Gene duplication and an accelerated evolutionary rate in 11S globulin genes are associated with higher protein synthesis in dicots as compared to monocots

Chun Li,Meng Li,Jim M Dunwell,Yuan-Ming Zhang

doi:10.1186/1471-2148-12-15

Abstract

BackgroundSeed storage proteins are a major source of dietary protein, and the content of such proteins determines both the quantity and quality of crop yield. Significantly, examination of the protein content in the seeds of crop plants shows a distinct difference between monocots and dicots. Thus, it is expected that there are different evolutionary patterns in the genes underlying protein synthesis in the seeds of these two groups of plants.ResultsGene duplication, evolutionary rate and positive selection of a major gene family of seed storage proteins (the 11S globulin genes), were compared in dicots and monocots. The results, obtained from five species in each group, show more gene duplications, a higher evolutionary rate and positive selections of this gene family in dicots, which are rich in 11S globulins, but not in the monocots.ConclusionOur findings provide evidence to support the suggestion that gene duplication and an accelerated evolutionary rate may be associated with higher protein synthesis in dicots as compared to monocots.

Highlights

Seed storage proteins are a major source of dietary protein, and the content of such proteins determines both the quantity and quality of crop yield
To shed light on the two questions above, we investigated the process of molecular evolution of the 11S globulin gene family, which is widely distributed in dicot and monocot species, by comparing the differing evolutionary patterns in the two groups
Our analyses suggested that gene duplication and an accelerated evolutionary rate in 11S globulin genes may be associated with higher protein synthesis in dicots than in monocots

Summary

Introduction

Seed storage proteins are a major source of dietary protein, and the content of such proteins determines both the quantity and quality of crop yield. Examination of the protein content in the seeds of crop plants shows a distinct difference between monocots and dicots. The amount of protein present in plant seeds varies from ~10% of the dry weight in most monocot (e.g. O_sativa, S. bicolor, S. italica, Z. mays and B. distachyon) to more than 30% in most dicots (e.g. G_max, R. communis, C. sativus and A. thaliana), and forms a major source of dietary protein [2,3,4,5,6,7]. Seed storage proteins can be classified into four groups: albumins, globulins, prolamins and glutelins [8]. Albumins and globulins comprise the storage proteins of dicots, whereas prolamins and glutelins are the major proteins in monocots [4,9,10]. We focus on the genes encoding the 11S-type globulins in this study

Methods

Results

Conclusion