| The color of flour and flour products is one of the most important indicators to evaluate wheat quality traits,The polyphenol oxidase(PPO)in wheat grain is the main cause of browning.browning affects not only the apparent quality of flour and its products,but also the lack of food properties and nutritional value.Therefore,the molecular genetic characteristics of PPO in wheat and its relationship with the quality traits were studied,which could provide reference and theoretical basis for the improvement of wheat quality traits in China,and also in China's food security and economy Development and other aspects.In this study,211 wheat landrace cultivars were used as materials.The PPO activity were determined by L-DOPA,cluster analysis was carried out.The molecular markers of the A ? B and D genomes were used to detect the molecular dynamics of PPO gene,the relationship between the distribution of different gene types and the activity of PPO were studied.Cloning and bioinformatics analysis of PPO gene on 2BL chromosome by homologous cloning,the molecular markers of PPO activity on 2BL chromosomes were developed and verified,The main results are as follows:1.The mean PPO activity of China's wheat landrace cultivars is 29.06AU·min-1·g-1,widely ranges from 9.23 AU·min-1·g-1 to 57.34 AU·min-1·g-1,has the potential for greater genetic improvement.low(<17 AU·min-1·g-1)?lower(17~27AU·min-1·g-1)?medium(27~35 AU·min-1·g-1)?higher(36~43 AU·min-1·g-1)?high(>43 AU·min-1·g-1)were divided into five categories by cluster analysis with PPO activity.The overall distribution was normal,The data of the lower active type interval were 58,accounting for 27.5%.2.Among wheat landrace cultivars in china,Ppo-A1b(Low PPO activity)?Ppo-B1b(High PPO activity)and Ppo-D1b(High PPO activity)Genotype were higher in frequency,73.9%?81.5% and 63.2%,respectively.the mean PPO activityof Ppo-A1 a was 40.5 AU·min-1·g-1,significantly higher than other types,Ppo-D1 a was 20.2 AU·min-1·g-1,the lowest.The distribution of the active interval was analyzed by A,B,D chromosome molecular markers,The results show that the higher the PPO activity,the greater the likelihood of Ppo-A1 a and Ppo-D1 b,and the higher the PPO activity,the greater the likelihood of Ppo-A1 b and Ppo-D1 a,There was no obvious trend in the distribution of F-8 on chromosome B.3.In the 211 tested wheat landrace,medium activity interval Ppo-A1b/Ppo-B1b/Ppo-D1a(31.86 AU·min-1·g-1)were the most,39.3% in Frequency,high activity Interval Ppo-A1a/ Ppo-B1a/ Ppo-D1b(45.92 AU·min-1·g-1)and Ppo-A1a/ Ppo-B1b/Ppo-D1b(43.06AU·min-1·g-1),1% and 13.4% in Frequency,respectively.low activity interval Ppo-A1b/ Ppo-B1a/ Ppo-D1a(15.32AU·min-1·g-1)and Ppo-A1b/ Ppo-B1b/Ppo-D1a(15.81AU·min-1·g-1),6.5% and 22.9% in Frequency,respectively.The same gene combination of the material is still part of the active deviation,PPO16,PPO16 and PPO29 were significantly different from the combination of different molecular markers,and the effect of F-8 was limited,A,B,and D groups of chromosomes are used in combination can increase the selectivity and efficiency.4.A PPO gene was cloned from wheat 2BL chromosome by homologous cloning,The g DNA sequence was 1824 bp and the c DNA sequence was 1575 bp,respectively.Encoding 524 amino acids,58.58 k D and 6.58 in p I.The method of bioinformatics is used to predict,It has three conserved domains,Tyrosinase,PPO1_DWL and PPO1_KFDV,respectively.Hydrophilic protein,no signal peptide,no transmembrane structure,18 serine(Ser)phosphorylation sites,17 threonine(Thr)phosphorylation sites and 3 tyrosine(Tyr)phosphorylation Site,respectively.5.A 2BL chromosome PPO activity molecular marker PPO-B5 was developed,it can amplified three bands(band a?band b?band c),four different types in all,named type A(band a?band b?band c),the mean activity was 29.75 AU·min-1·g-1,type B(band b?band c),the mean activity was 27.16 AU·min-1·g-1,type C(band a?band c),the mean activity was 34.39AU·min-1·g-1,type D(band c),the mean activity was23.78 AU·min-1·g-1,significant differences in the level(P<0.05).Sequence analysis showed that band a was 431 bp and the similarity was 99% with GQ30713.1,band b was 431 bp and the similarity was 99% with AB254810.1,The sequence differences occurred in the AB254804.1 second intron of 201 bp deletion and 12 SNPs,The band c is 192 bp,which is derived from group A chromosomes.Combined with A,D chromosome markers PPO18,PPO16 and PPO29 to verify it,HAHBHD(PPO18?PPO-B5? PPO16 amplified high activity band HA?band HB?band HD,respectively),Highest in the PPO activity,The mean activity was 43.67AU·min-1·g-1,Significantly higher than other types.LALBLD(PPO18?PPO-B5? PPO16 amplified low activity band LA?band LB?band LD,respectively),lowest in the PPO activity,The mean activity was 15.33AU·min-1·g-1,Three groups of molecular markers used in combination can be more accurate distinction between different varieties of wheat cultivars.PPO-B5 is a reliable,practical PPO active molecular marker. |
PDF Full Text Request