Genetic and Physio-Biochemical Characterization of a Novel Premature Senescence Leaf Mutant in Rice (Oryza sativa L.).

Yan He,Liangjian Li,Shaoqing Tang,Jian-Li Wu,Zhihong Zhang

doi:10.3390/ijms19082339

Yan He, Liangjian Li + Show 3 more

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https://doi.org/10.3390/ijms19082339

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Abstract

Premature senescence greatly affects the yield production and the grain quality in plants, although the molecular mechanisms are largely unknown. Here, we identified a novel rice premature senescence leaf 85 (psl85) mutant from ethyl methane sulfonate (EMS) mutagenesis of cultivar Zhongjian100 (the wild-type, WT). The psl85 mutant presented a distinct dwarfism and premature senescence leaf phenotype, starting from the seedling stage to the mature stage, with decreasing level of chlorophyll and degradation of chloroplast, declined photosynthetic capacity, increased content of malonaldehyde (MDA), upregulated expression of senescence-associated genes, and disrupted reactive oxygen species (ROS) scavenging system. Moreover, endogenous abscisic acid (ABA) level was significantly increased in psl85 at the late aging phase, and the detached leaves of psl85 showed more rapid chlorophyll deterioration than that of WT under ABA treatment, indicating that PSL85 was involved in ABA-induced leaf senescence. Genetic analysis revealed that the premature senescence leaf phenotype was controlled by a single recessive nuclear gene which was finally mapped in a 47 kb region on the short arm of chromosome 7, covering eight candidate open reading frames (ORFs). No similar genes controlling a premature senescence leaf phenotype have been identified in the region, and cloning and functional analysis of the gene is currently underway.

Highlights

Leaf senescence occurs in the final stage of plant development, with a series of complex physiological and biochemical alterations
The results showed that the protein levels were all apparently reduced in psl85 compared with wild type (WT) (Figure 3C)
The leaf senescence process was accelerated remarkably in psl85 from the seedling stage to grain-filling stage, with enormous changes of physiological and biochemical properties, such as declined photosynthetic capacity, increased MDA content, and disrupted reactive oxygen species (ROS) scavenging system, which might be responsible for the premature leaf senescence phenotype, and resulted in the poorer performance of major agronomic traits in psl85

Summary

Introduction

Leaf senescence occurs in the final stage of plant development, with a series of complex physiological and biochemical alterations. The most obvious visible sign of senescence is the leaf yellowing phenotype, which is caused by preferential breakdown of chlorophyll and chloroplasts, and accompanied by hydrolysis of macromolecules, such as proteins, lipids, and nucleic acids, and degeneration of mitochondria and nuclei [3,4]. During this senescence process, nutrients, such as nitrogen and phosphorus, are reallocated to the younger developing tissues to increase reproductive success [5]. The levels of many photosystem proteins, such as Lhca, Lhcb, and PsaA are degraded with the onset of leaf senescence, which might directly lead to a lower photosynthetic capacity [10,11]

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