J Syst Evol ›› 2012, Vol. 50 ›› Issue (3): 195-205.DOI: 10.1111/j.1759-6831.2012.00187.x

• Original Articles • Previous Articles     Next Articles

Evolution of the 4-coumarate:coenzyme A ligase (4CL) gene family: Conserved evolutionary pattern and two new gene classes in gymnosperms

1,2Hui GAO§ 1Dong-Mei GUO§ 1,2Wen-Juan LIU 1Jin-Hua RAN* 1Xiao-Quan WANG   

  1. 1(State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China)
    2(Graduate University of the Chinese Academy of Sciences, Beijing 100049, China)
  • Received:2011-05-29 Published:2012-05-14

Abstract: The 4-coumarate:coenzyme A ligase (4CL) is the branch point enzyme that channels the general phenylpropanoid metabolism into specific lignin and flavonoid biosynthesis branches. Genetic engineering experiments on the 4CL gene have been carried out in many species, but the precise functions of different gene members are still unresolved. To investigate the evolutionary relationships and functional differentiation of the 4CL gene family, we made a comprehensive evolutionary analysis of this gene family from 27 species representing the major lineages of land plants. The phylogenetic analysis indicates that both vascular and seed plant 4CL genes form monophyletic groups, and that three and two 4CL classes can be recognized in gymnosperms and angiosperms, respectively. The evolutionary rate and frequency of duplication of the 4CL gene family are much more conserved than that of the CAD/SAD (cinnamyl/sinapyl alcohol dehydrogenase) gene family, which catalyzes the last step in monolignol biosynthesis. This may be due to different selective pressures on these genes whose products catalyze different steps in the biosynthesis pathway. In addition, we found two new major classes of 4CL genes in gymnosperms.

Key words: 4CL, functional divergence, gene family evolution, lignin biosynthesis.