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.

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.