Allele Variation in Loci for Adaptive Response and Plant Height and its Effect on Grain Yield in Wheat

ABSTRACT

In the present study the microsatellite marker Xgwm261, linked to Rht 8 gene as well as allele specific markers for Ppd-D1 (Ppdl), Vrn-1A and Vrn-1D loci, and the gibberellic acid (GA) test were employed to examine the distribution of semi-dwarf and photoperiod response and vernalization genes in 21 old and modern Bulgarian, 4 introduced cultivars and 11 advanced breeding lines from the wheat germplasm collections of DAI, General Toshevo, Institute of Genetics, Sofia and IPGR, Sadovo. Several allele variants were identified at locus Xgwm261, among which the 192 bp allele can serve as a diagnostic marker for the presence of Rht 8 gene. The Ppd-D1a, vrn-A1 and vrn-D1 alleles were found in almost all wheat genotypes illustrating the relationship between the photoperiod and vernalization response and the adaptability to the regional environments. The photoperiod insensitivity allele (Ppd-D1a) was found in 93.3% of analyzed modern cultivars released during 1960–2003 and has been most probably introduced from the Ukrainian cultivar Bezostayal (192 bp allele at locus Xgwm261), which is the main donor of Rht 8 gene in Bulgarian wheat. All studied modern Bulgarian wheat cultivars excluding cv. Laska (vrn-A1, Vrn-D1) and cv. Gladiator 113 (Vrn-A1a, vrn-D1) were of winter type (vrn-A1 and vrn-D1). Allele Vrn-A1c determining also spring type was not found in the studied set of the old and modern Bulgarian wheat cultivars.

The association between specific alleles at the Rht-B1, Xgwm261, Ppd-D1, Vrn1 loci with plant height, heading time and some yield related traits was also examined. The results suggested that allele combination Ppd-D1a/vrn-A1, vrn-D1 led to earlier heading than the allele combination Ppd-D1b/vrn-A1, vrn-D1.

The recombinant genotypes obtained from the crosses between photoperiod sensitive spring and photoperiod insensitive winter type wheat behave differently under autumn and spring sowing. Under early spring sowing the earliest heading dates and yield per m² were observed in lines with Ppd-D1a/Vrn-A1, vrn-D1 and Ppd-D1b/Vrn-A1, vrn-D1 allele combinations.

Keywords:

• adaptation
• allele variation
• vernalization genes (Vrn)
• photoperiod response (Ppd)
• plant stature (Rht)
• polymerase chain reaction (PCR)
• wheat (T. aestivum L.)