Bluhm B H, Woloshuk C P
Department of Botany and Plant Pathology, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA.
Mol Plant Microbe Interact. 2005 Dec;18(12):1333-9. doi: 10.1094/MPMI-18-1333.
Fusarium verticillioides, a fungal pathogen of maize, produces fumonisin mycotoxins that adversely affect human and animal health. Basic questions remain unanswered regarding the interactions between the host plant and the fungus that lead to the accumulation of fumonisins in maize kernels. In this study, we evaluated the role of kernel endosperm composition in regulating fumonisin B1 (FB1) biosynthesis. We found that kernels lacking starch due to physiological immaturity did not accumulate FB1. Quantitative polymerase chain reaction analysis indicated that kernel development also affected the expression of fungal genes involved in FB1 biosynthesis, starch metabolism, and nitrogen regulation. A mutant strain of F. verticillioides with a disrupted a-amylase gene was impaired in its ability to produce FB1 on starchy kernels, and both the wild-type and mutant strains produced significantly less FB1 on a high-amylose kernel mutant of maize. When grown on a defined medium with amylose as the sole carbon source, the wild-type strain produced only trace amounts of FB1, but it produced large amounts of FB1 when grown on amylopectin or dextrin, a product of amylopectin hydrolysis. We conclude that amylopectin induces FB1 production in F. verticillioides. This study provides new insight regarding the interaction between the fungus and maize kernel during pathogenesis and highlights important areas that need further study.
轮枝镰孢菌是玉米的一种真菌病原体，可产生伏马菌素霉菌毒素，对人类和动物健康产生不利影响。关于宿主植物与真菌之间的相互作用导致伏马菌素在玉米籽粒中积累的基本问题仍未得到解答。在本研究中，我们评估了籽粒胚乳成分在调节伏马菌素B1（FB1）生物合成中的作用。我们发现，由于生理不成熟而缺乏淀粉的籽粒不会积累FB1。定量聚合酶链反应分析表明，籽粒发育也会影响参与FB1生物合成、淀粉代谢和氮调节的真菌基因的表达。一种α-淀粉酶基因被破坏的轮枝镰孢菌突变菌株在淀粉质籽粒上产生FB1的能力受损，并且野生型和突变菌株在玉米的高直链淀粉籽粒突变体上产生的FB1均显著减少。当在以直链淀粉作为唯一碳源的限定培养基上生长时，野生型菌株仅产生微量的FB1，但在支链淀粉或支链淀粉水解产物糊精上生长时，它会产生大量的FB1。我们得出结论，支链淀粉可诱导轮枝镰孢菌产生FB1。本研究为发病机制过程中真菌与玉米籽粒之间的相互作用提供了新的见解，并突出了需要进一步研究的重要领域。
