Identification and Gene Mapping of an Early Senescent Leaf Mutant esl11 of Rice

Abstract

As an essential process in the life of a plant, natural leaf senescence is necessary for adaptation to environmental diversity, whereas early leaf senescence can reduce per‐unit yield and cause inferior harvest quality during crop production. To explore the molecular mechanism of leaf senescence in rice (Oryza sativa L.), we studied an early senescence leaf (esl11) mutant obtained by ethyl methane sulfonate (EMS) mutagenesis. The leaves of the esl11 mutant showed normal growth and leaf coloration prior to the three‐leaf stage, but after this stage, all fully expanded leaves underwent yellowing and senescence from the edges of the leaf blade and tips, apart from the emerging leaves, which showed gradual growth. The net photosynthetic rate and photosynthetic pigment content of the tip and leaf base of the mutant esl11 were significantly lower than those of the wild type. The role of active oxygen species O2−, H2O2, and ⋅OH in the mutant increased, whereas the activities of MDA, peroxidase, superoxide dismutase, and catalase decreased compared with the wild type. The results of trypan blue staining on the senescent part of the leaf tip of the mutant esl11 indicated procedural death in part of the cell, whereas the wild type showed no change. The early leaf senescence trait in the mutant was controlled by of recessive nuclear gene, which was mapped to chromosome 7, with a physical range of 143.0 kb. The results of this study provide the foundation for important progress in gene cloning and functional analysis of the esl11 gene.