MYB1R1 and MYC2 Regulate ω-3 Fatty Acid Desaturase Involved in ABA-Mediated Suberization in the Russet Skin of a Mutant of ‘Dangshansuli’ (Pyrus bretschneideri Rehd.)

Abstract

Russeting, a disorder of pear fruit skin, is mainly caused by suberin accumulation on the inner part of the outer epidermal cell layers. ABA was identified as a crucial phytohormone in suberification. Here, we demonstrated that the ABA content in russet pear skin was higher than in green skin. Then, ABA was applied to explore the changes in phenotype and suberin composition coupled with RNA-Seq and metabolomics to investigate the probably regulatory pathway of ABA-mediated suberification. The results showed that ABA treatment increased the expression of ω-3 fatty acid desaturase (FAD) and the content of α-linolenic acid. We identified 17 PbFADs in white pear, and the expression of PbFAD3a was induced by ABA. In addition, the role of PbFAD3a in promoting suberification has been demonstrated by overexpression in Arabidopsis and VIGS assays in the fruitlets. GUS staining indicated that the promoter of PbFAD3a was activated by ABA. Furthermore, MYC2 and MYB1R1 have been shown to bind to the PbFAD3a promoter directly and this was induced by ABA via yeast one-hybrid (Y1H) screening and qRT–PCR. In summary, our study found that ABA induces the expression of MYC2 and MYB1R1 and activates the PbFAD3a promoter, contributing to the formation of russet pear skin. Functional identification of key transcription factors will be the goal of future research. These findings reveal the molecular mechanism of ABA-mediated suberization in the russet skin and provide a good foundation for future studies on the formation of russet skin.

Phytohormones regulate the non-redundant response of ω-3 fatty acid desaturases to low temperatures in Chorispora bungeana

“…On the other hand, it is confirmed in Arabidopsis that some TFs (such as WRKYs, MYCs, bHLHs and ICEs) occurred at the downstream of cold-induced JA signaling 54,56 , while some others (for example bZIPs) belong to the cold-responsive BR and/or ABA signaling pathways 57,68 . Additionally, a recent study in a mutant of Pyrus bretschneideri Rehd found that MYB1R1 and MYC2 regulate ω-3 FADs involved in ABA-mediated suberization 69 .…”

ABA-dependent suberization and aquaporin activity in rice (Oryza sativa L.) root under different water potentials

“…The enhanced ratio of the unsaturated to saturated fatty acid is clearly observed as a drought-tolerant mechanism in many plants ( Moradi et al., 2017 ; Jin et al., 2022 ) including rice ( Lenka et al., 2011 ) and maize ( Zi et al., 2022 ). Furthermore, ABA-mediated metabolism predominantly promoted the substances of suberization enhanced the activity of C18:3-ACP ( Wang et al., 2022 ). By contrast, the extreme drought condition resulted in the reduced membrane fluidity causing less function of cell membrane ( Rawat et al., 2021 ).…”

Transcriptome and metabolome analyses reveal phenotype formation differences between russet and non-russet apples

“…In pears, 19 DEGs related to plant hormone biosynthesis and signaling were identified, including ABA, GA, IAA, and ethylene. ABA content was higher in russet pears, and ABA treatment could increase russeting ( Wang et al., 2022 ). Many genes related to auxin and ethylene signaling pathways are highly expressed in russet apples ( Legay et al., 2015 ).…”