Integration of QTL detection and marker assisted selection for improving resistance to Fusarium head blight and important agronomic traits in wheat

Fusarium head blight(FHB), caused by Fusarium graminearum, is one of the most destructive wheat(Triticum aestivum L.) diseases worldwide. Identification of quantitative trait loci(QTL) conferring FHB resistance followed by marker assisted selection(MAS) is an efficient approach to breed FHB-resistant varieties. In this study, 38 additive QTL and 18 pairs of epistatic QTL for FHB resistance were detected in four environments using a population of recombinant inbred lines(RILs) derived from varieties Neixiang 188 and Yanzhan 1. Six QTL clusters were located on chromosomes 2D, 4B, 4D, 5A, 5D and 7B, suggesting possible polytrophic functions. Six elite lines with good FHB resistance and agronomic traits were selected from the same population using the associated markers. Our results suggest that MAS of multiple QTL will be effective and efficient in wheat breeding.

Detection of Genetic Markers of Am3 / Laizhou 953 Introgression Lines for Resistance to Fusarium Head Blight

Fusarium head blight （FHB） is a destructive disease widespread in warm humid and semi-humid areas, which not only causes yield and grain quality losses, but also produces myeatoxin deoxynivalenol, thus posing a serious threat to wheat production in the world. In this study, 15 introgression lines with signifi- cantly different levels of resistance to FHB were screened as experimental materials to detect the intmgressed fragments by SSR markers from BC4F5 progenies of Atrd/Laizhou 953. The results showed that the number of polymorphic markers detected on each chromosome varied greatly, and polymorphic markers detected on chromosomes 5D and 5A were more than on other chromosomes. Am3 fragment could be detected in 15 introgression lines with 38 pairs of primers; the number of detected introgressed fragments varied among different introgression lines. Among 21 linkage groups, no introgressed fragments were detected on chromosomes 1A, 6D and 7A; the largest number of intregressed fragments was detected on chromosomes 3D and 5B. In 15 intregression lines, three QTLs for plant height, spike length and disease index detected. Qdi-caas-5A, which was derived from Am3, might be related with Type III resistance.

Genetic analysis and gene mapping of a dwarf and liguleless mutation in barley

Leaf development underlies crop growth and productivity and has been a major target of crop domestication and improvement.However,most genes controlling leaf development in barley remain unknown.We identified a dwarf and liguleless(dl)mutant derived by ethylmethane sulfonate mutagenesis.The dl mutant showed dramatic changes in shoot architecture compared with wild-type(Yangnongpi 5)plants.Besides lacking ligules,the dl mutant showed much shorter plant height(28 cm)than Yangnongpi 5(78 cm).By map-based cloning,the dl gene was localized to a 56.58-kb genomic interval on the long arm of chromosome 7.A C-to-T single-nucleotide substitution was identified at exon position 790,and is a functional mutation resulting in a proline-to-serine substitution at the 264th amino acid residue of HORVU7Hr1G106960.Consequently,HORVU7Hr1G106960 was identified as the DL gene,encoding 269 amino acids and containing the Arabidopsis LSH1 and Oryza G1(ALOG)domain.DL is highly similar to rice OsG1-LIKE 1/2(OsG1L1/2)and sorghum AWN1/AWN1-10 at the amino acid level.Although the dl mutant allele showed no expression changes in selected tissues by real-time PCR,we propose HORVU7Hr1G106960 as a candidate gene conferring the dwarf and liguleless phenotype in barley.