Differential activation of potato 3-hydroxy-3-methylglutaryl coenzyme A reductase genes by wounding and pathogen challenge.
Potato genes encoding 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) were expressed in response to pathogen, elicitor, and wounding. HMGR catalyzes the rate-limiting step in isoprenoid biosynthesis leading to accumulation of phytoalexins and steroid glycoalkaloids. Wounding caused increases in HMGR mRNA levels. A rapid and transient peak occurred 30 minutes after wounding, followed by a slower peak at 14 hours; both were correlated with increased enzyme activity. Induction of HMGR mRNA by the soft rot pathogen Erwinia carotovora subsp carotovora or arachidonic acid began 8 hours after challenge and continued through 22 hours. Potato HMGR is encoded by a gene family. An HMGR gene-specific probe was used to demonstrate that one isogene of the HMGR family is pathogen activated and is distinct from isogene(s) that are wound activated. This provides evidence that defense-related increases in HMGR activity are due to mRNA level increases and that HMGR isogenes are activated differentially by wounding or pathogen challenge.
Yang
Z
Z
Department of Plant Pathology, Physiology, and Weed Science, Virginia Polytechnic Institute and State University, Blacksburg 24061-0330.
Park
H
H
Lacy
G H
GH
Cramer
C L
CL
D001095:Arachidonic Acids / Q000494:pharmacology; D005786:Gene Expression Regulation; D006903:Hydroxymethylglutaryl CoA Reductases / Q000235:genetics* / Q000378:metabolism; D007545:Isoproterenol / Q000378:metabolism; D007700:Kinetics; D005810:Multigene Family; D016973:Pectobacterium carotovorum / Q000502:physiology; D011198:Solanum tuberosum / Q000201:enzymology / Q000235:genetics* / Q000382:microbiology
D001095:Arachidonic Acids; D006903:Hydroxymethylglutaryl CoA Reductases; D007545:Isoproterenol