Title：
The NPR7-TGA6-MYB1 module promotes anthocyanin biosynthesis and integrates salicylic acid and strigolactone signaling in apple
Authors：
38(3):1-24
Corresponding
Author：
Lei Zhao, Zhaoyang Li, Di Ai, Miaoyi Li, Yujie Jiang, Lanxi Sha, Yuepeng Han, Jianping An*
Pubyear：
2026
Title of
Journal：
Plant Cell
Paper
Code：
Volume：
38
Number：
3
Page：
1–24
Others：
Classification：
Source：
Abstract：
The salicylic acid (SA) signal transduction pathway and its association with anthocyanin biosynthesis have been reported, but the molecular mechanisms underlying SA-mediated anthocyanin biosynthesis remain unclear. In this study, we elucidated the SA signaling pathway associated with anthocyanin biosynthesis and the crosstalk between SA and strigolactone (SL) in apple (Malus & times; domestica). MYELOBLASTOSIS 1 (MdMYB1) played a pivotal role in SA-induced anthocyanin biosynthesis, and the SA-responsive factor TGACG-MOTIF-BINDING FACTOR 6 (MdTGA6) facilitated anthocyanin accumulation by directly activating MdMYB1 expression. The key regulatory component of SA signaling, NONEXPRESSER OF PR GENES 7 (MdNPR7), potentiated MdTGA6-mediated transcriptional activation of MdMYB1, thereby sustaining MdTGA6-promoted anthocyanin biosynthesis. Furthermore, MdNPR7 physically interacted with MdMYB1 to enhance transcriptional activation of downstream anthocyanin biosynthetic genes. Additionally, SA-suppressed E3 ubiquitin ligase RING-H2 FINGER PROTEIN A2a (MdRHA2a) mediated ubiquitination and degradation of MdNPR7 in the absence of SA. The SL signaling repressor SUPPRESSOR OF MAX2 1-LIKE 8 (MdSMXL8) antagonized MdNPR7-promoted anthocyanin biosynthesis by dissociating the MdNPR7-MdTGA6 and MdNPR7-MdMYB1 protein complexes, thereby mediating SA-SL signaling crosstalk. Taken together, our results delineate the molecular mechanism of SA-induced anthocyanin biosynthesis and reveal a regulatory mode that may integrate the SA and SL signaling pathways to regulate anthocyanin production. MdNPR7 coordinates salicylic acid-induced anthocyanin biosynthesis by recruiting MdTGA6 and MdMYB1, while undergoing MdRHA2a-mediated ubiquitination in the absence of salicylic acid; additionally, MdNPR7 may bridge salicylic acid and strigolactone signals through interaction with MdSMXL8.
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