Karyotype And SCAR Analysis Of The Main Forages Of Pennisetum

Pennisetum forages genera belongs to Angiospermae,Gramineae,which widely distribute in tropical and subtropical regions.It is a kind of safe animal feed with high yield and quality.But from a long time,there are many phenomenon of homonyms and synonyms because of Pennisetum varieties(lines)confusion,which is not conducive to the effective development of breeding work and also lead to a great impact on production efficiency.Therefore,the karyotype analysis and RAPD analysis of the main Pennisetum strains(lines)were carried out in this study,the RAPD markers were successfully converted into more stable and reliable SCAR markers,which provided the theoretical foundation and scientific basis for the selective breeding and identification of Pennisetum.Main conclusions are as follows:(1)Karyotype Analysis of Pennisetum foragesThe chromosome number and karyotype of the root tip cells of 12 major Pennisetum strains(lines)were investigated with conventional pressing plate method.The results showed that the chromosome number of the 12 Pennisetum strains(lines)was constant,the chromosome number was x=7,the number of chromosomes was 2n=28,and the tetraploid strains(lines)included P.purpureum Schum.cv.Huanan,P.purpureum Schum.cv.Xijing,P.purpureum Schum.cv.Mott,P.purpureum Schum.cv.Purple,P.purpureum Schum.cv.Zhangzhou,P.purpureum Schum.cv.Gui minyin and P.purpureum cv.Ju juncao.The number of chromosomes is 2n=21,the triploid strains(lines)included P.purpureum Schum.cv.Laimu No.1,P.purpureum × P.americanum cv.Guicao No.1,(P.americanum × P.purpureum)× P.purpureum Schum.cv.Guimu No.1,P.purpureum × P.americanum cv.Reyan No.4 and P.americanum × P.purpureum.The karyotype asymmetry coefficients of the 12 Pennisetum strains(lines)ranged from 59%to 65%,and the chromosomes mainly consisted of chromosomes and chromosomes in the middle(m),with "1B","2B","1C" and "2C".This showed that they are more primitive type in the evolution.In addition to P.purpureum Schum.cv.Zhangzhou,(P.americanum × P.purpureum)× P.purpureum Schum.cv.Guimu No.1 and P.purpureum cv.Ju juncao three strains(lines),the other strains were found one or two pairs of satellites.(2)Analysis of RAPD markers of Pennisetum foragesGenetic diversity analysis of 24 common Pennisetum strains(lines)was carried out by RAPD marker technique.The results showed that 28 primers were screened from 120 RAPD primers,and 304 bands were amplified from 28 primers,included 249 polymorphic bands and polymorphism was 81.91%.The results indicated that Pennisetum has a high genetic diversity and a more complex genetic background.Cluster analysis was conducted by using NTSYSpc 2.0,and the genetic similarity coefficient ranged from 0.648 to 0.803.When the genetic similarity coefficient was 0.720,24 strains of Pennisetum were divided into seven groups:P.purpureum.cv.Feiji was classified as the first group;P.purpureum × P.americanum cv.Guicao No.1,P.americanum × P.purpureum(Fujian),P.purpureum.cv.Nanmu No.1 P.Purpureum.cv.Taixucao as the second group;P.americanum × P.purpureum cv.Minmu No.6 and P.purpureum.cv.Tainong No.2 as the third group;Pennisetum polystachyon(L.)Schult.and P.purpureum Schum.cv.Taiwan for the fourth group;P.purpureum × P.americanum cv.Reyan No.4 and P.purpureum.cv.Ju juncao as the fifth group;(P.americanum × P.purpureum)× P.purpureum Schum.cv.Guimu No.1(Fujian)and P.purpureum Schum.cv.Gui minyin as the sixth group;other strains as the seventh group.(3)Analysis of SCAR markers of Pennisetum foragesThe RAPD marker was transformed into a more stable and reliable SCAR marker.In this experiment,14 specific bands were identified,cloned and sequenced by RAPD markers,and 16 specific primers were designed and synthesized.SS8-22,SS43-22,SS85-22,SS106-22-1,SS24-2,SS76-4,SS84-20-2,SS114-6-1,SS106-8 and SS14-24-1 were successfully transformed into SCAR markers with a success rate of 62.50%.The SCAR markers appeared characteristic of stable amplification,clear strip,good repeatability.Using these 10 pairs of specific primers,seven types can be quickly and accurately identified from 24 strains(lines)of Pennisetum,including P.americanum × P.purpureum(Guangxi),P.purpureum Schum.cv.Xijing,P.purpureum Schum.cv.Purple,P.purpureum Schum.cv.N85,P.purpureum Schum.cv.Laimu No.1,P.purpureum Schum.cv.Gui minyin and P.purpureum.cv.Nanmu No.2.