Quantitative trait loci for Fusarium head blight resistance in wheat cultivars Yangmai 158 and Zhengmai 9023

Fusarium head blight(FHB)is one of the prevalent fungal diseases of wheat worldwide.Exploring new FHB resistance quantitative trait loci(QTL)in adapted wheat cultivars is a critical step for breeding new FHB-resistant cultivars.In this study,we developed a population of 236 F5:7 recombinant inbred lines(RILs)using two popular Chinese wheat cultivars,Yangmai 158 and Zhengmai 9023,with moderate FHB resistance to identify the QTL for FHB type II resistance.This population was evaluated for percentage of symptomatic spikelets per spike(PSS)using single floret injection in repeated greenhouse experiments.Mean PSSs were 33.2%for Yangmai 158 and 30.3%for Zhengmai 9023.A genetic linkage map of 1002 single nucleotide polymorphisms(SNPs)generated by genotyping-by-sequencing(GBS)was constructed for the RIL population.Six QTL were identified for FHB resistance,and three of them were repeatable in the both experiments.Zhengmai 9023 contributed the resistance allele at one repeatable QTL,designated as Qfhb.7D,whereas Yangmai 158 contributed the resistance alleles at the other two repeatable QTL,Qfhb.3AL and Qfhb.2DS.The additional QTL,Qfhb.4AS was significant in the mean PSS,and Qfhb.2DL and Qfhb.7AS were significant in only one experiment.Replacement of each allele individually at the three repeatable QTL significantly changed PSSs.Qfhb.3AL,Qfhb.2DS,and Qfhb.7D explained 8.35%to 9.89%,5.13%to 7.43%,and 6.15%to 9.32%of the phenotypic variations,respectively.The three repeatable QTL contributed by the two parents were additive and stacking the resistance alleles from all the three repeatable QTL showed the highest level of resistance in the current RIL population.Ten SNPs in the QTL regions of Qfhb.3AL,Qfhb.2DS,and Qfhb.7D were converted into KBioscience competitive allele-specific PCR(KASP)assays.One KASP marker for Qfhb.3AL was validated in a panel of wheat cultivars from China.Some of these KASP markers could be useful for marker-assisted selection to stack these QTL.

Changes of Rubisco in Flag Leaves of Wheat with Different Quality Types during Grain Filling Stage

[ Objective] In this study, the formation mechanism of grain quality of soft wheat was investigated to provide support for soft wheat breeding. [ Meth- od] Using soft and hard wheat varieties as experimental materials, changes of Rubisco （ribulose-1,5-bisphosphate carboxylase/oxygenase） degradation in flag leav- es with different quality types during grain fillLing stage were investigated. [ Result] Chlorophyll content and Rubisco content were both gradually reduced in flag leaves of wheat cultivars with different quality types during grain filling stage. Changes of Rubisco content were insignificant at early grain firing stage, but Rubisco content in flag leaves of soft wheat was higher than that of hard wheat at mid-late grain filling stage. Degradation products of Rubisco large subunits with molecular weight of 51 kD could be detected in flag leaves of various wheat cultivars. Rubisco in flag leaves of hard wheat Zheng 9023 was significantly earlier degraded com- pared with Yangnmi 15, indicating that leaf senescence in hard wheat was earlier than soft wheat, which suggested that the protein accumulation in wheat grains may be related with Rubisco degradation in flag leaves after anthesis. [ Conclusion] This study implied the foundation of soft wheat breeding and optimization of cultiva- tion and wheat management in the field.

Genetic Analysis of Grain Yield in a 7×7 Diallel Cross F_2 Population of Wheat(T.Aestivum L.)

