Characterization of Two Wheat-Thinopyrum ponticum Introgression Lines With Pyramiding Resistance to Powdery Mildew

Powdery mildew is one of the most devastating foliar diseases in wheat production. The wild relative Thinopyrum ponticum (2n = 10x = 70) has been widely used in wheat genetic improvement due to its superior resistance to both biotic and abiotic stresses. In the present study, two wheat-Th. ponticum introgression lines named SN0293-2 and SN0293-7 were developed from the progenies of a cross between the octoploid Trititrigia SNTE20 and common wheat, including the elite cultivar Jimai 22. They had a novel powdery mildew resistance gene (temporarily named PmSN0293) putatively from Th. ponticum pyramided with Pm2 and Pm52, exhibiting excellent Pm resistance at both the seedling and adult stages. Sequential GISH-FISH detected no signal of Th. ponticum in these two lines but a pair of T1BL center dot 1RS in SN0293-2. Chromosomal structural variations were also observed obviously in SN0293-2 and SN0293-7. Through the Wheat 660K SNP array, 157 SNPs, 134 of which were on 6A, were found to be specific to Th. ponticum. Based on the data combined with DNA re-sequencing, seven specific markers, including one CAPS marker on 2B and six CAPS and Indel markers on 6A, were developed, confirming their wheat-Th. ponticum introgression nature. Furthermore, the two lines displayed positive plant height and produced more kernels and higher 1,000-grain weight. Excellent resistance with desirable agronomic traits makes them valuable in wheat breeding programs.

Automated summary

In this study, two wheat-Th. ponticum introgression lines were developed, exhibiting excellent resistance to powdery mildew and desirable agronomic traits. Genetic analyses confirmed the introgression nature of these lines through specific markers and chromosomal structural variations.