Abscisic Acid (ABA ) Promotes the Induction and Maintenance of Pear (Pyrus pyrifolia White Pear Group) Flower Bud Endodormancy

Abstract

Dormancy is an adaptive mechanism that allows temperate deciduous plants to survive unfavorable winter conditions. In the present work, we investigated the possible function of abscisic acid (ABA) on the endodormancy process in pear. The ABA content increased during pear flower bud endodormancy establishment and decreased towards endodormancy release. In total, 39 putative genes related to ABA metabolism and signal transductions were identified from pear genome. During the para- to endodormancy transition, PpNCED-2 and PpNCED-3 had high expression levels, while PpCYP707As expression levels were low. However, during endodormancy, the expression of PpCYP707A-3 sharply increased with increasing cold accumulation. At the same time, the ABA content of pear buds declined, and the percentage of bud breaks rapidly increased. On the other hand, the expression levels of PpPYLs, PpPP2Cs, PpSnRK2s, and PpABI4/ABI5s were also changed during the pear flower bud dormancy cycle. Furthermore, exogenous ABA application to para-dormant buds significantly reduced the bud breaks and accelerated the transition to endodormancy. During the whole treatment time, the expression level of PpPP2C-12 decreased to a greater extent in ABA-treated buds than in control. However, the expression levels of PpSnRK2-1, PpSnRK2-4, and PpABI5-1 were higher in ABA-treated buds. Our results indicated that PpCYP707A-3 and PpNCEDs play pivotal roles on the regulation of endodormancy release, while ABA signal transduction pathway also appears to be involved in the process. The present work provided the basic information about the function of ABA-related genes during pear flower bud dormancy process.

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

“…The PpyDAM3 expression pattern in this study was consistent with the ABA content during the bud dormancy cycle (Li, Xu, et al, ; Yang et al, ) and it was disrupted by FLU treatments (Figure c). The overexpression of PpyCYP707A3 in pear calli decreased the ABA content and the DAM3 expression level (Figure e–g), implying that pear DAM3 gene expression is regulated by the endogenous ABA content.…”

“…In poplar, ABA signaling promotes plasmodesmata closure, which is a crucial process during dormancy in response to short‐day conditions (Tylewicz et al, ), and helps regulate the onset of bud dormancy. In pear buds, ABA contents increase during dormancy induction and maintenance, but then decrease towards endo‐dormancy release (Li, Xu, et al, ; Yang et al, ). In the present study, FLU treatments accelerated the endo‐dormancy release of pear buds (Figures b and S1), confirming that ABA is essential for regulating bud dormancy maintenance.…”

“…In pear buds, the PpyABF3 mRNA level and the abundance of the encoded protein increased during the natural dormancy process. Additionally, the PpyABF3 protein was degraded in response to dormancy release (Figure c) and a decrease in the ABA content of pear buds (Li, Xu, et al, ). A ubiquitin E3 ligase, KEEP ON GOING, is important for the ABF3 degradation in Arabidopsis, although there are additional mechanisms that mediate this degradation (Chen et al, ).…”

“…In this study, 1‐year‐old shoots from 30‐year‐old naturally growing “Suli” pear trees ( Pyrus pyrifolia White Pear Group) and 15‐year‐old naturally growing “Cuiguan” trees ( P. pyrifolia Nakai) were analysed. In 2016–2017, ‘Suli’ samples were collected as described by Li, Xu, et al (). In 2017–2018, lateral flower buds were collected from ‘Suli’ trees on September 15, October 1, October 15, November 1, November 15, December 1, December 15, January 1, January 15, February 5, and February 25 and from ‘Cuiguan’ trees on October 15, November 1, November 15, December 1, December 15, January 1, January 15, and February 5.…”

“…Low temperatures along with increasing abscisic acid (ABA) concentrations induce the endo‐dormancy of some rosaceous plant species (Michailidis et al, ; Niu et al, ; Yang et al, ). However, a long‐term exposure to low temperatures leads to endo‐dormancy release and a decrease in the ABA content of buds, likely due to the downregulated expression of ABA biosynthesis genes ( XERICO and NECD ) and the upregulated expression of an ABA catabolism gene ( CYP707A ) (Li et al, ; Zheng et al, ). The overexpression of VvCYP707A4 in grape decreases the ABA level and significantly enhances bud break (Zheng et al, ).…”