Wheeler Michael H, Bruton Benny D, Puckhaber Lorraine S, Zhang Jiuxu, Stipanovic Robert D
Southern Plains Agricultural Research Center, USDA, ARS, 2765 F&B Road, College Station, Texas 77845, USA.
J Agric Food Chem. 2004 Jun 30;52(13):4113-20. doi: 10.1021/jf0308298.
Monosporascus cannonballus causes root rot and vine decline in muskmelons and watermelons. Wild types of this fungus often undergo degenerative changes that have been associated with yellow to brown pigmentation, hypovirulence, dsRNA infection, and decreased production of perithecia. In this study, degenerate isolates that produced yellow to brown pigments and no perithecia were obtained from wild-type cultures that had been stored for extended periods of time. Cultures of the degenerate isolates were found to accumulate five related hexaketides when grown on potato-dextrose agar (PDA). In contrast, these hexaketides were present only in minute amounts in wild-type cultures unless grown on NaCl-amended PDA. 1,8-Dihydroxynaphthalene melanin was established to be present in wild-type M. cannonballus and absent in the degenerate isolates. Various melanin-related metabolites, however, were produced by the variants. Tricyclazole in PDA cultures blocked melanin biosynthesis by the wild types but had little effect on hexaketide production by the degenerate isolates.
炮弹孢单囊壳菌可导致甜瓜和西瓜发生根腐病和藤蔓衰退。这种真菌的野生型常常会发生退化性变化，这些变化与黄色至棕色色素沉着、低毒力、双链RNA感染以及子囊壳产量降低有关。在本研究中，从长期保存的野生型培养物中获得了产生黄色至棕色色素且无子囊壳的退化分离株。发现退化分离株的培养物在马铃薯葡萄糖琼脂（PDA）上生长时会积累五种相关的六酮类化合物。相比之下，这些六酮类化合物在野生型培养物中仅微量存在，除非在添加了氯化钠的PDA上生长。已确定1,8 - 二羟基萘黑色素存在于野生型炮弹孢单囊壳菌中，而在退化分离株中不存在。然而，这些变体产生了各种与黑色素相关的代谢产物。PDA培养物中的三环唑可阻断野生型的黑色素生物合成，但对退化分离株的六酮类化合物产生几乎没有影响。
