DataSheet_1_Unravelling the diversity in water usage among wild banana species in response to vapour pressure deficit.docx

The rise in global temperature is not only affecting plant functioning directly, but is also increasing air vapour pressure deficit (VPD). The yield of banana is heavily affected by water deficit but so far breeding programs have never addressed the issue of water deficit caused by high VPD. A reduction in transpiration at high VPD has been suggested as a key drought tolerance breeding trait to avoid excessive water loss, hydraulic failure and to increase water use efficiency. In this study, stomatal and transpiration responses under increasing VPD at the leaf and whole-plant level of 8 wild banana (sub)species were evaluated, displaying significant differences in stomatal reactivity. Three different phenotypic groups were identified under increasing VPD. While (sub)species of group III maintained high transpiration rates under increasing VPD, M. acuminata ssp. errans (group I), M. acuminata ssp. zebrina (group II) and M. balbisiana (group II) showed the highest transpiration rate limitations to increasing VPD. In contrast to group I, group II only showed strong reductions at high VPD levels, limiting the cost of reduced photosynthesis and strongly increasing their water use efficiency. M. acuminata ssp. zebrina and M. balbisiana thus show the most favourable responses. This study provides a basis for the identification of potential parent material in gene banks for breeding future-proof bananas that cope better with lack of water.

全球气温升高不仅直接影响植物生理功能，还会加剧空气水汽压差（Vapour Pressure Deficit, VPD）。香蕉产量极易受水分亏缺影响，但迄今为止的育种计划从未针对高VPD引发的水分亏缺问题开展相关研究。有研究提出，在高VPD条件下降低蒸腾速率是关键的耐旱育种性状，可避免过度失水、液压故障，并提升水分利用效率。本研究针对8个野生香蕉（亚）种，在叶片和整株水平上评估了VPD升高时的气孔与蒸腾响应，发现其气孔反应性存在显著差异。在VPD升高的条件下可划分为3种不同的表型组：第III组的（亚）种在VPD升高时仍能维持较高的蒸腾速率；而小果野蕉（M. acuminata ssp. errans，第I组）、小果野蕉原亚种红纹蕉（M. acuminata ssp. zebrina，第II组）以及野蕉（M. balbisiana，第II组）对VPD升高的蒸腾速率限制作用最强。与第I组不同，第II组仅在高VPD水平下才出现显著的蒸腾速率下降，这既能限制光合降低带来的成本，又能显著提升水分利用效率。因此，小果野蕉原亚种红纹蕉与野蕉展现出最具优势的响应特征。本研究为基因库中筛选潜在亲本材料提供了理论依据，有助于培育更能适应缺水环境的未来型香蕉品种。