J Integr Plant Biol. ›› 2003, Vol. 45 ›› Issue (6): 659-666.

• Research Articles •

Molecular Composition and Evolution of the Chalcone Synthase (CHS) Gene Family in Five Species of Camellia (Theaceae)

YANG Jun-Bo, TIAN Xin, LI De-Zhu, GUO Zhen-Hua

• Published:2003-06-15

Abstract:

The molecular composition and evolution of the chalcone synthase (CHS) gene family from five species in Camellia(Theaceae) are explored in this study. Sixteen CHS exon 2 from four Camellia species were amplified from total DNA by PCR method. Three sequences of the fifth species in Camellia and two sequences of Glycine max as the designated outgroups were obtained from GenBank. Our results indicated that CHS gene family in Camellia was differentiated to three subfamilies (A, B, C) during the evolutionary history with six groups (A1, A2, A3, B1, B2, C). Among them, only group A2 was possessed by all five species in this study. However, the other five groups were detected only in some species of the plants studied. All members of CHS gene family in this study had high sequence similarity, more than 90% among the members in the same subfamily and more than 78% among different subfamilies at nucleotide level. According to the estimated components of amino acids, the function of CHS genes in Camellia had been diverged. The nucleotide substitutions of the different groups were not identical. Based on phylogenetic analyse inferred from sequences of CHS genes and their deduced amino acid sequences, we concluded that the CHS genes with new function in this genus were evolved either by mutations on several important sites or by accumulation of the mutations after the gene duplication. A further analysis showed that the diversification of CHS genes in Camellia still occurred recently, and the evolutionary models were different to some extant among different species. So we assumed that the different evolutionary models resulted from the impacts of variable environmental elements after the events of speciation.

（中国科学院昆明植物研究所生物多样性与生物地理学开放实验室，昆明]650204）

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