<p><i>Colletotrichum
sublineolum</i> is the causal agent of sorghum
anthracnose, a very common and destructive fungal disease in warm and humid
areas, especially in West and Central Africa. Use of host plant resistance is
considered as the most important and effective control option for sorghum
diseases. To achieve this goal, identification and mapping resistance genes is
essential. In this study, we used an isolate of <i>C.</i> <i>sublineolum</i>, CsGL1, to
screen our sorghum germplasm and identified a resistant inbred line, P9830. We
developed a mapping population from a cross between P9830 and a susceptible
line, TAM428, for this research. The population was advanced to the F<sub>6</sub>
generation. Progenies were phenotyped at F<sub>2</sub>, F<sub>3</sub> and F<sub>6</sub>
generations for disease resistance against the pathogen, CsGL1. In the F<sub>2</sub>
generation, 460 individuals showed resistance and 149 individuals showed
susceptibility to CsGL1. This result fits the 3:1 segregation pattern expected
for resistance controlled by a single gene. Bulked segregant analysis with next
generation sequencing was used on selected F<sub>6</sub> recombinant inbred
lines. A significant peak containing 153 SNPs was observed on the distal end of
the long arm of chromosome 8. To verify resistance to CsGL1 was controlled by
genes in this region, indel and SNP markers were used between 59.4Mbp and 60.6Mbp
on chromosome 8 to fine map the resistance locus. One SNP marker located in the
gene <i>Sobic.008G166400</i> co-segregated
with resistance, and another two indel markers were discovered to be tightly
linked to the resistance locus. These three PCR-based SNP markers would be
useful for marker-assisted selection for improving anthracnose resistance
against CsGL1. Two candidate genes, <i>Sobic.008G166400</i>
and <i>Sobic.008G166550</i>, were found in
the locus. Both of the genes encode LRR proteins implicated in plant disease
defense response. The identity of DNA sequence between these two candidate
genes is 94.1%, possibly the result of tandem duplication. Another possible
ortholog in the region is <i>Sobic.008G167500</i>.
Quantitative PCR analysis showed that the expression level of <i>Sobic.008G166400</i> didn’t change
significantly in a resistant RIL, 17-12 but was induced in a susceptible RIL,
13-31, after CsGL1 infection. In conclusion, we mapped two candidate genes
conferring resistant to CsGL1 on chromosome 8, and <i>Sobic.008G166400</i> is more likely of the two to be determined as the
gene controlling resistance to CsGL1. </p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/11323721 |
| Date | 06 December 2019 |
| Creators | Xiaochen Xu (8086352) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/IDENTIFICATION_AND_MAPPING_OF_ANTHRACNOSE_RESISTANCE_GENES_IN_SORGHUM_i_SORGHUM_BICOLOR_i_L_MOENCH_/11323721 |
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