Premature senescence of leaves causes a reduced yield and quality of rice by affecting plant growth and development. The regulatory mechanisms underlying early leaf senescence are still unclear. The Leaf senescence 1 (LS1) gene encodes a C2H2-type zinc finger protein that is localized to both the nucleus and cytoplasm. In this study, we constructed a rice mutant named leaf senescence 1 (ls1) with a premature leaf senescence phenotype using CRISPR/Cas9-mediated editing of the LS1 gene. The ls1 mutants exhibited premature leaf senescence and reduced chlorophyll content. The expression levels of LS1 were higher in mature or senescent leaves than that in young leaves. The contents of reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD) were significantly increased and catalase (CAT) activity was remarkably reduced in the ls1 plants. Furthermore, a faster decrease in pigment content was detected in mutants than that in WT upon induction of complete darkness. TUNEL and staining experiments indicated severe DNA degradation and programmed cell death in the ls1 mutants, which suggested that excessive ROS may lead to leaf senescence and cell death in ls1 plants. Additionally, an RT-qPCR analysis revealed that most senescence-associated and ROS-scavenging genes were upregulated in the ls1 mutants compared with the WT. Collectively, our findings revealed that LS1 might regulate leaf development and function, and that disruption of LS1 function promotes ROS accumulation and accelerates leaf senescence and cell death in rice.

The Stress-Repressive Zinc Finger (SRZ) family is a class of zinc finger proteins in plants that has been closely associated with plant growth, development, and stress responses. In this study, we conducted a genome-wide identification of the SRZ family members and identified 14 and 10 members in rice and Arabidopsis, respectively. We further characterized their phylogenetic relationships, gene structures, conserved motifs, promoter cis-elements, synteny, and spatiotemporal expression patterns. To investigate the functional role of this family in rice, we generated targeted mutants of OsSRZ1 using the CRISPR/Cas9 system. Phenotypic analysis revealed that srz1 knockout mutants exhibited significantly reduced plant height. Notably, the homozygous mutant srz1 completely failed in panicle exsertion from the flag leaf sheath, resulting in complete enclosure, whereas the heterozygous mutant srz1(h) exhibited only partial panicle exsertion. Further cytological observations revealed abnormal floral organ development and premature anther senescence in srz1, accompanied by a significant reduction in seed setting rate—srz1(h) set significantly fewer seeds, whereas srz1 exhibited complete sterility with a seed setting rate of 0%. Collectively, these findings suggest that members of the SRZ family may play important roles in rice growth and development. Our results demonstrate that OsSRZ1 is a critical regulator of plant height and panicle exsertion by regulating internode elongation, and that its disruption leads to premature anther programmed cell death (PCD) and consequent seed setting failure.