Cytological Identification And Agronomical Traits Of T.Turgidum-Ae.comosa Amphidiploids

Aegilops L.is an important gene pools for improving the disease and insect resistance as well as stress tolerance of wheat.Ae.comosa(2n = 2x = 14,MM)is one of the diploid Aegilops species that possesses excellent resistance to stripe rust,powdery mildew and cereal aphids.The T.turgidum-Ae.comosa amphidiploids could be used as bridges to transfer the genetic material of Aegilops into wheat and further enrich the genetic diversity and improve the biological and abiotic resistance of wheat.We investigated the main agronomic traits and analysised FISH pattern of root tip cells for T.turgidum-Ae.comosa amphidiploids and their parents.The main results were as follows:1.The plants and seeds agronomic traits of 9 T.turgidum-Ae.comosa amphidiploids in S2 and S3 generations were investigated.The tiller numbers,plant height,flag length and width as well as seed widths/lengths of T.turgidum-Ae.comosa amphidiploids were situated between those of the tertaploid wheat and diploid Aegilops comosa parents or closer to the female tetraploid wheats.The spike and awn lengths of STM1-STM4 were longer than those of their parents,and both traits of STM5-STM9 were intermediated between their parents.The seed length and width,projection area and perimeter of T.turgidum-Ae.comosa amphidiploids were larger than those of their parents.The floret numbers,seed numbers and seed setting rates among and within the S2 and S3 generations were different.2.The stripe rust resistance of S2 and S3 generations of T.turgidum-Ae.comosa amphidiploids and their parents were investigated.The male parents Ae.comosa showed highly resistant to stripe rust with score 1,and that of the female tetraploid wheat parent Langdon is moderately susceptible to stripe rust with score 6,and TD312 is moderately resistant to stripe rust with score 4.All of T.turgidum-Ae.comosa amphidiploids in S2 and S3 generations were highly resistant to stripe rust with score 1 except for the S2 generation of STM4,with score 2.3.The chromosome numbers of T.turgidum-Ae.comosa amphidiploids in root tips of S2 and S3 generations were ranged from 37 to 42.The chromosome numbers varied among and within the crosses for S2 and S3 generations.4.The HMW-GS compositions of T.turgidum-Ae.comosa amphidiploids and their parents were analyzed.As expected,the HMW-GSs derived from the tetraploid wheats female parents and the Ae.comosa male parents were observed in all the amphidiploids in both S2 and S3 generations except for STM7.Unexpectedly,two HMW-GSs bands differed from those of their parents,were detected in STM7 amphidiploids in both S2 and S3 generations.5.For better identification the chromsomes of diploid Aegfilops comosa parents and T.turgidum-Ae.comosa amphidiploids,we screened different probes by fluorescence in situ hybridization(FISH).The results showed that all the probes(CTT)s,Oligo-pTa-71,Oligo-pSc119.2-1,Oligo-pTa-713,Oligo-pAs1-1 and Oligo-pTa535-1 had good signals on the Ae.comosa chromosomes,except for the weak signals for the last two probers.Four probe combinations of Oligo-pSc 119.2-1 + Oligo-pAsl-1,Oligo-pSc119.2-1+Oligo-pTa535-1,Oligo-pTa-71 +(CTT)5 and Oligo-pSc119.2-1 + Oligo-pTa-713 could distinguish 7 pairs of M chromosomes from Ae.comosa and the in situ hybridization patterns of Ae.comosa was established using the above probe combinations.Among the four probe combinations,Oligo-pTa-71 +(CTT)5 is the best one for identify 7 pairs of M chromosomes in diploid Ae.comosa.The results also showed that Oligo-pSc119.2-1,Oligo-pAs1-1 and Oligo-pTa-713 could differentiate all the A,B and M chromosomes in T.turgidum-Ae.comosa amphidiploids.6.The chromosomal numbers of T.turgidum-Ae.comosa amphidiploids in S3 generation were identified by FISH analysis.We identified complete amphidiploids plants with 42 chromosomes and intact A,B and M chromosomes from four amphidiploid crosses.Though some plants from two amphidiploids crosses(STM1 and STM5)had 42 chromosomes,they were involed in trisomic chromosomes of 2A,2M or 7M,respectiecly.Besides,the chromosome numbers for other plants were all less than 42.The lost chromosomes were predominantly by M chromosomes,followed by A chromosomes especially 2A,with B chromosomes lost at a very low frequency.