Suen Pui Kit, Zhang Siyi, Sun Samuel Sai-Ming
Institute of Plant Molecular Biology and Agriculture Biotechnology, The Chinese University of Hong Kong, Hong Kong SAR, China,
Plant Cell Rep. 2015 Jun;34(6):981-92. doi: 10.1007/s00299-015-1759-z. Epub 2015 Feb 6.
SlPAP1 is a phosphate starvation responsive purple acid phosphatase during tomato seed germination. Future research on its family members in tomato might improve the phosphate stress tolerance. Phosphate deficiency is a major constraint upon crop growth and yield. In response to phosphate deficiency, plants secrete acid phosphatases (APases) to scavenge organic phosphate from soil. In this study, we investigated the impact of Pi starvation on germination and seedling growth of tomato, and we then cloned and characterized a phosphate starvation responsive purple APase (SlPAP1) that expressed during tomato seedling growth. Our results showed that phosphate deficiency reduced germination and growth rates of tomato, and also increased intracellular and secretory APase activity in a concentration-dependent manner. An in-gel activity assay found that two APases of 50 and 75 kDa were secreted during conditions of phosphate deficiency. SlPAP1 is a single copy gene belonging to a small gene family. It was expressed as a cDNA of approximately 1.5 kbp encoding a secreted glycoprotein of 470 amino acids. Northern blot analysis showed that SlPAP1 was specifically expressed in root tissue during phosphate deficiency. SlPAP1 had high sequence identity (56-89%) with other plant PAPs and contained highly conserved metal-binding residues. SlPAP1 is the first PAP to be cloned and characterized from tomato. This study provides useful information for future research on PAP family members in tomato, leading to better understanding of phosphate deficiency in this important crop plant.
SlPAP1是番茄种子萌发过程中一种对磷饥饿有响应的紫色酸性磷酸酶。未来对番茄中其家族成员的研究可能会提高番茄对磷胁迫的耐受性。磷缺乏是作物生长和产量的主要限制因素。作为对磷缺乏的响应，植物会分泌酸性磷酸酶（APases）以从土壤中清除有机磷。在本研究中，我们调查了磷饥饿对番茄萌发和幼苗生长的影响，然后克隆并鉴定了一种在番茄幼苗生长期间表达的对磷饥饿有响应的紫色APase（SlPAP1）。我们的结果表明，磷缺乏降低了番茄的萌发率和生长速率，并且还以浓度依赖的方式增加了细胞内和分泌型APase的活性。凝胶内活性分析发现，在磷缺乏条件下分泌了两种分子量分别为50 kDa和75 kDa的APases。SlPAP1是一个小基因家族中的单拷贝基因。它被表达为一个约1.5 kbp的cDNA，编码一个由470个氨基酸组成的分泌型糖蛋白。Northern印迹分析表明，SlPAP1在磷缺乏时在根组织中特异性表达。SlPAP1与其他植物PAPs具有较高的序列同一性（56 - 89%），并包含高度保守的金属结合残基。SlPAP1是首个从番茄中克隆和鉴定的PAP。本研究为未来对番茄中PAP家族成员的研究提供了有用信息，有助于更好地理解这种重要农作物中的磷缺乏情况。
