Poster: Seed Biology

Abs # 552: Characterization of vicilins in Vigna luteola

Presenter:	Chlan, Caryl A., cchlan@louisiana.edu
Authors	Chlan, Caryl A. (A)   Salter, Michele  (A)   Xie, Zhongyu  (A)   Neigel, Joseph E (A)
Affiliations:	(A): The University of Louisiana at Lafayette

The major angiosperm globulin seed storage proteins are the legumins and vicilins. These protein groups were first defined by the sedimentation coefficients of the aggregated seed storage proteins in leguminous plants. Plant vicilins (7S) share a common ancestry and exhibit varying degrees of identity. We have characterized vicilin genes from the legume Vigna luteola. Initial studies utilized a PCR-based strategy to amplify a conserved vicilin region of 482 nucleotides. Multiple PCR products were sequenced and shown to be between 86 and 90% identical to a phaseolin vicilin sequence. One of these PCR products was used to probe a Southern blot ofVigna luteolagenomic DNA. We estimate that there are 2 - 4 copies per genome. We have isolated three PCR amplified genomic fragments that are about 99% identical to each other. This high degree of identity may be the result of a recent gene duplication event, or it may be that the changes in the nucleotide sequence we observed were the result of the high error rate of Taq polymerase. However, we also amplified two other vicilin-like sequences that were clearly different. Mid-embryogenesis RNA was extracted from developing Vigna luteola embryos, and used to generate a cDNA library. A vicilin clone was identified and sequenced. Based on the DNA sequence of the complete cDNA clone, primers were designed to amplify the coding region. A genomic vicilin gene was amplified and sequenced. Comparisons between the cDNA and genomic clone, as well as between the Vigna luteola vicilin and other plant vicilins are presented.