Overexpression of a Triticum aestivum Calreticulin gene (TaCRT1) Improves Salinity Tolerance in Tobacco

Abstract

Calreticulin (CRT) is a highly conserved and abundant multifunctional protein that is encoded by a small gene family and is often associated with abiotic/biotic stress responses in plants. However, the roles played by this protein in salt stress responses in wheat (Triticum aestivum) remain obscure. In this study, three TaCRT genes were identified in wheat and named TaCRT1, TaCRT2 and TaCRT3-1 based on their sequence characteristics and their high homology to other known CRT genes. Quantitative real-time PCR expression data revealed that these three genes exhibit different expression patterns in different tissues and are strongly induced under salt stress in wheat. The calcium-binding properties of the purified recombinant TaCRT1 protein were determined using a PIPES/Arsenazo III analysis. TaCRT1 gene overexpression in Nicotiana tabacum decreased salt stress damage in transgenic tobacco plants. Physiological measurements indicated that transgenic tobacco plants showed higher activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) than non-transgenic tobacco under normal growth conditions. Interestingly, overexpression of the entire TaCRT1 gene or of partial TaCRT1 segments resulted in significantly higher tolerance to salt stress in transgenic plants compared with their WT counterparts, thus revealing the essential role of the C-domain of TaCRT1 in countering salt stress in plants.

The involvement of wheat U‐box E3 ubiquitin ligase TaPUB1 in salt stress tolerance

“…To clarify how TaPUB1 regulates salt tolerance on the transcriptional level, qPCR analysis was performed on several salt stress and antioxidant enzyme‐related genes. These results show that TaPUB1 increased the expression of TaCHP and TaCRT1 , which could upregulate salt tolerance (Figure A, B; Li et al 2010; Xiang et al 2015), while it decreased the expression of TaGBF1 , which decreases stress tolerance (Figure C; Sun et al 2015). We also detected the expression levels of genes encoding ionic transporters; the expression of TdSOS1 , TmHKT1;4 , and TNHX‐1 were increased in TaPUB1 ‐OE (Figure D–F; Brini et al 2009; Amar et al 2013; Feki et al 2014).…”

“…Based on the expression levels of marker genes, TaPUB1 could upregulate the expression of TaCHP and TaCRT1 in response to salt stress. TaCHP plays a positive role in stress tolerance by downregulating ABA, and TaCRT improves salinity tolerance in overexpressing plants (Li et al 2010; Xiang et al 2015). However, TaPUB1 could negatively regulate the transcription of TaGBF1, which affects the plant's sensitivity to salt (Sun et al 2015).…”

Yield-related salinity tolerance traits identified in a nested association mapping (NAM) population of wild barley

“…Interestingly, barley calreticulin 1 ( CRH1 , GenBank: L27348.1) and calreticulin 2 ( CRH2 , GenBank: L27349.1), which are calcium-binding proteins, align to position 141.78 cM and may instead be the genes underlying this QTL (2H, 140–145 cM). Xiang et al 12. have shown that tobacco plants transformed with Triticum aestivum calreticulin gene ( TaCRT1 ) showed higher salinity tolerance compared to their wild-type counterparts.…”

Structures of parasite calreticulins provide insights into their flexibility and dual carbohydrate/peptide-binding properties

“…Since the same design has been used to study the two parasite structures, it might also be useful to solve other CRT subgroups, such as plant CRTs, plant parasite CRTs or the testis-specific mammalian CRT2 isoform (Persson et al, 2002). This would help to better define what it is that drives the functional differences of CRTs, an area which is still expanding (Johnson et al, 2001;Qiu et al, 2012;de Bruyn et al, 2015;Xiang et al, 2015) and possibly also to provide structural insights into some CRT2-mutation related diseases (Chiu et al, 2007). Coming back to the two parasite CRTs studied here, if one needs to block them without affecting the host CRT, selective inhibitory peptides or antibodies need to be developed, which is only possible if one can identify distinctive structural features in the parasite CRTs.…”