On January 22th, 2024, University of Science and Technology of Hanoi (USTH) held a doctoral thesis defense for PhD student Le Thi Lieu, majoring in Pharmacological, Medical and Agronomical Biotechnology with the thesis title: “Population structure and evolution of the rice blast fungus Magnaporthe oryzae in traditional and intensive agronomic contexts in Vietnam. Implications for genetic mapping of resistance to M.oryzae in rice germlines from Vietnam”.
The doctoral thesis was under the supervision of Prof. Lebrun Michel (University of Montpellier), and Dr. Hoang Thi Giang (Agricultural Genetics Institute)
The PhD thesis defense was attended by 5 members of the Thesis Jury, including:
- Assoc. Prof. Eric Lacombe, Chairman
- Prof. Tran Dang Hoa, Reviewer
- Assoc. Prof. La Tuan Nghia, Reviewer
- Assoc. Prof. Nguyen Thuy Duong, Member
- Dr. Le Hong Luyen, Member, Secretary
At the defense session, PhD student Le Thi Lieu presented the research results of her thesis to the jury.
According to PhD student Le Thi Lieu, Rice is one of the most important crops in Vietnam. However, its production faces many adverse conditions, including biotic and abiotic stresses. Among which, rice blast disease, caused by Magnaporthe oryzae fungus, is one of the most threats to rice production. Many methods were developed to control the blast disease but their effectivity is still limited. Understanding the population biology, genetic diversity and population structure of pathogen is a key for a better comprehension of the occurrence of new pathotypes and for the screening and breeding of cultivars with efficient resistances. Nevertheless, the knowledge of this field in Vietnam is still constrained. So, the aim of the present study was to fill the information gap on the genetic diversity, population biology and structure of Magnaporthe oryzae in two diverse agrosystems from different regions in Vietnam, using large population sampling and reliable molecular markers allowing comparison with former studies performed at the worldwide scale.
A set of 655 isolates was selected for genotyping by 13 SSR (simple sequence repeat) markers. All 655 genotyped isolates were subjected to mating type and fertility test. Both types of mating type were present in M. oryzae pathogen in Vietnam, with higher contribution of MAT1-2. Mating types were unevenly distributed among clusters and but relatively balanced in Northern mountainous area where rice is cultivated in both conventional and intensive agrosystems. The fertility was low in this pathogen population. Combined the results of mating type, female fertility and linkage disequilibirum, we hypothesized that clonal reproduction probably occurred in all clusters, but that sexual reproduction likely took place at least in some restricted areas in the Northern mountainous area for strains belonging to the cluster related to recombinant lineage in the world. Our study pictures the genetic diversity and population structure of the blast fungus in Vietnam that will be valuable for screening Vietnamese rice accessions for resistance to this devastating disease. We have selected a core-collection of 45 representative isolates to serve for further study on this rice blast pathogen.
The Thesis Jury highly appreciated PhD student Le Thi Lieu for her profound and practical research. The dissertation committee met in secret and voted, with a result of 5/5 votes in favor.
Before ending the defense session, PhD student Le Thi Lieu expressed her gratitude to her supervisors, lecturers and staff at USTH, family, and friends for their support and encouragement, which carried her to complete the thesis successfully.
Assoc. Prof. Nguyen Hai Dang – Vice Rector of USTH congratulated PhD student Le Thi Lieu for successfully defending her thesis and thanked Prof. Lebrun Michel and Dr. Hoang Thi Giang for their delicate supervision. Assoc. Prof. Nguyen Hai Dang wished PhD student Le Thi Lieu an abundant career ahead.
Some photos of the Doctoral thesis defense:
