[O31] Temperature Stress

[O31-05] Tomato Mutant HT7 Conferring Improved Fruit Set and Pollen Fertility under Long-Term Ambient High Temperature

(Invited Speaker)
*Nominated for Presentation Awards

^○Ken Hoshikawa^1,2,3, Dung Pham⁴, Hiroshi Ezura^2,3 (1.Biological Resources and Post-harvest Division, Japan International Research Center for Agricultural Sciences, Japan, 2.Faculty of Life and Environmental Sciences, University of Tsukuba, Japan, 3.Tsukuba Plant Innovation Research Center, University of Tsukuba, Japan, 4.Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan)

Heat stress (HS) is one such abiotic stress that causes multiple negative effects at all vegetative and reproductive stages in the plant life cycle. In the future that global warming proceeded, HS influence on food production will be an even more serious problem. Also, in tomato cultivation, HS is a major serious problem for tomato production throughout the world, and it reduces the yield and quality of tomato fruits due to significant effects on pollen development and fertility. To isolate a novel tomato breeding material for providing heat tolerance and to elucidate the molecular mechanism of the HS response in tomato cultivation, we isolated some mutants showing improved fruit setting ability under long-term ambient high temperature by testing over 4,000 lines of Micro-Tom tomato mutant collections and named them tomato heat-tolerant (HT) mutants. The HT mutants were categorized as displaying one of two types of fruit-setting: one showed parthenocarpic fruit-setting, and the other showed fruit-setting with seeds. Interestingly, among the HT mutants, HT 7 had a higher fruit number and seeded-fruit yield under long-term HS condition. In addition, the total pollen number and viability of HT 7 were much higher than those of the WT under both control and HS conditions. HT 7 succeeded at fertilization even under HS condition due to higher viable pollen production than that of the WT. HT 7 could be a valuable genetic resource for elucidating heat tolerance mechanisms as well as valuable breeding material for improving heat-tolerant fruit set in tomato.