Reaction of Wheat- Thinopyrum Progenies and Wheat Germplasm to Sharp Eyespot

Abstract

The objectives of this study were to test the reactions of wheat-Thinopyrum derivatives, wheat (Triticum aestivum L.) cultivars and breeding lines to sharp eyespot (caused by Rhizoctonia cerealis Van der Hoeven) and to understand the relationship between Thinopyrum chromosomes and sharp eyespot resistance. Using field nursery tests, 321 common wheat accessions and 56 wheat-Thinopyrum derivatives were tested in Xuzhou and Nanjing, Jiangsu Province, China. In Xuzhou, none of the accessions was highly resistant, while 52 accessions (including 34 common wheat accessions) were moderately resistant. Six common wheat cultivars, i.e., Xiaonong 8506-1, Xiaoyan 81, Jizhi 4001, Nongda 195, Xuzhou 8913, and Jingdong 3066A-3, had the relative resistance index greater than 0.7. In Nanjing, all the common wheat entries were moderately or highly susceptible. Only five accessions of wheat-Thinopyrum progenies showed moderately resistant reaction. The chromosome addition, substitution, and translocation lines TA3513, TA3516, TA351, and TA3519 involving chromosome 4Ai#2 or 4Ai#2S of Th. intermedium and the chromosome substitution line SS767 involving the homoeologous group 4 chromosome of Th. ponticum had the disease indexes smaller than the susceptible controls Sumai 3 and Yangmai 158, as well the moderately resistant controls Annong 8455 and Ningmai 9. This indicated that the homoeologous group 4 chromosomes from Th. intermedium and Th. ponticum were most likely associated with the reduction of disease indexes. Genomic in situ hybridization using St genomic DNA from Pseudoroegneria strigos as a probe demonstrated that chromosome 4Ai#2 belongs to J s genome of Th. intermedium and the homoeologous group 4chromosome of Th. ponticum belongs to J genome. Although sharp eyespot and eyespot develop similar shapes of symptoms on the basal stems of wheat, the eyespot resistance genes Pch1 and Pch2 carried by the wheat cultivars Madsen and Cappelle-Desprez, respectively, were not effective against sharp eyespot.