ABA‐responsive ABRE‐BINDING FACTOR3 activatesDAM3expression to promote bud dormancy in Asian pear

Abstract

Bud dormancy is indispensable for the survival of perennial plants in cold winters.Abscisic acid (ABA) has essential functions influencing the endo-dormancy status. Dormancy-associated MADS-box/SHORT VEGETATIVE PHASE-like genes function downstream of the ABA signalling pathway to regulate bud dormancy. However, the regulation of DAM/SVP expression remains largely uncharacterized. In this study, we confirmed that endo-dormancy maintenance and PpyDAM3 expression are controlled by the ABA content in pear (Pyrus pyrifolia) buds. The expression of pear ABRE-BINDING FACTOR3 (PpyABF3) was positively correlated with PpyDAM3 expression. Furthermore, PpyABF3 directly bound to the second ABRE in the PpyDAM3 promoter to activate its expression. Interestingly, both PpyABF3 and PpyDAM3 repressed the cell division and growth of transgenic pear calli. Another ABA-induced ABF protein, PpyABF2, physically interacted with PpyABF3 and disrupted the activation of the PpyDAM3 promoter by PpyABF3, indicating DAM expression was precisely controlled. Additionally, our results suggested that the differences in the PpyDAM3 promoter in two pear cultivars might be responsible for the diversity in the chilling requirements. In summary, our data clarify the finely tuned regulatory mechanism underlying the effect of ABA on DAM gene expression and provide new insights into ABA-related bud dormancy regulation. K E Y W O R D S ABF3, Abscisic acid, bud dormancy, DAM, pear

Fine tuning of hormonal signaling is linked to dormancy status in sweet cherry flower buds

“…It might also suggest that ABA response is saturated in the context of very high ABA levels during endodormancy, therefore limiting the effect of additional ABA. Nevertheless, we observed that dormancy release was triggered in buds treated with fluridone that inhibits ABA biosynthesis, as previously reported in pear (Yang et al 2020), thus suggesting that high ABA levels may act to maintain dormancy. This was further confirmed by the observed elevated ABA levels correlated with endodormancy in both cultivars, as well as the differences in ABA levels between the early and late flowering cultivars.…”

The MADS-Box Gene MdDAM1 Controls Growth Cessation and Bud Dormancy in Apple

“…Additional work is required to ascertain if the decrease of MdDAM1 gene expression in low-chill apple cultivars is due to this mutation or other effects such as epigenetic gene regulation at the transcriptional level as shown for the DAM6 gene present on the EVG locus ( Leida et al, 2012 ). It is also plausible that hormones such as abscisic acid (ABA) play a role in the regulation of MdDAM1 as shown for Maleae and Prunus DAM genes, namely, PpDAM1/PpDAM3 in Japanese pear ( P. prifolia ) and PmDAM6 in Japanese apricot ( Prunus mume ) ( Tuan et al, 2017 ; Falavigna et al, 2019 ; Yamane et al, 2019 ; Yang et al, 2020 ). ABA-mediated regulation of MADS-box genes orthologs of the SVP clade is also important in the distant tree hybrid aspen to promote growth cessation and bud dormancy ( Singh et al, 2019 ).…”

Structure and Expression of Bud Dormancy-Associated MADS-Box Genes (DAM) in European Plum

“…Also, a feedback regulatory mechanism has been described involving repression of PpDAM1 by an abscisic acid response element (ABRE)-binding transcription factor (PpAREB1) in pear (Tuan et al, 2017). More recently, pear ABRE-BINDING FACTOR3 (PpyABF3) has been reported to specifically bind and activate PpyDAM3 expression, whereas PpyABF2/PpAREB1 represses PpyDAM3 by dimerising with PpyABF3 (Yang et al, 2020). Among DAM regulatory proteins, the most studied ones are C-Repeat Binding Factors (CBF), which are able to bind and activate DAM promoters by yeast one-hybrid and transient expression experiments in Japanese apricot and pear (Saito et al, 2015;Niu et al, 2016;Zhao et al, 2018b).…”