Botanisches Institut, Universität Kiel, Am Botanischen Garten 1-9, 24118 Kiel, Germany.
Department of Plant Systems Biology, Flanders Institute of Biotechnology, B-9052 Gent, Belgium.
New Phytol. 2009 Mar;181(4):820-831. doi: 10.1111/j.1469-8137.2008.02710.x.
Phytosulfokine-α (PSK-α) is a disulfated pentapeptide described to act as a growth factor in suspension cells. In this study, the involvement of PSK signaling through the PSK receptor gene AtPSKR1 in Arabidopsis root growth was assessed.Expression studies of PSK precursor genes and of AtPSKR1 were performed in roots with RT-PCR and P:GUS analyses. Root elongation, lateral root formation, cell production and root cell elongation were analyzed in wild-type (wt) and in the receptor knockout mutant Atpskr1-T treated with or without synthetic PSK-α.Phytosulfokine and AtPSKR1 genes are differentially expressed in roots. PSK-α induced root growth in a dose-dependent manner without affecting lateral root density. Kinematic analysis established that enhancement of root growth by PSK-α was mainly caused by an increase in cell size. In Atpskr1-T, the primary roots were shorter as a result of reduced mature cell size and a smaller root apical meristem composed of fewer cells than in wt.The results indicate that PSK-α signaling through AtPSKR1 affects root elongation primarily via control of mature cell size. Root organogenesis, on the other hand,is not controlled by PSK-α.
植物磺肽素-α（PSK-α）是一种已被描述为在悬浮细胞中作为生长因子起作用的五肽硫酸盐。本研究评估了 PSK 信号通过拟南芥根生长中的 PSK 受体基因 AtPSKR1 的参与。通过 RT-PCR 和 P:GUS 分析对 PSK 前体基因和 AtPSKR1 的表达进行了研究。在野生型（wt）和受体敲除突变体 Atpskr1-T 中分析了根伸长、侧根形成、细胞产生和根细胞伸长，并用或不用合成 PSK-α 处理。PSK 和 AtPSKR1 基因在根中差异表达。PSK-α以剂量依赖的方式诱导根生长，而不影响侧根密度。动态分析表明，PSK-α对根生长的增强主要是由于细胞大小的增加。在 Atpskr1-T 中，由于成熟细胞尺寸减小和由细胞组成的根尖分生组织较小，主根较短，而 wt 中的细胞较小。结果表明，通过 AtPSKR1 的 PSK-α 信号主要通过控制成熟细胞大小来影响根伸长。另一方面，根器官发生不受 PSK-α控制。
