Development Of Flanking Markers For Wheat Grain Weight QTL And Structure And Expression Analysis Of TaGLW7

Thousand grain weight?TGW?is an important trait affecting wheat production.We previously identified a major QTL controlling TGW on the 2D chromosome of wheat using arecombinant inbred line?RIL?population constructed by the cross between Tibetan semi-wild wheat Q1028?Q1028?and Zhengmai 9023?ZM9023?.The positive allele of this QTL is from ZM9023.In this study,comparative genomics was used to develop and verify the molecular markers of QTgw.sau-2D QTL and thus to densify the genetic map,which laid the foundation for fine mapping of QTL and molecular-assisted breeding.OsGLW7 is an important gene that positively regulates grain size and grain weight in rice.And we have limited knowledge about its orthologs in wheat.Here,we isolated and identified the TaGLW7 gene in wheat,characterized its nucleotide and protein structures,analyzed its promoter sequence and its expression patterns.In addition,Hordeum vulgare?HvGLW7?,Oryza sativa?OsGLW7?,Brachypodium distachyon?BdGLW7?,Triticum turgidum?TtGLW7?,Triticum urartu?TuGLW7?,Aegilops tauschii?AtGLW7?used for comparative analysis.The results of this study are as follows:1.Based on the preliminary QTL mapping results,100 genes were detected in the target interval by using comparative genomics,and 32 single copy genes were identified further.In the promoter region of these genes,one high-resolution melting?HRM?co-dominant marker was successfully developed based on SNP,and two sequence characterized amplified regions?SCAR?dominant markers were developed in the gene coding region.All of these three markers were integrated into the genetic map and validated in three populations with different genetic backgrounds.2.The validation analysisof the newly developed markers 0C98-411and B0BB-10470 in three populations with different genetic backgrouds showed that the lines carrying QTgw.sau-2D were significantly higher than those without QTgw.sau-2D.Futher analysis indicated that 0C98-411 is a marker likely most tightly linked toQTgw.sau-2D.We also crossed the line carrying QTgw.sau-2D with a cutivar Chuannong 16 and obtained an F_2:3population.A few of lines with higher TGW in this population carrying QTgw.sau-2D were further screened by using the newly developed markers.3.TaGLW7,HvGLW7,TtGLW7 and AtGLW7 genes were mapped to the second chromosome of the corresponding species.Multiple comparisons showed that the GLW7 gene had two exons and one intron in all species excepturartu wheat.Protein structure analysis showed that GLW7 contained SBP conserved protein domain and two low complexity regions.4.Through phylogenetic analysis,we aggregated the GLW7 genes from all species into a phylogenetic tree.Compared with rice and Brachypodium,the HvGLW7 gene in barley is more closely related to the TaGLW7 gene in wheat.5.The expression pattern analysis showed that GLW7 was highly expressed in panicle organs,including wheat panicle,barley inflorescence and rice anther.In addition,biological stress significantly negatively regulated the expression of GLW7 gene in wheat and barley,and there was a significant correlation between the predicted expression patterns of transcription factor ABF2 and TaGLW7 gene.