Marker-assisted selection for combining stem rust and stripe rust resistance in wheat using rye derived genes

Stem rust and stripe rust are among the most devastating wheat (Triticum aestivum L.) diseases globally. This study used marker-assisted selection to incorporate two resistance genes, Sr59 and YrSLU (where SLU is Swedish University of Agriculture Science), derived from rye (Secale cereale L.), into elite wheat backgrounds. The initial cross combined Sr59 from line TA5095 and YrSLU from line #392 using kompetitive allele-specific PCR (KASP) markers. A three-step crossing scheme integrated these genes into adapted wheat lines. F₁ plants were crossed with the commercial wheat variety Linkert, followed by top-crossing with Navruz. Selected progeny were double top-crossed with an elite breeding line, SLU-Elite, producing generations TT₁ to TT₄ through self-pollination. Plants containing Sr59 and YrSLU were identified at each generation using KASP markers. Field trials in the TT₅ generation assessed agronomic performance and increased seed production. In the TT₆ and TT₇ generations, seedling resistance tests confirmed that Sr59 conferred robust resistance to Pgt races TTKSK, TTRTF, and TTTTF. YrSLU provided resistance against Pst races Psts10, Psts16, Psts7, and Psts13. However, TT₆ remained segregated for resistance to Pst race Psts7 (Warrior). By TT₇, consistent resistance to Psts7 was observed in pyramided lines. This study shows the effectiveness of crossing schemes integrating rye-derived resistance genes into wheat. KASP markers enabled precise selection, combining enhanced disease resistance with elite agronomic traits. These findings demonstrate a practical approach to improving wheat's resilience to rust diseases through targeted breeding.