玉米胚乳母本印记基因ZmVIL1的克隆及印记特性分析

印记基因在玉米籽粒发育中具有重要作用。玉米ZmVIL1是母本印记基因。本研究通过RACE扩增, 获得了ZmVIL1基因的cDNA全长, 约2.2 kb, 编码598个氨基酸。根据对B73和Mo17正反交授粉后14 d胚乳和胚中ZmVIL1等位基因的表达分析, 该基因仅在玉米胚乳中表现母本印记, 而在胚中则无印记现象。在郑58和昌7-2、黄C和178、PH6WC和PH4CV正反交14 d胚乳中ZmVIL1也表现印记, 因此该基因为基因特异性的二元印记。ZmVIL1在B73、Mo17正反交授粉后12~28 d胚乳中处于持续印记状态。组织表达模式研究表明ZmVIL1在营养生长和生殖生长阶段均有表达; ZmVIL1在玉米授粉后10 d籽粒、雌穗、雄穗、花丝中表达量较高, 其次是根、胚珠及授粉后25 d的胚中, 推测ZmVIL1在玉米籽粒及花发育过程中均具有重要功能。

Cloning and Imprinting Characterization Analyses of Paternally Expressed Gene ZmVIL1 in Maize Endosperm

Imprint genes play important roles in maize seed development. ZmVIL1 is a paternal-preferentially expressed gene. In this study, the full length of ZmVIL1 cDNA was cloned by RACE, which is about 2.2 kb and encodes a protein consisting of 598 amino acids. The analyses of allele expression of ZmVIL1 in endosperm and embryo at 14 days after pollination (DAP) of hybrids from reciprocal crosses between B73 and Mo17 indicated that ZmVIL1 was maternally imprinted in endosperm, while not in embryo. The allele expression was extensively evaluated in 14 DAP endosperm of hybrids form reciprocal crosses of Zheng 58 and Chang 7-2, Huang C and 178, PH6WC and PH4CV, and in 10-28 DAP endosperm of hybrids form reciprocal crosses of B73 and Mo17, suggesting that ZmVIL1 was gene-specific and binary imprinting and consistently imprinted in endosperm from 12 to 28 DAP. Expression pattern analyses demonstrated ZmVIL1 was constitutively expressed from vegetative to reproductive stages. ZmVIL1 was strongly expressed in seed at 10 DAP, immature tassels, immature ears and silk, and secondly expressed in ovule, embryo at 25 DAP and root, suggesting that ZmVIL1 plays important roles in maize seed and flower development.