以淀粉酶为标记选择水稻白叶枯病菌毒性基因突变体

TO ISOLATE VIRULENCE GENE MUTANTES OF XANTHOMONAS CAMPESTRISPV.ORYZAEUSING AMYLASE ACTVITY AS A MARKER

用转座子 Tn5诱变水稻白叶枯病菌日本系统小种1菌(?) FXOⅠ基因组,在平板上以淀粉酶活性作为指示性状,从6250个 Tn5诱变株中筛选出14个毒性基因突变体,它们失去了对水稻品种 IR26的致病性.其中有4个突变体同时也失去了诱导烟草产生过敏性反应的能力,被鉴定为 hrp 基因突变体。这些毒性基因突变体在生长特性,几种主要胞外水解酶(蛋白酶,果胶酶,纤维素酶和脂酶)活性等表型(?)化方面具有多效性。通过 Southern 吸印杂交,所有毒性基因突变体 DNA 的 EcoR Ⅰ片段与^(32)P 标记的 Tn5探针质粒都有同源杂交带,Tn5有4种不同类型的插入位点。

Transposon Tn5 mutagenesis in a wildtype strain JXO I of Xanthomonas campestris pv.oryzaewas conducted.Screening of 6 250 Tn5-induced clones on plates using amylase activity as a marker led to theisolation of 14 virulence gene mutants avirulent on susceptible rice cultivar IR26,4 of which lost the abilityto elicit a hypersensitive response on tobacco plants and were identified as hrp gene mutants.The pleiotropicalternation of phenotype of these mutants included the growth characteristics,and the activity ofprotenase,petase,cellulase and lipolysase.Southern blot analysis of EcoRI digested total DNA from allavirulent mutants with ^(32)p labelled Tn5-containing plasmid revealed that insertion of Tn5 occurred in at lesat4 different sites.