The disease severity index of pathogenicity test between wild-type strains and transformants.

<p>The disease severity index of pathogenicity test between wild-type strains and transformants.</p

Observation of <i>Fusarium verticillioides</i> wild strains and their enhanced green fluorescent protein <i>(EGFP)</i> transformants.

<p>Colony growth (5-day-culture) of each strain. (a) stalk rot wild strain Fv-s, (b) Fv-eGFPs1, an <i>EGFP</i> transformant of Fv-s, (c) Fv-eGFPs2, an <i>EGFP</i> transformant of Fv-s, (d) Fv-eGFPs3, an <i>EGFP</i> transformant of Fv-s, (e) ear rot wild strain Fv-e, (f) Fv-eGFPe1, an <i>EGFP</i> transformant of Fv-e, (g) Fv-eGFPe2, an <i>EGFP</i> transformant of Fv-e, (h) Fv-eGFPe3, an <i>EGFP</i> transformant of Fv-e.</p

Different degrees of enhanced green fluorescent protein <i>(EGFP)</i>-tagged <i>Fusarium verticillioides</i> infection in stalks of maize.

<p>A) The highest infected internode under the natural light and blue light (Fv-eGFPe1); B) the internode above the ear under the natural light and blue light (Fv-eGFPs1); C) the internode below the ear under the natural light and blue light (Fv-eGFPe1); D and E) the below infected internode under blue light (Fv-eGFPs1).</p

Maize ears infected with <i>EGFP</i>-tagged <i>Fusarium verticillioides</i> under blue light.

<p>A) a healthy kernel; B and C), ears infected by Fv-eGFPs1; D, E and F) ears infected by Fv-eGFPe1. Bars indicate 1 mm.</p

Detection of target EGFP gene of the strains by PCR amplification.

<p>a,b,c,d) were the transformants from different maize tissues, and e) was the wild type as negative control.</p

Hyphae of <i>Fusarium verticillioides</i> transformant spread the infected across cells with a rectangular extension.

<p>Hyphae of <i>Fusarium verticillioides</i> transformant spread the infected across cells with a rectangular extension.</p

Infection cycle of maize seeds inoculated with <i>Fusarium verticillioides</i> strains cultured from fluorescent kernels.

<p>A) a healthy maize seed (negative control); B) a seed infected with the re-separated strain of fluorescent kernels; C) discolored seedlings (5-day-growth) with the re-separated strain of fluorescent kernels; D) decayed and discolor radical (5-day-growth) infected with the re-separated strain of fluorescent kernels.</p

The Identification of Two Head Smut Resistance-Related QTL in Maize by the Joint Approach of Linkage Mapping and Association Analysis

<div><p>Head smut, caused by the fungus <i>Sphacelotheca reiliana</i> (Kühn) Clint, is a devastating threat to maize production. In this study, QTL mapping of head smut resistance was performed using a recombinant inbred line (RIL) population from a cross between a resistant line “QI319” and a susceptible line “Huangzaosi” (HZS) with a genetic map constructed from genotyping-by-sequencing (GBS) data and composed of 1638 bin markers. Two head smut resistance QTL were identified, located on Chromosome 2 (<i>q2</i>.<i>09HR)</i> and Chromosome 5 (<i>q5</i>.<i>03HR</i>), <i>q2</i>.<i>09HR</i> is co-localized with a previously reported QTL for head smut resistance, and the effect of <i>q5</i>.<i>03HR</i> has been validated in backcross populations. It was also observed that pyramiding the resistant alleles of both QTL enhanced the level of resistance to head smut. A genome-wide association study (GWAS) using 277 diverse inbred lines was processed to validate the mapped QTL and to identify additional head smut resistance associations. A total of 58 associated SNPs were detected, which were distributed in 31 independent regions. SNPs with significant association to head smut resistance were detected within the <i>q2</i>.<i>09HR</i> and <i>q5</i>.<i>03HR</i> regions, confirming the linkage mapping results. It was also observed that both additive and epistastic effects determine the genetic architecture of head smut resistance in maize. As shown in this study, the combined strategy of linkage mapping and association analysis is a powerful approach in QTL dissection for disease resistance in maize.</p></div

Genetic effects of head smut resistant QTL <i>q2</i>.<i>09HR</i> and <i>q5</i>.<i>03HR</i> in BC₄F₁ population.

<p>HZS stands for the allele contributed by susceptible parent HZS, QI319 stands for the allele contributed by the resistant parent QI319, the lighter gray part in the pie stands for the percentage of resistant plants within each group with the same genotype, the bracketed numbers stands for the total plants of each group. The probabilities of Analysis of Variance (ANOVA) among different allele combinations are noted in the brackets of pie right.</p

Distributions of head smut resistance QTL on chromosome 2 and 5 for the RIL population of QI319×HZS.

<p>Distributions of head smut resistance QTL on chromosome 2 and 5 for the RIL population of QI319×HZS.</p