Lan Xiujin

Inheritance in synthetic hexaploid wheat ‘RSP’ of sprouting tolerance derived from Aegilops tauschii Cosson

An artificial amphiploid ‘RSP’ (2n = 42, AABBDD) between tetraploid landrace Ailanmai (Triticum turgidum L., 2 = 28, AABB) and Aegilops tauschii (DD, 2n = 14) expressed high tolerance to preharvest sprouting which derived from Aegilops tauschii. To determine the inheritance of sprouting tolerance in ‘RSP’, it was crossed with six cultivars which vary in susceptibility to preharvest sprouting. Preharvest sprouting tolerance was assessed on F2 plants using germination towels. Preharvest sprouting tolerance was inherited as a recessive trait which was controlled by one gene.

The chromosomal locations of high crossability genes in tetraploid wheat Triticum turgidum L. cv. Ailanmai native to Sichuan, China

Chromosomal locations of crossability genes in tetraploid wheat Ailanmai with high crossability native to Jianyang of Sichuan province, China, was determined by aneuploid analysis employing the D-genome chromosome substitution lines of Langdon durum wheat and monosomic lines of common wheat, Abbondanza. High crossability of Ailanmai was attributed to recessive crossability alleles on chromosomes 1A, 6A and 7A. The effects of chromosomes 7A and 1A were stronger than chromosome 6A. These results indicated that high crossability in Chinese tetraploid wheat cv. Ailanmai and Chinese hexaploid wheat is controlled by different genetic systems.

Mapping QTLs for pre-harvest sprouting tolerance on chromosome 2D in a synthetic hexaploid wheat×common wheat cross

Based on segregation distortion of simple sequence repeat (SSR) molecular markers, we detected a significant quantitative trait loci (QTL) for pre-harvest sprouting (PHS) tolerance on the short arm of chromosome 2D (2DS) in the extremely susceptible population of F2 progeny generated from the cross of PHS tolerant synthetic hexaploid wheat cultivar ‘RSP’ and PHS susceptible bread wheat cultivar ‘88–1643’. To identify the QTL of PHS tolerance, we constructed two SSR-based genetic maps of 2DS in 2004 and 2005. One putative QTL associated with PHS tolerance, designatedQphs.sau-2D, was identified within the marker intervalsXgwm261-Xgwm484 in 2004 and in the next year, nearly in the same position, between markerswmc112 andXgwm484. Confidence intervals based on the LOD-drop-off method ranged from 9 cM to 15.4 cM and almost completely overlapped with marker intervalXgwm261-Xgwm484. Flanking markers near this QTL could be assigned to the C-2DS1-0.33 chromosome bin, suggesting that the gene(s) controlling PHS tolerance is located in that chromosome region. The phenotypic variation explained by this QTL was about 25.73–27.50%. Genotyping of 48 F6 PHS tolerant plants derived from the cross between PHS tolerant wheat cultivar ‘RSP’ and PHS susceptible bread wheat cultivar ‘MY11’ showed that the allele ofQphs.sau-2D found in the ‘RSP’ genome may prove useful for the improvement of PHS tolerance.

Evaluation of Aegilops tauschii Cosson for preharvest sprouting tolerance

On day 21, total germination percentages of threshed seeds of Ae. tauschii ranged from 0.0 to 92.6, indicating a large variation in preharvest sprouting tolerance. Out of 46 Ae. tauschii accessions, seven had a germination index lower than ten, which indicates good tolerance to preharvest sprouting and usefulness for common wheat (Triticum aestivum L.) improvement. The variety tauschii showed a germination percentage and a germination index much higher than that of var. strangulata. Furthermore, the tough and tenacious glumes of Ae. tauschii also had an effect on tolerance to preharvest sprouting.