Physiological and Transcriptome Analyses of Early Leaf Senescence for ospls1 Mutant Rice (Oryza sativa L.) during the Grain-Filling Stage

Abstract

Early leaf senescence is an important agronomic trait that affects crop yield and quality. To understand the molecular mechanism of early leaf senescence, Oryza sativa premature leaf senescence 1 (ospls1) mutant rice with a deletion of OsVHA-A and its wild type were employed in this study. The genotype-dependent differences in photosynthetic indexes, senescence-related physiological parameters, and yield characters were investigated during the grain-filling stage. Moreover, RNA sequencing (RNA-seq) was performed to determine the genotype differences in transcriptome during the grain-filling stage. Results showed that the ospls1 mutant underwent significant decreases in the maximal quantum yield of photosystem II (PSII) photochemistry (Fv/Fm), net photosynthesis rate (Pn), and soluble sugar and protein, followed by the decreases in OsVHA-A transcript and vacuolar H+-ATPase activity. Finally, yield traits were severely suppressed in the ospls1 mutant. RNA-seq results showed that 4827 differentially expressed genes (DEGs) were identified in ospls1 mutant between 0 day and 14 days, and the pathways of biosynthesis of secondary metabolites, carbon fixation in photosynthetic organisms, and photosynthesis were downregulated in the senescing leaves of ospls1 mutant during the grain-filling stage. In addition, 81 differentially expressed TFs were identified to be involved in leaf senescence. Eleven DEGs related to hormone signaling pathways were significantly enriched in auxin, cytokinins, brassinosteroids, and abscisic acid pathways, indicating that hormone signaling pathways participated in leaf senescence. Some antioxidative and carbohydrate metabolism-related genes were detected to be differentially expressed in the senescing leaves of ospls1 mutant, suggesting that these genes probably play response and regulatory roles in leaf senescence.

Transcriptome Arofile of Brassica rapa L. Reveals the Involvement of Jasmonic Acid, Ethylene, and Brassinosteroid Signaling Pathways in Clubroot Resistance

“…KOBAS v.2.0 software was used to identify the significantly enriched pathways corresponding to the DEGs [45]. Pathways with a corrected p value < 0.05 were considered statistically significant [46].…”

Identification and genetic analysis of EMS-mutagenized wheat mutants conferring lesion-mimic premature aging

“…It was found [44] that water deficit during grain filling period could cause premature senescence of flag leaves, but the senescence process could be delayed by changing hormone concentration of plants. There are many reasons for rice premature aging, for example, the effect of NAC transcription factors on abscisic acid (ABA) [25], the functional impairment of calcium-dependent protein kinase OsCPK12 [28], the deletion of gene fragment [29], the response and regulation of genes related to antioxidant and carbohydrate metabolism [45], and so on. Based on the research experience of rice early senescence, further work should be focused on the cloning and functional verification of candidate gene for premature aging.…”

Identification and genetic analysis of EMS-mutagenized wheat mutants conferring lesion-mimic premature aging

“…It was found [37] that water deficit during grain filling period could cause premature senescence of flag leaves, but the senescence process could be delayed by changing hormone concentration of plants. There are many reasons for rice premature aging, for example, the effect of NAC transcription factors on abscisic acid (ABA) [19], the functional impairment of calcium-dependent protein kinase OsCPK12 [22], the deletion of gene fragment [23], the response and regulation of genes related to antioxidant and carbohydrate metabolism [38], and so on. Based on the research experience of rice early senescence, further work should be focused on the cloning and functional verification of candidate gene for premature aging.…”