Genetic basis of the very short life cycle of ‘Apogee’ wheat

Background: ‘Apogee’ has a very short life cycle among wheat cultivars (flowering 25 days after planting under a long day and without vernalization), and it is a unique genetic material that can be used to accelerate cycling breeding lines. However, little is known about the genetic basis of the super-short life of Apogee wheat. Results: In this study, Apogee was crossed with a strong winter wheat cultivar ‘Overland’, and 858 F2 plants were generated and tested in a greenhouse under constant warm temperature and long days. Apogee wheat was found to have the early alleles for four flowering time genes, which were ranked in the order of vrn-A1 \u3e VRN-B1 \u3e vrn- D3 \u3e PPD-D1 according to their effect intensity. All these Apogee alleles for early flowering showed complete or partial dominance effects in the F2 population. Surprisingly, Apogee was found to have the same alleles at vrn-A1a and vrn-D3a for early flowering as observed in winter wheat cultivar ‘Jagger.’ It was also found that the vrn-A1a gene was epistatic to VRN-B1 and vrn-D3. The dominant vrn-D3a alone was not sufficient to cause the transition from vegetative to reproductive development in winter plants without vernalization but was able to accelerate flowering in those plants that carry the vrn-A1a or Vrn-B1 alleles. The genetic effects of the vernalization and photoperiod genes were validated in Apogee x Overland F3 populations. Conclusion: VRN-A1, VRN-B1, VRN-D3, and PPD-D1 are the major genes that enabled Apogee to produce the very short life cycle. This study greatly advanced the molecular understanding of the multiple flowering genes under different genetic backgrounds and provided useful molecular tools that can be used to accelerate winter wheat breeding schemes

Rapid Cycling in Spring Wheat: Genetics and Use in Converting Winter Wheat for Rapid Cycling

Backcrossing winter wheat (Triticum aestivum L.), due to vernalization, takes 4–5 years. Rapid cycling of spring wheat reduces generation times, thus expediting backcrossing. In this study, a spring wheat ‘Apogee’ was crossed to winter wheats ‘Goodstreak’, ‘Overland’, and ‘NW07505’ to understand and transfer rapid cycling genes. Our aims were to 1) study rapid cycling genes in segregating populations of Overland × Apogee, NW07505 × Apogee, and Goodstreak × Apogee; 2) evaluate allelic variation and effects of rapid cycling genes Vrn-A1, Ppd-D1, Rht-B1 and Rht-D1 on flowering date and plant height in the F5 of Goodstreak × Apogee and in the BC1F1 of Goodstreak//Goodstreak/Apogee; 3) develop rapid cycling recurrent parent (RCRP) of the three winter wheat lines; 4) determine which generation of selfing population is better for creating RCRP; 5) verify phenotypic data with molecular markers to identify rapid cycling lines. Segregation analysis revealed that not less than three or four rapid cycling genes segregated in winter x spring crosses. The effect of Vrn-A1 was greater than the other loci on flowering in the F 5 and BC1F1 populations. The F5 progenies that contained Apogee genotype flowered earlier and was shorter than Goodstreak and epistasis between Rht-B1b/Rht-D1b was the major effect on reducing plant height in the F5 population. These results indicated that rapid cycling progeny can be used for reducing generation time in backcross breeding. Supplementing molecular markers with phenotypic data can be used to understand the effect of rapid cycling genes and assist selection for the earliest flowering lines

Understanding a Rapid Cycling Winter Wheat Background From ‘Goodstreak × Apogee’ Using the KASP Assay

<div>Rungravee Boontung, Ahmed Sallam, Liuling Yan and P. Stephen Baenziger. 2016.Understanding a Rapid Cycling Winter Wheat Background From ‘Goodstreak × Apogee’ Using the KASP Assay. Plant Science Retreat Conference. 14-15, October, 2016. University of Nebraska-Lincoln, Nebraska City, USA. P8.</div

Additional file 1: Table S1. of Genetic basis of the very short life cycle of ‘Apogee’ wheat

Primers used in PCR reactions for identification of allelic variation at vrn-A1, VRN-B1, vrn-D3, and PPD-D1. (DOCX 18 kb