Studies On The Phenotypic Variations In Pi9-transgenic Rice R288 And Its Hybrid Combinations

The transgenic technology has become a new technical approach for the genetic improvement of rice varieties. With the progress of transgenic rice research, people attached more and more importance to combine transgenic technologies with conventional rice breeding technologies, strengthened studies on the field genetic expression and variation of agronomic traits in transgenic rice progenies, which laid a solid foundation for the use of transgenic technologies in rice germplasm innovation, the improvement of the existing rice varieties, and the utilization of transgenic rice in rice production.In this study, the main experimental materials were self-crossing progenies and its hybrid combinations of Pi9-transgenic rice R288. The genetic stability, disease-resistance and its phenotypic variations of these transgenic rice varieties were analyzed in this thesis through the molecular detection, identification of resistance to rice blast and agronomic traits inspect. The main results were as follows:1. PCR analysis showed that the exotic gene Pi9 had been integrated into the genomes of transgenic rice R288 and its hybrids. The exotic gene Pi9 can be inherited stably in transgenic rice.2. The identification of resistance to rice blast showed that the resistance of foreign gene Pi9 haven't expressed effectively in transgenic rice R288 and its hybrids. Namely, a phenomenon of gene silencing occurred.3. Agricultural traits of transgenic rice progenies varied in different ranges. Comparing to the check, most of the progenies with exotic gene Pi9 decreased the growth duration, plant height, seed-setting, sword leaf length and width; while the panicle number was increased. And the most obvious phenotypic variations in transgenic rice happened mainly on plant height, panicle length, sword leaf length and width, seed-setting, etc. The variance of most other traits was not significant. Moreover, the degrees of variance differed among 5 lines of self-crossing progenies of transgenic Pi9 rice R288, the smallest variation lines was 131. There were few agronomic traits variations between T₅ and T₄ generation, and it was significant in fewer lines only. As the self-crossing generation went on, the phenotypic variance becoming smaller and tend to the check.4. Comparing to the check hybrids, the investigated agronomic traits of transgenic hybrid rice lines were also varied in different ranges. Most of the transgenic hybrid rice lines decreased the plant height and seed-setting; while the panicle number and grains per panicle was increased. And the most obvious phenotypic variations in transgenic hybrids happened mainly on plant height, seed-setting and 1000-grain weight, etc. The variance of most other traits was not significant. Moreover, the degrees of variance differed among transgenic hybrid combinations, Different transgenic lines crossed with the same male sterile lines or the same transgenic lines crossed with different male sterile lines were also having a different level of variation. Transgenic lines crossed with jin23A had fewer variations than crossed with 044S or 134S; the same male sterile lines crossed with transgenic lines 131 have fewer variations than crossed with other lines. There were few agronomic traits variations between transgenic hybrid combinations crossed by T₄ and T₃ generation, and it was significant in fewer hybrids only. As the self-crossing generation of the transgenic lines went, the phenotypic variances of transgenic hybrids were also becoming smaller and tend to the check.