Gunlayarat Bhusudsawang: Department of Biotechnology, Faculty of Science and Technology, Rangsit Campus, Thammasat University, Pathum Thani 12120, Thailand.
Ratchanee Rattanawong: Nong Khai Rubber Research Center, Rubber Research Institute of Thailand, Rubber Authority of Thailand, Rattanawapi District, Nong Khai 43120, Thailand.
Thitaporn Phumichai: Rubber Research Institute of Thailand, Rubber Authority of Thailand, Bangkok 10900, Thailand.
Wirulda Pootakham: National Science and Technology Development Agency, Thailand Science Park, Khlong Luang, Pathum Thani 12120, Thailand.
Sithichoke Tangphatsornruang: National Science and Technology Development Agency, Thailand Science Park, Khlong Luang, Pathum Thani 12120, Thailand. ORCID
Kittipat Ukoskit: Department of Biotechnology, Faculty of Science and Technology, Rangsit Campus, Thammasat University, Pathum Thani 12120, Thailand.
Girth growth is an important factor in both latex and timber production of the rubber tree. In this study, we performed candidate gene association mapping for girth growth in rubber trees using intron length polymorphism markers (ILP) in identifying the candidate genes responsible for girth growth. The COBL064_1 marker developed from the candidate gene () regulating cellulose deposition and oriented cell expansion in the plant cell wall showed the strongest association with girth growth across two seasons in the Amazonian population and was validated in the breeding lines. We then applied single molecule real-time (SMRT) circular consensus sequencing (CCS) to analyze a wider gene region of the to pinpoint the single nucleotide polymorphism (SNP) that best explains the association with the traits. A SNP in the 3' UTR showing linkage disequilibrium with the COBL064_1 most associated with girth growth. This study showed that the cost-effective method of ILP gene-based markers can assist in identification of SNPs in the candidate gene associated with girth growth. The SNP markers identified in this study added useful markers for the improvement of girth growth in rubber tree breeding programs.
