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Title: Sequencing of an Anthracnose-resistant sorghum genotype and mapping of a major QTL reveal strong candidate genes for Anthracnose resistance

item BURRELL, A. MILLIE - Texas A&M University
item SHARMA, ARUN - Sakata Seed America, Inc
item PATEL, NIKHIL - Texas A&M University
item COLLINS, S. DELROY - Texas A&M University
item Anderson, William - Bill
item ROONEY, WILLIAM - Texas A&M University
item KLEIN, PATRICIA - Texas A&M University

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2014
Publication Date: 12/16/2014
Citation: Burrell, A., Sharma, A., Patel, N., Collins, S., Anderson, W.F., Rooney, W.L., Klein, P.E. 2015. Sequencing of an Anthracnose-resistant sorghum genotype and mapping of a major QTL reveal strong candidate genes for Anthracnose resistance. Crop Science. 55:1-10.

Interpretive Summary: Sorghum (Sorghum bicolor) is an important grain, forage and potential biofuel crop worldwide. One of the most damaging diseases of the crop is anthracnose (Colletotrichum sublineolum). The most successful method of combating the disease is through plant breeding. A genetic marker for resistance was developed through the production of 117 F5 recombinant inbred lines (segregating inbred lines developed through self-fertilization to the fifth generation). These lines were screened for resistance at four locations. One major gene four resistance was found on chromosome 5. However, once sequencing of the DNA at the resistant location was completed, numerous amino acid changes were found to suggest that more than one gene is involved in resistance.

Technical Abstract: Anthracnose, caused by the fungal pathogen Colletotrichum sublineolum Henn. ex. Sacc. and Trotter 1913, is an economically damaging disease of sorghum [Sorghum bicolor (L.) Moench] in hot and humid production regions of the world. Control of anthracnose is almost exclusively through the use of genetic resistance. To further elucidate genetic resistance to anthracnose, a recombinant inbred line population derived from the cross of BTx623 (susceptible) and SC748-5 (resistant) was created. A linkage map was constructed using 117 F5 individuals that were genotyped using Digital Genotyping, a genotyping-by-sequencing method developed specifically for C4 grasses, on an Illumina GAIIx. The linkage map consists of 619 single nucleotide polymorphism markers and three microsatellites with a total map length of 1269.9 cM. The population was phenotyped for anthracnose in four different environments. Using both composite interval mapping and inclusive composite interval mapping (ICIM), one major quantitative trait locus (QTL) on chromosome 5 was consistently identified as the source of anthracnose resistance in all environments. Sequencing genomic DNA from SC748-5 and comparison to BTx623 genomic sequence revealed numerous amino acid changes in annotated disease-resistance genes located in the area under the anthracnose QTL. This suggests that the genetic architecture for anthracnose resistance in SC748-5 is not under the control of one gene but, more likely, a linkage block containing several resistance genes.