Molecular Cytogenetic Study Of The Wheat-Thinopyrum Intermedium Progenies

Wild relatives of wheat had proved to possess a pool of useful genetic variability that could be applied to effective breeding programs all over the world.Thinopyrum intermedium was one of the most widely used wheat relatives in wheat breeding,because it had big spike with floribunda,disease resistance,cold resistance,drought resistance,saline tolerance and other excellent features.Though many researches had been done on the utilization of Th.intermedium in wheat breeding,so far,excellent genes in Th.intermedium are far from elucidated,explored and utilized.What's more,we could find excellent genes or excellent allelic variation of Th.intermedium through the hybrid of different Th.intermedium and wheat.Therefore,it's urgent to introduce excellent genes into wheat to broaden genetic basis of modem wheat cultivars.In this study,23 wheat-Th.intermedium progenies were characterized using morphological traits,HWM-GS,cytological and molecular analysis,and lay a foundation for their use in future.The main results were described as follows:1.The analysis of agronomic characters and HWM-GS constitute:The investigation of main agronomic characters on the 23 wheat-Th.intermedium progenies showed that spike number per plant had the highest variation.Its coefficient of variation(CV)has reached to 28.8%,the range of variation from 2.0 to 9.0 and its average was 5.0.On the contrary,the CV of plant height was lowest,its CV was only 9.6%,the variation extent was 70.0?137.0 cm and its average was 116.3cm.The average of spikelet number,number of grains per spike and spike length was 22.8?36.5 and 14.3cm,respectively.And their variation extent was 14.0?29.0?12.0?75.0 and 10?21cm,respectively.Four materials(zhongl 99-200?zhong526?zhong233 and zhong231)had the character of big spike and theiraverage spike length had excessed 17.0cm.The average length and width of flag leaf was 25.9cm and" 1.5cm,the variation extent was 12.5?40.0cm and 0.8?2.6cm,respectively.Analysis statistically in average rate of seed setting showed that it varied from 22.22%to 94.74%.Result of SDS-PAGE indicated that 10(43.5%)of the analyzed 23 progenies of wheat-Th.intermedium had the combination type of HWM-GS,Null?7+9?2+12.While 5(21.7%)of them had the type of HWM-GS,Null?7+8?2+12.In addition,there were 3,2 and 2 materials had the type 1?7+8?2+12,1?8.2+12 and Null?7+8?5+10,their proportion was 13%?8.7%and 8.7%,respectively.Four materials(zhong209?zhong517?zhong462 and zhong530)had excellent subunits 5+10.2.The analysis of GISH and statistics of chromosome number in root tip cell:The observation of root tip cells of the 23 progenies of wheat-Th.intermedium showed that 19(82.6%)of them had the chromosome number 2n=42.Two of them(zhong243 and zhong265)had the chromosome number 2n=43 and their proportion was 8.7%.Otherwise,the chromosome number of zhong530 and zhong462 was 2n=44 and 2n=56,respectively.According to further analysis using GISH with the genome of Th.intermedium DNA as a probe and Chinese spring DNA as a block,we found that both of 19 materials with 2n=42,contained 2 chromosomes of Th.intermedium and 40 chromosomes of wheat,were disomic substitution line.Two materials(zhong243 and zhong265)with 2n=43,had 41 chromosomes of wheat and 2 chromosomes of Th.Intermedium,were additional-substitution line.Zhong530 with 2n=44,contained 42 chromosomes of wheat and 2 chromosomes of Th,Intermedium,was disomic addition line.Zhong462 had 42 chromosomes of wheat and 14 chromosomes of Th.Intermedium,was a octaploid.3.The molecular cytological analysis of Zhong233:Based on the results above,we identified an alien substitution line of wheat-Th.intermedium,i.e.Zhong 233 with big spike,using FISH,SSR and EST-SSR molecular marker analysis.Its chromosome number in root tip cells was 2n=42,contained 2 chromosomes of Th.intermeium and 40 chromosomes of wheat.GISH in pollen mother cells with the genome of Th.intermedium DNA as a probe and Chinese spring DNA as a block showed that 2 chromosomes of Th.intermedium usually paired as 2111 at the metaphase I of meiosis.FISH result using pAsl probe indicated that a pair of 2D chromosomes were absent in Zhong 233.Molecular marker analysis further conformed that 2D chromosomes of Zhong 233 were substituted by a pair of Th.interedium chromosomes,and Zhong 233 was a stable disomic substitution line.