RESUMO
KEY MESSAGE: The Mendelian gene conferring resistance to Soybean mosaic virus Strain SC20 in soybean was fine-mapped onto a 79-kb segment on Chr.13 where two closely linked candidate genes were identified and qRT-PCR verified. Soybean mosaic virus (SMV) threatens the world soybean production, particularly in China. A country-wide SMV strain system composed of 22 strains was established in China, among which SC20 is a dominant strain in five provinces in Southern China. Resistance to SC20 was evaluated in parents, F1, F2 and the F2:7 RIL (recombinant inbred line) population derived from a cross between Qihuang-1 (resistant) and NN1138-2 (susceptible). The segregation ratio of resistant to susceptible in the populations suggested a single dominant gene involved in the resistance to SC20 in Qihuang-1. A "partial genome mapping strategy" was used to map the resistance gene on Chromosome 13. Linkage analysis between 178 RILs and genetic markers showed that the SC20-resistance gene located at 3.9 and 3.8 cM to the flanking markers BARCSOYSSR_13_1099 and BARCSOYSSR_13_1185 on Chromosome 13. Subsequently, a residual heterozygote segregating population with 346 individuals was developed by selfing four plants heterozygous at markers adjacent to the tentative SC20-resistance gene; then, the candidate region was delimited to a genomic interval of approximately 79 kb flanked by the new markers gm-ssr_13-14 and gm-indel_13-3. Among the seven annotated candidate genes in this region, two genes, Glyma.13G194700 and Glyma.13G195100, encoding Toll Interleukin Receptor-nucleotide-binding-leucine-rich repeat resistance proteins were identified as candidate resistance genes by quantitative real-time polymerase chain reaction and sequence analysis. The two closely linked genes work together to cause the phenotypic segregation as a single Mendelian gene. These results will facilitate marker-assisted selection, gene cloning and breeding for the resistance to SC20.
Assuntos
Resistência à Doença/genética , Genes de Plantas , Glycine max/genética , Doenças das Plantas/genética , Potyvirus , Sequência de Aminoácidos , China , Mapeamento Cromossômico , Genes Dominantes , Marcadores Genéticos , Fenótipo , Doenças das Plantas/virologia , Glycine max/virologiaRESUMO
Soybean mosaic virus (SMV) in soybean [Glycine max (L.) Merr.] is a destructive foliar disease in soybean-producing countries worldwide. In this study, F(2), F(2:3), and F(7:11) recombinant inbred lines populations derived from Kefeng No.1 × Nannong 1138-2 were used to study inheritance and linkage mapping of the SMV strain SC8 resistance gene in Kefeng No.1. Results indicated that a single dominant gene (designated R(SC8)) controls resistance, which is located on chromosome 2 (MLG D1b). A mixed segregating population was developed by selfing two heterozygous plants (RHL153-1 and RHL153-2) at four markers adjacent to the locus and used in fine mapping R(SC8). In addition, two genomic-simple sequence repeats (SSR) markers BARCSOYSSR_02_0610 and BARCSOYSSR_02_0616 were identified that flank the two sides of R(SC8). Sequence analysis of the soybean genome indicated that the interval between the two genomic-SSR markers is 200 kb. QRT-PCR analysis of the candidate genes determined that five genes (Glyma02g13310, 13320, 13400, 13460, and 13470) are likely involved in soybean SMV resistance. These results will have utility in cloning, transferring, and pyramiding of the R(SC8) through marker-assisted selection in soybean breeding programs.
Assuntos
Genes de Plantas/genética , Glycine max/genética , Glycine max/virologia , Imunidade Inata/genética , Vírus do Mosaico/fisiologia , Mapeamento Físico do Cromossomo/métodos , Doenças das Plantas/imunologia , Mapeamento Cromossômico , Segregação de Cromossomos/genética , Cromossomos de Plantas/genética , Regulação da Expressão Gênica de Plantas , Estudos de Associação Genética , Ligação Genética , Genótipo , Endogamia , Padrões de Herança/genética , Doenças das Plantas/genética , Doenças das Plantas/virologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Glycine max/imunologiaRESUMO
Soybean mosaic virus (SMV) is one of the most destructive viral diseases in soybean and causes severe reduction of soybean yield and destroys the seed quality. However, the production of SMV resistant plants by transgenic is the most effective and economical means. Based on our previous yeast two-hybrid assay, the GmVma12 was selected as a strong candidate gene for further function characterization. Here we transformed soybean plants with a construct containing inverted repeat of-GmVma12 sequence to analyze the role of GmVma12 during SMV invasion. Totals of 33 T0 and 160 T1 plants were confirmed as positive transgenic plants through herbicide application, PCR detection and LibertyLink® strip screening. Based on the segregation ratio and Southern Blot data, T1 lines No. 3 and No. 7 were selected to generate T2 plants. After SMV-SC15 inoculation, 41 T1 and 38 T2 plants were identified as highly resistant, and their quantification disease levels were much lower than non-transformed plants. The transcript level of GmVma12 in T2 plants decreased to 70% of non-transformed plants. The expression level of SMV-CP transcript in T2 transgenic plants was lower than that in non-transformed plants and SMV CP protein in T2 plants could not be detected by Enzyme-linked Immunosorbent assay, which indicated that SMV production would be inhibited in transgenic plants. Moreover, coat mottles of T2 seeds were obliterated significantly. In conclusion, inverted repeat of the hairpin structure of GmVma12 interfered with the transcription of GmVma12, which can induce resistance to SMV in soybean. This research lays the foundation for the mechanism of SMV pathogenesis, and provides new ideas for SMV prevention and control.