MdJa2 Participates in the Brassinosteroid Signaling Pathway to Regulate the Synthesis of Anthocyanin and Proanthocyanidin in Red-Fleshed Apple

Mengyu Su; Shuo Wang; Wenjun Liu; Ming Yang; Zongying Zhang; Nan Wang; Xuesen Chen

doi:10.3389/fpls.2022.830349

MdJa2 Participates in the Brassinosteroid Signaling Pathway to Regulate the Synthesis of Anthocyanin and Proanthocyanidin in Red-Fleshed Apple

Front Plant Sci. 2022 May 9:13:830349. doi: 10.3389/fpls.2022.830349. eCollection 2022.

Authors

Mengyu Su^{1

2}, Shuo Wang^{1

2}, Wenjun Liu^{1

2}, Ming Yang³, Zongying Zhang^{1

2}, Nan Wang^{1

2}, Xuesen Chen^{1

2}

Affiliations

¹ State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, China.
² Collaborative Innovation Center of Fruit & Vegetable Quality and Efficient Production in Shandong, Tai'an, China.
³ College of Continuing Education, Shandong Agricultural University, Tai'an, China.

Abstract

Anthocyanin and proanthocyanidin play important roles in plant secondary metabolism. Although previous studies identified many transcription factors involved in anthocyanin and proanthocyanidin synthesis, the effects of MADS-box transcription factors are unclear in apple. Brassinosteroids (BRs) are steroid hormones that affect plant flavonoid biosynthesis, but the underlying regulatory mechanism is not yet well established. In this study, we identified a MADS-box transcription factor, MdJa2, which contained a highly conserved MADS-box domain and belonged to the STMADS11 subfamily. Additionally, MdJa2 was responsive to BR signal, and the overexpression of MdJa2 inhibited the synthesis of anthocyanin and proanthocyanidin. The silencing of MdJa2 in "Orin" calli promoted anthocyanin and proanthocyanidin accumulations. Moreover, MdJa2 interacted with MdBZR1. MdJa2 was revealed to independently regulate anthocyanin and proanthocyanidin synthesis pathways. The MdJa2-MdBZR1 complex enhanced the binding of MdJa2 to the promoters of downstream target genes. Our research provides new insights into how MADS-box transcription factors in the BR signaling pathway control the accumulations of anthocyanin and proanthocyanidin in red-fleshed apple.

Keywords: MdBZR1; MdJa2; anthocyanin; brassinosteroid; proanthocyanidin; red-fleshed apple.