Molecular cloning of three light-harvesting complex II protein genes and their expression analysis under low temperature stress in Dimocarpus longana Lour.

摘要

The LHCab genes which encode light-harvesting chlorophyll a/b-binding proteins are key photosynthetic genes in all green plants, with important roles in light-driven chemical reactions and in photoprotection. In this study, three LHCab genes were isolated from longan (Dimocarpus longana Lour.) by reverse-transcription-PCR. DLCab1, DLCab2, and DLCab4 contained open reading frames (ORFs) of 792, 798, and 861 nucleotides, encoding proteins of 263, 265, and 286 amino acid residues, respectively. Comparison of the deduced amino acid sequences of DLCab1 and DLCab2 revealed 56.9% identity, while the amino acid sequence of DLCab4 exhibited low homologies to DLCab1 and to DLCab2 (33.9% and 31.1%, respectively). Sequence and phylogenetic analyses demonstrated that the three DLCab genes of longan were similar to the genes of other species at both the nucleotide and amino acid levels. Quantitative real-time PCR revealed that the mRNAs of the three DLCab genes were expressed most abundantly in leaves, with lower levels of expression in roots and stems. In all tissues tested, expression of the three DLCab genes changed with time under low temperature stress. Constitutive expression suggests that these three DLCab genes are important throughout the life-cycle of longan and are particularly critical in the response of longan to cold stress.