Abstract
Kengyiliahirsuta (Keng, 1959) J. L. Yang, C. Yen et B. R. Baum, 1992, a perennial hexaploidy species, is a wild relative species to wheat with great potential for wheat improvement and domestication. The genome structure and cross-species homoeology of K.hirsuta chromosomes with wheat were assayed using 14 single-gene probes covering all seven homoeologous groups, and four repetitive sequence probes 45S rDNA, 5S rDNA, pAs1, and (AAG)10 by FISH. Each chromosome of K.hirsuta was well characterized by homoeological determination and repeats distribution patterns. The synteny of chromosomes was strongly conserved in the St genome, whereas synteny of the Y and P genomes was more distorted. The collinearity of 1Y, 2Y, 3Y and 7Y might be interrupted in the Y genome. A new 5S rDNA site on 2Y might be translocated from 1Y. The short arm of 3Y might involve translocated segments from 7Y. The 7 Y was identified as involving a pericentric inversion. A reciprocal translocation between 2P and 4P, and tentative structural aberrations in the subtelomeric region of 1PL and 4PL, were observed in the P genome. Chromosome polymorphisms, which were mostly characterized by repeats amplification and deletion, varied between chromosomes, genomes, and different populations. However, two translocations involving a P genome segmental in 3YL and a non-Robertsonial reciprocal translocation between 4Y and 3P were identified in two independent populations. Moreover, the proportion of heterozygous karyotypes reached almost 35% in all materials, and almost 80% in the specific population. These results provide new insights into the genome organization of K.hirsuta and will facilitate genome dissection and germplasm utilization of this species.
Highlights
The 45S rDNA sites of wheat were physically mapped in four different homoeologous groups, as noted in the short arms of 1A, 1B, 6B and 5D, and 7DL (Mukai et al 1991)
In K. hirsuta, 45S rDNA sites were mapped in the short arms of 5St, 1P, and 5P
The 45S rDNA sites in 1P and 5P detected in the present study were consistent with those in the P genome of A. cristatum (Said et al 2018). 5S rDNA sites were physically mapped on chromosomes homoeologous group 1 (1AS, 1BS, 1DS) and group 5 (5AS, 5BS, and 5DS) (Mukai et al 1990)
Summary
L. Yang, 1990, is a perennial genus belonging to the tribe Triticeae (family Poaceae), species of which are commonly distributed in central Asia and the Qinghai–Tibetan plateau (Yen and Yang 1990). Steppes, the fringes of forests, and semi deserts or extremely dry deserts at altitudes from 1100 to 4750 m (Yang et al 1992). 32 species and subspecies have been documented in this genus (Cai 1999). R. Baum, 1992, is a species of Kengyilia, which is distributed in Qinghai and Gansu in China. K. hirsuta can be found around sandy areas in high altitude regions, owing to its high tolerance to cold hardness and drought, as well as its distinct perennial characteristics. K. hirsuta has potential genetic resources for utilization in cereal crop development
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