Ubiquitination-Related MdBT Scaffold Proteins Target a bHLH Transcription Factor for Iron Homeostasis

Zhao, Qiang; Ren, Yi-Ran; Wang, Qingjie; Wang, Xiaofei; You, Chun‐Xiang; Hao, Yu‐Jin

doi:10.1104/pp.16.01323

Cited by 100 publications

(101 citation statements)

References 51 publications

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“…In addition, MdbHLH104 was identified as the target protein of MdBT2, and overexpression of MdBT2 facilitated its degradation (Zhao et al, ). Considering ABA‐modulated MdbZIP44 protein stability and the interaction between MdBT2 and MdbZIP44, we speculated that MdBT2 might regulate MdbZIP44 protein stability.…”

Section: Resultsmentioning

confidence: 99%

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Apple bZIP transcription factor MdbZIP44 regulates abscisic acid‐promoted anthocyanin accumulation

Yao

et al. 2018

Plant Cell & Environment

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226

182

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Phytohormone abscisic acid (ABA) induces anthocyanin biosynthesis; however, the underlying molecular mechanism is less known. In this study, we found that the apple MYB transcription factor MdMYB1 activated anthocyanin biosynthesis in response to ABA. Using a yeast screening technique, we isolated MdbZIP44, an ABA-induced bZIP transcription factor in apple, as a co-partner with MdMYB1. MdbZIP44 promoted anthocyanin accumulation in response to ABA by enhancing the binding of MdMYB1 to the promoters of downstream target genes. Furthermore, we identified MdBT2, a BTB protein, as an MdbZIP44-interacting protein. A series of molecular, biochemical, and genetic analysis suggested that MdBT2 degraded MdbZIP44 protein through the Ubiquitin-26S proteasome system, thus inhibiting MdbZIP44-modulated anthocyanin biosynthesis. Taken together, we reveal a novel working mechanism of MdbZIP44-mediated anthocyanin biosynthesis in response to ABA.

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Section: Resultsmentioning

confidence: 99%

“…BT2 is involved in various hormone and stress responses in Arabidopsis (Mandadi et al, ). In apple, MdBT2 has been confirmed to negatively regulate iron homeostasis by degrading MdbHLH104 (Zhao et al, ). Here, MdbZIP44 was identified as another MdBT2‐interacting protein.…”

Section: Discussionmentioning

confidence: 99%

Apple bZIP transcription factor MdbZIP44 regulates abscisic acid‐promoted anthocyanin accumulation

Yao

et al. 2018

Plant Cell & Environment

Self Cite

226

182

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“…In Arabidopsis , the transcription of AtBT2 is responsive to various hormone and stress treatments (Mandadi et al ., ). In apple, MdBT2 mediates Fe homeostasis and anthocyanin accumulation by regulating the stability of MdbHLH104 and MdbZIP44 proteins, respectively (Zhao Q. et al ., ; An et al ., ).…”

Section: Discussionmentioning

confidence: 97%

MdbHLH93, an apple activator regulating leaf senescence, is regulated by ABA and MdBT2 in antagonistic ways

Zhang

et al. 2019

New Phytologist

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Summary The molecular mechanism of leaf senescence in apple (Malus domestica) is still not fully understood. We used gene expression analysis and protein–protein interactions to decipher the relationships of abscisic acid (ABA) and two proteins, MdbHLH93 and MdBT2, in the senescence process. We found that MdbHLH93 promoted leaf senescence and the expression of senescence‐related genes, which exhibited similar effects to ABA on leaf senescence. MdbHLH93 activated directly the transcription of MdSAG18. We also found that an ABA‐responsive protein, MdBT2, interacted directly with MdbHLH93, and induced the ubiquitination and degradation of the MdbHLH93 protein, and thus delayed leaf senescence. Our findings provide new insights into the regulatory network of leaf senescence through the functional interactions among ABA, MdbHLH93 and MdBT2.

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“…Since apple calli were firstly used in the studies of anthocyanin‐related genes (Xie et al ., ), they have been widely adopted in gene function studies in the apple, including flavonoid biosynthesis (Hu et al ., ), the fruit acidity (Zhao et al ., ), fruit ripening (Li et al ., ) and abiotic stress (Sun et al ., ). The use of apple calli enabled the researchers to easily observe effect of genes in the homologous system, thus greatly accelerating the study of gene functions in apples.…”

Section: Discussionmentioning

confidence: 99%

BBX16, a B‐box protein, positively regulates light‐induced anthocyanin accumulation by activating MYB10 in red pear

Bai

Tao

Tang

et al. 2019

Plant Biotechnology Journal

236

180

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Summary The red coloration of pear (Pyrus pyrifolia) results from anthocyanin accumulation in the fruit peel. Light is required for anthocyanin biosynthesis in pear. A pear homolog of Arabidopsis thaliana BBX22, PpBBX16, was differentially expressed after fruits were removed from bags and may be involved in anthocyanin biosynthesis. Here, the expression and function of PpBBX16 were analysed. PpBBX16's expression was highly induced by white‐light irradiation, as was anthocyanin accumulation. PpBBX16's ectopic expression in Arabidopsis increased anthocyanin biosynthesis in the hypocotyls and tops of flower stalks. PpBBX16 was localized in the nucleus and showed trans‐activity in yeast cells. Although PpBBX16 could not directly bind to the promoter of PpMYB10 or PpCHS in yeast one‐hybrid assays, the complex of PpBBX16/PpHY5 strongly trans‐activated anthocyanin pathway genes in tobacco. PpBBX16's overexpression in pear calli enhanced the red coloration during light treatments. Additionally, PpBBX16's transient overexpression in pear peel increased anthocyanin accumulation, while virus‐induced gene silencing of PpBBX16 decreased anthocyanin accumulation. The expression patterns of pear BBX family members were analysed, and six additional BBX genes, which were differentially expressed during light‐induced anthocyanin biosynthesis, were identified. Thus, PpBBX16 is a positive regulator of light‐induced anthocyanin accumulation, but it could not directly induce the expression of the anthocyanin biosynthesis‐related genes by itself but needed PpHY5 to gain full function. Our work uncovered regulatory modes for PpBBX16 and suggested the potential functions of other pear BBX genes in the regulation of anthocyanin accumulation, thereby providing target genes for further studies on anthocyanin biosynthesis.

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Ubiquitination-Related MdBT Scaffold Proteins Target a bHLH Transcription Factor for Iron Homeostasis

Cited by 100 publications

References 51 publications

Apple bZIP transcription factor MdbZIP44 regulates abscisic acid‐promoted anthocyanin accumulation

Apple bZIP transcription factor MdbZIP44 regulates abscisic acid‐promoted anthocyanin accumulation

MdbHLH93, an apple activator regulating leaf senescence, is regulated by ABA and MdBT2 in antagonistic ways

BBX16, a B‐box protein, positively regulates light‐induced anthocyanin accumulation by activating MYB10 in red pear

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