| ABSTRACT: Rice (Oryza sativa L.) is one of the most important food crops and almost half of the world population depends on it as the major source of nutritional calories. In china, rice is cultivated over 30 million hectares, about 50 percent of which is hybrid rice. Hybrid rice has a distinct yield advantage over inbred varieties, however, is vulnerable to the attack of wide range of destructive insects. To control insects, insecticides are commonly used today. But chemical control is not only ineffective, but also deleterious to human beings, animals and beneficial insects. It is economical and effective to control insects with the insect-resistant varieties, nevertheless which might be bred barely by the traditional methods because of the scarce insect-resistant germplasms. Recent advances in plant biotechnology make it possible to produce insect-resistant rice.Here, we reported that three insecticidal genes (sck: signal-Q?7Y-KDEL; sbk: signaI-CryIA(C)-KDEL; gna: Galanthus nivalis agglutinin gene) were introduced into the elite CMS (Cytoplasmic Male Sterile) restorer lines (SH527, SHI 63), CMS maintainer lines (D62B, D297B, D702B), PTGMS (Photoperiod-Temperature sensitive Genie Male Sterile) restorer line (W2008) and PTGMS (612S) and 198 independent lines were obtained with bombardment or Agrobacterium-mediated transformation. It was difficult to do genetic transformation of different indica varieties. Then, we selected and constructed a set of indica varieties easy to be transformed, consisting of the parents of CMS and PTGMS hybrid rice including SH527, D297B, W2008 and 612S. When the calli from them were used as the target for transformation, the highest percentage of obtaining transgenic plants was 2.41%.It was indicated that the exogenic genes were integrated and inherited in the transgenic plants with molecular analysis and selection by Hygromycin B, but the insect-resistance genes were lost in few transgenic plants. Some homozygous transgenic lines have been already obtained. The nontransgenic plants could get the exogenic genes while hybridized with transgenic plants. The expression of the transgenes would be lowered if their vectors were similar.The resistance to insects of the transgenic plants was improved through genetic engineering. After fed the first instar of corn borer (Ostrinia nubilalis) with the forage treated with the total protein extracts from the transgenic rice plants containing sck and/or sbk for twelve days, the average weight of one larva was from 15 to 22mg, that fed with the forage treated with the total protein extracts from the nontransgenic rice plants was from 28 to 30mg and that fed with the forage untreated with the total protein extracts from rice plants was 37.60mg. In field evaluation, the percentages of damaged tillers of transgenic SH527 plants containing sck or sbk by bombardment were 15.31% or 10.54% and that of the relative check plants was 35.60%. Similarly, the percentage of damaged tillers of transgenic W2008 plants containing sck or sbk by bombardment was 22.29% or 10.54% and that of the relative check plants was 40.89%.The introducing exogenic genes and the tissue culturing courses had some effects on the agronomic traitsof their recipient plants, but most of these variations could not be delivered to their progenies. For example, the plant height of the first progeny of transgenic SH527 plants containing gna was 66.7cm, of nontransgenic plants regenerated from the calli was 84.0cm and of the check plants from seeds was 107.3cm. However, the height of the second or third progeny plants was similar to the check plants. The agronomic traits of the first progeny of transgenic W2008 plants containing sck were influenced by the transgenes, the discrepancies vanished between transgenic and nontransgenic plants by the time of the second or third progeny.The transgenic hybrid lines were produced from hybridization of G46A, D62A and D702A X SH527-$c? In field evaluation, the percentages of the damaged plants of the three hybrid lines were 20%,50% and... |
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