水稻黄单胞菌水稻致病变种的超氧化物歧化酶活性及诱导

ACTIVITIES OF SUPEROXIDE DISMUTASE IN XANTHOMONAS ORYZAE PV. ORYZAE AND ITS INDUCTION

以水稻黄单胞菌水稻致病变种 (Xanthomonasoryzaepv .oryzae)的毒性菌株PXO99A和无毒菌株PXO99A(pBUavrXa1 0 F1 ) ,检测液体培养中菌体超氧化物歧化酶 (SOD)活性变化 ,以说明SOD与菌株致病性的关系。结果表明 ,菌体SOD活性高峰出现于延迟期末 ,之后下降 ;毒性菌株SOD活性高于无毒菌株。两个菌株的SOD活性的胞内定位均以胞质为主 ,占总活性的 70 %以上 ;酶体周质中SOD活性占总活性的 2 0 %～ 30 %。以 50～ 80 0 μmol/L外源O-2 处理细菌培养物 1h ,可诱导菌体中SOD活性的增加。其中以 2 0 0 μmol/LO-2 处理SOD活性最高 ;1 2h菌龄培养物的诱导效果优于 2 4h培养物 ;对毒性菌株SOD的诱导作用更为明显。外源O-2 处理后细菌存活率明显降低 ,2 4h培养物的存活率下降大于 1 2h培养物 ;毒性菌株存活率下降大于无毒菌株。

The activities of superoxide dismutase(SOD) in Xanthomonas oryzae pv. oryzae were determined to demonstrate the correlation of SOD activities with the bacterial virulence. In liquid culture, SOD activities of the tested strains reached the maxima at the end of lag phase and then declined. The virulent strain PXO99 A showed higher SOD activities than the avirulent strain PXO99 A(pBUavr Xa10.F1). Analysis on the subcellular location indicated that SOD activities detected from the cytoplasm and periplasm were over 70% and 20%～30% of the total, respectively. Treatment of the bacterial culture for 1?h with exogenous O - 2 at concentration of 50～800?μmol/L induced SOD activities of both the strains. The treatment with 200?μmol/L resulted in the highest SOD activities. The effect of exogenous O - 2 on SOD induction was more significant in 12?h culture than in 24?h culture, and more notable for the virulent strain PXO99 A. The treatment with exogenous O - 2 resulted in significantly decreased survival rate off both the strains. The decreases of survival rate were greater in 24?h culture than in 12?h culture, and more significantly for the virulent strain than for the avirulent one.