National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, 110067, India.
Planta. 2024 Jul 1;260(2):38. doi: 10.1007/s00425-024-04470-7.
Our findings shed light on the regulation of anthocyanin and proanthocyanidin biosynthesis in chickpea seed coats. Expression of R2R3-MYB transcription factors CaLAP1 and CaLAP2 enhanced the anthocyanins and proanthocyanidins content in chickpea. The seed coat color is a major economic trait in leguminous crop chickpea (Cicer arietinum). Anthocyanins and proanthocyanidins (PAs) are two classes of flavonoids that mainly contribute to the flower, seed coat and color of Desi chickpea cultivars. Throughout the land plant lineage, the accumulation of anthocyanins and PAs is regulated by MYB and bHLH transcription factors (TFs), which form an MBW (MYB, bHLH, and WD40) complex. Here, we report two R2R3-MYB TFs in chickpea belonging to the anthocyanin-specific subgroup-6, CaLAP1 (Legume Anthocyanin Production 1), and CaLAP2 (Legume Anthocyanin Production 2), which are mainly expressed in the flowers and developmental stages of the seeds. CaLAP1 and CaLAP2 interact with TT8-like CabHLH1 and WD40, forming the MBW complex, and bind to the promoter sequences of anthocyanin- and PA biosynthetic genes CaCHS6, CaDFR2, CaANS, and CaANR, leading to anthocyanins and PA accumulation in the seed coat of chickpea. Moreover, these CaLAPs partially complement the anthocyanin-deficient phenotype in the Arabidopsis thaliana sextuple mutant seedlings. Overexpression of CaLAPs in chickpea resulted in significantly higher expression of anthocyanin and PA biosynthetic genes leading to a darker seed coat color with higher accumulation of anthocyanin and PA. Our findings show that CaLAPs positively modulate anthocyanin and PA content in seed coats, which might influence plant development and resistance to various biotic and abiotic stresses.
我们的研究结果揭示了羽扇豆种皮中花色苷和原花色素生物合成的调控机制。R2R3-MYB 转录因子 CaLAP1 和 CaLAP2 的表达增强了羽扇豆中的花色苷和原花色素含量。种皮颜色是豆科作物鹰嘴豆(Cicer arietinum)的一个主要经济性状。花色苷和原花色素(PAs)是两类主要贡献于花、种皮和 Desi 鹰嘴豆品种颜色的类黄酮。在整个陆地植物谱系中,花色苷和 PAs 的积累受 MYB 和 bHLH 转录因子(TFs)调控,它们形成一个 MBW(MYB、bHLH 和 WD40)复合物。在这里,我们报告了鹰嘴豆中的两个 R2R3-MYB TF,属于花色苷特异亚组-6,CaLAP1(Legume Anthocyanin Production 1)和 CaLAP2(Legume Anthocyanin Production 2),它们主要在花和种子发育阶段表达。CaLAP1 和 CaLAP2 与 TT8 样 CabHLH1 和 WD40 相互作用,形成 MBW 复合物,并与花色苷和 PA 生物合成基因 CaCHS6、CaDFR2、CaANS 和 CaANR 的启动子序列结合,导致羽扇豆种皮中花色苷和 PA 的积累。此外,这些 CaLAPs 部分补充了拟南芥 sextuple 突变体幼苗中花色苷缺失的表型。CaLAPs 在鹰嘴豆中的过表达导致花色苷和 PA 生物合成基因的表达显著升高,导致种皮颜色更深,花色苷和 PA 积累更高。我们的研究结果表明,CaLAPs 正向调节种皮中花色苷和 PA 的含量,这可能影响植物的发育和对各种生物和非生物胁迫的抗性。
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