Genetic factors affecting Fusarium head blight resistance improvement from introgression of exotic Sumai 3 alleles (including Fhb1, Fhb2, and Fhb5) in hard red spring wheat.

BACKGROUND: Fusarium head blight resistance genes, Fhb1 (for Type-II resistance), Fhb2 (Type-II), and Fhb5 (Type-I plus some Type-II), which originate from Sumai 3, are among the most important that confer resistance in hexaploid wheat. Near-isogenic lines (NILs), in the CDC Alsask (susceptible; n = 32) and CDC Go (moderately susceptible; n = 38) backgrounds, carrying these genes in all possible combinations were developed using flanking microsatellite markers and evaluated for their response to FHB and deoxynivalenol (DON) accumulation in eight environments. NILs were haplotyped with wheat 90 K iSelect assay to elucidate the genomic composition and confirm alleles' presence. Other than evaluating the effects of three major genes in common genetic background, the study elucidated the epistatic gene interactions as they influence FHB measurements; identified loci other than Fhb1, Fhb2, and Fhb5, in both recurrent and donor parents and examined annotated proteins in gene intervals. RESULTS: Genotyping using 81,857 single nucleotide polymorphism (SNP) markers revealed polymorphism on all chromosomes and that the NILs carried < 3% of alleles from the resistant donor. Significant improvement in field resistance (Type-I + Type-II) resulted only among the CDC Alsask NILs, not the CDC Go NILs. The phenotypic response of NILs carrying combinations of Sumai 3 derived genes suggested non-additive responses and Fhb5 was as good as Fhb1 in conferring field resistance in both populations. In addition to Fhb1, Fhb2, and Fhb5, four to five resistance improving alleles in both populations were identified and three of five in CDC Go were contributed by the susceptible parent. The introgressed chromosome regions carried genes encoding disease resistance proteins, protein kinases, nucleotide-binding and leucine rich repeats' domains. Complex epistatic gene-gene interactions among marker loci (including Fhb1, Fhb2, Fhb5) explained > 20% of the phenotypic variation in FHB measurements. CONCLUSIONS: Immediate Sumai 3 derivatives carry a number of resistance improving minor effect alleles, other than Fhb1, Fhb2, Fhb5. Results verified that marker-assisted selection is possible for the introgression of exotic FHB resistance genes, however, the genetic background of the recipient line and epistatic interactions can have a strong influence on expression and penetrance of any given gene.

A rapid immunochromatographic test to detect the lily mottle virus.

We developed a rapid immunochromatographic strip (ICS) test for lily mottle virus (LMoV). The test is based on a double-antibody sandwich format and employs two distinct anti-LMoV polyclonal antibodies (IgG3 and IgG4). The first antibody, IgG3 was conjugated with colloidal gold, and the second antibody, IgG4 was used as the capture antibody at the test line. The performance of the ICS test was evaluated and the results obtained were compared with a quadruplex RT-PCR assay. When serial dilutions of purified LMoV were tested, the LMoV detection limit of the ICS test was 8.0 × 10(-9) mg/mL, which was in complete agreement with the results of quadruplex RT-PCR. Compared with quadruplex RT-PCR, the specificity and sensitivity of ICS were 98.7 and 100%, respectively. There was therefore significant agreement between the results obtained from the two tests (κ = 0.982). The ICS test therefore appears to be broadly applicable, and will be especially useful in the field, as well as in areas without laboratory facilities, to support efforts to detect and control LMoV.

Development of an immunochromatographic strip test for rapid detection of lily symptomless virus.

A rapid immunochromatographic strip (ICS) test for specific detection of lily symptomless virus (LSV) was developed. The test is based on a double-antibody sandwich format and employs two distinct anti-LSV polyclonal antibodies (IgG1 and IgG2). The first antibody, IgG1 was used as the detection antibody conjugated to colloidal gold and the second antibody, IgG2 was used to as the capture antibody at the test line. The performance of the ICS test was evaluated and the results obtained were compared with a quadruplex RT-PCR assay. When serial dilutions of purified LSV were tested, the LSV detection limit of the ICS test was 6.0 × 10(-8)mg/mL, which was the same as the quadruplex RT-PCR assay. Relative to quadruplex RT-PCR, the specificity and sensitivity of the ICS were 98.6% and 100%, respectively for field leaf samples. There was significant agreement between the results of the ICS and quadruplex RT-PCR tests (κ = 0.983). Compared with conventional lily virus detection methods, our ICS test has many advantages: simple, fast, low cost, high sensitivity and specificity, and has applications in the laboratory and in the field to detect and control LSV.