Joost O, Bianchini G, Bell A A, Benedict C R, Magill C W
Department of Plant Pathology and Microbiology, Texas A&M University College Station 77843, USA.
Mol Plant Microbe Interact. 1995 Nov-Dec;8(6):880-5. doi: 10.1094/mpmi-8-0880.
Gossypium barbadense cottons are typically more resistant to wilt pathogens than are Gossypium hirsutum cultivars. Both species make terpenoid phytoalexins in response to infection, implicating isoprenoid biosynthesis as a factor in resistance. Conserved regions in plant 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), the first enzyme in the terpene biosynthesis pathway, were used to design polymerase chain reaction primers for cloning a fragment of a cotton HMGR gene. The clone was used as a probe on Northern blots to show that induction of HMGR mRNA following introduction of Verticillium dahliae spores into the vascular system is much more rapid in Seabrook Sea Island, a restant G. barbadense cotton, than it is in Rowden, a susceptible G. hirsutum. The amount of HMGR mRNA returned to near control levels in 4 days in the former variety but continued to accumulate in the latter. Specific enzyme activity of HMGR also increased more rapidly in stele extracts of Seabrook Sea Island than in Rowden.
海岛棉通常比陆地棉品种更能抵抗枯萎病病原体。这两个物种在受到感染时都会产生萜类植保素，这表明类异戊二烯生物合成是抗性的一个因素。植物萜类生物合成途径中的第一个酶——3-羟基-3-甲基戊二酰辅酶A还原酶（HMGR）的保守区域，被用于设计聚合酶链反应引物，以克隆棉花HMGR基因的一个片段。该克隆产物用作Northern杂交的探针，结果显示，将大丽轮枝菌孢子引入维管系统后，抗性海岛棉品种“Seabrook海岛棉”中HMGR mRNA的诱导比感病陆地棉品种“Rowden”快得多。在前者中，HMGR mRNA的量在4天内恢复到接近对照水平，而在后者中则继续积累。“Seabrook海岛棉”中柱提取物中HMGR的比酶活性也比“Rowden”增加得更快。
