The NAC Family Transcription Factor OsNAP Confers Abiotic Stress Response Through the ABA Pathway

Abstract

Plants respond to environmental stresses by altering gene expression, and several genes have been found to mediate stress-induced expression, but many additional factors are yet to be identified. OsNAP is a member of the NAC transcription factor family; it is localized in the nucleus, and shows transcriptional activator activity in yeast. Analysis of the OsNAP transcript levels in rice showed that this gene was significantly induced by ABA and abiotic stresses, including high salinity, drought and low temperature. Rice plants overexpressing OsNAP did not show growth retardation, but showed a significantly reduced rate of water loss, enhanced tolerance to high salinity, drought and low temperature at the vegetative stage, and improved yield under drought stress at the flowering stage. Microarray analysis of transgenic plants overexpressing OsNAP revealed that many stress-related genes were up-regulated, including OsPP2C06/OsABI2, OsPP2C09, OsPP2C68 and OsSalT, and some genes coding for stress-related transcription factors (OsDREB1A, OsMYB2, OsAP37 and OsAP59). Our data suggest that OsNAP functions as a transcriptional activator that plays a role in mediating abiotic stress responses in rice.

Barley plants over-expressing the NAC transcription factor geneHvNAC005show stunting and delay in development combined with early senescence

“…However, we tested two lines of these plants in our own greenhouse and observed a premature senescence phenotype comparable with that of HvNAC005 in barley. In rice, Chen et al (2014) reported no change in the phenotypes of OsNAP over-expression lines, in contrast to results reported by Liang et al (2014). The discrepancies in the effects on phenotypes might relate to the use of different promoters in the various studies.…”

“…We did, in fact, make preliminary drought experiments in the greenhouse; however, these did not indicate any significant effects of HvNAC005 over-expression on drought tolerance (data not shown). The strong phenotype of the over-expressing lines in our case may have obscured any positive effects that might be evident with plants with less severe phenotypes, as was seen in the studies of Chen et al (2014).…”

“…TaNAC69 : Xue et al (2011) and OsNAP : Chen et al (2014). We did, in fact, make preliminary drought experiments in the greenhouse; however, these did not indicate any significant effects of HvNAC005 over-expression on drought tolerance (data not shown).…”

“…NAC transcription factors also play essential roles in the senescence processes in crop plants. RNA interference studies of wheat Gpc-B1 , encoding the NAC protein NAM-B1, resulted in delayed leaf senescence and significant reduction in grain zinc, iron, and protein content (Uauy et al , 2006; Waters et al , 2009), and OsNAP, a positive regulator of senescence in rice, affects the grain-filling period and grain yield (Chen et al , 2014; Liang et al , 2014). …”

“…The NAC-a5 and -a6 subgroups (Shen et al , 2009) contain several NAC transcription factors that have been shown to be involved in the regulation of senescence, for example, AtNAP (Guo and Gan, 2006), TtNAM-B1 (Uauy et al , 2006), ANAC047 (Kim et al , 2014), and OsNAP (Liang et al , 2014), as well as in abiotic stress responses and tolerance (e.g. Xue et al , 2011; Chen et al , 2014). …”