Possible Reasons Affecting Different Phytophthora infestans Populations in Tomato and Potato Isolates in Thailand
Mati Koppel
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear authors,
It was a pleasure reading your manuscript. I have added some comments, which I suggest you consider in your revision. Generally, you should consider the use of oomycete instead of fungi for P. infestans. See the attached pdf for more comments.
Comments for author File: 
Comments.pdf
Author Response
Journal: Diversity (ISSN 1424-2818)
Manuscript ID: diversity-2611035
Type: Review
Title: Possibly reason affecting different Phytophthora infestans populations in tomato and potato isolates in Thailand
Response to reviewers
Reviewer 1:
Comment: It was a pleasure reading your manuscript. I have added some comments, which I suggest you consider in your revision. Generally, you should consider the use of oomycete instead of fungi for P. infestans. See the attached pdf for more comments.
Response: Corrected as suggestion
- Corrected:
fungi to oomycete
mtDNA to mitochondriaDNA (mtDNA)
- Rewrite: ‘This disease is caused by the oomycete Phytophthora infestans’ to ‘This disease is caused by the oomycete Phytophthora infestans that was responsible for the Irish potato famine of the 1840s [1,2]’.
- Additional information had been added for Topic 4. Change in infestans population structure in Thailand:
The main reason for the P. infestans population in tomatoes not changing is due to the absence of factors affecting its life cycle, such as the lack of pressure, the absence of migration of new genotypes, and the disappearance of sexual reproduction. This is because tomato pro-duction in Thailand during the 20th and 21st centuries is a minor crop that alternates with the main crop, which is rice. As a result, disease management in tomato crops does not extensively use fungicides, and this lack of intervention does not exert any force on the life cycle of pathogens.
The P. infestans genotypes that affect tomatoes are US-1 and US-1.3, which are the most widespread genotypes in tomato and potato production worldwide. Furthermore, experiments attempting cross-infections from potato isolates to inoculated tomatoes did not result in successful infection responses (Personal communication). This outcome confirms that the aggressive genotype from potatoes is not exerting pressure to replace the original genotype in tomatoes. In a study by Petchaboon et al. [11], it was found that only the A1 mating type was present, indicating that sexual reproduction had not occurred. Therefore, these factors contribute to the persistence of the original P. infestans genotype in the tomato population.
- Additional information on hypothesis 1 had been added:
When focusing solely on Thailand, the first hypothesis regarding sexual reproduction is less likely to be evident. This is because the mating of P. infestans requires the presence of both A1 and A2 mating types in the same area, the infection of the same leaf, and the formation of oospores for zygote formation [32]. The emergence of a new genotype occurs through the sexual process, resulting in the appearance of different clonal lineages of different mating types. Furthermore, other evidence of sexual reproduction includes several general indicators, such as the presence of both mating types in a 50:50 ratio, readily found oospores in the field, a large number of co-existing clonal lineages, and a large number of genotypes. These pieces of evidence have been consistently observed in northern Europe [33].
According to the information on the mating type of P. infestans in Thailand during the periods of 2000-2002 and 2006-2009, as provided by Petchaboon et al. [11], Jaimasit and Prakob [12], and Sopee [13], only the A1 mating type was identified. Based on this data, we can conclude that the new genotypes of potato isolates in Thailand do not result from sexual reproduction.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe review paper analyzes the population structure and possible reasons of changes in Thailand populations of Phytophthora infestans during 1994-2009. The analyze is based on quite old data published in rather small number of papers. The paper gives a comprehensive overview of studies of Thailand potato late blight populations done so far despite of previously mentioned shortcomings. The majority of cited references are from the same period when the pathogen isolates were collected. The number of cited recent publications is quite small.
The authors state at the end of the paper that the population structure of P. infestans in Thailand needs to be continuously monitored to provide more accurate and updated information. This statement needs more comprehensive reasoning. Several Asian countries (like India, Vietnam, China, Philippines etc) participating in the AsiaBlight initiative have intensively studied the structures of P. infestans populations in recent years. Adding short summary of recent changes in P.infestans populations in these countries could serve as a good reason for conducting new studies in Thailand.
Comments on the Quality of English LanguageParts needing revision:
Page 1 - "The conditions in north and northeast Thailand are humid and cold..."., On a global scale, the temperature is rather warm, therefore this part needs some additions or rewording.
Page 5. "5. Factors affecting different responses of tomato and potato populations to metalaxyl". To correct to Phytophthora infestans populations.
