Molecular Cytogenetic Characterization Of The Derivatives From Trigeneric Hybrids Involving Triticum, Psathyrostachys And Secale

Wheat (Triticum aestivum L.) is the earliest domestication and most widely planted crop. It is treated as staple food for 35% of the world’s population due to its high yield, nutrition value, wide distribution, and the role in food trade across the world. However, wheat cultivars production and breeding have been hindered by the shrinking of cultivated area, population increase, scarce resources, food safety and narrow genetics background. Triticeae (Poaceae) includes many wild species, which can provide potential genetic resources with the enhanced resistance to stress environment such as diseases, insect pests, drought, and salinity. Psathyrostachys huashanica Keng ex Kuo and Rye (Secale cereale L.) paly a vital role in the tertiary gene pools of common wheat, which show strong resistance to stripe rust, powdery mildew, wheat scab and various characteristics of resistance. Thus, they could act as excellent exogenous gene resources.In this study, we used wheat-P.huashanica (PHW-SA,2n= 56, AABBDDNsNs) and hexaploid triticale (Zhongsi 828,2n= 42, AABBRR) to obtain the F1 wheat-P. huashanica-rye hybrids. The derivative lines with variation types were obtained by selfing of the F1 wheat-P. huashanica-rye hybrids. The F4 trigeneric hybrids were preliminarily identified by molecular cytogenetic techniques. We screened out 13 new triticale lines with highly resistant to wheat stripe rust from F5 trigeneric hybrid by using genomic in situ hybridization and disease resistance screening. The main results were shown as follows:1. The average chromosome configuration at MI in pollen mother cells (PMCs) of trigeneric hybrids F4 was 2n= 1.71 Ⅰ+20.26 Ⅱ+0.04 Ⅲ+0.001 Ⅳ, chromosome number ranged from 39 to 46. The frequency of the lines with 42 chromosomes were more than 50%. At meiotic metaphase I, a number of univalents were found in most PMCs, bivalent numbers varied from 18.64 to 21.65, multivalents consisted of trivalents and tetravalents were observed in 40% of the plants. Those lines with 42 chromosomes have normal chromosome pairing with a small quantity of univalents and multivalents. The apical karyotype of trigeneric hybrids F5 of 40 lines showed that chromosome number ranged from 40 to 45, the average number of chromosome was 42.35. There were 24 lines with 42 chromosomes.2. We didn’t observe any signal when using P. huashanica total genomic DNA labeled with digoxigenin-11-dUTP as probe and common wheat J-11 as blocker to detect the F4 and F5 trigeneric hybrids lines.11-14 chromosomes showed signals when S. cereale total genomic DNA was used as the probe. There were 12～14 rye chromosomes in the 24 lines. On the other hand, GISH analysis revealed that rye chromosomes had normal chromosome pairing with a small quantity of univalents at the meiotic metaphase I.3. We screened out 13 new triticale lines with high resistance to wheat stripe rust from F5 trigeneric hybrids by GISH and disease resistance screening. At MI of those 13 lines, the frequency of univalent was low, trivalents or tetravalents were observed in three strains (612-4,625-1,626-1). GISH analysis revealed that 14 rye chromosomes paired good at MI and uniformly separated into two daughter cells at meiosis anaphase.4. SDS-PAGE analysis among the F5 trigeneric hybrids showed that the bands of HMW-GS in some seeds were the same as Zhongsi 828. Many seeds retained the special bands of wheat-P. huashanica amphiploid.