Isolation And Functional Analysis Of Transcription Factor TaNAC6A Of SR3Wheat

Over the years, plants have been facing many biotic and abiotic stresses, including drought, cold, high salinity and pathogen infection. To cope with these stresses, plants have been evolved a series of morphological and biochemical traits. The complex reaction mechanisms of stress resistance rely on a series of regulatory genes. These regulatory genes are working through encoding functional proteins or regulatory proteins.The typical example of these regulatory mechanisms is transcription factor. Transcription factors respond to the environmental stimuli by signaling cascade, and through direct interaction or combination with other proteins to bound with a composition-specific regulatory gene in regulatory network.We have used common wheat c.v. Jinan177(JN177, Triticum aestivum L.2n=42) and Thinopyum poriticum (2n=70), a salt and drought tolerant grass to generated a new somatic hybrid introgression line Shanrong No.3(SR3). Former results showed that some chromatin fragments of T. ponticumintergrated into SR3’s genome, and a high frequency of allelic variation and a vast transcriptomic and proteomic change inSR3happened, indicating that SR3is an excellent material for investigating genetic variation, isolating stress tolerance associated genes, and dissecting themechanisms underlying stress response.In this study, based on a screening of the expression patterns of SR3genes involved in the pathway during abiotic stress, we cloned a novel stress-inducible NAC gene, TaNAC6A, that responds to drought, high salinity, hormones and other abiotic stresses from SR3full length cDNA library. This NAC gene has900bp and encodes299amino acids. TaNAC6A includes a transcription activation domain in the C-terminal, and a DNA binding domain (NAC-domain). The RT-PCR data revealed that the expression of TaNAC6A was induced by high salinity, H2O2and ABA stresses. Subcellular localization assay indicated that the TaNAC6Awas targeted to the nuclei. It was a nuclear localization protein. The results of transcription activation assays in yeast cells revealed that TaNAC6A encodes a NAC transcription activator. In order to learn the functions of TaNAC6A, we overexpressed this gene in Arabidopsis thaliana (Col-O). The overexpressionlines increased the tolerance to abiotic stresses. Under high salinity, H2O2and ABA stresses, roots of overexpression lines were significantly longer and stronger than wild type, indicating that TaNAC6A can increase tolerance of plantsto the ion, hormone and other abiotic stresses.In soils, OE lines survived from the drought treatment but the control died.Overexpressing TaNAC6A affects overexpression plant development. The OE lines showedsmaller rosettesin size and stunted growth of leaves with severelyupward-curling blades. It was found that the inflorescence stems were oftenpendent after they bore siliques. qRT-PCR analysis showed that the seedlings of overexpressing lines had significantly induced expression of the xylan biosynthesis-related geneFRA8andXCP1. TaNAC6A overexpression had also deduced the cellulose synthase genes CesA7.