Abstract
Areca catechu L. is a commercially important palm tree widely cultured in tropical and subtropical areas. Its growth and production are severely hindered by the increasing threat of drought. In the present study, we investigated the physiological responses of areca seedlings to drought stress. The results showed that prolonged drought-induced yellowing on the overall area of most leaves significantly altered the chlorophyll fluorescence parameters, including maximum chemical efficiency (Fv/Fm), photochemical efficiency of PSII (Y(II)), photochemical chlorophyll fluorescence quenching (qP) and non-photochemical chlorophyll fluorescence quenching (NPQ). On the 10th day of drought treatment, the contents of proline in the areca leaves and roots increased, respectively, by 12.2 times and 8.4 times compared to normal watering. The trigonelline levels in the leaves rose from 695.35 µg/g to 1125.21 µg/g under 10 days of water shortage, while no significant changes were detected in the content of trigonelline in the roots. We determined the gene encoding areca trigonelline synthase (AcTS) by conducting a bioinformatic search of the areca genome database. Sequence analysis revealed that AcTS is highly homologous to the trigonelline synthases in Coffea arabica (CaTS 1 and CaTS 2) and all possess a conserved S-adenosyl- L-methionine binding motif. The overexpression of AcTS in Arabidopsis thaliana demonstrated that AcTS is responsible for the generation of trigonelline in transgenic Arabidopsis, which in turn improves the drought resilience of transgenic Arabidopsis. This finding enriches our understanding of the molecular regulatory mechanism of the response of areca to water shortage and provides a foundation for improving the drought tolerance of areca seedlings.
Highlights
Drought presents an increasing threat to plant survival and distribution due to global climate change
Studies on the drought tolerance mechanisms of tropical plants can broaden our understanding of the evolution of drought tolerance systems in plant realms
We analyzed how drought affected the photosynthetic activities of the leaves of areca seedlings
Summary
Drought presents an increasing threat to plant survival and distribution due to global climate change. Drought stress antagonistically regulates plant growth and development via environmental stimuli including elevated temperature, high salinity and limited water availability [1,2,3,4]. The abscisic acid (ABA) signaling pathway in plants is the core mechanism for modulating leaf transpiration and water content by regulating stomatal closure under drought stress [5,6,7]. In concert with stomatal closure, the impermeable cuticle covering plant leaves acts as a crucial transpiration barrier that reduces water loss from plant leaves, thereby helping plants to survive drought conditions [8,9,10]. Osmotic adjustment is a highly efficient strategy adopted by plants to alleviate drought-induced osmotic damage to cells at the cellular level, playing a pivotal role in plant adaptation to drought stress [13,14]. The self-protective strategies adopted by plants against drought stress are multidimensional, and deciphering these complicated regulation networks is necessary for furthering our understanding of drought resilience in plants
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