Characterisation of the whole-genome wide hexokinase gene family unravels the functional divergence in pear (<i>Pyrus bretschneideri</i> Rehd.)

Hexokinase genes <i>(HXK</i>) encode enzymes that play an important role in fruit quality and plant development because they participate in the first step of the glycolytic pathway for sugar accumulation and metabolism. In this study, the authors conducted analysis of the phylogeny, gene structure, and expression of <i>HXK</i> genes in pear (<i>Pyrus bretschneideri</i> Rehd.), comparing them with 7 other plant species. A total of 10 <i>HXK</i> protein sequences from pear and 33 <i>HXK</i>s from 7 other species were identified and clustered into 4 groups, matching their motif classification. Duplication events and motif structure variation attributed the diversification of <i>HXK</i> genes, supported by differential expression pattern of <i>PbrHXKs</i> from pear fruit transcriptome data and qRT – PCR verification. Combining pear fruit soluble sugar content data and analyses above, <i>PbrHXK1</i>and <i>PbrHXK3</i> were identified as important candidate genes in sorbitol, fructose, and glucose accumulation during pear fruit development. <i>PbrHXK1</i>and <i>PbrHXK3</i> were identified as important candidate genes in sorbitol, fructose, and glucose accumulation during pear fruit development. Subsequent research on these highly expressed <i>PbrHXKs</i> will benefit the enhancement of sugar content and quality in pear.己糖激酶基因（Hexokinase genes, HXK）所编码的酶在果实品质形成与植物生长发育过程中发挥关键作用，因其参与糖积累与代谢的糖酵解途径的第一步反应。本研究中，研究者对梨（Pyrus bretschneideri Rehd.）中的HXK基因进行了系统发育、基因结构及表达模式分析，并与其他7种植物的同类基因进行了比较。研究共鉴定得到梨中的10条HXK蛋白序列，以及其余7个物种的33条HXK序列，这些序列可被聚类为4个类群，与基序分类结果完全匹配。基因复制事件与基序结构变异是HXK基因功能分化的主要成因，该结论得到了梨果实转录组数据中PbrHXKs的差异表达模式以及实时定量反转录聚合酶链反应（qRT-PCR）验证的支持。结合梨果实可溶性糖含量数据与上述分析结果，研究者鉴定出PbrHXK1与PbrHXK3为梨果实发育过程中参与山梨醇、果糖及葡萄糖积累的重要候选基因。PbrHXK1与PbrHXK3为梨果实发育过程中参与山梨醇、果糖及葡萄糖积累的重要候选基因。后续针对这些高表达PbrHXKs的研究，将有助于提升梨的糖分含量与果实品质。