Analysis Of Qualities And Genetic Diversity Among Barley Germplasm Resources

Barley is an important food raw material and can be used for many things such as food,vinification and healthcare. It is widely planted in the world. Recently, as the beer andhealthcare industry had developed rapidly, the demand of barley was growing substantially.But the nutritional and chemical qualities of barley accessions used for the production wereuneven, and the quatities of excellent barley accessions were less in our contry at present.Therefore,292barley core accessions, which were collected from the genetic resources centerof the International Center for Agricultural Research in the Dry Areas （ICARDA）, wereselected to study on the agronomic traits, betaine contents, and the analysis of geneticdiversity with SSR markers. In addtion, the excellent barley accessions with a good potentialfor development and utilization, were screened preliminarily by betaine content andagronomic traits. The chemical qualities of these accessions were also evaluated in the study.The results would offer fundmental information to enrich the quantities of excellentgermplasm and guide selection in barley breeding program. The key results were presented asfollows.1. A single-factor experiment was performed for optimization of the TP-M13-SSR（simple sequence repeat with tailed primer M13） analysis system in barley, with changingconcentrations of template DNA, dNTP, Taq DNA polymerase, Mg2+, SSR forward primer,SSR reverse primer and M13fluorescently-labeled primer. Finally, the TP-M13-SSR analysissystem was established with the following conditions: in a total of10μL reaction solution,1.0μL10×PCR buffer without Mg2+, MgCl₂（20mmol/L）1.2μL,0.3μL dNTPs （10mmol/L）,1μL template DNA （20ng/μL）,0.15μL Taq DNA polymerase （5U/μL）,0.3μL primer SSR-TF（0.1μmol/L）,0.3μL primer SSR-R （1μmol/L） and0.2μL M13fluorescent primer （1μmol/L）.The optimized system could amplify the clear and polymorphic bands.2. With the optimized system, genetic diversity of292barley accessions was analyzedby twenty-one SSR combinations. The results showed that the nineteen pairs of SSR primers，which were selected from the twenty-one pairs, amplified136allelic loci in292barleyaccessions. Each primer pairs could produce3-12allelic loci with7.16allelic loci in theaverage. The values of polymorphism information content （PIC） of these SSR products werefrom0.35to0.89, and94.74%loci displayed a great of polymorphism. In the nineteen pairsof SSR primers, primer SSR17was effective to detect DNA variations among those barleyaccessions. The cluster analysis using UPGMA method based on the data of SSRs showed that292barley accessions were divided into eight groups, which are coincident to thecollection areas of barley accessions. It would be assume that Syria, Tajikistan, Yemen, China,Algeria and Libya might be the centers of origination of barley accessions.3. The six agronomic traits had great differences in the292barley accessions, especiallythe grain number per spike. The analysis of betaine content showed that the concentration ofbetaine was0.20～20.90mg/g fresh weight in the accessions, with an average of2.62mg/gfresh weight and78.52%in the coefficient of variance. The betaine contents of58%barleyaccessions ranged from1to3mg/g fresh weight. The accessions with the highest and lowestbetaine contents were orignated from Greece and Uzbekistan, respectively. Two of SSR loci,SSR4and SSR16, were positive correlated with betaine contenti n significant level （P＜0.01）,indicating the two SSRs could be the effective markers for screening accessions/cultivars inbreeding program.4. Seventeen excellent barley accessions, which have potential to produce healthprotection foods, were selected by using the evaluation indexes of flag leaf area, plant height,chlorophyll content （SPAD values） and betaine content, and their chemical qualities wereanalyzed. The results showed that the chemical qualities of these accessions varied somewhatin the leaves. The contents of soluble flavonoid compounds and betaine were remarkabledifference in the17barley accessions. The average scavenging rates for DPPH·, OH·andABTS+were26.96%,6.02%and18.44%, respectively. Moreover, the scavenging rate ofOH·varied greatly with barley accessions. The correlation analysis showed that the solubleflavonoid compounds was positively correlated with scavenging DPPH·and OH·（P<0.05）.The betaine content was positive correlated with the rate of OH·scavenging （P <0.05）.5. Twelve barley accessions were selected by three indexes, which were the ratio of grainnumber and spike length≥6.00/cm,1000-grain weight≥42/g and the betaine content≥1.00mg/g fresh weight. These accessions were considered as excellent accessions becausethey had potential to produce good quality of beer. The quality of exterior andphysic-chemistry was analyzed for these accessions, and the results showed that the color,odor and uniformity were not significant difference in the seeds of these accessions, butremarkable differences were observed in grain weight, moisture content and germination rate,especially the germination rate. The protein contents varied in different accessions before andafter seed germination. In general, the contents of glutenin, hordein and albumin in theseaccessions were45%～50%,15%～20%and15%～20%of total content of grain protein,respectively, and globulin was the lowest. After germination, the content of albumin increased by50%, the globulin decreased50%in the green malt, and the contents of hordein andglutenin reduced slightly.