| Wheat is one of the staple food crops in the world.Stripe rust of wheat,caused by Puccinia striiformis f.sp.tritici,seriously threatens the production of wheat in many regions of the world.Utilization of wheat resistance resources can reduce the need for fungicides for controlling this disease.Compared with race-specific resistance,durable resistance can combat against the rust population more effectively.The mechanism underlying durable resistance is also an important subject of plant biology research.There are data showing that the winter wheat cultivars ’Qing Shumai(QS)’ and ’Luke’ possess durable resistance to stripe rust.Our Laboratory has constructed a ’Mingxian 169(MX169,susceptible wheat)’ × QS population that consisted of 276 F6:8 recombinant inbred lines(RILs).The author of this paper advanced the population to F9:11.The 276 RILs were tested for stripe rust resistance in five environments(involving two locations:Gansu and Shandong,and four seasons:2009 to 2012)and were genotyped at 84 DNA marker loci.The main results include:(1)A major QTL was detected on the long arm of chromosome 6D(6DL)and it was designated as QYr.cau-6DL.It is novel compared to the previously reported Yr genes and QTL.(2)A SSR marker(gpw5179)was found to be tightly linked with QYr.cau-6DL and it can be well applicable to the selection for this QTL.(3)Based on the DNA markers gpw5179 and cssfr5(diagnostic of Yr18),160 F2:3 families were selected from QQ × ’RL6058’(a spring wheat harboring Yr18)and were tested for two years.The result indicates that the effect size of QYr.cau-6DL was approximately equal to that of Yr18 and they acted well additively.The combination of QYr,cau-6DL and Yr18 could reduce the severities to about 15%.This result was consistent across both spring and winter wheat backgrounds.(4)QYr.cau-6DL was further evidenced that it may confer a form of durable resistance.Base on these results,we believe that QYr.cau-6DL has a great potential value for practical breeding.The high temperature adult plant resistance of Luke was characterized.(1)It was susceptible at low temperatures at all stages of growth,and showed varying degrees of resistance at high temperatures at different growth stages.I also found that in the case of prolonged time under high temperature treatment,some resistance could be induced even at the seedling stage of Luke plants.Expression of the resistance was considerably enhanced at jointing and later growth stages.The induction could be effective when the temperature was as low as 18℃.The duration required for the induction of resistance decreased with the increase of temperature.The optimal induction of resistance occurred at the pathogenic stage of symaptom appearance.(2)The transcriptome of Luke was analyzed for high and low temperature treatments using the second generation sequencing technology.A total of 174,138 Unigene were assembled with the average length of 561 nt based on both the high temperature treatment and low temperature control.There were 15,837 differentially expressed Unignese according to the standards of FDR≤0.001 and log2FC>1.The results of Pathway enrichment of differential expression and the real-time quantitative PCR analysis showed that related genes of reactive oxygen species might play an important role in the high temperature resistance;ABC transporter and UDP-glycosyltransferase may participate in the expression of high temperature resistance.But salicylic acid and jasmonic acid and a variety of RGA,PRs were not involved in the expression of the high temperature resistance.(3)The earlier transcript of high temperature resistance in Luke was generated by means of the expression sequencing on two test samples(27℃ for 12 h)and a control sample(14℃ for 12 h).Ninety-seven candidate gene fragments were selected by the expression sequencing and real-time quantitative PCR.These candidates constitute a basis for indentifying genes modulating high temperature resistance using RNA interference,RIL co-segregation,and transgenic methods. |
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