马唐生防菌画眉草弯孢霉毒素α,-βdehydro-curvularin对马唐叶绿体功能的影响

 马唐(Digitaria sanguinalis (L.) Scop.)生防菌画眉草弯孢霉(Curvularia eragrostidis)菌株QZ2000产生一种具有除草剂活性毒素α,β-dehydrocurvularin。通过研究该毒素对马唐类囊体膜光合活性的影响,发现毒素对马唐类囊体膜希尔反应活性、非环式光合磷酸化活性、Mg²⁺-ATP酶活性和Ca²⁺-ATP酶活性均有较强的抑制作用,并且Mg²⁺-ATP酶较Ca²⁺-ATP酶对毒素更为敏感,但毒素不抑制环式光合磷酸化活性。毒素对马唐叶片叶绿素含量影响较小。从试验结果还可看出,非环式光合磷酸化与希尔反应活性及ATP酶活性呈明显的正相关。上述结果表明,该毒素影响马唐叶绿体的功能。另外,根据我们的试验结果及文献报道,该毒素还具有抗菌活性和杀线虫活性,推测叶绿体可能不是该毒素的惟一作用位点。

The effect of α,β-dehydrocurvularin, a toxin from a bioherbicidal candidate Curvularia eragrostidis, on chloroplast function of Digitaria sanguinalis

C. eragrostidis strain QZ2000 is a potential biocontrol agent for large crabgrass (D. sanguinalis). Strain QZ2000 produces a mycotoxin with herbicidal activity, which is identified as α,β-dehydrocurvularin. The effect of mycotoxin on photochemical activity of large crabgrass thylakiod membranes was studied. It was found that mycotoxin strongly inhibited the activities of Hill reaction, non-cyclic photophosphorylation (PSP)and the activities of Mg²⁺-ATPase and Ca²⁺-ATPase, but it did not affect the activity of cyclic PSP and had little impact on photosynthetic pigment content. Mg²⁺-ATPase was more sensitive to mycotoxin than Ca²⁺-ATPase. The activities of non-cyclic PSP showed significant positive correlation with the activities of Hill reaction and ATPase. These results suggest that the mycotoxin affects the function of chloroplast. In addition, in terms of our research and other related researches about the antifungal and nematicidal activity of this mycotoxin, we deduce that chloroplast is not the unique site of the mycotoxin action.