The Study Genetic Differentiation Of Agropyron Cristatum Populations Based On Genomic Size, Phenotypic Traits And Chlorophyll Content

Agropyron cristatum?L.?Gaertn.,is a type species of Agropyron belonging to the Triticeae Poaceae.It is a perennial herb.A.cristatum is a cross-pollinated plant,which contains only P genome and is a homologous polyploid species,widely distributed worldwide.A.cristatum is a kind of good forage grass,which is also the main part of alpine grassland meadow.At the same time some of its fine characters are excellent gene resources of wheat crop and forage grass.Previous studies showed that there was significant genetic differentiation among herbage from different geographic sources and habitats,but the cause of genetic differentiation was not clear.The lack of understanding of phenotypic differentiation,genome-size variation and physiological index variation caused by the global wide distribution of agrocytes further hinders the understanding of the genetic differentiation mechanism of agrocytes and hinders the efficient utilization and effective protection of agrocytes planting resources.Therefore,164 species of A.cristatum were selected in this study,including 74 species in Central Asia,18 species in East Asia,47species in Middle East,20 species in Qinghai-tibet plateau,3 species in Europe and 2species in America.The genome size of 125 tetraploid A.cristatum,chlorophyll A content,chlorophyll B content and total chlorophyll content of 86 species tetraploid A.cristatum and 10 phenotypic traits of 129 tetraploid A.cristatum,were determined.In order to study the genetic differentiation of A.cristatum,the above parameters were statistically analyzed.Results show:1.Using diploid A.cristatum PI578519 as the control,55 of A.cristatum ploidy were detected by flow cytometry.The results were:16 of diploid,39 of tetraploid.Moreover,the solution suitable for genomic size determination of A.cristatum was Tris-MgCl₂ Buffer,which was lysed for 25 min and stained for 20 min.2.In terms of genome size,the variation trend of the four populations is that the population of East Asia?11.3083 Gb?is successively higher than that of Central Asia?10.7708 Gb?,the Middle East?10.7639 Gb?and Qinghai-tibet?10.4512 Gb?,and the genome size of the population of East Asia is significantly higher than that of the other three populations,and the average value of genome size of the population of East Asia is0.5375Gb larger than that of the Middle East.3.In terms of phenotypic traits,the plant height?47.16cm?in Central Asia was successively higher than that in Europe?43.58cm?,East Asia?43.37cm?and Middle East?39.40cm?,and there was a significant difference between Central Asia and Middle East?P<0.05?.The spike length?65.90mm?in Central Asia was successively higher than that in the Middle East?53.08mm?,East Asia?50.07mm?,and Qinghai-tibet population?37.88mm?.Moreover,the spike length in Central Asia was significantly higher than that in the Middle East,East Asia,and Qinghai-tibet population.The spikelet number in East Asia?31.54?was higher than that in Central Asia?29.90?,Middle East?28.85?and Qinghai-tibet?28.29?.The spikelet length?12.62mm?in Central Asia was successively higher than that in the Middle East?10.48mm?,East Asia?10.09mm?,and Qinghai-tibet population?8.40mm?.The Central Asia population was significantly higher than that in the Middle East,East Asia,and Qinghai-tibet population,and there were significant differences between Qinghai-tibet population and that in the Middle East and East Asia.The floret number?7.56?in Central Asia was significantly higher than that in Middle East?6.77?,East Asia?6.54?and Qinghai-tibet?5.71?.The glum length?4.63mm?of the Central Asian population was successively higher than that of the Middle East?4.28mm?,East Asia?4.01mm?and Qinghai-tibet population?2.71mm?.The Central Asian population was significantly higher than that of the Middle East,East Asia and Qinghai-tibet population,and there were significant differences between the populations of Qinghai-tibet and the Middle East and East Asia.The glum awn length?3.21mm?of the Central Asian population was successively higher than that of the Middle East?3.16mm?,East Asia?2.82mm?and Qinghai-tibet population?2.23mm?,and the Qinghai-tibet population was significantly lower than that of Central Asia,Middle East and East Asia.The lemma length?7.33mm?of the Central Asian populations was successively higher than that of East Asia?6.48mm?,the Middle East?6.48mm?and the Qinghai-tibet populations?5.58mm?.The Central Asian populations were significantly higher than the other three populations,and there were significant differences between Qinghai-tibet populations and the Central Asian and Middle eastern populations.The lemma awn length?3.22mm?in the Middle East was successively higher than that in Central Asia?2.80mm?,East Asia?2.68mm?,and Qinghai-tibet population?2.03mm?.The Qinghai-tibet population was significantly lower than that in the Middle East,Central Asia,and lower than that in the Middle East,and there were significant differences between the populations in Central Asia and the Middle East.The spike width?17.27 mm?of Central Asian populations was successively higher than that of East Asian populations?15.13 mm?,Qinghai-tibet populations?14.98 mm?,and middle eastern populations?14.78 mm?.4.In terms of chlorophyll content,the content of chlorophyll A in Central Asian populations?1.1937 mg/g?was successively higher than that in East Asia?1.1890 mg/g?,the Middle East?1.0899 mg/g?and Qinghai-tibet populations?1.5837 mg/g?,and the content of chlorophyll A in Central Asian populations was significantly higher than that in the Middle East and Qinghai-tibet populations.The content of chlorophyll B?0.8936 mg/g?in Central Asian populations was significantly higher than that in East Asia?0.7717 mg/g?,Middle East?0.7463 mg/g?and Qinghai-tibet populations?0.6713 mg/g?.The total chlorophyll content of populations in Central Asia?2.0873 mg/g?was successively higher than that in East Asia?1.9607 mg/g?,the Middle East?1.8362 mg/g?,and the Qinghai-tibet population?1.2420 mg/g?.However,in the three groups of data,the difference between East Asian and Middle eastern populations is only within 0.1.5.This shows that there are abundant genetic variations among A.cristatum populations,and the genetic differentiation among A.cristatum populations in Central Asia,East Asia,the Middle East and Qinghai-tibet is relatively obvious;The tetraploid A.cristatum of East Asian populations may be the result of the intercross of diploid A.cristatum and Mongolicum in East Asia;The A.cristatum of Qinghai-tibet population is migrated and expanded from the A.cristatum of Central Asia population,it is possible that some genes are lost due to sudden changes in the environment,which results the traits of the plant were lower than those of other populations.