Four polygalacturonase gene family members were highlighted that contribute to elucidate the roles of polygalacturonase during the fertility conversion process in male-sterile wheat. Polygalacturonase (PG) belongs to a large family of hydrolases with important functions in cell separation during plant growth and development via the degradation of pectin. Specific expressed PGs in anthers may be significant for male sterility research and hybrid wheat breeding, but they have not been characterized in wheat (Triticum aestivum L.). In this study, we systematically studied the PG gene family using the latest published wheat reference genomic information. In total, 113 wheat PG genes were identified, which could be classified into six categories A–F according to their structure characteristics and phylogenetic comparisons with Arabidopsis and rice. Polyploidy and segmental duplications in wheat were proved to be mainly responsible for the expansion of the wheat PG gene family. RNA-seq showed that TaPGs have specific temporal and spatial expression characteristics, in which 12 TaPGs with spike-specific expression patterns were detected by qRT-PCR in different fertility anthers of KTM3315A, a thermo-sensitive cytoplasmic male-sterile wheat. Four of them specific upregulated (TaPG09, TaPG95, and TaPG93) or downregulated (TaPG87) at trinucleate stage of fertile anthers, and further aligning with the homologous in Arabidopsis revealed that they may undertake functions such as anther dehiscence, separation of pollen, pollen development, and pollen tube elongation, thereby inducing male fertility conversion in KTM3315A. These findings facilitate function investigations of the wheat PG gene family and provide new insights into the fertility conversion mechanism in male-sterile wheat.

中文翻译：

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多聚半乳糖醛酸酶基因家族的综合分析突出了与小麦花粉发育和雄性生育力相关的候选基因（Triticum aestivum L.）

强调了四个多聚半乳糖醛酸酶基因家族成员，它们有助于阐明多聚半乳糖醛酸酶在雄性不育小麦育性转换过程中的作用。多聚半乳糖醛酸酶（PG）属于水解酶大家族，通过果胶降解在植物生长发育过程中的细胞分离中发挥重要作用。花药中特定表达的 PG 可能对雄性不育研究和杂交小麦育种具有重要意义，但尚未在小麦 (Triticum aestivum L.) 中对其进行表征。在本研究中，我们利用最新发表的小麦参考基因组信息系统地研究了 PG 基因家族。共鉴定出 113 个小麦 PG 基因，根据其结构特征和与拟南芥和水稻的系统发育比较，可将其分为 A-F 六类。小麦中的多倍体和节段重复被证明是小麦PG基因家族扩增的主要原因。RNA-seq 显示 TaPGs 具有特定的时空表达特征，其中通过 qRT-PCR 在热敏细胞质雄性不育小麦 KTM3315A 的不同育性花药中检测到 12 个具有穗特异性表达模式的 TaPGs。其中四种在可育花药三核期特异性上调（TaPG09、TaPG95和TaPG93）或下调（TaPG87），进一步与拟南芥中的同源物比对表明它们可能承担花药开裂、花粉分离、花粉发育等功能。和花粉管伸长，从而在 KTM3315A 中诱导雄性生育力转换。