黄杰 宋剑灵 安娜 邹晓燕 李季肤 刘国道 陈志坚

摘  要：低磷胁迫是限制作物生长和产量的重要因素之一。磷饥饿响应因子PHR（phosphate starvation response）是植物磷信号调控网络中的关键因子，具有调控植物磷平衡的生物学功能。本研究在柱花草（Stylosanthes guianensis）中克隆到转录因子SgPHR1和SgPHR2基因。SgPHR1和SgPHR2基因cDNA全长分别为1413 bp和849 bp，编码470和282个氨基酸残基，蛋白分子量分别为51.4 kD和30.9 kD。SgPHR1和SgPHR2均为SANT家族成员，包含MYB蛋白结构域和CC蛋白结构域，并具有多个潜在的磷酸化位点。亚细胞定位预测表明，SgPHR1和SgPHR2均定位于细胞核中。实时定量PCR结果表明，SgPHR1基因在柱花草根和叶中的表达量高于茎中的表达量，而SgPHR2基因在叶中表达量显著高于根和茎。缺磷（-P）和缺氮（-N）处理均显著增强了SgPHR1和SgPHR2在柱花草根中的表达。不同缺磷时间处理结果进一步表明了SgPHR1和SgPHR2在转录水平上响应低磷胁迫，暗示SgPHR1和SgPHR2可能参与了柱花草对低磷胁迫的应答。本研究结果为解析柱花草响应低磷胁迫的分子机制提供了候选基因。

关键词：低磷胁迫;柱花草;PHR;基因表达;转录因子

Abstract： Low phosphorus （P） stress is one of the constraints limiting crop growth and yield. PHR （phosphate starvation response） is the key factor in P signaling network， regulating plant phosphate （Pi） homeostasis. In this study， two transcription factors， SgPHR1 and SgPHR2， were cloned in stylo （Stylosanthes guianensis）. The full length of SgPHR1 and SgPHR2 was 1413 bp and 849 bp， encoding 470 and 282 amino acid residues， respectively. The protein molecular weight of SgPHR1 and SgPHR2 was 51.4 kD and 30.9 kD， respectively. Both SgPHR1 and SgPHR2 belonged to the SANT family and contained MYB protein domain and CC protein domain. Both SgPHR1 and SgPHR2 included a set of potential phosphorylation sites. Subcellular localization prediction indicated that both SgPHR1 and SgPHR2 localized to the nucleus. Real-time quantitative PCR results showed that the transcript of SgPHR1 in leaves and roots was higher than that in stems， while SgPHR2 exhibited the highest expression in leaves. Furthermore， the expression of SgPHR1 and SgPHR2 was up-regulated by both -P and nitrogen （-N） deficient treatments in stylo roots. The transcription level of SgPHR1 and SgPHR2 was found to be increased during -P treatments， suggesting that SgPHR1 and SgPHR2 involved in stylo response to Pi starvation. This study would provide candidate genes for investigating the mechanism of stylo response to P deficiency.

Keywords： low phosphorus stress; Stylosanthes; phosphate starvation response; gene expression; transcription factor

磷（phosphorus，P）是植物生长发育所必需的大量营养元素之一，参与植物多种生理生化过程，如光合作用、能量和脂类代谢等[1-3]。然而，土壤磷的有效性低，特别是在酸性土壤中，磷容易被铝（Al）和铁（Fe）等金属元素结合形成不能被植物直接吸收和利用的难溶性磷[4-5]。因此，低磷胁迫是酸性土壤上限制作物生长和产量的重要因素之一[6]。在低磷环境下，植物表现出植株矮小，生长缓慢，叶色暗绿和根系发育受阻等胁迫症状[7]。……