Location: Chemistry ResearchTitle: Rapid defense responses in maize leaves induced by Spodoptera exigua caterpillar feeding Author
|Tzin, Vered - Boyce Thompson Institute|
|Hojo, Yuko - Okayama University|
|Strickler, Susan - Boyce Thompson Institute|
|Bartsch, Lee - Boyce Thompson Institute|
|Archer, Cairo - Boyce Thompson Institute|
|Ahern, Kevin - Boyce Thompson Institute|
|Shaoqun, Zhou - Boyce Thompson Institute|
|Galis, Ivan - Okayama University|
|Mueller, Lukas - Boyce Thompson Institute|
|Jander, Georg - Boyce Thompson Institute|
Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/13/2017
Publication Date: 8/22/2017
Citation: Tzin, V., Hojo, Y., Strickler, S.R., Bartsch, L.J., Archer, C.M., Ahern, K.R., Shaoqun, Z., Christensen, S.A., Galis, I., Mueller, L.A., Jander, G. 2017. Rapid defense responses in maize leaves induced by Spodoptera exigua caterpillar feeding. Journal of Experimental Botany. 68(16):4709-4723.
Interpretive Summary: The U.S. spends over 3 billion dollars a year on insecticides and applies over 100 million lbs of these toxins in an effort to control insect pests. Despite large investments in pesticide-based control, there is continued crop loss and environmental contamination. Scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL, in collaboration with Boyce Thompson Institute were searching for natural solutions to insect resistance and discovered key sets of genes and defense chemicals that are rapidly produced by the plants in response to the leaf eating caterpillar beet armyworm (Spodoptera exigua). Through genetic analysis, it was determined that these defense genes play significant roles in the regulation of resistance to caterpillar feeding. Knowledge of the role of these defense genes will contribute to molecular breeding strategies that will benefit corn growers by promoting natural insect resistance and reducing the need for costly toxic insecticide applications.
Technical Abstract: Insects such as beet armyworm caterpillars (Spodoptera exigua) cause extensive damage to maize (Zea mays) by consuming foliar tissue. Maize plants respond to insect attack by triggering defense mechanisms that involve massive changes in gene expression, biosynthesis of specialized metabolites and defense signaling. To investigate dynamic maize responses to caterpillar feeding, leaves of maize inbred line B73 were infested with S. exigua for 1 to 24 hours, followed by comprehensive transcriptomic and metabolomic characterization. Our results show that the most significant gene expression responses of maize to caterpillar feeding occur rapidly within 4 to 6 hours after infestation. However, both gene expression and metabolite profiles continued to change during the entire 24-hour experiment, while expression of photosynthetic genes gradually repressed. Furthermore, through mutant analysis of Dissociation transposon insertions in maize inbred line W22, we examined the effects of gene knockouts involved in the benzoxazinoid (Bx1 and Bx2) and jasmonic acid (Lox8) biosynthesis, which are critical for protection from herbivory in maize. Together, these results show that maize leaves implement chemical defenses within one hour after the initiation of caterpillar attack. Thus, maize-caterpillar interactions are significantly affected through the induced biosynthesis of specialized metabolites, thereby conferring defense to insect herbivores.