Morphological, genetic, and chemical polymorphism of Curcuma kwangsiensis

Previously, Chinese Gajutsu available in Japan was identified, from the chloroplast trnK gene sequence, to be the rhizomes of Curcuma phaeocaulis and two genotypes of C. kwangsiensis. Although we defined the two genotypes, the pl and gl types, on the basis of the nucleotide difference, their external features did not correspond to the two phenotypes described in the literature. In this paper, to investigate the relationship between genotype and phenotype of C. kwangsiensis, a field investigation was carried out in its main cultivation areas of Guangxi Zhuangzu Autonomous Region and Guangdong Province, China, and sequence analysis of the trnK gene and single-nucleotide polymorphism (SNP) analysis of the nuclear 18S rRNA gene were performed on the collected specimens. Four genotypes of C. kwangsiensis were recognized from the combined 18S rRNA gene-trnK gene sequences: homozygote-K(gl)Wtk type, homozygote-K(pl)Ztk type, heterozygote-K(gl)Wtk type, and heterozygote-Ltk type. Among the four genotypes, C. kwangsiensis in a field used for cultivation of Gajutsu was of heterozygote-K(gl)Wtk type. Formation of a heterozygote in the 18S rRNA gene might be a result of crossbreeding of C. kwangsiensis with several Curcuma species which had cytosine at nucleotide position 234. GC analysis of the rhizomes revealed that C. kwangsiensis was characterized by camphor and beta-elemene, and by detecting additional components such as curdione and curcumenol Curcuma species involved in the formation of the heterozygote might be speculated upon.