A Novel Nuclear-Localized CCCH-Type Zinc Finger Protein, OsDOS, Is Involved in Delaying Leaf Senescence in Rice

Abstract

Leaf senescence is a developmentally programmed degeneration process, which is fine tuned by a complex regulatory network for plant fitness. However, molecular regulation of leaf senescence is poorly understood, especially in rice (Oryza sativa), an important staple crop for more than half of the world population. Here, we report a novel nuclear-localized CCCH-type zinc finger protein, Oryza sativa delay of the onset of senescence (OsDOS), involved in delaying leaf senescence in rice. The expression of OsDOS was down-regulated during natural leaf senescence, panicle development, and pollination, although its transcripts were accumulated in various organs. RNAi knockdown of OsDOS caused an accelerated age-dependent leaf senescence, whereas its overexpression produced a marked delay of leaf senescence, suggesting that it acts as a negative regulator for leaf senescence. A genome-wide expression analysis further confirmed its negative regulation for leaf senescence and revealed that, in particular, the jasmonate (JA) pathway was found to be hyperactive in the OsDOS RNAi transgenic lines but impaired in the OsDOS overexpressing transgenic lines, indicating that this pathway is likely involved in the OsDOS-mediated delaying of leaf senescence. Furthermore, methyl JA treatments of both seeds and detached leaves from the RNAi and the overexpressing transgenic lines showed hyperand hyporesponses, respectively, consistent with the negative regulation of the JA pathway by OsDOS. Together, these results indicate that OsDOS is a novel nuclear protein that delays leaf senescence likely, at least in part, by integrating developmental cues to the JA pathway.

SOMNUS, a CCCH-Type Zinc Finger Protein inArabidopsis, Negatively Regulates Light-Dependent Seed Germination Downstream of PIL5

“…Other plant proteins have similar zinc finger motifs. These include PEI1 from Arabidopsis, which regulates embryogenesis (Li and Thomas, 1998), SZF1 and SZF2 from Arabidopsis, which regulate salt responses , and DOS from rice (Oryza sativa), which regulates leaf senescence (Kong et al, 2006). Another Arabidopsis zinc finger protein, FRIGIDA-ESSENTIAL1 (FES1), has a single zinc finger motif (CX 7 CX 5 CX 3 H) and has been shown to delay flowering in the presence of FRIGIDA by activating the expression of FLOWERING LOCUS C (Schmitz et al, 2005).…”

Protein Disulfide Isomerase-2 of Arabidopsis Mediates Protein Folding and Localizes to Both the Secretory Pathway and Nucleus, Where It Interacts with Maternal Effect Embryo Arrest Factor

“…However, in each of these examples, the corresponding precursor polypeptide contains both a signal peptide and a nuclear localization signal (NLS). PDI2 is not predicted to harbor a NLS, although ~43% of the known nuclear proteins in yeast also do not possess an obvious NLS (Lange et al, 2007), and several nuclear proteins lacking a NLS have been described in plants (Kong et al, 2006;Pomeranz et al, 2009) and animals (Asally and Yoneda, 2005;Rout et al, 2003). Thus, it is possible that PDI2 contains a new type of NLS, or is directed into the nucleus through an NLS-independent mechanism as has been hypothesized for other nuclear proteins (Kong et al, 2006;Pomeranz et al, 2009).…”

Characterization and fine mapping of a new early leaf senescence mutant es3(t) in rice

“…The above two genes have not yet been cloned, while some senescence-associated loci have been cloned and regulated leaf senescence through a different pathway in rice. For example, the nuclear-localized CCCH-type zinc finger protein, OsDOS, is involved in delaying leaf senescence by integrating developmental cues to the jasmonic acid pathway in rice (Kong et al 2006). The OsPSE1 may regulate premature senescence by a novel pectate lyase-mediated mechanism in rice (Wu et al 2013).…”