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Molecular genetic analysis of off-type plants identified from normal F1 hybrid cultivars of sweet pepper (Capsicum annuum L.)

Lee, J. H., Kim, S.
Journal of horticultural science & biotechnology 2011 v.86 no.4 pp. 349-352
Capsicum annuum, biotechnology, cultivars, cytoplasm, cytoplasmic male sterility, environmental factors, genetic analysis, genetic factors, heterozygosity, horticulture, hybrids, inbred lines, leaves, microsatellite repeats, pathogens, random amplified polymorphic DNA technique, self-pollination, sweet peppers
Off-type plants occasionally appear when growing F1 hybrid cultivars of sweet pepper (Capsicum annuum L.). In this study, possible genetic factors responsible for the appearance of off-types were evaluated using two off-type sweet peppers selected out of 120 F1 hybrids. The general morphology of off-type plants showed a stunted stature, narrow leaf shape, and small round-shaped fruits.We hypothesised that these off-type plants might have arisen by inadvertent self-pollination of maternal parental lines, since most sweet pepper F1 hybrids are known to be produced by handemasculation. Indeed, none of the sweet pepper cultivars analysed in this study contained male-sterile cytoplasm, confirming that cytoplasmic male-sterility was not used during F1 hybrid seed production. If the off-type plants were derived from self-pollination of maternal lines, the genetic make-up of the off-type plants should be different from that of normal F1 hybrids. However, the RAPD and SSR marker amplification profiles of off-type and normal F1 hybrids showed no polymorphism, whereas one RAPD and five polymorphic SSR markers were identified among five other F1 sweet pepper cultivars, indicating that the genetic make-up of the off-type and normal F1 hybrids were almost identical. Furthermore, two SSR markers that showed heterozygosity in both off-type and normal F1 hybrids, segregated in the self-pollinated progenies of both off-type and normal F1 hybrids, indicating that the off-type plants were not maternal inbred lines. Taken together, these results suggest that the off-type F1 sweet pepper plants could have arisen due to other environmental factors or by infection with an unknown pathogen.