Estudo de resistência à murcha-de-fusarium e identificação de QTLs em feijeiro-comum

• Autor(a) principal: Valdo, Stella Cristina Dias
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/8960
• topic: Phaseolus vulgaris L.; Marcadores moleculares; Linhagens endogâmicas recombinantes; Fusarium oxysporum f. sp. phaseoli; Phaseolus vulgaris L.; Resistance; Molecular markers; Recombinant inbred lines; Fusarium oxysporum f. sp. phaseoli; FITOTECNIA::MELHORAMENTO VEGETAL

The common bean (Phaseolus vulgaris) crop plays an important role in the culture and economy of Brazil. It is cultivated in all Brazilian regions and is affected by several diseases like fusarium wilt which is caused by Fusarium oxysporum f. sp. phaseoli (soil-born fungus). This disease brings significant losses in common bean culture and genetic resistance is the primary form of control. One of the core goals of breeding programs is the development of resistant cultivars, therefore the objectives of this work are: i) To select F. oxysporum f. sp. phaseoli resistant F5:7 lines resulted from the crossing between Ouro Branco X CNFP10132, under controlled field and environment conditions ii) To identify SSR markers and QTL-linked SNPs associated with the resistance of common bean to fusarium wilt using 92 recombinat inbred lines(RILs) resulted from the crossing between Ouro Branco x CNFP10132. In the first study, 140 lines, the breeders Ouro Branco and CNFP10132, BRS Esplendor (resistant) and BRS Supremo (susceptible) as controls were evaluated. Field trials were conducted in a center pivot area where natural infestation of the pathogen occurs. The treatments were evaluated in summer and winter crop and the experimental design used was 12x12 triple lattice. The two controlled environment trials were conducted in a completely randomized design. The treatments were inoculated by cutting and immersing the roots in a conidial suspension, which was adjusted to 1x106 conidia/ml for five minutes. The evaluation was performed using a scale of nine grades that represent the severity of the disease: 1 – absence of symptoms and 9 – over 75% of foliage with wilt symptoms. Data were submitted to analysis of variance and Scott-Knott test for both environments. The area under the disease progress curve (AUDPC) and genetic parameters were estimated for controlled environment tests. Significant differences were observed for crops and for controlled environment trials, indicating that environment influences directly the severity of the disease. Highly significant differences were found for lines in all environments evaluated, demonstrating the existence of genetic variability, which allows the selection of resistant lines resistant to fusarium wilt. Treatments were classified in different groups according to the Scott-knott test. When considering the lowest averages in field, controlled environment and AUDPC, the strains Ouro Branco x CNFP 10132.140, Ouro Branco x CNFP 10132.49, Ouro Branco x CNFP 10132.12, Ouro Branco x CNFP 10132.90 and Ouro Branco x CNFP 10132.48 were prominent and are candidates to produce a breeding program. Heritability estimates were high for all environments, mean of 85.48% for field and 95.47% for controlled environment. Therefore, selection for resistance to F. oxysporum f. sp. phaseoli of these lines, will be successful. In the second study it was extracted DNA from 92 lines and from genitors for genotyping with SSRs and SNPs. In order to obtain the localization of these markers, sequences of the primers were aligned to the andean genome of the common bean. The method of single marker (analysis of QTLs based on linear regression) was used to identify QTLs associated with fusarium wilt resistance. These markers were considered significant when brought up p-value <0.05. Ninety-three markers were linked to 104 QTLs associated with fusarium wilt resistance and among these, were considered significant in more than one environment PV 115, PV 251, BARC-PV-0004089, BARC-PV-0004548, BARC-PV-0003450, BARC-PV-0006051, BARC-PV-0003368 , BARC-PV-0005477 and BARC-PV-0004897. However only the BARC-PV-0003450 marker was highly significant in the two environment controled trials (p <0.001) and winter crop (p <0.01) and explained up to 21.5% of the phenotypic variance. Subsequently, the gene annotation was made considering the location of all markers that were significant at p <0.01 comprising 500 kb before and after the localization. 960 coded transcripts were annotated. It was observed in gene annotation that BARC-PV-0003450 marker is located on the chromosome 8, 338.54 kb distant of the gene Phvul.008G014700 which is associated with the putative protein RPP13 related to disease resistance, identified in Arabidopsis thaliana. This protein belongs to the third class of resistance genes that encloses the domain called Leucine-Rich Repeats (LRR). This domain is involved in the recognition of the pathogen by the host during the infection process. Therefore, this marker is suitable for marker- assisted selection aiming the development of cultivars resistant to fusarium wilt.