Identification Of Genotypes Related To Wheat Colour And Mining Relatively Superior Alleles In Bread Wheat Kernels

Polyphenol oxidize（PPO）and yellow pigment content are the main characterswhich have significant influences on the apparence of wheat-based products in wheatgrain. PPO caused unexpected colour in flour processing, and high yellow pigmentcontent caused flour yellowness increasing, making the flours lightness decreasing.They are the main reason why the flour colour is not welcomed by consumers. So itwill be more important to breed new cultivars which flour is more light by geneticsimprovement in the future quality breeding.Research shows that the main genes which control PPO activities and yellowpigment content have been cloned and developed corresponding functional markersfor selecting the allelic variants. In the present study, a total of313wheat germplasmsin the study which are provied by Henan agricultural University containing173landraces cultivars, the current cultivars and81new developed lines for regional testin2009-2010and2010-2011and57durum wheat lines were used and their grainpolyphenol oxidase (PPO) activity and yellow pigment content were evaluated. PPOand phytoene synthase (PSY) genes allelic variants, associated with grain PPOactivity and yellow pigment content, respectively, were identified by the method ofPCR amplification with functional markers,and Ppo-A1g were cloned by isogenesisprimers, their associations with phenotypes were analyzed. The main results obtainedin this study are summarized below.1. The wheat cultivars were less in Huang-Huai wheat region which containsexcellent allelic variants influencing low PPO activity and low yellow pigmentcontent,13of254materials, has excellent alleles combination Ppo-A1b/Ppo-D1a andPsy-A1b/Psy-B1b. Cultivars are Gaoyou503、Yuanfeng898、Jinmai54、Lumai15、Jimai38、 Fan6、 Aifeng3、 Yuanzhu、 Ji5092、 Jiai9、 Yumai3、 Yumai1andZhengmai0856，respectively. PPO activities of the13wheat cultivars are low ataverage of18.8. In addition, the cultivars contain alleles combinationPsy-A1b/Psy-B1b which belong to low yellow pigment content gene combination, taking an important role in reducing yellow pigment content. These cultivars whichhas lower PPO activity and yellow pigment content can be an ideal breeding parentsin the future’ quality breeding.2. The full-length sequence of common wheat Ppo-A1g was isolated and relatedwith low PPO activity. The PPO activities of four varieties of wheat Ji874-109、Qinfeng1、Chiyacao、Hongquanmang are16.3、15.9、25.3、18.5,respectively. Throughthe sequence alignment analysis with Ppo-A1a and Ppo-A1b found that the sequenceof Ppo-A1g lacking191bp at upstream is same with Ppo-A1a,but at the downstreamexists more InDel and SNP site, basing on Alternative splicing theory, this differencecauses decreasing of the gene’ expression and the grain PPO activity declining.3. In this study exists the phenomenon that phenotype and genotype is notcoincident in some cultivars, especially the PPO activity and genotype. Study showsthat some materials PPO activities have significant difference, especially genotypesbelong to the activity of low PPO wheat varieties Xinong6028and Mazamai. TheirPPO activities are54.0and60.8, respectively. We assume that there are some newmain QTL in the genome playing an important role in the PPO activities.4. We found that allelic variant Psy-A1a also exist in Psy1locus in durum, it is acomplement to before research. Our study shows that there are not only twogenotypes Psy-A1d and Psy-A1e in Psy1loci in Italian durum, but also Psy-A1a. Theallele exists both durum and common wheat. So our research makes the genotypes atpsy1loci more abundant in durum. The study also indicated that in markers assistedselection breeding, just use YP7A-2can not confirm allelic variant at Psy-A1loci, weneed to use YP7A-2and YP7A at the same to identify the allelic variation to improvethe result reliabilitily. It is need to confirmation veracity and repeat of the makersfunction further because of its limited.