Yu Shu, Amaral Douglas, Brown Patrick H, Ferguson Louise, Tian Li
Department of Plant Sciences, University of California, Davis, Davis, CA, United States.
University of California Cooperative Extension Kings County, Hanford, CA, United States.
Front Plant Sci. 2023 Sep 22;14:1240442. doi: 10.3389/fpls.2023.1240442. eCollection 2023.
Pistachio ( L.), an economically and nutritionally important tree crop, relies on winter chill for bud endodormancy break and subsequent blooming and nut production. However, insufficient winter chill poses an increasing challenge in pistachio growing regions. To gain a better understanding of the physiological and biochemical responses of endodormant pistachio buds to chilling accumulation, we investigated the global gene expression changes in flower buds of pistachio cv. Kerman that were cultivated at three different orchard locations and exposed to increasing durations of winter chill. The expression of genes encoding β-1,3-glucanase and β-amylase, enzymes responsible for breaking down callose (β-1,3-glucan) and starch (α-1,4-glucan), respectively, increased during the endodormancy break of pistachio buds. This result suggested that the breakdown of callose obstructing stomata as well as the release of glucose from starch enables symplasmic trafficking and provides energy for bud endodormancy break and growth. Interestingly, as chilling accumulation increased, there was a decrease in the expression of (), encoding an enzyme that uses carotenoids as substrates and catalyzes the rate-limiting step in abscisic acid (ABA) biosynthesis. The decrease in expression suggests ABA biosynthesis is suppressed, thus reducing inhibition of endodormancy break. The higher levels of carotenoid precursors and a decrease in ABA content in buds undergoing endodormancy break supports this suggestion. Collectively, the temporal transcriptome and biochemical analyses revealed that the degradation of structural (callose) and non-structural (starch) carbohydrates, along with the attenuation of ABA biosynthesis, are critical processes driving endodormancy break in pistachio buds.
阿月浑子（Pistacia vera L.）是一种具有重要经济和营养价值的果树作物，其芽的内休眠解除以及随后的开花和坚果生产依赖于冬季低温。然而，冬季低温不足对阿月浑子种植区构成了日益严峻的挑战。为了更好地了解处于内休眠状态的阿月浑子芽对低温积累的生理和生化反应，我们研究了在三个不同果园地点种植并暴露于不同时长冬季低温下的阿月浑子品种克尔曼（Kerman）花芽中的全球基因表达变化。在阿月浑子芽的内休眠解除过程中，分别负责分解胼胝质（β - 1,3 - 葡聚糖）和淀粉（α - 1,4 - 葡聚糖）的β - 1,3 - 葡聚糖酶和β - 淀粉酶编码基因的表达增加。这一结果表明，阻碍气孔的胼胝质分解以及淀粉中葡萄糖的释放能够实现共质体运输，并为芽的内休眠解除和生长提供能量。有趣的是，随着低温积累的增加，编码一种以类胡萝卜素为底物并催化脱落酸（ABA）生物合成限速步骤的酶的（）表达下降。（）表达的下降表明ABA生物合成受到抑制，从而减少了对内休眠解除的抑制。内休眠解除的芽中类胡萝卜素前体水平较高以及ABA含量下降支持了这一观点。总体而言，时间转录组和生化分析表明，结构性（胼胝质）和非结构性（淀粉）碳水化合物的降解以及ABA生物合成的减弱是驱动阿月浑子芽内休眠解除的关键过程。
