, C.; Hamberg, M.; Brinkmann, J.; Scholz, J.; Dickmanns, A.; Feussner, I.; Ficner, R. Crystal structures of Physcomitrella patens AOC1 and AOC2: Insights into the enzyme mechanism and differences in substrate specificity. Plant Physiol. 2012, 160, 1251–1266. [Google Scholar] [CrossRef] [PubMed]
  12. Riemann, M.; Haga, K.; Shimizu, T.; Okada, K.; Ando, S.; Mochizuki, S.; Nishizawa, Y.; Yamanouchi, U.; Nick, P.; Yano, M.; et al. Identification of rice Allene Oxide Cyclase mutants and the function of jasmonate for defence against Magnaporthe oryzae. Plant J. 2013, 74, 226–238. [Google Scholar] [CrossRef] [PubMed]
  13. Maucher, H.; Stenzel, I.; Miersch, O.; Stein, N.; Prasad, M.; Zierold, U.; Schweizer, P.; Dorer, C.; Hause, B.; Wasternack, C. The allene oxide cyclase of barley (Hordeum vulgare L.)—cloning and organ-specific expression. Phytochemistry 2004, 65, 801–811. [Google Scholar] [CrossRef] [PubMed]
  14. Pi, Y.; Liao, Z.; Jiang, K.; Huang, B.; Deng, Z.; Zhao, D.; Zeng, H.; Sun, X.; Tang, K. Molecular cloning, characterization and expression of a jasmonate biosynthetic pathway gene encoding allene oxide cyclase from Camptotheca acuminata. Biosci. Rep. 2008, 28, 349. [Google Scholar] [CrossRef]
  15. Stenzel, I.; Otto, M.; Delker, C.; Kirmse, N.; Schmidt, D.; Miersch, O.; Hause, B.; Wasternack, C. ALLENE OXIDE CYCLASE (AOC) gene family members of Arabidopsis thaliana: Tissue- and organ-specific promoter activities and in vivo heteromerization. J. Exp. Bot. 2012, 63, 6125–6138. [Google Scholar] [CrossRef]
  16. Isayenkov, S.; Mrosk, C.; Stenzel, I.; Strack, D.; Hause, B. Suppression of allene oxide cyclase in hairy roots of Medicago truncatula reduces jasmonate levels and the degree of Mycorrhization with Glomus intraradices. Plant Physiol. 2005, 139, 1401–1410. [Google Scholar] [CrossRef]
  17. Zhao, Y.; Dong, W.; Zhang, N.; Ai, X.; Wang, M.; Huang, Z.; Xiao, L.; Xia, G. A wheat allene oxide cyclase gene enhances salinity tolerance via jasmonate signaling. Plant Physiol. 2014, 164, 1068–1076. [Google Scholar] [CrossRef]
  18. Wu, Q.; Wang, H.; Wu, J.; Wang, D.; Wang, Y.; Zhang, L.; Huang, Z.; Yu, D. Soybean GmAOC3 promotes plant resistance to the common cutworm by increasing the expression of genes involved in resistance and volatile substance emission in transgenic tobaccos. J. Plant Boil. 2015, 58, 242–251. [Google Scholar] [CrossRef]
  19. Hazman, M.; Hause, B.; Eiche, E.; Nick, P.; Riemann, M. Increased tolerance to salt stress in OPDA-deficient rice ALLENE OXIDE CYCLASE mutants is linked to an increased ROS-scavenging activity. J. Exp. Bot. 2015, 66, 3339–3352. [Google Scholar] [CrossRef]
  20. Guo, H.M.; Li, H.C.; Zhou, S.R.; Xue, H.W.; Miao, X.X. Cis-12-oxo-phytodienoic acid stimulates rice defense response to a piercing-sucking insect. Mol. Plant 2014, 7, 1683–1692. [Google Scholar] [CrossRef]
  21. Liu, H.; Wang, Y.; Wang, S.; Li, H. Cloning and characterization of peanut allene oxide cyclase gene involved in salt-stressed responses. Genet. Mol. Res. 2015, 14, 2331–2340. [Google Scholar] [CrossRef] [PubMed]
  22. Zhou, Y.; Chen, L.; Xu, Y.; Wang, Y.; Wang, S.; Ge, X. The CfAOS and CfAOC genes related to flower fragrance biosynthesis in Cymbidium faberi could confer drought tolerance to transgenic tomatoes. Int. J. Agric. Biol. 2018, 20, 883–892. [Google Scholar]
  23. Yang, Y.X.; Wu, C.; Ahammed, G.J.; Wu, C.; Yang, Z.; Wan, C.; Chen, J. Red light-induced systemic resistance against root-knot nematode is mediated by a coordinated regulation of salicylic acid, jasmonic acid and redox signaling in watermelon. Front. Plant Sci. 2018, 9, 899. [Google Scholar] [CrossRef] [PubMed]
  24. Yang, Y.X.; Wang, M.M.; Ren, Y.; Onac, E.; Zhou, G.; Peng, S.; Xia, X.J.; Shi, K.; Zhou, Y.H.; Yu, J.Q. Light-induced systemic resistance in tomato plants against root-knot nematode Meloidogyne incognita. Plant Growth Regul. 2015, 76, 167–175. [Google Scholar] [CrossRef]
