Chiang C C, Hadwiger L A
Program in Genetics and Cell Biology, Washington State University, Pullman 99164-6430.
Mol Plant Microbe Interact. 1991 Jul-Aug;4(4):324-31. doi: 10.1094/mpmi-4-324.
Two pea genes, pI39 and pI230, which are specifically induced by two forma specials of Fusarium solani, encode closely related proteins with predicted molecular masses (Mr) of 8.2 and 8 kDa, respectively. Both proteins contain a signal sequence and are cleaved to mature proteins of Mr 5 kDa as indicated by an in vitro translation system. The mature proteins contain about 17% cysteine residues and have the potential to form four disulfide bonds. The two proteins share extensive homology in their signal sequences but much less homology as mature proteins. The cysteine residues of the mature proteins are highly conserved, suggesting functional importance. Southern hybridization suggests these genes belong to a multigene family. The relative accumulations of mRNA levels indicate that the two genes are expressed somewhat differentially. In both the compatible (susceptible) and incompatible reactions between F. solani and pea tissue, pI39 mRNA accumulates more slowly than pI230 mRNA and accumulates to relatively high levels after 24 hr of inoculation. The increase in accumulation of pI230 mRNA occurs within 6 hr and thus correlates with an initial suppression of the growth of both the compatible and incompatible pathogen, which is cytologically observable at 6 hr. pI39 and pI230 belong to a distinct class of pathogenesis-related proteins characterized previously, which are associated with and thus may contribute to nonhost resistance in plants.
两个豌豆基因pI39和pI230分别由茄丝核菌的两个专化型特异性诱导，它们编码的蛋白质密切相关，预测分子量（Mr）分别为8.2 kDa和8 kDa。如体外翻译系统所示，这两种蛋白质都含有信号序列，并被切割成Mr为5 kDa的成熟蛋白。成熟蛋白含有约17%的半胱氨酸残基，有可能形成四个二硫键。这两种蛋白质在信号序列上有广泛的同源性，但作为成熟蛋白时同源性要低得多。成熟蛋白的半胱氨酸残基高度保守，表明其功能重要性。Southern杂交表明这些基因属于一个多基因家族。mRNA水平的相对积累表明这两个基因的表达略有差异。在茄丝核菌与豌豆组织的亲和（感病）和非亲和反应中，pI39 mRNA的积累比pI230 mRNA慢，接种24小时后积累到相对较高水平。pI230 mRNA积累的增加在6小时内发生，因此与亲和及非亲和病原体生长的初始抑制相关，这在6小时时在细胞学上是可观察到的。pI39和pI230属于先前已鉴定的一类独特的病程相关蛋白，它们与植物的非寄主抗性相关，因此可能对其有贡献。