In order to obtain genetic information for grain yield, seven genetically diverse wheat cultivars were crossed in an incomplete diallel to study the inheritance of grain yield using F_2 progenies for two years. Significant differences were observed among genotype, year and genotype × year interaction for grain yield, and both general combining ability(GCA) and specific combining ability(SCA) were also highly significant for grain yield, suggesting that the trait was controlled by both additive and non-additive effect. The GCA estimates revealed that the best combiners for grain yield were Yangmai 5 and Ningmai 9. Adequacy tests revealed that data of grain yield was fully adequate for genetic interpretation. Over-dominance genetic effects were important for the expression of grain yield. Grain yield exhibited moderately high value of narrow sense heritability(h_N^2=66.98% and h_N^2=72.37%).

Breeding for the resistance to Fusarium head blight of wheat in China

With the changes of climate and cultivation systems, the Fusarium head blight(FHB) epidemic area in China has extended since 2000 from the reaches of the Yangtze River to the north and west winter wheat region.Breeding for FHB resistance in wheat is an effective way to control the disease.Chinese wheat breeders commenced research on FHB in the 1950 s.Sumai 3, Ning 7840,Yangmai 158, Ningmai 9 and other cultivars with improved FHB resistance were developed through standard breeding methods and widely applied in production or breeding programs.In addition to intervarietal crosses,alien germplasm was used to improve FHB resistance of wheat.Addition, substitution and translocation lines with alien chromosomes or chromosome fragments were created to enhance FHB resistance.Somaclonal variation was also used to develop a FHB resistant cv.Shengxuan 3 and other cultivars with moderate resistance to FHB were released by such methods.QTL(quantitative trait loci) for FHB resistance were characterized in cultivars originating from China.The major QTL, Fhb1, was identified on chromosome 3 BS in Sumai 3, Ning 894037, Wangshuibai and other Chinese resistant sources.Diagnostic molecular markers for Fhb1 have been applied in wheat breeding and breeding lines with improved FHB resistance and desirable agronomic traits have been obtained.However, breeding for FHB resistance is a long-term task, new technologies are likely to increase the efficiency of this process and better FHB resistance of new cultivars is expected to be achieved within the next decade.

Effects of CeCl_3 and LaCl_3 on callus and root induction and the physical response of tobacco tissue culture

La3＋ and Ce3＋ have positive effects on plant growth and production. Although it is well known that rare earth elements promote cell growth. The biological effects of La^（3＋） and Ce^（3＋） on callus, shoot and root induction in tobacco are still unclear. The relationships among callus induction, rooting, enzyme activities and stomatal characteristics in tobacco are unknown. The objectives of this study were to identify the relationships between the induction of calluses, shoots, roots, stomata and enzyme activities. The induction percentages of calluses, buds, roots were recorded at 5,10,15, 20 and 25 days after La^（3＋） and Ce^（3＋） treatments. Peroxidase isoenzyme activity was determined by electrophoresis. The characteristics of the stomata were observed under an optical microscope. Our results show that low concentrations of Ce^（3＋）（〈15 mg/L） result in increases in the induction percentages of calluses,buds and roots, but La^（3＋）（〉5 mg/L） inhibits the induction of calluses, buds and roots. There are more peroxidase isoenzyme bands in Ce^（3＋） treatments than in La^（3＋） treatments. This is consistent with the induction percentages of calluses,buds and roots in Ce^（3＋） and La^（3＋） treatments. High enzyme activities may promote the induction of calluses, buds and roots. The stomata area and stomata number of leaves are significantly different between La^（3＋） treatments and Ce^（3＋） treatments. La^（3＋） improves the stomata area and number. Based on these results, we speculate that La^（3＋） may promote the development of the photosynthetic system. Ce^（3＋）may promote tobacco growth and rooting by improving enzyme activities.

Economic and Tax Policies Carried out in Austria in Response to the COVID-19 Crisis

Austria was one of the first countries in Europe to introduce invasive govern-mental measures against the spreading of t he coronavirus.As of 16 March,the government implemented a nationwide lockdown which stipulated that homes may be left for specific reasons only.However,the measures taken by the Austrian government obviously proved to be successful.