Regulatory Role of ONAC016 in the promotion of Leaf Senescence in Rice (Oryza sativa L.)

Abstract

Leaf senescence, the final stage of leaf development, is regulated by complex network of senescence associated genes (SAGs). Several NAC transcription factors have been found to regulates leaf senescence in Arabidopsis, but only a few senescence-associated NAC TFs have been identified in rice. In this study, we identified new senescence-associated NAC TF in rice, ONAC016. We found that ONAC016 expression level increased during senescence. onac016 T-DNA KO mutants showed stay green phenotype during dark-induced and natural senescence condition, while onac016-D T-DNA overexpression mutants showed early senescence phenotype, suggesting ONAC016 acts as senescence promoting NAC TF. Furthermore, we found that ONAC016 expression is induced by ABA, and onac016 mutants showed stay-green phenotype during ABA induced senescence. By microarray and qRT-PCR analysis, several Senescence-Associated Genes (NOL, OsNAP), Chlorophyll Degradation Genes (OsSGR, OsNYC1), and ABA signaling genes (ABF1) were down-regulated in onac016 under Dark-Induced Senescence condition. These results suggest that ONAC016 plays an important role in promotion of leaf senescence through ABA-signaling pathway.

Keywords: rice, leaf senescence, NAC, Transcription factor, ONAC016, Knock out, overexpression, stay-green

Student number: 2016-29815