| Summary: | The purpose of this study was to explore the regulation of <i>BcMYB44</i> on anthocyanin synthesis and drought tolerance of non-heading Chinese cabbage. The <i>BcMYB44</i> gene was cloned from the purple inbred line ‘NJZX1-3’ and its green mutant ‘NJZX1-0’. Sequence analysis confirmed that BcMYB44 belongs to the R2R3-MYB family and has the highest homology with BnMYB44. Subcellular localization revealed that BcMYB44 is a nuclear protein. Yeast two-hybrid (Y2H) and Bimolecular Fluorescent Complimentary (BiFC) experiments showed that BcMYB44 interacts with BcPAP1 and BcEGL3. Pigment detection of BcPAP1 and BcMYB44 protein activity in N. benthamiana indicates that <i>BcMYB44</i> plays a negative regulatory role by inhibiting the expression of key structural genes (<i>F3H</i>, <i>DFR</i>, etc.) in anthocyanin synthesis. Virus-induced gene silencing (VIGS) further confirmed this inhibition. Analysis of drought tolerance of non-heading Chinese cabbage based on VIGS showed that pTY-S plants are more resistant to drought than pTY-BcMYB44 plants. The results indicate that <i>BcMYB44</i> has a positive regulatory role in drought stress, which most likely is achieved by inhibiting anthocyanin accumulation, regulating stomatal movement, and improving osmotic regulation and homeostasis of reactive oxygen species (ROS).
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