Department of Biological Sciences, National Sun Yat-sen University, 804 Kaohsiung, Taiwan.
J Plant Physiol. 2010 Jul 1;167(10):838-47. doi: 10.1016/j.jplph.2010.01.005. Epub 2010 Feb 2.
In this report a full-length cDNA, SPCP2, which encoded a putative papain-like cysteine protease was isolated from senescent leaves of sweet potato (Ipomoea batatas). SPCP2 contained 1101 nucleotides (366 amino acids) in its open reading frame, and exhibited high amino acid sequence identities (ca. 68% to 83%) with plant cysteine proteases, including Actinidia deliciosa, Arabidopsis thaliana, Brassica oleracea, Phaseolus vulgaris, Pisum sativa, Vicia faba, Vicia sativa and Vigna mungo. RT-PCR analysis showed that SPCP2 gene expression was enhanced significantly in natural senescent leaves and in dark-, abscisic acid- (ABA-), jasmonic acid- (JA-) and ethephon-induced senescent leaves, but was almost not detected in mature green leaves, stems, and roots. Transgenic Arabidopsis with constitutive SPCP2 expression exhibited earlier floral transition from vegetative to reproductive growth, higher percentage of incompletely developed siliques per plant, reduced average fresh weight and lower germination percentage of seed, and higher salt and drought stress tolerance compared to those of control. Based on these results we conclude that sweet potato papain-like cysteine protease, SPCP2, is a functional senescence-associated gene, and its expression causes altered developmental characteristics and stress responses in transgenic Arabidopsis plants.
在本报告中，从甘薯（Ipomoea batatas）衰老叶片中分离出全长 cDNA SPCP2，该 cDNA 编码一种假定的木瓜蛋白酶样半胱氨酸蛋白酶。SPCP2 的开放阅读框包含 1101 个核苷酸（366 个氨基酸），与植物半胱氨酸蛋白酶（包括 Actinidia deliciosa、Arabidopsis thaliana、Brassica oleracea、Phaseolus vulgaris、Pisum sativa、Vicia faba、Vicia sativa 和 Vigna mungo）具有高度的氨基酸序列同一性（约 68%至 83%）。RT-PCR 分析表明，SPCP2 基因在自然衰老叶片以及黑暗、脱落酸（ABA）、茉莉酸（JA）和乙烯利诱导的衰老叶片中表达显著增强，但在成熟绿叶、茎和根中几乎检测不到。与对照相比，组成型表达 SPCP2 的转基因拟南芥表现出更早的花发育从营养生长到生殖生长的转变、每株植物未完全发育的蒴果的百分比更高、平均鲜重降低和种子发芽率降低以及对盐和干旱胁迫的耐受性提高。基于这些结果，我们得出结论，甘薯木瓜蛋白酶样半胱氨酸蛋白酶 SPCP2 是一个功能性衰老相关基因，其表达导致转基因拟南芥植物发育特征和应激反应发生改变。
