数字农科院2.0

IbMYB1-4 positively regulates purple stem and influences leaf color via dosage effect of gene expression in sweetpotato (Ipomoea batatas (L.) Lam.)

文献类型： 外文期刊

作者： Fang Dong;Yanlan Huang;Wen Dong;Ya Zhang;Shidong Kang;Wei Xiang;Jiawen Yao;Yangcang Gong;Chaofan Zhang;Qiang Li;Daowei Zhang

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期刊名称： Theoretical and Applied Genetics

ISSN： 0040-5752

年卷期： 2026 年 139 卷 1 期

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收录情况： SCIE（2025版） ; ; EI（2025版）

摘要： In sweetpotato, the quantitative variation of anthocyanin accumulation produces a continuous color spectrum that underpins both ornamental appeal and nutritional quality across cultivar species. Although previous studies have established that the expression of IbMYB1 is essential for purple pigmentation in germplasm, this gene exists in multiple copies within the polyploid genome, rendering the resulting genetic complexity incompletely understood to date. Here, we found that hexaploid genome of sweetpotato contains at least five IbMYB1 copies, designated IbMYB1-1, IbMYB1-2a/b, IbMYB1-3 and IbMYB1-4. Gene sequence cloning, transgenic complementation and high-resolution spatial expression analyses revealed that the previously uncharacterized IbMYB1-4 is specifically expressed in the stem cortex and leaf epidermis, where it orchestrates the differential accumulation of distinct anthocyanin monomers, resulting in vines that range from purple to near-black. Yeast one-hybrid screening and dual-luciferase reporter assays confirmed that the bHLH transcription factor IbbHLH2 binds to a canonical G-box motif within the IbMYB1-4 promoter, thereby reinforcing IbMYB1-4 expression. Reciprocal F1 populations derived from the interspecific hybridizations of ‘Purple_X20’ × ‘X99’ and ‘Black_leaf’ × ‘X99’ exhibited strict co-segregation between IbMYB1-4 and the single dominant Purple (P) locus which is linked to the purple color of stem. Moreover, the purple-black foliage traits may have been regulated by a dosage-dependent interaction between P locus and a putative R locus, likely attributable to the differential expression of IbMYB1-4. Collectively, these findings provide a novel genetic resource for sweetpotato breeding programs and expand the theoretical framework for the targeted improvement of pigmented germplasm.

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