Transgressive segregation for phenological traits in barley explained by two major QTL alleles with additivity

Abstract

Quantitative trait loci (QTL) analysis can contribute to a deeper understanding of crop phenology. The parents of a barley mapping population have similar growth and development profiles, but the progeny show transgressive segregation for phenological traits. These phenotypes were measured in eight field experiments, using different planting dates over 3 years. Five QTL, on four chromosomes, were detected for anthesis date. The four maturity QTL were on the same chromosomes as the anthesis QTL. Five QTL for grain filling were detected on all chromosomes. Three QTL, on chromosomes 1H and 2H, were detected for photoperiod sensitivity. Both parents contributed higher value alleles for all traits, except for photoperiod sensitivity. QTL epistasis was not significant. Two QTL explained most of the phenotypic variation for anthesis and physiological maturity. Non-parental combinations of alleles at these loci account for the phenotypic transgressive segregation. Candidate genes for these QTL effects are eps2S (2H) and denso (3H). QTL for other traits had smaller effects and were coincident with genes and/or QTL for the same traits reported in other germplasm.

Genetic control of pre-heading phases in the Steptoe × Morex barley population under different conditions of photoperiod and temperature

“…This locus had a greater effect on SE than LS, and it interacted with the environment less than Ppd-H1, with the late allele from Steptoe. Large effects from QTLs in the same bin for heading, which have been associated to Eam6, have been also reported in other populations in a wide range of conditions, both in low and high latitudes (Márquez-Cedillo et al 2001;Moralejo et al 2004;Castro et al 2008) and in autumn, winter and spring sowings, with or without vernalisation, and under short or long photoperiods (Cuesta-Marcos et al 2008a, b). Therefore, it seems highly probable that the QTLs that we detected reflect the segregation of Eam6 in the Steptoe 9 Morex population.…”

Quantitative trait locus analysis of spot blotch and leaf rust resistance in the BCD47 × Baronesse barley mapping population

“…The LR resistance QTLs on chromosomes 2H and 3H were coincident with the two main QTLs controlling flowering time in the population (Castro et al. 2008).…”

“…The LR resistance QTLs on chromosomes 2H and 3H were coincident with the two main QTLs controlling flowering time in the population (Castro et al 2008). In both cases, Baronesse contributed the resistance alleles, which precludes the simple explanation of an association between flowering time and disease severity: the early alleles in both QTLs correspond to different parents, BCD47 on 2H and Baronesse on 3H.…”

“…The DH mapping population was developed using the Hordeum bulbosum method and consists of 409 lines. In this study, a randomly selected sample of 100 lines was used in all the experiments but 3 (Table 1), together with the linkage map developed by Vales et al (2005), Rossi et al (2006) and Castro et al (2008). The map comprises a total length of 808.9 cM, including 59 markers in 13 linkage groups.…”

Preventing Potential Diseases of Crop Plants Under the Impact of a Changing Environment

“…Infection at an early stage of growth reduces yield by 30%. The leaf rust-resistant QTLs identified on chromosomes 2H and 3H were cosegregating with loci for flowering time (Castro et al, 2008). Three loci (Rphq1, Rphq2, and Rphq3) identified at the seedling stage explained 55% of phenotypic variation for this trait, whereas five loci were stage specific and explained 60% of phenotypic variation (Qi et al, 1998).…”