Discovering candidate genes that regulate resin canal number in Pinus taeda stems by integrating genetic analysis across environments, ages, and populations

• Published in: The New phytologist Vol. 205; no. 2; pp. 627 - 641
• Main Authors: Westbrook, Jared W, Walker, Alejandro R, Neves, Leandro G, Munoz, Patricio, Resende, Marcio F. R., Jr, Neale, David B, Wegrzyn, Jill L, Huber, Dudley A, Kirst, Matias, Davis, John M, Peter, Gary F
• Format: Journal Article
• Language: English
• Published: England Academic Press 01.01.2015; New Phytologist Trust; Wiley Subscription Services, Inc
• Subjects: Animals; Bark; bark beetles; biofuel; Biofuels; Breeding; Canals (anatomy); Coleoptera - physiology; DNA sequences; feedstocks; forest trees; Gene mapping; Genes; Genes, Plant; Genetic analysis; Genetic diversity; Genetic Variation; genomic selection; genotype × environment interactions; Growth rings; marker-assisted selection; Nucleotides; Oleoresins; pedigree; Pest resistance; Pine trees; Pinus; Pinus elliottii; Pinus taeda; Pinus taeda - chemistry; Pinus taeda - genetics; Pinus taeda - metabolism; Plant breeding; Plant Stems - chemistry; Plant Stems - genetics; Plant Stems - metabolism; Plant structures; pleiotropy; Polymorphism, Single Nucleotide; Population genetics; Quantitative Trait Loci; Regulators; Resins, Plant - chemistry; Scolytidae; Single-nucleotide polymorphism; Stems; terpene; Terpenes; terpenoids; Xylem; Xylem - chemistry; Xylem - metabolism; forest trees; genomic selection; biofuel; genotype × environment interactions; terpene; pleiotropy; bark beetles
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.13074

Genetically improving constitutive resin canal development in Pinus stems may enhance the capacity to synthesize terpenes for bark beetle resistance, chemical feedstocks, and biofuels. To discover genes that potentially regulate axial resin canal number (RCN), single nucleotide polymorphisms (SNPs) in 4027 genes were tested for association with RCN in two growth rings and three environments in a complex pedigree of 520 Pinus taeda individuals (CCLONES). The map locations of associated genes were compared with RCN quantitative trait loci (QTLs) in a (P. taeda × Pinus elliottii) × P. elliottii pseudo‐backcross of 345 full‐sibs (BC1). Resin canal number was heritable (h² ˜ 0.12–0.21) and positively genetically correlated with xylem growth (rg ˜ 0.32–0.72) and oleoresin flow (rg ˜ 0.15–0.51). Sixteen well‐supported candidate regulators of RCN were discovered in CCLONES, including genes associated across sites and ages, unidirectionally associated with oleoresin flow and xylem growth, and mapped to RCN QTLs in BC1. Breeding is predicted to increase RCN 11% in one generation and could be accelerated with genomic selection at accuracies of 0.45–0.52 across environments. There is significant genetic variation for RCN in loblolly pine, which can be exploited in breeding for elevated terpene content.