Study of marker-assisted selection of vernalization and frost tolerance in Barley

Freezing tolerance is a major component of winter hardiness and the ability of plant to survive subfreezing temperatures. Recent advances of cloned genes and molecular markers in barley provide molecular breeders with the means to develop new and simple PCR-based molecular markers which can be used to select frost-tolerant genotypes quickly without stress simulation. In this paper، five molecular markers associated with two frost tolerance and vernalization QTLs (Vrn-H1/Fr-H1، Fr-H2 and Vrn-H2) were tested in 24 barley genotypes consisting of winter، facultative and spring habit types. Genotypes were characterized in terms of frost tolerance under artificial freezing test at -12°C. The marker HvBM5A related to Vrn-H1/Fr-H1، resulted to be the best predictor for assisted selection within this germplasm، because there is a highly significant difference in maximum quantum yield of the PSII photochemistry (Fv/Fm) and electrolyte leakage of organized groups in this marker. Also HvCBF3 marker was more associated than HvCBF14 at Fr-H2 with the frost tolerance. The evaluation of Fv/Fm showed that frost stress the photochemical efficiency of photosystem II to decline significantly that generally، this reduction in resistant genotypes (winter and intermediate growth types) was less than susceptible (spring habit). Furthermore frost stress causes serious damages on plants by injuring the cell membrane that investigation on this collection showed significant difference between mean of this trait in susceptible genotypes (spring type) 0. 381 and mean of cold tolerant genotypes (winter and facultative growth habit types) 0. 174.