Identification and validation of QTL for Sclerotinia midstalk rot resistance in sunflower by selective genotyping. Theor Appl Genet

State Plant Breeding Institute (720), University of Hohenheim, Stuttgart, Germany.
Theoretical and Applied Genetics (Impact Factor: 3.79). 08/2005; 111(2):233-42. DOI: 10.1007/s00122-005-2004-x
Source: PubMed


Midstalk rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is an important cause of yield loss in sunflower (Helianthus annuus L.). Objectives of this study were to: (1) estimate the number, genomic positions and genetic effects of quantitative trait loci (QTL) for resistance to midstalk rot in line TUB-5-3234, derived from an interspecific cross; (2) determine congruency of QTL between this line and other sources of resistance; and (3) make inferences about the efficiency of selective genotyping (SG) in detecting QTL conferring midstalk rot resistance in sunflower. Phenotypic data for three resistance (stem lesion, leaf lesion and speed of fungal growth) and two morphological (leaf length and leaf length with petiole) traits were obtained from 434 F3 families from cross CM625 (susceptible) × TUB-5-3234 (resistant) under artificial infection in field experiments across two environments. The SG was applied by choosing the 60 most resistant and the 60 most susceptible F 3 families for stem lesion. For genotyping of the respective F 2 plants, 78 simple sequence repeat markers were used. Genotypic variances were highly significant for all traits. Heritabilities and genotypic correlations between resistance traits were moderate to high. Three to four putative QTL were detected for each resistance trait explaining between 40.8% and 72.7% of the genotypic variance ( p̃TS). Two QTL for stem lesion showed large genetic effects and corroborated earlier findings from the cross NDBLOSsel (resistant) × CM625 (susceptible). Our results suggest that SG can be efficiently used for QTL detection and the analysis of congruency for resistance genes across populations.

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    • "Degener et al. (1998) evaluaron la variabilidad de las respuestas de 85 líneas de girasol de Alemania y EUA a la infección del tallo, utilizando el protocolo francés de inoculación en hojas (Bertrand y Tourvieille, 1987). Micic et al. (2005) detectaron tres QRL's (Loci de resistencia cuantitativa que controlan resistencias horizontales) relacionados con la podredumbre del tallo. Realizando inoculaciones directamente sobre la parte media del tallo, Castaño et al. (1993, 1989) cuantifi caron la longitud de la podredumbre y evaluaron la variabilidad de la lesión del tallo en una serie de líneas de girasol francesas. "
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