Transcriptome analysis and metabolic profiling reveal the key role of α-linolenic acid in dormancy regulation of European pear

First author: Gilad Gabay; Affiliations: Institute of Plant Sciences, Volcani Research Center (火山研究中心植物科学研究所): Rishon Lezion, Israel

Corresponding author: Moshe A Flaishman

Deciduous trees require sufficient chilling during winter dormancy to grow. To decipher the dormancy-regulating mechanism, we carried out RNA sequencing (RNA-Seq) analysis and metabolic profiling of European pear (Pyrus communis L.) vegetative buds during the dormancy phases. Samples were collected from two cultivars that differed greatly in their chilling requirements: ‘Spadona’ (SPD), a low chilling requirement cultivar; and Harrow Sweet (HS), a high chilling requirement cultivar. Comparative transcriptome analysis revealed >8500 differentially expressed transcripts; most were related to metabolic pathways. Out of 174 metabolites, 44 displayed differential levels in both cultivars, 38 were significantly changed only in SPD, and 15 only in HS. Phospholipids were mostly accumulated at the beginning of dormancy, sugars between before dormancy and mid-dormancy, and fatty acids, including α-linolenic acid, at dormancy break. Differentially expressed genes underlying previously identified major quantitative trait loci (QTLs) in linkage group 8 included genes related to the α-linolenic acid pathway, 12-oxophytodienoate reductase 2-like, and the DORMANCY-ASSOCIATED MADS-BOX (DAM) genes, PcDAM1 and PcDAM2, putative orthologs of PpDAM1 and PpDAM2, confirming their role for the first time in European pear. Additional new putative dormancy-related uncharacterized genes and genes related to metabolic pathways are suggested. These results suggest the crucial role of α-linolenic acid and DAM genes in pear bud dormancy phase transitions.

落叶乔木在冬季休眠时需要足够的低温。为了解析林木中休眠调控机制，作者对处于冬眠时期的欧洲梨营养芽进行了转录组和代谢组分析。作者的研究材料为两个具有明显差异的栽培种：低冷需求的Spadona和高冷需求的Harrow Sweet。比较转录组鉴定了超过8500个差异表达转录本，大多数转录本与代谢通路相关。在174个代谢物中，44个在两个栽培种中均表现出差异，38个仅在Spadona中显著差异，15个仅在Harrow Sweet中显著差异。磷脂在休眠起始时显著积累，糖在休眠前和休眠中期显著积累，而包括α-亚麻酸在内的脂肪酸在休眠结束后显著积累。先前鉴定的8号连锁群上的QTL位点区域的基因包括与α-亚麻酸通路相关基因、12-氧代植二烯酸还原酶OPR2、休眠先关MADS-box基因PcDAM1和PcDAM2以及这两个基因的同源基因存在差异表达。另外，作者还鉴定到了一些新的休眠相关的未知功能基因和一些与代谢通路相关基因。本文的结果揭示了α-亚麻酸和DAM基因在欧洲梨营养芽休眠状态转变中发挥重要作用。

通讯：Moshe A Flaishman (https://www.agri.gov.il/people/583.aspx)

个人简介：落叶果树的开花和果实发育；苹果、梨和无花果的改良育种；无花果和梨的常规育种。

doi: https://doi.org/10.1093/jxb/ery405

Journal: Journal of Experimental Botany

First Published: 26 December, 2018