Department of Botany and Plant Pathology, and Agricultural Research Service-United States, Purdue University, West Lafayette, IN 47907.
Proc Natl Acad Sci U S A. 1983 Nov;80(21):6576-80. doi: 10.1073/pnas.80.21.6576.
Susceptibility of sorghum to the fungal pathogen Periconia circinata and sensitivity to its host-specific toxin are determined by the semidominant allele at the pc locus. Pretreatment of susceptible seedlings with cycloheximide or cordycepin for 4 hr before treatment with the toxin protected the seedlings against toxin-induced loss of electrolytes and prevented development of disease symptoms. In vivo incorporation of [(3)H]leucine into protein was inhibited 91% and 47% by cycloheximide and cordycepin, respectively, but was not affected by the toxin. Gel electrophoresis and fluorography of in vivo-labeled proteins extracted from non-treated and toxin-treated root tips of near-isogenic susceptible and resistant lines revealed a selective increase in radioactivity of a protein band at M(r) 16,000 only in preparations from toxin-treated susceptible root tips. Two-dimensional gel electrophoresis separated the M(r) 16,000 band into four proteins and confirmed the increased rate of synthesis. Products of in vitro translation were substantially enriched with the four M(r) 16,000 proteins when total RNA from toxin-treated susceptible root tips was used in a cell-free protein-synthesizing system. Because the proteins that increase are common to both susceptible and resistant genotypes, the toxin apparently interferes with a regulatory function, perhaps a function of the pc locus, and thereby alters gene expression in the susceptible genotype. The data suggest but do not establish that phytotoxicity results from the increased rate of synthesis of the specific proteins.
高粱对真菌病原体佩里孔尼亚·西库林纳（Periconia circinata）的易感性及其对其宿主特异性毒素的敏感性由 pc 基因座的半显性等位基因决定。在用毒素处理易感幼苗之前，用环己酰亚胺或虫草素预处理 4 小时，可保护幼苗免受毒素诱导的电解质损失，并防止疾病症状的发展。用 [(3)H]亮氨酸在体内掺入蛋白质分别被环己酰亚胺和虫草素抑制 91%和 47%，但不受毒素影响。凝胶电泳和来自近等基因敏感和抗性系根尖的未经处理和用毒素处理的根尖端的体内标记蛋白质的荧光显影显示，仅在来自用毒素处理的敏感根尖端的制剂中，M(r)16,000 的蛋白质带的放射性显著增加。二维凝胶电泳将 M(r)16,000 带分为四种蛋白质，并证实了合成速率的增加。当用来自用毒素处理的敏感根尖端的总 RNA 在无细胞蛋白质合成系统中使用时，体外翻译的产物大大富集了四种 M(r)16,000 蛋白质。由于增加的蛋白质是易感和抗性基因型共有的，因此毒素显然干扰了调节功能，也许是 pc 基因座的功能，从而改变了易感基因型中的基因表达。这些数据表明但不能确定植物毒性是由于特定蛋白质合成速率的增加所致。
