| Triticale(×Triticosecale Witmack)is a new species obtained from Triticum and Sfecale species through sexual hybridization and chromosome doubling of hybrid F1.Hexaploid triticale plays a very important role in the production because it combined the excellent agronomic characters of two parents,such as the high yield and good quality from common wheat,and luxuriant growth,high disease resistance,strong stress tolerance and high lysine content from rye.Hybridization of hexaploid triticale and common wheat is not only an important way to introduce rye excellent genes into common wheat,but also an important means to improve hexaploid triticale.Therefore,cytological analysis of the hybrids of hexaploid triticale and common wheat is of great importance for improving common wheat and triticale.In this study,hexaploid triticale ZJL51-60 and ZJL61-70 were used as female parent hybridized with common wheat cultivars.Through the count of root tip chromosome,genomic in situ hybridization(GISH)and fluorescence in situ hybridization(FISH)analysis explored the chromosome number and composition in F2 hybrid.The main findings are as follows:(1)Cytological identification found that female parent ZJL51-60 is 2D(2A)chromosome substitution lines(2n=42).ZJL61-70 has two types,type I is 2D(1A)chromosome substitution lines(2n=42);type II is 2D(1A)chromosome substitution lines with losing a 6B chromosome(2n=41).(2)The number of root tip chromosomes in 144 F2 hybrids were observed.The number of chromosomes was normal distribution range from 37-54 and concentrated in 44.The average number of chromosome per plant was 43.76.The average number of A,B,D and R genomes was 12.77,13.73,7.42 and 8.38;the distribution of chromosome number in D and R groups showed a significant difference.Each seed has an average of 1.47 chromosomes that are not recognized.(3)Chromosomes in A and B geome have losing in various degree.Overall,the genetic stability of B genome was higher than A genome.1Ahas the highest frequency of loss in A genome in F2 hybrids which were derived from 2D(2A)chromosome substitution lines hexaploid triticale × common wheat,indicating that a single 2A may affect the normal pairing of 1 A.In addition to the material itself the frequency of loss of 6A and 5B in hybrid F2 was the highest.(4)The number of chromosomes in group D and R were concentrated in 7 and 9,which indicated that the chromosome of group R might have stronger competitive advantage than group D chromosome.There are 86 seeds(59.72%)losing 2D chromosome,indicating that the 2D chromosome in the hybrid offspring in the transmission capacity may be weak.There was a difference in the frequency of transmission between different chromosomes in D and R groups.The average number of 1D-7D was 1.02,1.24,1.02,0.83,1.22,0.95 and 1.14,the transmission frequency was 5D(85.42%)>7D(81.94%)>6D(78.47%)>1D=3D(76.39%)>4D(61.86%).The average number of 1R-7Rin F2hybrids was 1.28,1.13,1.12,1.17,1.29,1.09 and 1.30,the transmission frequency was 7R(87.50%)>1R=5R(84.03%)>4R(82.6 4%)>2R(78.47%)>3R(76.39%)>6R(74.31%).(5)The chromosomes 5D and 1R in the hybrid F2 appeared higher frequency,and mainly in the form of 2,indicating that the satellite may affect the transmission of chromosomes in the offspring.(6)There were chromosomal fragments in 6.94%of the seeds,and chromosomal translocation appeared in 13.89%of the seeds.The results showed that the hybridization of hexaploid triticale and common wheat could improve the chromosome structural variation,and these variations may be caused by the fission-fusion of chromosomes. |
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