Maryani M M, Morse M V, Bradley G, Irving H R, Cahill D M, Gehring C A
School of Biological and Chemical Sciences, Deakin University, Geelong, Victoria, 3217, Australia.
J Exp Bot. 2003 Jun;54(387):1553-64. doi: 10.1093/jxb/erg174. Epub 2003 Apr 28.
Plant natriuretic peptide immuno-analogues (irPNP) have previously been shown to affect a number of biological processes including stomatal guard cell movements, ion fluxes and osmoticum-dependent water transport. Tissue printing and immunofluorescent labelling techniques have been used here to study the tissue and cellular localization of irPNP in ivy (Hedera helix L.) and potato (Solanum tuberosum L.). Polyclonal antibodies active against human atrial natriuretic peptide (anti-hANP) and antibodies against irPNP from potato (anti-StPNP) were used for immunolabelling. Tissue prints revealed that immunoreactants are concentrated in vascular tissues of leaves, petioles and stems. Phloem-associated cells, xylem cells and parenchymatic xylem cells showed the strongest immunoreaction. Immunofluorescent microscopy with fluorescein isothiocyanate (FITC)-conjugated goat anti-rabbit IgG supported this finding and, furthermore, revealed strong labelling to stomatal guard cells and the adjacent apoplastic space as well. Biologically active immunoreactants were also detected in xylem exudates of a soft South African perennial forest sage (Plectranthus ciliatus E. Mey ex Benth.) thus strengthening the evidence for a systemic role of the protein. In summary, in situ cellular localization is consistent with physiological responses elicited by irPNPs reported previously and is indicative of a systemic role in plant homeostasis.
植物利钠肽免疫类似物（irPNP）此前已被证明会影响许多生物过程，包括气孔保卫细胞运动、离子通量和渗透依赖性水分运输。本文采用组织印迹和免疫荧光标记技术来研究irPNP在常春藤（Hedera helix L.）和马铃薯（Solanum tuberosum L.）中的组织和细胞定位。使用对人心房利钠肽有活性的多克隆抗体（抗hANP）和来自马铃薯的抗irPNP抗体（抗StPNP）进行免疫标记。组织印迹显示，免疫反应物集中在叶片、叶柄和茎的维管组织中。韧皮部相关细胞、木质部细胞和薄壁木质部细胞显示出最强的免疫反应。用异硫氰酸荧光素（FITC）偶联的山羊抗兔IgG进行免疫荧光显微镜检查支持了这一发现，此外，还显示对气孔保卫细胞和相邻的质外体空间也有强烈标记。在南非一种软质多年生森林鼠尾草（Plectranthus ciliatus E. Mey ex Benth.）的木质部渗出物中也检测到了生物活性免疫反应物，从而加强了该蛋白具有系统作用的证据。总之，原位细胞定位与先前报道的irPNPs引发的生理反应一致，表明其在植物体内稳态中具有系统作用。
