| Rice stripe, caused by rice stripe virus (RSV), is one of the most damaging diseases in temperate regions of East Asia. In China, rice stripe is increasing in severity, particularly in Jiangsu province. The resistance to rice stripe can be divided into resistance against RSV and small brown planthopper (SBPH), so it is necessary to explore new resistant genes against RSV and resources against SBPH. Basing on the genetics of resistance to RSV and SBPH, this work was consisted of optimizing inoculation methods, scanning for resistant varieties, detetction of resistant genes/QTLs and fine mapping of major genes.The results were as follows:1) Establishing of inoculation system of RSV and SBPH.We optimized the inbred system of SBPH and RSV inoculation methods of field test, mass inoculation test and seedling test. Meanwhile, we innovated the 12 days inoculation test as a new method. We also optimized inoculation methods of testing resistance to SBPH. These research with be useful for later study.2) Scanning for resistant varieties with new RSV resistant gene.In this study, resistance to rice stripe in 735 rice landraces was scanned. According to the allelic tests with Stvb-i, two varieties (IR24 and Habataki) carrying new resistant gene were selected to construct genetic populations and map quantitative trait loci (QTL). Meanwhile, QTL for RSV resistance in’Zhaiyeqing8’,’IR36’and’Kasalath’, and QTL for SPHB in’Zhaiyeqing8’were also scanned. Then, major QTLs detected in ’Kasalath’and’Habataki’were seletcted for fine mapping.3) Gene mapping of rice stripe resistance with different poputions.The partial resistant gene with main effect on chromosome 11 in IR24 was validated using chromosome segement substitution lines (CSSLs), and secondary population was constructed for fine mapping. This QTL were roughly mapped to a 720.6Kb region using 2780 F2:3 families, and 137 recombinant lines were planted to F3:4 and homogenious plants selected for fine mapping.With four inoculation methods,85 backcross inbred lines (BILs) of Sasanishiki (japonica)×Habataki(indica) was used to map QTL conferring resistance to rice stripe virus (RSV). Two main effect QTLs (qSTVll.l and qSTV11.2) on chromosome 11 were genetically linked, and mapped in the interval G257-RM457 and RM457-RM187, respectively. Fine mapping of qSTV11.1 and qSTV11.2 was carried out using 147 recombined BC3F2:3 lines selected from 2750 BC3F2 plants of the cross Sasanishiki/SL437. The qSTV11.1 was finally localized to a 333.2Kb interval (R15-RM209), which was physically about 230 Kb away from that of the well known Stvb-i. The other locus, qSTV11.2, was delimited into a 203.9 Kb region (R69-R73).IR36 is highly resistant to rice stripe disease. QTLs against RSV were detected on chromosomes 1,3,4,5,7,10,11 and 12 across two years. Of these QTLs, three were repeatedly detected, they were:one on chromosome 1 (interval RM488-RM128, PVE of 3.2-6.8%) and two on chromosome 11 (interval RM332-RM202, PVE of 11.8-32.9% and interval RM202-RM287, PVE of 6.0-24.8%, respectively). And the QTL of interval RM332-RM202 was allelic with the well known Stvb-i. The resistance mechanism in IR36 was consisted of resistance to virus infection, tolerance to virus, tolerance to feeding of vector and antixenosis.Using a doubled haploid lines (DHs) bred from the cross ZYQ8 x JX17 and four separate inoculation methods to genetically dissect the rice stripe resistance present in ZYQ8. Two linked RSV resistance QTLs were located on chromosome 1, and one on chromosome 11, jointly explaining 30-44% of the trait variance. The main-effect qSTV11 was mapped close to the established RSV resistance gene Stvb-i. For resistance to SBPH, three QTLs were located, mapping to chromosomes 1,2 and 11 and jointly explaining 44-51% of the trait variance. The large-effect qSBPHl (PVE>30%) appears to be a novel QTL conferring a degree of tolerance and antibiosis against SBPH. Analysis of a set of chromosome segment substitution lines showed rice stripe resistance genes/QTLs are commonly exsisted on the long arm of chromosome 1.4) Fine mapping of a main effect qSTV11 in KasalathThe stability of was validated using 39 established chromosome segment substitution lines. Fine mapping of qSTV11 was carried out using 372 recombinant BC3F2:3 and 399 BC3F3:4 lines selected from 7018 BC3F2 plants of the cross SL-234/Koshihikari.Four SSR (Simple Sequence Repeat), ten InDel and one CAPS markers were developed to narrow qSTVll locus. The qSTV11 was finally localized to a 39.2 Kb region that contains seven annotated genes. Marker-resistance association analysis suggested qSTV11 was distributed in diverse landraces coming from different regions. These results will provide a basis for map-based cloning of qSTV11,and benefit for the improvement of RSV resistance in rice varieties. |
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