Molecular Cloning and Expression Analysis of an Lhcb2 Gene from Hevea brasiliensis

Based on the gene sequence identified from the rubber tree (Hevea brasiliensis) genome, an 849 bp cDNA containing an ORF of 798 bp was isolated from the leaf tissue by using the RTPCR technique. The gene denoted HbLhcb21 was predicted to encode 265 amino acids with a theoretical molecular weight of 2866 kD and isolectric point of 542; the protein was promised to be a thylakoid protein of chloroplast; the protein contains one conserved lightharvesting chlorophyll a/b binding protein domain, three transmembrane helices and two Cterminal helices, a trimerization motif, several chlorophyll and carotenoid binding sites, which could be grouped into the LHCB2 subfamily based on the evolutionary relationship. Homologous analysis showed that HbLhcb21 shared an identity of about 95% with the homologs in Ricinus communis, Gossypium hirsutum, Vitis vinifera, Fragaria vesca or Theobroma cacao, suggesting a highly conserved evolution. Expression analysis indicated that HbLhcb21 was mainly expressed in the leaves, with a gradual increase as along with the leaf maturity, but a sharp decrease in senescing leaves.