Two distinct mechanisms of water and energy conservation confer drought tolerance in chili mutants

Water deficit has a profound influence on reduction in chili fruit production. Gamma radiation induced mutation plant thus seeds of Tavee 60 chili were subjected by gamma ray at 200 Gy to improve drought-tolerant chilies. Drought-tolerant screening was carried out at M 2 –M 4 . Here, two drought-tolerant chilies, namely CaWDT-1 and CaWDT-2, were selected among different gamma-radiated lines. To determine their physiological responses under water deficit and genetic variation compared to Tavee 60, an original cultivar. Seven-week-old plants were water-withheld for 8 days and their physiological parameters were measured at 0, 4, and 8 days after water deficit. Their molecular characteristics were determined based on 20 inter simple sequence repeats (ISSR) primers. Results showed that dehydration for 8 days slightly diminished relative water content (RWC) of CaWDT-1, while photosynthetic rate also reduced but maintained yield in spite of withholding water. Drought did not affect leaf area of all genotypes but inhibited stem size. CaWDT-2 had larger leaves and its stems were trivially suppressed under drought, with accumulation of proline at low RWC. CaWDT-2 showed vigor, achieving high fruit yields although shrunken during drought. ISSR data separated CaWDT-1 from CaWDT-2 at Jaccard’s similarity coefficient 0.84, confirming different phenotypes with diverse mechanisms for drought tolerance. CaWDT-1 conserved water within the plant and had high efficiency of photosynthesis under drought stress, while CaWDT-2 reserved energy source before and during water shortage as advantageous for yield production. CaWDT-1 and CaWDT-2 showed potential as chili genotypes for cultivation in drought-prone areas.