  25. Nahar, K.; Kyndt, T.; De Vleesschauwer, D.; Höfte, M.; Gheysen, G. The jasmonate pathway is a key player in systemically induced defense against root knot nematodes in rice. Plant Physiol. 2011, 157, 305–316. [Google Scholar] [CrossRef] [PubMed]
  26. Zhao, W.; Zhou, X.; Lei, H.; Fan, J.; Yang, R.; Li, Z.; Hu, C.; Li, M.; Zhao, F.; Wang, S. Transcriptional evidence for cross talk between JA and ET or SA during root-knot nematode invasion in tomato. Physiol. Genom. 2018, 50, 197–207. [Google Scholar] [CrossRef] [PubMed]
  27. Naor, N.; Gurung, F.B.; Ozalvo, R.; Bucki, P.; Sanadhya, P.; Miyara, S.B. Tight regulation of allene oxide synthase (AOS) and allene oxide cyclase-3 (AOC3) promote Arabidopsis susceptibility to the root-knot nematode Meloidogyne javanica. Eur. J. Plant Pathol. 2018, 150, 149–165. [Google Scholar] [CrossRef]
  28. Zhou, Y.; Ge, L.; Li, G.; He, P.; Yang, Y.; Liu, S. In silico identification and expression analysis of Rare Cold Inducible 2 (RCI2) gene family in cucumber. J. Plant Biochem. Biotechnol. 2019. [Google Scholar] [CrossRef]
  29. Guo, S.; Zhang, J.; Sun, H.; Salse, J.; Lucas, W.J.; Zhang, H.; Zheng, Y.; Mao, L.; Ren, Y.; Wang, Z.; et al. The draft genome of watermelon (Citrullus lanatus) and resequencing of 20 diverse accessions. Nat. Genet. 2013, 45, 51–58. [Google Scholar] [CrossRef]
  30. Zhou, Y.; Li, J.; Wang, J.; Yang, W.; Yang, Y. Identification and characterization of the glutathione peroxidase (GPX) gene family in watermelon and its expression under various abiotic stresses. Agronomy 2018, 8, 206. [Google Scholar] [CrossRef]
  31. Jiang, K.; Liao, Z.; Pi, Y.; Huang, Z.; Hou, R.; Cao, Y.; Wang, Q.; Sun, X.; Tang, K. Molecular cloning and expression profile of a jasmonate biosynthetic pathway gene for allene oxide cyclase from Hyoscyamus niger. Mol. Boil. 2008, 42, 381–390. [Google Scholar] [CrossRef]
  32. Liu, B.; Wang, W.; Gao, J.; Chen, F.; Wang, S.; Xu, Y.; Tang, L.; Jia, Y. Molecular cloning and characterization of a jasmonate biosynthetic pathway gene for allene oxide cyclase from Jatropha curcas. Acta Physiol. Plant. 2010, 32, 531–539. [Google Scholar] [CrossRef]
  33. Lu, X.; Lin, X.; Shen, Q.; Zhang, F.; Wang, Y.; Chen, Y.; Wang, T.; Wu, S.; Tang, K. Characterization of the jasmonate biosynthetic gene allene oxide cyclase in Artemisia annua L., source of the antimalarial drug artemisinin. Plant Mol. Biol. Rep. 2011, 29, 489–497. [Google Scholar] [CrossRef]
  34. Habora, M.E.E.; Eltayeb, A.E.; Oka, M.; Tsujimoto, H.; Tanaka, K. Cloning of allene oxide cyclase gene from Leymus mollis and analysis of its expression in wheat–Leymus chromosome addition lines. Breed. Sci. 2013, 63, 68–76. [Google Scholar] [CrossRef]
  35. Wang, M.X.; Ma, Q.P.; Han, B.Y.; Li, X.H. Molecular cloning and expression of a jasmonate biosynthetic gene allene oxide cyclase from Camellia sinensis. Can. J. Plant Sci. 2016, 96, 109–116. [Google Scholar] [CrossRef]
  36. Hofmann, E.; Zerbe, P.; Schaller, F. The crystal structure of Arabidopsis thaliana allene oxide cyclase: Insights into the oxylipin cyclization reaction. Plant Cell 2006, 18, 3201–3217. [Google Scholar] [CrossRef]
  37. Gu, X.C.; Chen, J.F.; Xiao, Y.; Di, P.; Xuan, H.J.; Zhou, X.; Zhang, L.; Chen, W.S. Overexpression of allene oxide cyclase promoted tanshinone/phenolic acid production in Salvia miltiorrhiza. Plant Cell Rep. 2012, 31, 2247–2259. [Google Scholar] [CrossRef]
  38. Martinez-Medina, A.; Fernandez, I.; Lok, G.B.; Pozo, M.J.; Pieterse, C.M.; Van Wees, S.C. Shifting from priming of salicylic acid- to jasmonic acid-regulated defences by Trichoderma protects tomato against the root knot nematode Meloidogyne incognita. New Phytol. 2017, 213, 1363–1377. [Google Scholar] [CrossRef]
