Identification of new nodulin cDNAs from yellow lupine by differential display

In this study several sequences that represent yellow lupine nodulin genes are identified. Four different cDNA clones were isolated from a lupine nodule cDNA library and sequenced. Database search revealed that the deduced amino acid of one clone, DD3A20, shows near 80% amino acid similarity to plant stearoyl-acyl carrier protein desaturases and contains crucial amino acids in the fatty acid binding domain which are characteristic for stearoyl-ACP desaturases. The other sequences seem to be unique. Nearly identical signal peptide sequences are present at the N-termini of the DD4A9 and DD2T15 putative proteins. Northern analysis indicated that the pattern of expression of the Lldd4A9, Lldd2A18 and Lldd2T15 genes is the same as that of the lupine leghemoglobin gene LllbII, while the desaturase gene Ll3A20 is turned on at least 3 days earlier. Ll3A20 is also expressed in lupine fruits. RT-PCR analysis of the Lldd3A20 and Lldd2T15 expression confirmed organ-specific and temporal pattern of expression in nodules.