Elferjani Raed, Pahari Shankar, Soolanayakanahally Raju, Ballantyne Krista, Nambara Eiji
Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada.
Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
Front Plant Sci. 2024 Dec 23;15:1385414. doi: 10.3389/fpls.2024.1385414. eCollection 2024.
Drought conditions severely curtail the ability of plants to accumulate biomass due to the closure of stomata and the decrease of photosynthetic assimilation rate. Additionally, there is a shift in the plant's metabolic processes toward the production of metabolites that offer protection and aid in osmoadaptation, as opposed to those required for development and growth. To limit water loss via non-stomatal transpiration, plants adjust the load and composition of cuticle waxes, which act as an additional barrier. This study investigates the impact of soil water deficit on stomatal and epicuticular water losses, as well as metabolic adjustments in two canola ( L.) cultivars-one drought-tolerant and the other drought-sensitive. Specifically, we examined the effect of a drought treatment, which involved reducing water holding capacity to 40%, on the levels of cysteine, sucrose, and abscisic acid (ABA) in the leaves of both cultivars. Next, we looked for potential differences in night, predawn, and early morning transpiration rates and the epicuticular wax load and composition in response to drought. A substantial rise in leaf cysteine was observed in both canola cultivars in response to drought, and a strong correlation was found between cysteine, ABA, and stomatal conductance, indicating that cysteine and sulfur may play a role in controlling stomatal movement during drought stress. Attributes related to CO diffusion (stomatal and mesophyll conductance) and photosynthetic capacity were different between the two canola cultivars suggesting a better management of water relations under stress by the drought-tolerant cultivar. Epicuticular waxes were found to adjust in response to drought, acting as an additional barrier against water loss. Surprisingly, both canola cultivars responded similarly to the metabolites (cysteine, sucrose, and ABA) and epicuticular waxes, indicating that they were not reliable stress markers in our test setup. However, the higher level of phenylalanine in the drought-tolerant canola cultivar is suggestive that this amino acid is important for adaptation to drier climates. Furthermore, a multitrait genotype-ideotype distance index (MGIDI) revealed the likely role of aspartic acid in sustaining nitrogen and carbon for immediate photosynthetic resumption after drought episodes. In conclusion, leveraging amino acid knowledge in agriculture can enhance crop yield and bolster resistance to environmental challenges.
干旱条件会严重限制植物积累生物量的能力，这是由于气孔关闭以及光合同化率降低所致。此外，植物的代谢过程会发生转变，朝着产生有助于保护和渗透适应的代谢物方向发展，而非侧重于发育和生长所需的代谢物。为了限制通过非气孔蒸腾作用造成的水分流失，植物会调整角质层蜡质的负载量和成分，角质层蜡质起到了额外的屏障作用。本研究调查了土壤水分亏缺对气孔和表皮水分损失的影响，以及对两个油菜（L.）品种（一个耐旱，另一个对干旱敏感）代谢调节的影响。具体而言，我们研究了将持水量降低至40%的干旱处理对两个品种叶片中半胱氨酸、蔗糖和脱落酸（ABA）水平的影响。接下来，我们寻找两个品种在夜间、黎明前和清晨蒸腾速率以及表皮蜡质负载量和成分方面因干旱而产生的潜在差异。在两个油菜品种中均观察到，干旱导致叶片半胱氨酸含量大幅上升，并且发现半胱氨酸、ABA与气孔导度之间存在很强的相关性，这表明半胱氨酸和硫可能在干旱胁迫期间控制气孔运动中发挥作用。两个油菜品种之间与CO扩散相关的属性（气孔导度和叶肉导度）以及光合能力有所不同，这表明耐旱品种在胁迫条件下对水分关系的管理更好。研究发现表皮蜡质会因干旱而发生调整，起到防止水分流失的额外屏障作用。令人惊讶的是，两个油菜品种对代谢物（半胱氨酸、蔗糖和ABA）和表皮蜡质的反应相似，这表明在我们的试验设置中，它们并非可靠的胁迫标记物。然而，耐旱油菜品种中较高水平的苯丙氨酸表明，这种氨基酸对于适应更干燥的气候很重要。此外，一个多性状基因型 - 理想型距离指数（MGIDI）揭示了天冬氨酸在干旱事件后维持氮和碳以立即恢复光合作用方面可能发挥的作用。总之，在农业中利用氨基酸知识可以提高作物产量并增强对环境挑战的抵抗力。
