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| Author(s): |
Patrícia Pompermayer
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2004-07-02 |
| Advisor: | Marcio de Castro Silva Filho |
| Abstract | |
A particularly common source of wounding in plants is caused by herbivore insects. ln monocotyledonous plants, the defense mechanisms against herbivores are still poorly understood and few studies have addressed the expression of genes induced by herbivore insects. ln the present study it has been characterized the sugarcane responses to the attack of the sugarcane borer (Diatraea saccharalis) by analyzing the expression of a set of genes whose orthologues have been shown to be related to insect attack in dicotyledonous plants. Gene expression analysis was performed by Northern Blot. The following Expressed Sequence Tags (ESTs) obtained from the cluster consensi bank of Sugarcane EST Transcriptome Project (SUCEST) were used as probes: polyphenol oxidase (PPO), lipoxygenase (LOX2), hevein-like protein (HEL), cystatin (CYS) and β-actin (internal control). The results showed that PPO and HEL gene expression increased by 10 to 12- fold in relation to the control. The expression of CYS, MT1 and LOX2 genes were also increased, although as not as the same extent for PPO and HEL genes. Based on these expression studies the cloning of the HEL and PPO promoter regions was attempted. After cloning a 1100 bp fragment corresponding to the 5 upstream region of the sugarcane HEL coding sequence, the search for regulatory sequences involved on plant defense was performed. Soon after three deletions of the promoter region were carried out and the resulting fragments were fused to the uidA (GUS) reporter gene. These gene constructs were expressed in sugarcane plants in order to study its regulation in response to hebivory. The results showed that the promoter region is positively regulated by hebivory. The results of that study bring new insights on heterologous expression of insect resistant genes in sugarcane plants. (AU) | |