Genome-wide association study (GWAS) of leaf cuticular wax components in Camelina sativa identifies genetic loci related to intracellular wax transport

Authors: Luo, Zinan; Tomasi, Pernell; FAHLGREN, NOAH - Danforth Plant Science Center; Abdel-Haleem, Hussein

Submitted to: BMC Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2019
Publication Date: 5/7/2019
Publication URL: https://handle.nal.usda.gov/10113/6428482
Citation: Luo, Z., Tomasi, P., Fahlgren, N., Abdel-Haleem, H.A. 2019. Genome-wide association study (GWAS) of leaf cuticular wax components in Camelina sativa identifies genetic loci related to intracellular wax transport. Biomed Central (BMC) Plant Biology. 19:187. https://doi.org/10.1186/s12870-019-1776-0.
DOI: https://doi.org/10.1186/s12870-019-1776-0

Interpretive Summary: Camelina sativa (L. Crantz), a crop originated in southeastern Europe and southwestern Asia, is showing renewed public interest due to its exceptional level of omega-3 essential fatty acids and high seed oil content. These oil qualities, combined with positive agronomic attributes such as early maturity, low-input requirements for water, nutrients and pesticides, broader adaptability to diverse environments and resistance against insects and pathogens, make C. sativa an ideal alternative resource for biofuel and animal feedstock in the development of sustainable agriculture. This study presents the first GWAS study on C. sativa. As many as 50 phenotypic traits related to leaf wax accumulation in Camelina were used to identify putative SNPs associated with these traits. The significant SNPs were positioned in genes directly or indirectly controlling cuticular wax biosynthesis and related to drought tolerance. These identified SNPs could be used as useful tool and molecular markers in marker-assisted selection to breed C. sativa cultivars.

Technical Abstract: It is important to explore renewable alternatives (e.g. biofuels) that can produce energy sources to help reduce reliance on fossil oils, and reduce greenhouse gases and waste solids resulted from fossil oils consumption. Camelina sativa is an oilseed crop which has received increasing attention due to its short life cycle, broader adaptation regions, high oil content, high level of omega-3 unsaturated fatty acids, and low-input requirements in agriculture practices. To expand its Camelina production areas into arid regions, there is a need to breed for new drought-tolerant cultivars. Leaf cuticular wax is known to facilitate plant development and growth under water-limited conditions. Dissecting the genetic loci underlying leaf cuticular waxes is important to breed for cultivars with improved drought tolerance. Here we combined phenotypic data and single nucleotide polymorphism (SNP) data from a spring C. sativa diversity panel using genotyping-by-sequencing (GBS) technology, to perform a large-scale genome-wide association study (GWAS) on leaf wax compositions. A total of 42 SNP markers were significantly associated with 15 leaf wax traits including major wax components such as total primary alcohols, total alkanes, and total wax esters as well as their constituents. The vast majority of significant SNPs were associated with long-chain carbon monomers (carbon chain length longer than C28), indicating the important effects of long-chain carbon monomers on leaf total wax biosynthesis. These SNP markers are located on genes directly or indirectly related to wax biosynthesis such as maintaining endoplasmic reticulum (ER) morphology and enabling normal wax secretion from ER to plasma membrane or Golgi network-mediated transport. These loci could potentially serve as candidates for the genetic control involved in intracellular wax transport that might directly or indirectly facilitate leaf wax accumulation in C. sativa and can be used in future marker-assisted selection (MAS) to breed for the cultivars with high wax content to improve drought tolerance.