| In the Tibetan Plateau,soil salinization due to climate change is often accompanied by drought stress.Barley is a long-standing food crop on the Qinghai-Tibet Plateau,which has adapted to the harsh ecological environment of the Qinghai-Tibet Plateau in the process of long-term evolution and domestication,and has adversity traits such as salinity tolerance,drought resistance and cold resistance,which provides beneficial genes for the stress resistance and improvement of modern crop varieties.Longzi black barley is a specialty of Longzi County,Tibet Autonomous Region,and is a geographical identification product.Drought and salinization are stress factors that affect their yields.MYB gene family transcription translation MYB transcription factor is the most important family of transcription factors in plants,which is involved in the regulation of phenylpropane secondary metabolic pathway and the regulation of physiological and biochemical reactions under arid saline stress.For this study,Longzi black barley(four-sided black barley,hexagonal black barley)and Xila 22(control)were selected as experimental materials to analyze the physiological response under mixed salinity and simulated drought stress.On this basis,the bioinformatics method was used to analyze the members of the MYB gene family and analyze the quantitative expression under stress to clarify the structural characteristics and characteristics of the members of the MYB gene family,analyze the expression differences under mixed saline-alkali stress and drought stress,study the resistance tolerance mechanism of the MYB gene family and screen the key genes.The main conclusions are as follows:(1)Under the treatment of drought stress,with the increase of drought degree,the MDA content,SOD activity and proline content of barley leaves increased,among which the increase of Longzi four-sided black barley and Longzi hexagonal black barley increased more than that of the control variety Xila 22,and was more sensitive to drought stress response,especially in Longzi hexagonal black barley.(2)Under mixed saline-alkali stress,the MDA content,SOD activity and proline content of barley leaves showed certain parabolic changes with the increase of stress concentration.Among them,the combined effect of p H value and saline concentration had a greater effect on the MDA content,SOD activity and proline content of barley.Longzi four-sided black barley and Longzi hexagonal black barley were more sensitive to the physiological stress response of mixed salt and alkali than the control material Xila No.22,and the performance of Longzi hexagonal black barley was more obvious.(3)Using bioinformatics methods,119 members of the barley MYB gene family with typical R structure were identified from the barley genome,which can be divided into three subfamilies: 1R,R2-R3 and 3R;119 barley MYB family members were distributed on 7 chromosomes of barley;The conserved domain of MYB is mainly located between the second and third helixes of the two R repeats;Through subcellular localization analysis,117 MYB genes were localized in the nucleus and 2 were localized to mitochondria.The domain,motifs and gene structure of barley MYB are relatively conserved.Synlinear analysis showed that 38 parallel repeat events occurred in the barley MYB gene;Multiple stress and hormonal cis-acting elements were found in the upstream promoter region of the gene.Using fluorescence quantitative PCR on 14 representative genes from three subfamilies within the MYB gene family,we found that the expression of genes increased first but then decreased with increasing mixed saline alkali concentration and drought stress,indicating that MYB gene family genes may be involved in the regulation of drought-and mixed saline alkaline stress in barley.Further analysis and study of MYB gene family is important for mining the drought resistance and salt alkali resistance genes and signaling pathway in Longzi black barley. |
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