The Effect of Photoperiod and Vernalization Genes on Phenology of Bread Wheat (Treaticum aestivum L.) in Three Genetic Backgrounds Using Near-isogenic Lines (NILs)

Flowering time in bread wheat is controlled by three groups of genes including photoperiod (Ppd), vernalization (Vrn) and earliness per se (Eps). The objective of the present study was to assess the effect of photoperiod and vernalization genes on phenology of bread wheat using near-isogenic lines (NILs) in three genetic backgrounds.

Genomic DNA was extracted from parents, the earliest and the latest heading genotypes of each BC5F2 population obtained from backcrossing three Iranian cultivars including Roshan, Mahdavi and Kalheydari (recurrent parents) with Australian cultivar, Excalibur (donor parent). PCR was performed using specific primers for Ppd and Vrn genes.

Excalibur and Mahdavi had Ppd-D1a allele whereas Kalheydari and Roshan were carrying Ppd-D1b allele. As it was expected, early and late heading progeny of Mahdavi were similar to parents. Late heading progeny of Roshan was homozygote and similar to recurrent parent whereas early heading progeny was heterozygote. Early and late heading progeny of Kalheydari were heterozygote. The reason for this could be the presence of modifier genes that are influenced by genetic background. Excalibur, Kalheydari and Mahdavi were possessed Vrn-B1a and vrn-D1 alleles, while Roshan carried vrn-B1 and Vrn-D1a alleles in Vrn-B1 and Vrn-D1 loci, respectively. Since Excalibur, Kolhaydari and Mahdavi did not show genetic diversity, as it was expected, early and late heading progeny were similar to their parents. In Roshan background, since vrn-B1 and Vrn-D1a improve earliness, early and late heading progeny were similar to recurrent parent.

The Ppd-D1a allele discriminated early and late heading progeny of Roshan genetic background. This result showed the importance and role of this gene on earliness. Early and late heading progeny of Roshan were similar to Vrn-B1 and Vrn-D1 loci. The reason is phenotypic selection for earliness in backcrossing program, where genes controlling late maturity have not selected during phenotypic selection.