Comparative functional analysis of six drought-responsive promoters in transgenic rice

Abstract

Rice production is greatly affected by environmental stresses such as drought and high salinity. Transgenic rice plants tolerant to such stresses are expected to be produced. Stress-responsive promoters with low expression under normal growth conditions are needed to minimize the adverse effects of stress-tolerance genes on rice growth. We performed expression analyses of drought-responsive genes in rice plants using a microarray, and selected LIP9, OsNAC6, OsLEA14a, OsRAB16D, OsLEA3-1, and Oshox24 for promoter analysis. Transient assays using the promoters indicated that AREB/ABF (abscisic acid (ABA)-responsive element-binding protein/ABA-binding factor) transcription factors enhanced expressions of these genes. We generated transgenic rice plants containing each promoter and the β-glucuronidase (GUS) reporter gene. GUS assays revealed that the LIP9 and OsNAC6 promoters were induced by drought, high salinity, and ABA treatment, and both promoters showed strong activity under normal growth conditions in the root. The other promoters were strongly induced by stresses and ABA, but showed low activity under normal growth conditions. In seeds, GUS staining showed that Oshox24 expression was low and expressions of the other genes were high. Transgenic rice plants overexpressing OsNAC6 under the control of the Oshox24 promoter showed increased tolerance to drought and high salinity, and no growth defects. These data suggest that the Oshox24 promoter is useful to overexpress stress-tolerance genes without adversely affecting growth.

The transcriptional regulatory network in the drought response and its crosstalk in abiotic stress responses including drought, cold, and heat

“…Stress-responsive Arabidopsis SNAC genes such as RD26 and ATAF1 , and rice SNAC genes such as SNAC1 , OsNAC6 / SNAC2 , and OsNAC5 can improve drought and/or high-salt stress tolerance when overexpressed (Tran et al, 2004; Hu et al, 2006; Nakashima et al, 2007; Takasaki et al, 2010; reviewed in Nakashima et al, 2012). Stress-responsive overexpression of NACs utilizing rice stress-responsive LIP9 , OsNAC6 , or OsHox24 promoters is effective in inducing stress tolerance without the inhibitory effects of NAC on plant growth (Nakashima et al, 2007, 2012, 2014; Takasaki et al, 2010). Recent studies have suggested that the root-specific promoter RCc3 is useful for the overexpression of SNACs such as SNAC1 and OsNAC10 to enhance the abiotic stress tolerance of rice in field conditions (Jeong et al, 2010, 2013; Redillas et al, 2012).…”

“…These results indicate that SNACs have important roles in the control of abiotic stress responses and tolerance and that it is possible to improve stress tolerance by overexpressing SNACs using suitable promoters in the field. The many kinds of drought-responsive or tissue/organ-specific promoters reported for roots and stomata might be effective tools to control the expression of drought-responsive factors that cause growth defects at the right time and right position (Nakashima et al, 2007, 2014; Rai et al, 2009; Wu et al, 2009; Xiao et al, 2009; Yi et al, 2010; Ganguly et al, 2011; Yang and Xiong, 2011; Bang et al, 2013; Rusconi et al, 2013). …”

Comprehensive analysis of regulatory elements of the promoters of rice sulfate transporter gene family and functional characterization ofOsSul1;1promoter under different metal stress

“…Various studies have examined the role of promoters by fusing it with GUS reporter gene and subsequently analyzing the transgenic plants. 37,38 In this study, 1.5 kb upstream region from translation initiation site of OsSul1;1 was PCR amplified using oligonucleotide primers with digestion sites (Table S1), digested with restriction enzymes and cloned in binary vector pBI121 by replacing CaMV35S promoter (Fig. S3A and B).…”

Wsi18 promoter from wild rice genotype, Oryza nivara, shows enhanced expression under soil water stress in contrast to elite cultivar, IR20

“…Comparative functional analysis of different stress responsive promoters in general and among different rice varieties has provided useful results which led to improved specificity and inducibility of stress responsive genes (Yi et al 2010;Nakashima et al 2014). Wsi18 promoter element, isolated from O. sativa cultivar Nakdong, was found to drive high levels of reporter GFP expression throughout the plant body, including flowers, with predominant activity in the whole grain on exposure of transgenic rice plants to drought and high salinity conditions (Yi et al 2011).…”