Zhu B, Chen T H, Li P H
Department of Horticultural Sciences, University of Minnesota, St. Paul 55108, USA. zhub@uacrac 1.ucr.edu
Planta. 1996;198(1):70-7. doi: 10.1007/BF00197588.
The expression patterns of plant defense genes encoding osmotin and osmotin-like proteins imply a dual function in osmotic stress and plant pathogen defense. We have produced transgenic potato (Solanum commersonii Dun.) plants constitutively expressing sense or antisense RNAs from chimeric gene constructs consisting of the cauliflower mosaic virus 35S promoter and a cDNA (pA13) for an osmotin-like protein. Transgenic potato plants expressing high levels of the pA13 osmotin-like protein showed an increased tolerance to the late-blight fungus Phytophthora infestans at various phases of infection, with a greater resistance at an early phase of fungal infection. There was a decrease in the accumulation of osmotin-like mRNAs and proteins when antisense transformants were challenged by fungal infection, although the antisense transformants did not exhibit any alterations in disease susceptibility. Expression of pA13 sense and antisense RNAs had no effect on the development of freezing tolerance in transgenic plants when assayed under a variety of conditions including treatments with abscisic acid or low temperature. These results provide evidence of antifungal activity for a potato osmotin-like protein against the fungus P. infestans, but do not indicate that pA13 osmotin-like protein is a major determinant of freezing tolerance.
编码渗透素和类渗透素蛋白的植物防御基因的表达模式表明其在渗透胁迫和植物病原体防御中具有双重功能。我们构建了由花椰菜花叶病毒35S启动子和一个类渗透素蛋白的cDNA（pA13）组成的嵌合基因构建体，并产生了组成型表达正义或反义RNA的转基因马铃薯（Solanum commersonii Dun.）植株。在感染疫霉（Phytophthora infestans）的不同阶段，表达高水平pA13类渗透素蛋白的转基因马铃薯植株对晚疫病真菌的耐受性增强，在真菌感染早期具有更强的抗性。当反义转化体受到真菌感染时，类渗透素mRNA和蛋白的积累减少，尽管反义转化体在疾病易感性方面没有表现出任何变化。在包括脱落酸处理或低温处理在内的各种条件下进行检测时，pA13正义和反义RNA的表达对转基因植物抗冻性的发育没有影响。这些结果提供了一种马铃薯类渗透素蛋白对疫霉具有抗真菌活性的证据，但并不表明pA13类渗透素蛋白是抗冻性的主要决定因素。
