Spring droughts occurring at early stages of plant growth are a challenge in cultivation of spring cereals. Therefore, the aim of this study was to analyze a response of spring triticale seedlings to drought and to investigate the regeneration during early rehydration after drought. Drought was initiated at seedling growth: heterotrophic growth, when they are tolerant to water shortage and autotrophic growth, when they are drought-sensitive. Measurements and analyses were carried out on the fourth day of drought and after 24 h of rehydration, when seedlings were autotrophic. Gene expression was analyzed for TaLEA1 , TaSRG6, TaHOP and rbcL . Plant condition was assessed based on a degree of the seedling dehydration, chlorophyll content, membrane damage, gas exchange and photosynthetic activity. The expression of TaSRG6 during dehydration did not depend on the growth phase or genotype. We found that the level of TaSRG6 transcript can be a reliable indicator of the effectiveness of plant regeneration during early rehydration. Moreover, 24-h rehydration did not inhibit drought-induced senescence, as evidenced by maintaining low chlorophyll level in the drought-sensitive seedlings in the autotrophic phase. Drought applied in the heterotrophic phase did not affect chlorophyll levels either directly or after rehydration. We speculate that changes in the TaLEA1 transcript level may be a reliable indicator of defense mechanism activation in the phase of autotrophic growth. The initiation of drought during the heterotrophic and autotrophic phases of spring triticale seedlings triggers distinct patterns of physiological and molecular responses to rapid rehydration.
Ostrowska et al. (Fri,) studied this question.