Responses of Oryza sativa japonica sub-species to infection with Rice yellow mottle virus
The distribution of Rice yellow mottle virus(RYMV) was compared in the partially resistant upland rice Oryza sativa japonica cv. Azucena and in the susceptible O. sativa indica cv. IR64, which are the two parents of a doubled haploid population studied for several traits, including genetic determinants of resistance to RYMV infection. Symptom expression, distribution and accumulation of viral coat protein and nucleic acid were studied in inoculated leaves, systemically infected leaves and apices, and in leaf host tissues. Initially, the resistance was apparent as delayed virus detection and multiplication which led to a lower virus content in inoculated leaves and in systemically infected organs. Later, the resistance was less apparent as virus titers became progressively similar in the two cultivars. Then, tolerance was observed, as symptom expression was less pronounced in cv. Azucena than in IR64, despite similar virus contents. In host tissues, partial resistance was associated with the delayed detection of virus in the bundle sheaths (mestomes) of Azucena, and, later, the mestome invasion paralleled the decline in resistance. The mature leaves of both cultivars always escaped infection. Partial virus resistance resulted from the expression of quantitative trait locus on chromosome 12, whereas tolerance is a characteristic of O. japonica, including the expression of QTL1. An impaired cell to cell movement through the mestome, possibly reinforced by slow vascular movement, are proposed to explain the partial resistance. © 2000 Academic Press. All rights reserved.
| Main Authors: | , , , , , , , |
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| Format: | article biblioteca |
| Language: | eng |
| Subjects: | H20 - Maladies des plantes, F30 - Génétique et amélioration des plantes, Oryza sativa, Oryza glaberrima, virus des végétaux, résistance aux maladies, http://aims.fao.org/aos/agrovoc/c_5438, http://aims.fao.org/aos/agrovoc/c_5436, http://aims.fao.org/aos/agrovoc/c_5985, http://aims.fao.org/aos/agrovoc/c_2328, |
| Online Access: | http://agritrop.cirad.fr/536058/ http://agritrop.cirad.fr/536058/1/document_536058.pdf |
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