| The global problem of drought threatens agricultural production and constrains sustainable agricultural development in the twenty-first century. Excessive water loss in plants commonly causes drought stress and induces early senescence. In this study, we isolated an early senescence leaf mutant of rice, designated as early senescence 1 (es1). The leaves of es1-1 undergo water loss in the seedling stage (as reflected by marginal whiting and wilting) and display early senescence in the three-leaf stage. We performed anatomical analysis of es1 and the genetic analysis, allelic test and fine mapping through map-based cloning strategy were also be conducted. The main results were as follows:1) Genetic analysis of the phenotype of F2 segregation generation showed that ratio of wild type phenotype to early senescence in every combination is 3:1. It indicated that the character is a qualitative character controlled by a single recessive nuclear gene.2) The ESI gene was cloned by map-based cloning method. There was only one point mutation in the esl. This nucleotide substitution lead to a changed splicing locus, transcription terminate advanced. Then, confirmation test was performed. ES1 encodes a SCAR-like protein 2, which is a component of the SCAR/WAVE complex, involved in actin polymerization and functioning.3) Introduction of a mutation in ESI significantly increased the number of stomata per unit leaf area in es1-1, with most of these stomata being in a half-open and half-closed state. This change resulted in excessive water loss and accelerated water flow in es1-1, thereby enhancing the water absorption capacity of the roots and water transport capacity of the stems as well as promoting in vivo enrichment of metal ions cotransported with water.4) Expression of ES1 is higher in the leaves and leaf sheaths than in other plant tissues, which is consistent with its role in controlling water loss from the leaves. GFP-ES1 fusion proteins are ubiquitously distributed in the cytoplasm of plant cells.Collectively, our data suggest that ES1 is important for regulating water loss in rice. |
