| Rice is one of the important food crops in China, and the rice production affects daily lives of people. The rice blast is one of the main diseases of rice, which has a serious effect on rice production. Therefore, exploring new blast resistance genes and breeding new varieties with blast resistance is the most economical, environmentally friendly and effective strategies to overcome this problem. In this study, three rice blast resistance genes, Pil, Pi2and Pi9, were introduced into a leading japonica cultivar, Kongyu131, and some improved lines were obtained. Furthermore, we conducted quantitative trait loci (QTL) analysis of rice blast resistance, plant height and heading date using advanced backcross populations derived from Jin23B and Qingguai-1. These results could provide theoretical basis for exploring new rice blast resistance genes, breeding new varieties with blast resistance and improving agronomic traits of rice. The main results are as follows:1. The introduction of three blast resistance genes, Pil, Pi2and Pi9, into Kongyu131greatly improved the blast resistance. However, because Pi2and Pi9are closely linked to the heading date gene Hdl, the improved version of Kongyu131heads later than Kongyu131. In order to restore the normal heading date of improved Kongyu131, elimination of Hdl is of great necessity. In2012, two hybrid lines containing Pi2and Pi9genes, respectively, were obtained. In2013, results of field survey in Wuhan showed that the improved Kongyu131containing Pi2only headed at the same day with Kongyu131, while the improved Kongyu131containing Pi9only headed four days later than Kongyu131, which indicated that the heading gene Hdl was still in the improved Kongyu131containing Pi9.2. The BC3F1population and its BC3F2population derived from Jin23B/QGA-lwere developed. The tillering leaf blast, heading leaf blast and panicle blast resistance performance of the two populations in2011and2012were observed and used for QTL mapping. A total of13QTLs were detected in2years. Blast resistance QTLs were mainly distributed on chromosome6and7, and stably detected in two years. qBR6flanking by L6ID3F and ZH6111on chromsome6, was responsibile for the three traits in two years, and accounted for the maximum phenotypic varaition. qBR6was responsibile for tillering leaf blast, heading leaf blast and panicle blast resistance, had a LOD score of19.39,28.39,33.94,13.73,28.35and29.23in201land2012, and explained24.93%,36.48%,31.91%,19.91%,25.27%and28.95%of the phenotypic variation, respectively. Two Panicle blast resistance QTL, qBR4-land qBR4-2, were located to chromosome4. qPH4-1had a LOD score of3.69and7.64in2011and2012, and accounted for12.31%and18.47%of the phenotypic variation, respectively. qPH4-2had a LOD score of2.53and6.76in2011and2012, accounting for8.82%and16.92%of the phenotypic variation, respectively.Two blast resistance QTL, qBR7-1and qBR7-2, were mapped on chromosome7. qBR7-1was responsibile for tillering leaf blast, heading leaf blast and panicle blast resistance, had a LOD score of7.83,14.98,30.17,3.18,29.33and20.75in201land2012, and explained8.87%,16.47%,27.94%,4.12%,26.31%and18.71%of the phenotypic variation, respectively. qBR7-2was responsibile for panicle blast resistance and was only detected in2012with a LOD score of4.61, accounting for3.43%of the phenotypic variation.3. Meanwhile, the heading date and plant height of the BC3F1population and its BC3F2population were measured and subjected to QTL mapping. In two years,9QTLs for heading date and6QTLs for plant height were identified in these populations. The maximum effect QTLs of heading date and plant height were in the same location, all on chromosome7. The heading date QTL, qHD7-3, had a LOD score of37.07in2011and explained41.05%of the phenotypic variation, and its additive effect was11.68. The plant height QTL, qPH7-2had a LOD score of43.73and42.66in2011and2012, accounting for54.17%and54.39%of the phenotypic variation, and the additive effect was21.60and19.95, respectively. qHD7-3and qPH7-2were both located between marker RM214-RM5543, where Ghd7is located, suggesting that it may be the allele of Ghd7. Heading date QTL qHD2was mapped between marker ZH282and RM71on chromosome2, with a LOD score of4.56and4.99in2011and2012, which could explain4.31%and7.99%of the phenotypic variation respectively. Heading date QTL qHD4was mapped between marker RM241 and RM317on chromosome4, with a LOD score of2.89and2.67in2011and2012, interpreting9.42%and8.78%of the phenotypic variation respectively. The regions of qHD2and qPH4have no genes reported about HD and PH previously, thus the region might be a new gene. |
PDF Full Text Request