A Comparative Study of Selected Physical and Biochemical Traits of Wild-Type and Transgenic Sorghum to Reveal Differences Relevant to Grain Quality.

Roya J Ndimba,Bongani K Ndimba,Jens Kossmann,Luke Mehlo,Alban Barnabas,Johanita Kruger

doi:10.3389/fpls.2017.00952

Abstract

Transgenic sorghum featuring RNAi suppression of certain kafirins was developed recently, to address the problem of poor protein digestibility in the grain. However, it was not firmly established if other important quality parameters were adversely affected by this genetic intervention. In the present study several quality parameters were investigated by surveying several important physical and biochemical grain traits. Important differences in grain weight, density and endosperm texture were found that serve to differentiate the transgenic grains from their wild-type counterpart. In addition, ultrastructural analysis of the protein bodies revealed a changed morphology that is indicative of the effect of suppressed kafirins. Importantly, lysine was found to be significantly increased in one of the transgenic lines in comparison to wild-type; while no significant changes in anti-nutritional factors could be detected. The results have been insightful for demonstrating some of the corollary changes in transgenic sorghum grain, that emerge from imposed kafirin suppression.

Highlights

800 million of the world’s population suffer from undernourishment, with the highest levels (∼23%) found in Sub-Saharan Africa (FAO, IFAD, and WFP, 2015)
This study has revealed a number of important differences in quality characteristics amongst and between two independent transgenic sorghum lines and their wild-type counterpart
Transgenic grains were found to have a higher proportion of floury endosperm types, were conspicuously less dense and featured smaller protein body structures in comparison to wild-type grains

Summary

Introduction

800 million of the world’s population suffer from undernourishment, with the highest levels (∼23%) found in Sub-Saharan Africa (FAO, IFAD, and WFP, 2015). High rates of population growth coupled with severe climatic conditions often result in a chronic supply-demand mismatch (Knox et al, 2012). Grain sorghum [Sorghum bicolor (L) Moench], is one of Africa’s most prized indigenous cereals that has been relied upon for centuries as a major food security crop (Dicko et al, 2006). 43% of all major staple foods produced on the continent are known to incorporate some aspect of sorghum grain (Etuk et al, 2012), and as a result, the crop is frequently cited as Africa’s second most important cereal, after maize (Hassan, 2015). An overreliance on sorghum as a basic staple is not recommended due to several nutritional shortcomings associated with its grain. Sorghum’s dominant storage proteins, the kafirins, are difficult to

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Conclusion