23 Allele Tests of High Pigment Genotypes Using Root Anthocyanin Expression Jones, C . M . 1 , Myers, J . R . 2 and Chetelat, R . T . 1 1 TGRC, Dept . of Vegetable Crops, Univ . of California, Davis CA 95616 2 Department of Horticulture, Oregon State University, Corvallis, OR 97330 Numerous studies have examined the carotenoid content and genetics of high pigment tomatoes . The C . M . Rick Tomato Genetics Resource Center (TGRC) maintains accessions with hp - 1, hp - 1 w , hp - 2 and hp - 2 j , as well as dg and Ip . Historically, the nomenclature of the high pigment mutants has been somewhat confusing . Thompson (1955) originally proposed that an interaction of two recessive genes ( hp 1 and hp 2 ) was required for the high pigment phenotype . Thompson et al (1962) later modified this to a single gene, hp . Soressi (1975) described hp - 2, a phenotypically similar mutation induced by EMS in cv San Marzano, which was not an allele of the original hp .   (Note that Thompson (1955) used subscript hp 1 and hp 2, and there is no indication that the orignal high pigment tomato studied, Webb Special, contains hp - 2 . ) Mochizuki and Kamimura (1986; 1985) used seedlings grown under yellow film to test the allelism of hp, hp 1, hp 2 and dg and concluded they were all mutations at the same locus . The distinction between hp , and hp 1 in the Mochizuki and Kamimura (1986; 1985) study is unclear . Van Tuinen et al . (1997) suggested that hp - 1 be used for hp . Recent studies however have clarified that hp - 1 and hp - 2 are separate loci with hp - 1 located on chromosome 2 (Yen et al . , 1997) and hp - 2 located on chromosome 1 (Van Tuinen et al . , 1997) .   Kerr (1965) described a method using anthocyanin expression in the hypocotyl of seedlings below the soil line