Genetic analysis and QTL mapping for multiple biotic stress resistance in cassava

PLoS One. 2020 Aug 5;15(8):e0236674. doi: 10.1371/journal.pone.0236674. eCollection 2020.

Abstract

In Sub-Saharan Africa cassava (Manihot esculenta Crantz) is one of the most important food crops where more than 40% of the population relies on it as their staple carbohydrate source. Biotic constraints such as viral diseases, mainly Cassava Mosaic Disease (CMD) and Cassava Brown Streak Disease (CBSD), and arthropod pests, particularly Cassava Green Mite (CGM), are major constraints to the realization of cassava's full production potential in Africa. To address these problems, we aimed to map the quantitative trait loci (QTL) associated with resistance to CBSD foliar and root necrosis symptoms, foliar CMD and CGM symptoms in a full-sib mapping population derived from the genotypes AR40-6 and Albert. A high-density linkage map was constructed with 2,125 SNP markers using a genotyping-by-sequencing approach. For phenotyping, clonal evaluation trials were conducted with 120 F1 individuals for two consecutive field seasons using an alpha-lattice design at Chambezi and Naliendele, Tanzania. Previously identified QTL for resistance to CBSD foliar symptoms were corroborated, and a new putative QTL for CBSD root necrosis identified (qCBSDRNc14AR) from AR40-6. Two QTL were identified within the region of the previously recognized CMD2 locus from this population in which both parents are thought to possess the CMD2 locus. Interestingly, a minor but consistent QTL, qCGM18AR, for CGM resistance at 3 months after planting stage was also detected and co-localized with a previously identified SSR marker, NS346, linked with CGM resistance. Markers underlying these QTL may be used to increase efficiencies in cassava breeding programs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breeding
  • Disease Resistance / genetics*
  • Genetic Testing
  • Genotype
  • Manihot / genetics*
  • Manihot / physiology
  • Manihot / virology
  • Plant Diseases / genetics*
  • Plant Diseases / virology
  • Potyviridae / genetics
  • Potyviridae / pathogenicity
  • Quantitative Trait Loci / genetics*
  • Stress, Physiological / genetics
  • Tanzania

Grants and funding

This work was funded by the Bill and Melinda Gates Foundation (BMGF) grant no. OPPGD1016 to MF, IITA. Work by JB and JL was supported by BMGF grant OPPGD1493 to Dr. Steve Rounsley, who at the time was at the University of Arizona. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.