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ARS Home » Research » Publications at this Location » Publication #118232
Title: EXOGENOUS METHYL JASMONATE INDUCES VOLATILE EMISSIONS IN COTTON PLANTS.

Author
item Rodriguez Saona, Cesar
item Crafts-Brandner, Steven
item PARE, PAUL - TEXAS TECH. UNIVERSITY
item Henneberry, Thomas

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Natural enemies of insect pests use odors emitted from damaged plants in prey/host location. Current studies indicate that these compounds are also emitted from plants exposed to methyl jasmonate (MeJA). Methyl jasmonate is a plant hormone involved in protection against insects. We investigated whether MeJA causes the emission of compounds that are released from insect-damaged cotton. Cotton treated with MeJA released the same "induced" compounds as observed for insect-damaged plants. These compounds are called "induced" because they are newly synthesized in plants after insect damage. The timing of the "induced" compounds emitted from plants treated with MeJA or insects followed a similar pattern, with maximal release during the middle of the day, when natural enemies are more active. Compounds emitted from plants treated with MeJA were not only released from leaves that received the treatment but also from untreated portions of the plant. Our results indicate that MeJA can cause the emission of compounds in cotton important in host-searching behavior of natural enemies. This work will be of general interest to scientists interested in plant protection and improvement of biological control agents.

Technical Abstract: Methyl jasmonate (MeJA) is a phytohormone that induces plant chemical defenses against insect herbivores. We investigated the effect of exogenous MeJA on the emission of herbivore-induced volatiles; these volatile chemicals can signal natural enemies of the herbivore to the damaged plant. Exogenous treatment of glanded cotton with MeJA induced the eemission of the same volatile compounds as observed for herbivore-damaged plants. Cotton plants treated with MeJA emitted elevated levels of the terpenes (E)-B-ocimene, linalool, (3E)-4,8-dimethyl-1,3,7-nonatriene, (E,E)-A-farnesene, (E)-B-farnesene, and (E,E)-4,8,12-trimethyl-1,3,7,11- tridecatetraene compared to untreated controls. Other induced components included (Z)-3-hexenyl acetate, methyl salicylate, and indole. Methyl jasmonate treatment did not cause the release of any of the stored terpenes such as A-pinene, B-pinene, A-humulene, and (E)-B-caryophyllene. In contrast, these compounds were emitted in relatively large amounts from cotton due to physical disruption of glands by the herbivores. The timing of volatile release from plants treated with MeJA or herbivores followed a diurnal pattern with maximal volatile release during the middle of the photoperiod. Similar to herbivore-treated plants, MeJA treatment led to the systemic induction of (Z)-3-hexenyl acetate, (E)-B-ocimene, linalool, (3E)-4,8-dimethyl-1,3,7-nonatriene, (E,E)-A-farnesene, (E)-B-farnesene, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene. Our results indicate that treatment of cotton with MeJA can directly and systemically induce the emission of volatiles that may serve as odor cues in the host-search behavior of natural enemies.