Differential effects of cultivated and wild barley 5H chromosomes on heading characters in wheat‐barley chromosome addition lines

摘要

The importance of heading time for cereal crops is demonstrated by its influence on the adaptability to various environmental conditions. The wide adaptability of bread wheat (Triticumaestivum L., 2n=6x=42) results from its varietal variation in the heading time. The genetic control of heading time in wheat is determined by three characters, i.e. vernalization requirement, photoperiodic sensitivity and narrow-sense earliness (Yasuda and Shimoyama 1965; Kato and Yamagata 1988). Vernalization requirement means the sensitivity of the plant to cold treatment for accelerating spike primordium formation, and is controlled mainly by three major genes, Vrn-A1, Vrn-B1 and Vrn-D1 located on chromosomes 5A, 5B and 5D, respectively (reviewed by Flood and Halloran 1986; gene designation after McIntosh et al. 1998). The photoperiodic (long-day) response is determined by dominant genes, Ppd1, Ppd2 and Ppd3, controlling insensitivity to a long-day photoperiod, located on chromosomes 2D, 2B and 2A, respectively (reviewed by Worland et al. 1998). On the other hand, narrow-sense earliness or earliness per se is the earliness of fully vernalized plants grown under long-day conditions, and controlled by polygenes with minor effects (Kato and Wada 1999).Early maturity is one of the most important objectives of wheat breeding, especially in Japan where wheat must be harvested before the rainy season. Barley (Hordeum vulgare L., 2n=2x=14) genetically matures earlier than wheat (Yasuda 1989). It would be possible to develop wheat varieties as early in maturity as barley, if the early heading trait of barley could be transferred into the wheat genome. To manipulate barley chromosomes in the wheat genome, two sets of wheat-barley chromosome addition lines were produced: ‘Betzes’ barley 2H to 7H chromosomes added to ‘Chinese Spring’ wheat (Islam et al. 1981) and ‘New Golden’ barley 5H and 6H chromosomes added to ‘Shinchunaga’ wheat (Koba et al. 1997). In the previous study, we examined the effects of additional barley chromosomes on heading characters in wheat by using the two sets of wheat-barley chromosome addition lines (Murai et al. 1997a). The results indicated that genetic effects of the barley 5H chromosomes are accelerating narrow-sense earliness, decreasing the vernalization requirement and/or increasing photoperiodic sensitivity in wheat. There are two explanations for the alteration of heading characters in wheat-barley addition lines: 1) the effect of barley gene(s) for heading characters located on the additional 5H chromosome, which can be expressed in the wheat genome, and 2) the effect of chromosome number of homoeologous group 5, that is an aneuploid effect. Previously, we indicated that the decreased vernalization requirement in ‘Shinchunaga’ wheat–‘New Golden’ barley 5H chromosome addition line was caused by a barley major dominant gene for spring habit, Sh2, located on the ‘New Golden’ 5H chromosome (Murai et al. 1997a).In this study, we examined the effects of different barley 5H chromosomes under an identical wheat genetic background using two wheat-barley addition lines, i.e. cultivated barley ‘New Golden’ 5H chromosome added to ‘Shinchunaga’ wheat (Shi-NG5H) and wild barely H. vulgare ssp. spontaneum 5H chromosome added to ‘Shinchunaga’ wheat (Shi-Spn5H). Differential effects of the NG5H and Spn5H chromosomes on heading characters in wheat demonstrated that the heading characters were altered by the effect of barley genes located on the 5H chromosome, not by the aneuploid effect.