  39. Cerrudo, I.; Keller, M.M.; Cargnel, M.D.; Demkura, P.V.; De Wit, M.; Patitucci, M.S.; Pierik, R.; Pieterse, C.M.; Ballaré, C.L. Low red/far-red ratios reduce Arabidopsis resistance to Botrytis cinerea and jasmonate responses via a COI1-JAZ10-dependent, salicylic acid-independent mechanism. Plant Physiol. 2012, 158, 2042–2052. [Google Scholar] [CrossRef]
  40. Kazan, K.; Manners, J.M. The interplay between light and jasmonate signalling during defence and development. J. Exp. Bot. 2011, 62, 4087–4100. [Google Scholar] [CrossRef] [Green Version]
  41. Thorpe, M.R.; Ferrieri, A.P.; Herth, M.M.; Ferrieri, R.A. 11C-imaging: Methyl jasmonate moves in both phloem and xylem, promotes transport of jasmonate, and of photoassimilate even after proton transport is decoupled. Planta 2007, 226, 541–551. [Google Scholar] [CrossRef] [PubMed]
  42. Lacombe, B.; Achard, P. Long-distance transport of phytohormones through the plant vascular system. Curr. Opin. Plant Boil. 2016, 34, 1–8. [Google Scholar] [CrossRef] [PubMed]
  43. Heil, M.; Ton, J. Long-distance signalling in plant defence. Trends Plant Sci. 2008, 13, 264–272. [Google Scholar] [CrossRef] [PubMed]
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Figure 1. Domain analyses of the putative ClAOC1 and ClAOC2 proteins.
Figure 1. Domain analyses of the putative ClAOC1 and ClAOC2 proteins.
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Figure 2. Alignment of the deduced amino acid sequence of ClAOC1 and ClAOC2 with other AOC proteins from different plant species. The eight β-strands are underlined. The accession numbers of AOC proteins are as follows: JcAOC, ACZ06580.1; OsAOC, ABV45432.1; HnAOC, AAU11327.1; AaAOC, ADL16493.1; SlAOC, CAC83760; TaAOC1, AHA93095.1; GhAOC1, ALG62635.1; LmAOC, AFP87304.1; CsAOC, ADY38579.1; GmAOC3, AEE99198.1; HvAOC, CAC83766.1; Ljaoc1, AB600747.1.
Figure 2. Alignment of the deduced amino acid sequence of ClAOC1 and ClAOC2 with other AOC proteins from different plant species. The eight β-strands are underlined. The accession numbers of AOC proteins are as follows: JcAOC, ACZ06580.1; OsAOC, ABV45432.1; HnAOC, AAU11327.1; AaAOC, ADL16493.1; SlAOC, CAC83760; TaAOC1, AHA93095.1; GhAOC1, ALG62635.1; LmAOC, AFP87304.1; CsAOC, ADY38579.1; GmAOC3, AEE99198.1; HvAOC, CAC83766.1; Ljaoc1, AB600747.1.
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Figure 3. Phylogenetic analysis of AOC proteins from different plant species. The phylogenetic tree was created by MEGA 7.0 using the NJ method based on full-length amino acid sequences of AOC proteins from different plant species. The bootstrap value was set to 1000 replicates. The protein IDs and sources of all AOC proteins are listed in Table S2.
Figure 3. Phylogenetic analysis of AOC proteins from different plant species. The phylogenetic tree was created by MEGA 7.0 using the NJ method based on full-length amino acid sequences of AOC proteins from different plant species. The bootstrap value was set to 1000 replicates. The protein IDs and sources of all AOC proteins are listed in Table S2.
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Figure 4. The gene structures of AOC family genes from different plant species (B) based on the phylogenetic relationship (A). The green boxes, blue boxes, and black lines indicate UTRs, CDSs, and introns, respectively.
Figure 4. The gene structures of AOC family genes from different plant species (B) based on the phylogenetic relationship (A). The green boxes, blue boxes, and black lines indicate UTRs, CDSs, and introns, respectively.
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Figure 5. Relative mRNA levels of ClAOC1 (A) and ClAOC2 (B) determined by qRT-PCR in different tissues of watermelon. The β-actin gene was used as the internal control to standardize for each reaction. L, leaf; R, root; S, stem; SA, stem apex; F, flower; Fr, fruit.