Page 6. "" ...approximately 4500 million tons annually, are imported". This should be corrected to the actual figure.
The authors use the wrong term "potato seeds" - the correct is "seed potatoes"
Author Response
Reviewer2:
Reviewer: The review paper analyzes the population structure and possible reasons of changes in Thailand populations of Phytophthora infestans during 1994-2009. The analyze is based on quite old data published in rather small number of papers. The paper gives a comprehensive overview of studies of Thailand potato late blight populations done so far despite of previously mentioned shortcomings. The majority of cited references are from the same period when the pathogen isolates were collected. The number of cited recent publications is quite small.
Response: Updated information with references have been included as suggestion.
Reviewer: The authors state at the end of the paper that the population structure of P. infestans in Thailand needs to be continuously monitored to provide more accurate and updated information. This statement needs more comprehensive reasoning. Several Asian countries (like India, Vietnam, China, Philippines etc) participating in the AsiaBlight initiative have intensively studied the structures of P. infestans populations in recent years. Adding short summary of recent changes in P.infestans populations in these countries could serve as a good reason for conducting new studies in Thailand
Response: Additional information has been added:
- The importance of P. infestans population study
- infestans is one of the most aggressive pathogens and has been classified as 'high risk,' mainly because of its high adaptability to the host [55]. P. infestans has a vast genome (240 Mb), consisting of many structures that can develop variable strains and undergo rapid mutations, such as conserved gene sequences with a low number of repeats [56, 57]. Additionally, P. infestans exhibits high levels of genetic diversity through the sexual process, resulting in high adaptability. For these reasons, controlling the disease using resistant varieties is less likely to be successful due to the pathogen's rapid adaptation, which outpaces the host's resistance development [56]. Understanding the dynamics of P. infestans populations is an effective strategy for the development of a more sustainable disease management."
Currently, potato production in Asia has expanded dramatically and accounts for over 40% of the world's production [58]. A late blight network for Asia, AsiaBlight, was established following the success of EuroBlight. It is an inclusive network of scientists, farmers, and other stakeholders working on potato late blight disease. The cooperation and data sharing among researchers from across Asia will contribute to the sustainable production of healthy potato crops, thereby improving nutrition and food security for billions of people in Asia. The net-work's objective is to generate a coarse-scale map of P. infestans populations in Asia, which includes the development of an integrated approach to manage late blight disease [59].
The study of P. infestans populations, based on mating type, evaluating fungicide effectiveness, and assessing genotypic variation, is necessary for understanding the aggressiveness and adaptability of the pathogen. This understanding is crucial for effective late blight disease management. P. infestans populations can be identified using standard methods such as metalaxyl sensitivity, allozyme analysis, RG 57 DNA fingerprinting, mtDNA haplotypes, SSRs, and 12-plex SSRs [35]. In Thailand, studies by Petchaboon et al. [11], Jaimasit and Prakob [12], and Sopee [13] have revealed that the majority of damages are attributed to the importation of infected seed potatoes, as determined by these standard methods.
A review article on the dynamics of P. infestans populations in the major potato production areas of Asia has indicated that the migration of the pathogen from Europe and America also plays a significant role in P. infestans population changes in several countries in Asia. These countries include Japan, South Korea, China, Taiwan, South Asian countries, Nepal, Bangladesh, India, and Pakistan [35].
Parts needing revision:
Reviewer: Page 1 - "The conditions in north and northeast Thailand are humid and cold..."., On a global scale, the temperature is rather warm, therefore this part needs some additions or rewording.
Response: During the period between December to February that refers to as the winter season in Thailand, the conditions in the north and northeast Thailand are high humidity (>90%) and low temperatures (on average 21 °C). T
Reviewer: Page 5. "5. Factors affecting different responses of tomato and potato populations to metalaxyl". To correct to Phytophthora infestans populations.
Response: Corrected to “5. Factors affecting different responses to metalaxyl in P. infestans populations of tomato and potato isolates”
Reviewer: Page 6. "" ...approximately 4500 million tons annually, are imported". This should be corrected to the actual figure.
Response: Corrected as suggestion “Between 2015 and 2019, the rate of imported potatoes, including both processing and seed potatoes, increased by 15.43% [OAE, 2019]. More specifically, for seed potatoes, the total import of 7,099 tons in 2021 originated from the United Kingdom, Australia, the Netherlands, America, and Canada [OAE, 2021].”
Reviewer: The authors use the wrong term "potato seeds" - the correct is "seed potatoes"
Response: Corrected as suggestion
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript has been sufficiently approved
