On July 15, 2026, the University of Science and Technology of Hanoi (USTH) organized the university-level doctoral thesis defense for PhD candidate Bui Phuong Thao, majoring in Pharmacological, Medical and Agronomical Biotechnology, with the thesis entitled: “Utilizing CRISPR/Cas9 system to induce targeted mutations of MLO genes related to soybean powdery mildew resistance.”
The thesis was supervised by Assoc. Prof. Dr. Do Tien Phat from the Institute of Biology, Vietnam Academy of Science and Technology, and Dr. Nguyen Van Phuong from the University of Science and Technology of Hanoi, Vietnam Academy of Science and Technology.
The defense was conducted in accordance with academic procedures
During the defense, PhD candidate Bui Phuong Thao presented the principal contents and findings of her thesis, focusing on the application of CRISPR/Cas9 genome-editing technology to enhance powdery mildew resistance in soybean.
Following the presentation, members of the Evaluation Committee raised questions and discussed the research methodology, the reliability of the findings, the stability of disease-resistance traits across generations, and the potential application of the generated soybean lines in future breeding programs.
Applying genome-editing technology to develop disease-resistant soybean varieties
Soybean is an economically and nutritionally important crop, providing valuable sources of oil and protein for human consumption and animal feed. However, soybean production is threatened by various diseases, including powdery mildew caused by the fungus Erysiphe diffusa.
Powdery mildew can inhibit plant growth and development while reducing crop yield, seed quality and germination. Under conditions favorable to fungal growth, the disease may cause yield losses of up to 60%.
Against this background, the thesis developed and applied the CRISPR/Cas9 system to induce targeted mutations in GmMLO genes associated with powdery mildew susceptibility in ĐT26, a Vietnamese elite soybean cultivar.
Rather than focusing solely on the identification and utilization of resistance genes, the research explored an alternative approach by reducing the effects of susceptibility genes that facilitate fungal infection. This represents a promising strategy for developing crop varieties with improved and potentially durable disease resistance.
Significant scientific findings
The study successfully generated several forms of mutations in GmMLO genes and confirmed their inheritance across successive generations. At the T2 generation, the research obtained triple- and quadruple-knockout mutant lines involving multiple GmMLO genes.
When challenged with Erysiphe diffusa, all mutant plants demonstrated enhanced powdery mildew resistance compared with wild-type plants. In particular, two quadruple-mutant lines showed reductions in disease severity of up to 36.4%, while conidial density on the leaf surface decreased by between 1.5 and four times.
The enhanced resistance was stably maintained across generations. Under net-house conditions, the mutant plants showed no significant adverse effects on plant growth, development or the nutritional composition of the seeds compared with wild-type plants. Notably, the study obtained homozygous mutant lines that combined enhanced powdery mildew resistance with a transgene-free status at the T2 generation.
One of the most significant contributions of the thesis is the first reported generation of simultaneous mutations in multiple MLO genes in soybean using the CRISPR/Cas9 system. The findings provide further evidence of the involvement of GmMLO genes in soybean susceptibility to powdery mildew and offer valuable genetic materials for future soybean research and breeding programs.
New potential for soybean breeding programs
The outcomes of the thesis not only contribute to a better understanding of the functions and interactions of genes associated with powdery mildew susceptibility, but also provide a foundation for further studies on soybean resistance to other fungal diseases.
The Evaluation Committee acknowledged the novelty, scientific significance and potential applications of the research. The successful defense marked the culmination of PhD candidate Bui Phuong Thao’s dedicated and persistent academic journey.
USTH congratulates PhD candidate Bui Phuong Thao on achieving this important academic milestone and wishes her continued success in her research career and future contributions to scientific advancement and sustainable agriculture.
