The IAA- and ABA-responsive transcription factor CgMYB58 upregulates lignin biosynthesis and triggers juice sac granulation in pummelo
The IAA- and ABA-responsive transcription factor CgMYB58 upregulates lignin biosynthesis and triggers juice sac granulation in pummelo
复制标题
IAA 和 ABA 响应转录因子 CgMYB58 上调木质素生物合成并触发柚子汁囊颗粒化
DOI：
10.1038/s41438-020-00360-7
复制
发表时间：
2020-09-01
影响因子：
8.7
通讯作者：
Xu, Juan
中科院分区：
文献类型：
--
作者：
Shi, Meiyan;Liu, Xiao;Xu, Juan
在柑橘中，木质素在汁囊中的过度积累导致颗粒化和令人不快的果实质地和味道。通过整合代谢表型和转录组学分析，我们发现702个差异表达基因（DEG），包括24个转录因子（TF），与木质素含量显著相关。CgMYB58在华农红肉柚（Citrus grandis）果实中的高转录水平进一步被鉴定为参与木质素过量积累的关键R2R3 MYB TF。CgMYB58的瞬时表达导致柚果实中果皮中木质素含量的增加，而其稳定过表达显著促进木质素积累并上调19个木质素生物合成基因。在这些基因中，CgPAL 1、CgPAL 2、Cg4CL 1和CgC3 H通过与其启动子区的相互作用受到CgMYB 58的直接调节。此外，我们还发现吲哚乙酸（IAA）和脱落酸（阿坝）处理可以影响柚果实汁囊粒化。在HR柚中，阿坝显著促进了这一颗粒化过程，而IAA有效地抑制了这一过程。总之，这些结果提供了新的见解，在柑橘类水果中的木质素积累机制。通过外源IAA抑制CgMYB 58及其靶基因的表达，缓解了果实汁囊粒化现象，揭示了外源IAA抑制CgMYB 58及其靶基因表达的理论依据。
In citrus, lignin overaccumulation in the juice sac results in granulation and an unpleasant fruit texture and taste. By integrating metabolic phenotyping and transcriptomic analyses, we found 702 differentially expressed genes (DEGs), including 24 transcription factors (TFs), to be significantly correlated with lignin content. CgMYB58 was further identified as a critical R2R3 MYB TF involved in lignin overaccumulation owing to its high transcript levels in Huanong Red-fleshed pummelo (HR, Citrus grandis) fruits. Transient expression of CgMYB58 led to an increase in the lignin content in the pummelo fruit mesocarp, whereas its stable overexpression significantly promoted lignin accumulation and upregulated 19 lignin biosynthetic genes. Among these genes, CgPAL1, CgPAL2, Cg4CL1, and CgC3H were directly modulated by CgMYB58 through interaction with their promoter regions. Moreover, we showed that juice sac granulation in pummelo fruits could be affected by indole-3-acetic acid (IAA) and abscisic acid (ABA) treatments. In HR pummelo, ABA significantly accelerated this granulation, whereas IAA effectively inhibited this process. Taken together, these results provide novel insight into the lignin accumulation mechanism in citrus fruits. We also revealed the theoretical basis via exogenous IAA application, which repressed the expression of CgMYB58 and its target genes, thus alleviating juice sac granulation in orchards.