Production And Identification Of The Octoploid Triticale Derived From Trigeneric Hybrids

Wheat（Triticum aestivum L.）is one of the three major food crops,and which is treated as staple food for one-third of the world’s population.However,due to the frequent occurrence of farmland pollution,food safety,resource shortages,heavy rainfall,and high-temperature heat waves,the breeding target of high yield,stable yield,and good quality is severely challenged.Secale L.,as a closely related species of wheat,which can provide the potential genetic resources of disease resistance,cold and drought resistance,salt and alkali resistance,and barrenness tolerance.Therefore,it could provide excellent gene resources for wheat genetic improvement.Octoploid triticale is a new synthetic species,which was obtained by doubling the chromosomes of hybrid F₁between hexaploid wheat（ABBDDD）and rye（RR）.It include the whole genome of wheat and rye,and have the characteristics of cold resistance,salt and alkali resistance,high protein content,full grain,strong growth of both wheat and rye.Furthmore,it is easy to hybridize with common wheat,so it is an important bridge to transferring rye genes to wheat.However,with the rapid evolution of various disease physiological races,octoploid triticale is gradually losing its resistance.As well as cytogenetic instability and narrow genetic diversity,it is difficult to improve the yield and quality of octoploid triticale.In this study,we hybridized the wheat-P.huashanica amphiploid（PHW-SA,2n=8x=56,AABBDDNs Ns）with the hexaploid triticale（Zhongsi 828,2n=6x=42,AABBRR）to obtain the F₁hybrids.A new octoploid triticale line K15-1515-1,with enhanced stripe rust resistance,was identified from the F₈generation of wheat-P.huashanica-rye hybrids.The results are as follows:1.When using P.huashanica total genomic DNA as probe and common wheat J-11 as blocker,we didn’t detect any signal of P.huashanica in line K15-1515-1.GISH and FISH analyses revealed that the chromosome constitution of K15-1515-1 was same as common octoploid triticale（2n=8x=56,AABBDDRR）,which contained a complete set of wheat genome chromosomes（1A-7A,1B-7B,1D-7D）and 14 rye genome chromosomes（1R-7R）.The chromosome constitution of the selfed F₉generation seeds of K15-1515-1 was same as F₈generation using molecular cytogenetics method.The results suggested that the octoploid triticale K15-1515-1 was relatively cytogenetically stable.2.The agronomic characters of K15-1515-1 combined the characters of the parents,such as longer and wide leaf,more tillering,more spikelet numbers,full grain,and high self-setting rate.Moreover,K15-1515-1 was later-mature than Zhongsi828 for 15 days,and which could be a supplier supplying forage when other plants went out of use.3.K15-1515-1 and PHW-SA were highly resistant to stripe rust,showing only 0;infection types.Zhongsi 828 was susceptible to stripe rust,showing infection of type 4.We hybridized K15-1515-1 with the wheat varieties of Sichuan,and obtained some hybrid offspring.The results lay the foundation for further wheat breeding with stripe rust resistance.