Table_1_Overexpression of a SDD1-Like Gene From Wild Tomato Decreases Stomatal Density and Enhances Dehydration Avoidance in Arabidopsis and Cultivated Tomato.PDF

Stomata are microscopic valves formed by two guard cells flanking a pore, which are located on the epidermis of most aerial plant organs and are used for water and gas exchange between the plant and the atmosphere. The number, size and distribution of stomata are set during development in response to changing environmental conditions, allowing plants to minimize the impact of a stressful environment. In Arabidopsis, STOMATAL DENSITY AND DISTRIBUTION 1 (AtSDD1) negatively regulates stomatal density and optimizes transpiration and water use efficiency (WUE). Despite this, little is known about the function of AtSDD1 orthologs in crop species and their wild stress-tolerant relatives. In this study, SDD1-like from the stress-tolerant wild tomato Solanum chilense (SchSDD1-like) was identified through its close sequence relationship with SDD1-like from Solanum lycopersicum and AtSDD1. Both Solanum SDD1-like transcripts accumulated in high levels in young leaves, suggesting that they play a role in early leaf development. Arabidopsis sdd1-3 plants transformed with SchSDD1-like under a constitutive promoter showed a significant reduction in stomatal leaf density compared with untransformed sdd1-3 plants. Additionally, a leaf dehydration shock test demonstrated that the reduction in stomatal abundance of transgenic plants was sufficient to slow down dehydration. Overexpression of SchSDD1-like in cultivated tomato plants decreased the stomatal index and density of the cotyledons and leaves, and resulted in higher dehydration avoidance. Taken together, these results indicate that SchSDD1-like functions in a similar manner to AtSDD1 and suggest that Arabidopsis and tomatoes share this component of the stomatal development pathway that impinges on water status.

气孔为微观阀门，由围绕气孔两侧的保卫细胞构成，位于大多数地上植物器官的表皮上，用于植物与大气之间的水分和气体交换。气孔的数量、大小及分布均在发育过程中根据环境条件的变化而设定，从而使植物能够最小化恶劣环境的影响。在拟南芥中，气孔密度与分布1（AtSDD1）负向调控气孔密度，并优化蒸腾作用及水分利用效率（WUE）。尽管如此，关于AtSDD1同源基因在作物物种及其野生抗逆近缘种中的功能知之甚少。在本研究中，通过其与番茄Solanum lycopersicum中的SDD1-like和AtSDD1的序列关系，从抗逆野生番茄Solanum chilense（SchSDD1-like）中鉴定了SDD1-like。这两种SDD1-like转录本在幼叶中积累水平较高，表明它们在早期叶片发育中发挥重要作用。在构成性启动子下，将SchSDD1-like转入拟南芥sdd1-3植株中，与未转化的sdd1-3植株相比，转化植株的气孔叶片密度显著降低。此外，叶片脱水应激测试表明，转基因植株气孔数量的减少足以减缓脱水过程。在栽培番茄植株中过表达SchSDD1-like降低了子叶和叶片的气孔指数和密度，并导致更高的脱水规避能力。综上所述，这些结果表明SchSDD1-like以与AtSDD1相似的方式发挥作用，并暗示拟南芥和番茄在影响水分状况的气孔发育途径中共享这一成分。