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LcbHLH92 from sheepgrass acts as a negative regulator of anthocyanin/proanthocyandin accumulation and influences seed dormancy
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Zhao PC, Li XX, Jia JT, Yuan GX, Chen SY, Qi DM, Cheng LQ*, Liu GS*
PubYear : 2018
Volume : DOI: 10.1093/jxb/ery335  Issue : 
Publication Name : Journal of Experimental Botany
Page number : 
Abstract : 

Sheepgrass (Leymus chinensis) is an important native forage grass, and it is widely grown in north China. Differential dormancy exists in sheepgrass germplasms with different seed colors. To decipher and find potential genes underlying this phenomenon, we compared the transcript profiles of yellow seeds with weak dormancy and brown seeds with strong dormancy, and we found a transcription factor LcbHLH92 which is negatively correlated with those of anthocyanin/proanthocyanidin-specific pathway genes, anthocyanidin synthase (ANS) and anthocyanidin reductase (ANR). The LcbHLH92 gene had two transcripts, LcbHLH92a and LcbHLH92b, and their expression could be induced by ABA, cold and NaCl. Overexpression of LcbHLH92a or LcbHLH92b in Arabidopsis significantly inhibited the transcript levels of dihydroflavonol reductase (DFR) and ANS genes in leaves and seeds, which resulted in a decrease in anthocyanins and proanthocyanidins, respectively. Importantly, transgenicArabidopsis seeds with a yellow color showed a higher germination rate than did wild-type controls with a brown seed color. Moreover, LcbHLH92a and LcbHLH92b repressed the transcription of Transparent Testa8 (TT8), ANSDFR, and ANR possibly by elevating the transcript levels of Jasmonate-ZIM-domain proteins (JAZs) through binding to their promoters. In summary, this is the first investigation of LcbHLH92 and its relationship to anthocyanin/proanthocyanidin biosynthesis and seed dormancy.

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