Parasitism by Cuscuta pentagona sequentially induces JA and SA defence pathways in tomato.
While plant responses to herbivores and pathogens are well characterized, responses to attack by other plants remain largely unexplored. We measured phytohormones and C(18) fatty acids in tomato attacked by the parasitic plant Cuscuta pentagona, and used transgenic and mutant plants to explore the roles of the defence-related phytohormones salicylic acid (SA) and jasmonic acid (JA). Parasite attachment to 10-day-old tomato plants elicited few biochemical changes, but a second attachment 10 d later elicited a 60-fold increase in JA, a 30-fold increase in SA and a hypersensitive-like response (HLR). Host age also influenced the response: neither Cuscuta seedlings nor established vines elicited a HLR in 10-day-old hosts, but both did in 20-day-old hosts. Parasites grew larger on hosts deficient in SA (NahG) or insensitive to JA [jasmonic acid-insensitive1 (jai1)], suggesting that both phytohormones mediate effective defences. Moreover, amounts of JA peaked 12 h before SA, indicating that defences may be coordinated via sequential induction of these hormones. Parasitism also induced increases in free linolenic and linoleic acids and abscisic acid. These findings provide the first documentation of plant hormonal signalling induced by a parasitic plant and show that tomato responses to C. pentagona display characteristics similar to both herbivore- and pathogen-induced responses.
Runyon
Justin B
JB
Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA.
Mescher
Mark C
MC
Felton
Gary W
GW
De Moraes
Consuelo M
CM
D000040:Abscisic Acid / Q000096:biosynthesis; D034182:Cuscuta / Q000254:growth & development*; D003517:Cyclopentanes / Q000378:metabolism*; D019787:Linoleic Acid / Q000096:biosynthesis; D008042:Linolenic Acids / Q000096:biosynthesis; D018551:Solanum lycopersicum / Q000378:metabolism* / Q000469:parasitology; D054883:Oxylipins / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism*; D036226:Seedlings / Q000254:growth & development; D013997:Time Factors
D003517:Cyclopentanes; D008042:Linolenic Acids; D054883:Oxylipins; D010937:Plant Growth Regulators; C011006:jasmonic acid; D000040:Abscisic Acid; D019787:Linoleic Acid; D020156:Salicylic Acid