Email: lgy111@126.com

Lr34/Yr18/Pm38/Sr57, Lr27/Yr30/Sr2, Lr46/Yr29/Pm39/Sr58 and Lr67/Yr46/Pm46/Sr55 are four durable resistant genes in wheat. Each one provides partial resistance without race-specificity to leaf rust, stripe rust, stem rust and powdery mildew in adult plant stage. When deployed with each other, resistance will be enhanced, but the effect of four genes together is unclear.

In this study, we pyramided these four genes into recurrent parent Jimai229 through marker assisted selection. Four BC6F4 lines, namely 2L819, 2L857, 2L859 and 2L861, contain all four genes, one BC6F4 line namely 2L863 contains none of the four genes were developed to evaluate disease resistance and yield. All lines contain four genes are highly resistant to leaf rust, stripe rust and powdery mildew at adult plant stage in the field, but the leaf tip necrosis become more and more severe from heading stage to grain filling stage. At late Grain Filling stage, half of the flag leaf are necrotic.

We also observed the pseudo-black chaff, symptoms of Sr2, at flowering stage. Yield was evaluated with interval contrast design with three duplication in Jinan, Shandong Province. The production of 2L863 is 8.06 t ha−1, while the production of 2L819, 2L857, 2L859 and 2L861 are 7.96, 7.07, 7.41 and 7.90 t ha−1. Compared with 2L863, production reduction are 1.23%, 12.30%, 8.10%, 1.95%,.

There is no significant differences for Plant height, grain number per spike and Spike number per acreage. The thousand grain weight of 2L863 is 36.1g, while that of 2L819, 2L857, 2L859 and 2L861 are 33.87g, 33.10g, 32.04g and 34.38g respectively. In conclusion, pyramiding 4 wheat durable resistant genes improve resistance to rusts and powdery mildew effectively, but leaf tip necrosis are too severe to maintain production.

How many genes and what combination will provide adequate resistance with less production penalty need further investment.