Application Of Yr10,Yr18 And Yr36 Genes In Wheat Improvement For Stripe Rust Resistance

Wheat stripe rust,caused by Puccinia striiformis Westend.f.sp.tritici?Pst?,is a fungal disease that threats yield and grain quality.It can reduce 20%-30% of yield production in normal epidemic years,and even 50%-60% in severe epidemic years.Fungicides can effectively reduce yield losses,but extended usage of fungicides pollutes environment and can cause resistant or tolerant strains of Pst.Using resistant cultivars is the most economical,safe and effective approach to control wheat stripe rust.It is important to improve wheat disease resistance through marker-assisted selection and pyramiding of stripe rust resistance genes in common wheat.In the present study,we focus on the stripe rust resistance genes Yr10,Yr18 and Yr36,and introgress them into 17 major cultivars in Shandong and Henan provinces using marker-assisted selection.The main results are as follow:1.In the BC₃F₁ generation,plants were grown in an environment with severe stripe rust.It was easy to screen the gain of resistance,especially for the progenies from highly susceptible varieties.Using markers,we identified sister lines with and without a target gene of Yr10,Yr18 or Yr36.By comparing positive?with a target gene?and negative?without a target gene?sister lines,we found that the target genes improved stripe rust resistance in selected background,especially in recurrent parental lines that are highly susceptible to Pst.Target genes also reduced yield losses as measured by the one-thousand-kernel weight.2.In the BC3F2 and BC₄F₂ generations,we tested some lines in Chengdu,Sichuan,a region popular for wheat stripe rust.We found 14 pairs of sister lines displayed significant improvement on Pst resistance.Among lines with a target gene Yr10,Yr18 or Yr36,their progenies segregared on Pst ressitance,but progenies of the lines lacking a target gene were all susceptible to Pst.3.In the BC₃F₁ generation,plants appeared morphologically similar to the recurrent parents.We started to pyramide target genes using positive BC₃F₁ plants from the same recurrent parent.In 2015,we obtained sixteen lines with two target genes: three on Yr10+Yr18?BC₃F₁/BC₃F₁?,two on Yr18+Yr36?BC₃F₁/BC₃F₁?,and eleven on Yr10+Yr36?BC₃F₁/BC₃F₁?.In 2015,we started to pyramide all three target genes using the signle-double gene model?namely 1+2,BC₃F₁/BC₃F₁//BC4F1?or the double-double gene model?namely 2+2,BC₃F₁/BC₃F₁// BC₃F₁/BC₃F₁?.In 2016,we generated three-gene lines from ‘Jinan 17',‘Jimai 19',‘Jimai 20',‘Jimai 55',Tainong 18',‘Zhoumai 16',‘Yumai 49-198',and ‘Yannong 19'.In this study,we generated wheat germplasm with Yr10,Yr18 and/or Yr36 by using traditional breeding and marker assisted selection.Advanced lines with one or more target genes are more resistant to wheat stripe rust than the sister lines without a target gene.The resistant lines have been used in wheat breeding programs in Shandong and Sichuan,China.