| Psathyrostachys huashanica Keng(2n=2x=14,Ns Ns)is a diploid perennial cross-pollinated plant from Psathyrostachys Necski,Poaceae.It was regarded as a valuable genetic resource in wheat improvement for its many excellent traits,such as early maturation,high resistance to wheat disease(rust,powdery mildew,FHB and take-all),high tolerance to salinity,alkalinity and cold,dwarf and a lot of tillers.Wheat-P.huashanica derived lines developed from distant hybridization and chromosomal engineering were important middle materials to utilize P.huashanica Ns genome.This research screened five derived lines from F6-7 progeny of heptaploid hybrid H8911(2n=49,AABBDDNs)×Triticum durum line Trs-372(2n=28,AABB),named DH5,DH88,DH66,TR77,and DH109.Methods of cytologic observation,in situ hybridization(GISH and Mc-FISH),molecular markers(EST-STS,SSR,SCAR and wheat SNP array)combine with field traits investigation were adopted to give these derived lines detailed analysis.The main results are as follows:(1)Preliminary karyotype analysis of P.huashanica:preliminary chromosomal karyotype analysis was performed to the exogenous parent P.huashanica and its karyotype formula was 2n=2x=14=12m(4sat)+2sm,Stebbins'karyotype was‘2A'and average arm ratio was 1.4.P.huashanica situated at a higher level within the genus,but the whole genus was at a low level of evolution in the plant kingdom.(2)Cytologic observation showed the chromosome constitution of DH5 was 2n=42+Ti=21?+Ti(Ti indicated small chromosome segment),GISH experiments showed that DH5 contained a small chromosome segment from P.huashanica.The segment could not pair with wheat chromosomes in meiosis metaphase?,but it could inherit to offspring through male parent with a transmission of 1/2.Molecular markers confirmed this small segment was from the short arm of P.huashanica 5Ns.Through markers conversion developed eight pairs of SCAR markers were designed to track P.huashanica 5Ns chromosome.Agronomic traits investigation showed DH5had short plant height,high stripe rust resistance and the small segment did not affect DH5 in agronomic traits.(3)Cytologic observation showed the chromosome constitution of DH88 was 2n=44=22?;GISH experiments showed that DH88 contained a pair of P.huashanica chromosome which could pair and transmission normally in wheat background.EST-STS markers showed the alien chromosome in DH88 was from 6Ns chromosome of P.huashanica.DH88 had high resistance to stripe rust probably because the addition of P.huashanica 6Ns chromosomes.(4)Cytologic observation showed the chromosome constitution of DH66 was 2n=42=21?;GISH analysis showed that a pair of wheat chromosome was substituted by chromosome of P.huashanica in DH66,and the pair alien chromosome could pair and transmission to progeny normally.Mc-FISH showed DH66 lost its a pair of wheat5D chromosome.Molecular markers confirmed DH66 contained P.huashanica 5Ns chromosome but without wheat 5D chromosome.An obvious crossing point appeared in position of 5D chromosome according to the results of wheat 15K SNP array.Combining with four kinds molecular markers showed a pair of wheat 5D chromosome was substituted by P.huashanica 5Ns chromosome in DH66.DH66with superior stripe rust resistance,dwarfing plant height,and a longer dough stability time,thus,could be employed as an important germplasm for the genetic improvement of disease-resistant and high-quality wheat.(5)Mitosis observation showed the chromosome constitution of TR77 was 2n=42=21?,with two chromosomes whose more 1/2 construction were replaced by alien chromosomes.Meiosis analysis showed TR77 was a cytologic stability wheat-P.huashanica translocation line.Results of molecular markers and Mc-FISH analysis showed 5DL-3DS·3DLand 3DS-Ns L·Ns S were formed in TR77.Therefore,TR77was a wheat-P.huashanica dual translocation line.According to wheat 15K SNP array analysis of TR77,the translocated physical posistion was close to centromere between 202.3 Mb and 213.1 Mb of 5D chromosome.TR77 exhibited conical and awnless spikes,taller plant,longer spikes,more kernels per spike and better powdery mildew resistance in all period than its parents.TR77 can be an important germplasm for improving powdery mildew resistance and yields in wheat breeding,and for dual translocation research.(6)The similarity and difference between derived line DH109 and DM131:DH109 was screened from wheat-P.huashanica derived progenies and DM131 was screened from wheat-L.mollis derived progenies.Molecular cytogenetic methods confirmed that the two lines are 3Ns(3D)disomic substitution line,but DH109 was a wheat-P.huashanica 3Ns(3D)disomic substitution line and DM131 was a wheat-L.mollis 3Ns(3D)disomic substitution line.The two lines had similar cytologic observation and GISH results,which demonstrated they were both stable wheat-alien derived lines.However,the two lines had bad applicablity in STS and SCAR markers and entirely different FISH karyotype.In agronomic traits,the two lines both expressed mild susceptible to stripe rust,high resistance to powdery mildew in seeding age;but for FHB,DH109 expressed high resistance but DM131 expressed high susceptible.In morphological traits,DH109 had bigger kernel and DM131 had longer spike and more tiller number.In grain quality,two lines were intermediated between two wheat parents.In conclusion,the entered of P.huashanica 3Ns and L.mollis 3Ns would result in many differences of traits change in wheat.The two lines could be used in wheat powdery mildew and FHB resistance breeding and for differentiation comparison of Ns chromosome in Psathyrostachys Necski and Leymus Hochst..Preliminary chromosomal karyotype analysis of P.huashanica provided a theoretical basis for further researches of this relative species;identification of the five derived lines enriched the genetic germplasm of wheat,and had important utilization values for disease resistance,high yield and high quality wheat breeding;the comparison of the Ns chromosomes from different genera introduced to wheat background provides references for studying the genetic and evolutionary relationship of wheat relative species. |
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