Over‐expression of (1,3;1,4)‐β‐D‐glucanase isoenzyme EII gene results in decreased (1,3;1,4)‐β‐D‐glucan content and increased starch level in barley grains
2017
Han, Ning | Na, Chenglong | Chai, Yuqiong | Chen, Jianshu | Zhang, Zhongbo | Bai, Bin | Bian, Hongwu | Zhang, Yuhong | Zhu, Muyuan
BACKGROUND: High content of (1,3;1,4)‐β‐d‐glucan in barley grains is regarded as an undesirable factor affecting malting potential, brewing yield and feed utilization. Production of thermostable bacterial (1,3;1,4)‐β‐glucanase in transgenic barley grain or supplementation of exogenous bacterial (1,3;1,4)‐β‐glucanase has been used to improve malt and feed quality. The aim of the present study was to investigate the effect of over‐expression of an endogenous (1,3;1,4)‐β‐glucanase on β‐glucan content and grain composition in barley. RESULTS: A construct containing full‐length HvGlb2 cDNA encoding barley (1,3;1,4)‐β‐glucanase isoenzyme EII under the control of a promoter of barley D‐Hordein gene Hor3‐1 was introduced into barley cultivar Golden Promise via Agrobacterium‐mediated transformation, and transgenic plants were regenerated after hygromycin selection. The T₂ generation of proHor3:HvGlb2 transgenic lines showed increased activity of (1,3;1,4)‐β‐glucanase in grains. Total β‐glucan content was reduced by more than 95.73% in transgenic grains compared with the wild‐type control. Meanwhile, over‐expression of (1,3;1,4)‐β‐glucanase led to an increase in 1000‐grain weight, which might be due to elevated amounts of starch in the grain. CONCLUSION: Manipulating the expression of (1,3;1,4)‐β‐glucanase EII can control the β‐glucan content in grain with no apparent harmful effects on grain quality of transgenic plants. © 2016 Society of Chemical Industry
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