College of Horticulture, South China Agricultural University, Guangdong 510642, People's Republic of China.
Mol Biol Rep. 2013 Jan;40(1):159-69. doi: 10.1007/s11033-012-2045-6. Epub 2012 Oct 17.
Self-incompatibility (SI) is one important factor that can result in Citrus seedlessness. However, the molecular mechanism of SI in Citrus is not clear yet. To isolate the pistil's SI-related genes, a suppression subtractive hybridization library was constructed using mature pistils of 'Wuzishatangju' mandarin (SI) as the tester and mature pistils of 'Shatangju' mandarin (self-compatibility, SC) as the driver. 229 differentially expressed cDNA clones from 967 positive clones were sequenced and identified. Differentially expressed ESTs are possibly involved in the SI reaction of 'Wuzishatangju' through a regulating signaling pathway, serine/threonine phosphatase activity, receptor kinase, embryonic development, gibberellin stimulus, or transcription. 11 out of 36 SI candidate genes displayed different expression patterns in various tissues and stages after self- and cross-pollination of 'Wuzishatangju'. The expression of CaBP (WY65), a senescence-protease (WY372), an unknown gene (WY283), and a WRKY (WY17) were up-regulated in the styles of 'Wuzishatangju' while higher expression of WY190 was observed in styles of 'Shatangju'. Highest expression levels of WY65, WY372, an annexin (WY598), the zinc-finger protein (WY376), a C2-protein (WY291), and an unknown gene (WY318) were detected in styles at 3 days after self-pollination of 'Wuzishatangju' while lowest levels were observed in styles at 3 days after cross-pollination of 'Wuzishatangju' × 'Shatangju'. The potential involvement of these genes in the SI reaction is discussed.
自交不亲和性（SI）是导致柑橘无核的一个重要因素。然而，柑橘 SI 的分子机制尚不清楚。为了分离雌蕊的 SI 相关基因，以‘梧孜沙糖桔’（SI）的成熟雌蕊为测试者，‘沙糖桔’（自交亲和，SC）的成熟雌蕊为驱动者，构建了一个抑制性消减杂交文库。从 967 个阳性克隆中，有 229 个差异表达的 cDNA 克隆被测序和鉴定。差异表达的 ESTs 可能通过调节信号通路、丝氨酸/苏氨酸磷酸酶活性、受体激酶、胚胎发育、赤霉素刺激或转录参与‘梧孜沙糖桔’的 SI 反应。在自交和杂交授粉后，‘梧孜沙糖桔’的不同组织和阶段中，36 个 SI 候选基因中的 11 个表现出不同的表达模式。在‘梧孜沙糖桔’的花柱中，WY65（钙结合蛋白）、WY372（衰老蛋白酶）、WY283（未知基因）和 WY17（WRKY）等 11 个基因的表达上调，而 WY190 在‘沙糖桔’的花柱中表达较高。在‘梧孜沙糖桔’自交后 3 天的花柱中，WY65、WY372、WY598（ annexin）、WY376（锌指蛋白）、WY291（C2 蛋白）和 WY318（未知基因）的表达水平最高，而在‘梧孜沙糖桔’ב沙糖桔’杂交授粉后 3 天的花柱中表达水平最低。讨论了这些基因在 SI 反应中的潜在作用。
