DOI: 10.1094/CC-82-0706 |  VIEW ARTICLE

Molecular Characterization of a Novel Methionine-Rich delta-Kafirin Seed Storage Protein Gene in Sorghum (Sorghum bicolor L.).

L. Izquierdo (1,2) and I. D. Godwin (1,3). (1) School of Land and Food Sciences, The University of Queensland, St Lucia, QLD 4072, Australia. (2) Present address: Centre for Plant Conservation Genetics, Southern Cross University, Lismore NSW 2480 Australia. (3) Corresponding author. Phone: +61-7-3365-2141. Fax: +61-7-3365-1177. E-mail: <i.godwin@uq.edu.au> Cereal Chem. 82(6):706-710. Accepted August 24, 2005. Copyright 2005 AACC International, Inc.

We have isolated, cloned, and characterized a 660 bp full length cDNA encoding a putative seed storage protein gene, delta-kafirin (AY834250), from developing seeds of sorghum (Sorghum bicolor) inbred line SPV-475. Translation of the DNA sequence predicts a 16-kDa polypeptide (precursor) of 147 amino acids, rich in methionine residues (17%). Reverse Transcriptase-PCR (RT-PCR) and Real Time-PCR revealed delta-kafirin is only expressed in developing seeds. delta-Kafirin exhibited 96% identity with another methionine-rich sorghum seed storage protein (AY043223). Interestingly, this delta-kafirin gene contained two insertions rich in ATG codons encoding five more methionine residues than AY043223. Comparison of the sorghum delta-kafirin proteins with other seed storage proteins from maize, rice, and Brazil nut revealed conserved domains, mainly at the N-terminus. This similarity, in particular to the zeins, suggests these proteins shared a common ancestor and that the variation observed occurred after the separation of the species.