| dc.description.abstract | Abstract
In nature, crop plants constantly encounter various biotic and abiotic stresses, which can severely affect agricultural productivity. Pathogens, particularly, are limiting factors reducing crops quality and quantity seriously. Genetic engineering of disease-resistance through transferal of plant defense-related genes into crop is a valuable disease-control approach. Among the defense genes used to genetically engineer systemic acquired resistance in plants, Arabidopsis NPR1 (nonexpresser of PR genes) is of particular interest for its being a central regulator of plant defense responses. The exploration of empolying Arabidopsis NPR1 (AtNPR1) gene for genetics engineering disease-resistance in tomato plants have led to the production of transgenic tomato lines conferring broad-spectrum disease-resistance, especially to vascular and leaf pathogens. In this work, the possible resistance mechanism employed by a selected AtNPR1 transgenic line and its interactions with Ralstonia solanacerarum were further studied. The results showed that some PR (pathogenesis-related) genes were constitutively expressed at a high level in the leaf tissues of the transgenic plants and thus may account for the enhanced resistances to the leaf pathogens. By further employing cDNA microarray approach, using customized tomato cDNA microarray, a group of putative AtNPR1 overexpression-induced genes were identified and a model for defense mechanism is proposed. By cross-referencing these data with the microarray data obtained from other abiotic stress studies, possible cross-links between biotic stress and heavy metal stress response were revealed. Evaluation of the horticulture traits of the transgenic tomato showed that the transgenic plants responded similarity, as did the wild type plants under drought and salinity stress. Furthermore, because none of the transgenic lines generated in the genetic background of CL5915 tomato cultivar conferred enhanced resistance to virus diseases, a tomato cultivars, CLN2116B, which carries the resistance trait to tomato yellow leaf curl virus was used as the background cultivar for transformation with AtNPR1. New CLN2116B transgenic plants were selected and characterized. Molecular analyzes revealed that expression of some PR genes was constitutively enhanced in these transgenic plants, suggesting a potential enhanced of disease-resistance in these transgenic plants. | en_US |