Characterization of a stearoyl-acyl carrier protein desaturase gene from potential biofuel plant, Pongamia pinnata L.

A new full length cDNA clone encoding stearoyl-ACP desaturase (SAD) was isolated from seeds of Pongamia pinnata, an oil yielding legume plant. The cDNA clone (PpSAD) contained a single open reading frame of 1182-bp coding for 393 amino acids with a predicted molecular mass of 45.04 kDa, and shares similarity with SAD from other plants. Characteristics of the deduced protein were predicted and analyzed using molecular homology modeling; its three dimensional structure strongly resembled the crystal structure of Ricinus communis (RcSAD). Southern blot analysis indicated that 'sad' is a multiple copy gene and was a member of a small gene family. Expression analysis using quantitative real-time PCR revealed that the gene showed marked distinct expression during different stages of seed developments. The results of the expression analysis in this study, combined with existing research, suggest that 'sad' gene may be involved in the regulation of plant seed growth and development.