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Title: REGULATION OF HMG-COA REDUCTASE IN GOSSYPOL FORMATION IN COTTON PLANTS

Author
item BIANCHINI, GRACIELA - TEXAS A&M UNIVERSITY
item BENEDICT, C - TEXAS A&M UNIVERSITY
item JOOST, OSCAR - TEXAS A&M UNIVERSITY
item MAGILL, CLINT - TEXAS A&M UNIVERSITY
item Bell, Alois - Al

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/11/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) has a great significance in the production of isoprenoid compounds. In cotton stele tissue HMGR plays an important role in the synthesis of terpenoid phytoalexins where are pathogen response compounds. We inoculated two different cotton cultivars with Verticillium dahliae, causal agent of Verticillium wilt which, represents a serious problem in the cultivation of this crop. The induction of terpenoid phytoalexins by V. dahliae was subsequently studied using the tolerant cultivar Gossypium barbadense L. cv Seabrook Sea Island 12B2 (Seabrook) and the susceptible variety Gossypium hirsutum cv Rowden. G. barbadense is a lower yielding Egyptian cotton, interspecifically compatible with G. hirsutum. The rapid increase of the enzyme activity in the Seabrook variety, compared to the Rowden cultivar is correlated with the increase of HMGR mRNA levels. The peak of maximum activity appeared to be delayed by 24 h in the susceptible Rowden variety (101.9 nmol MVA/h/mg of protein) compared to the tolerant Seabrook (122.8 nmol MVA/h/ mg of protein). This study provides evidence that the defense-related increases in HMGR activity are due to mRNA level increases. The significance of these results for the regulation of HMGR and its role in plant defense mechanisms are discussed.