Figure 5. Relative mRNA levels of ClAOC1 (A) and ClAOC2 (B) determined by qRT-PCR in different tissues of watermelon. The β-actin gene was used as the internal control to standardize for each reaction. L, leaf; R, root; S, stem; SA, stem apex; F, flower; Fr, fruit.
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Figure 6. The expression of ClAOC1 (A) and ClAOC2 (B) during the development of flesh and rind at different stages based on the transcriptome data. The expression levels were indicated FPKM values. DAP, day after pollination.
Figure 6. The expression of ClAOC1 (A) and ClAOC2 (B) during the development of flesh and rind at different stages based on the transcriptome data. The expression levels were indicated FPKM values. DAP, day after pollination.
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Figure 7. qRT-PCR analysis of ClAOC1 and ClAOC2 under different hormones treatments, including JA (A,B), SA (C), and ET (D). The leaves (A,C,D) or roots (B) of the watermelon seedlings were used to examine the expression levels of ClAOC1 and ClAOC2 using qRT-PCR at different time points (0, 1, 3, 9, and 24 h) with different hormones treatments.
Figure 7. qRT-PCR analysis of ClAOC1 and ClAOC2 under different hormones treatments, including JA (A,B), SA (C), and ET (D). The leaves (A,C,D) or roots (B) of the watermelon seedlings were used to examine the expression levels of ClAOC1 and ClAOC2 using qRT-PCR at different time points (0, 1, 3, 9, and 24 h) with different hormones treatments.
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Figure 8. qRT-PCR analysis of expression of ClAOC1 and ClAOC2 in leaves (A) and roots (B) of inoculation with nematode under the treatments of white light (RKN), red light and water control (RL), nematode under red light (RR) and white light and clean water (CK).
Figure 8. qRT-PCR analysis of expression of ClAOC1 and ClAOC2 in leaves (A) and roots (B) of inoculation with nematode under the treatments of white light (RKN), red light and water control (RL), nematode under red light (RR) and white light and clean water (CK).
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Table
Table 1. The basic characterizations of ClAOC genes in watermelon.
Table 1. The basic characterizations of ClAOC genes in watermelon.
GeneGene IDGenomic PositiongDNA (bp)ORF (bp)Length (aa)pIMW (kDa)GRAVY
ClAOC1Cla016453Chr11: 21540468 .. 21542845 (+)23787412468.7428.86−0.268
ClAOC2Cla003512Chr3: 13175215 .. 13176809 (+)159510053349.6236.67−0.309
gDNA, genomic DNA; bp, base pair; ORF, open reading frame; aa, amino acid; MW, molecular weight; pI, isoelectric point; GRAVY, grand average of hydropathicity.

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Li, J.; Guang, Y.; Yang, Y.; Zhou, Y. Identification and Expression Analysis of Two allene oxide cyclase (AOC) Genes in Watermelon. Agriculture 2019, 9, 225. https://doi.org/10.3390/agriculture9100225

AMA Style

Li J, Guang Y, Yang Y, Zhou Y. Identification and Expression Analysis of Two allene oxide cyclase (AOC) Genes in Watermelon. Agriculture. 2019; 9(10):225. https://doi.org/10.3390/agriculture9100225

Chicago/Turabian Style

Li, Jingwen, Yelan Guang, Youxin Yang, and Yong Zhou. 2019. "Identification and Expression Analysis of Two allene oxide cyclase (AOC) Genes in Watermelon" Agriculture 9, no. 10: 225. https://doi.org/10.3390/agriculture9100225

APA Style

Li, J., Guang, Y., Yang, Y., & Zhou, Y. (2019). Identification and Expression Analysis of Two allene oxide cyclase (AOC) Genes in Watermelon. Agriculture, 9(10), 225. https://doi.org/10.3390/agriculture9100225

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