Study of Defense Genes Expression Induced by Leaf Herbivory in Roots of Insect-resistant Maize
Open Access
- Author:
- Zhu, Lixue
- Graduate Program:
- Agronomy
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- July 16, 2010
- Committee Members:
- Dawn S Luthe, Thesis Advisor/Co-Advisor
Dawn S Luthe, Thesis Advisor/Co-Advisor - Keywords:
- expression
defense gene
herbivory
maize - Abstract:
- There is a long-term coevolutionary relationship between plants and their insect herbivores, which results in plants mounting defenses against the insects. The study of plant herbivore defense is a popular field that allows researchers to investigate the mechanisms of plant defense. The motivation of this study is to obtain information, which can be used in the long-term to design herbivore control for agricultural crops. By examining the plant defense responses in leaf and root, I hypothesize that aboveground herbivory induces defense gene transcript levels in both the aboveground and belowground parts of the insect-resistant maize inbred line Mp708. To prove this hypothesis, I examined changes in different defense gene expression in response to caterpillar feeding in maize whorl and root tissues. The results indicate that leaf herbivory does induce defense gene expression in insect-resistant maize leaves and roots. Previous research has shown that a cysteine protease called Mir1-CP accumulates in the whorls of insect-resistant maize Mp708. This research investigates mir1 gene transcript levels and Mir1-CP accumulation in the leaves and roots after feeding by the fall armyworm (Spodoptera frugiperda) larvae, in V7 growth stage of maize. Experiment observations suggest that there is aboveground and belowground communication of maize. Defense gene expression during the different growth stages of maize was also investigated in this study. At different development stages maize may exhibit various levels of insect resistance and defense. This could result in variations of defense gene transcript levels in response to herbivory. This research reveals that aboveground herbivory increases defense genes transcript levels both in aboveground and belowground parts of insect-resistant maize inbred line Mp708. And different growth stages exhibit different expression patterns of these genes in Mp708.