Antinutritional factors in pearl millet grains: Phytate and goitrogens content variability and molecular characterization of genes involved in their pathways.

Eleonora Boncompagni,Theophilus Tenutse Kwaku Zu,Erik Nielsen,Maria Gloria Daminati,Eleonora Cominelli,Prakash Irappa Gangashetty,Gregorio Orozco-Arroyo,Stefania Grando,Francesca Sparvoli,Khalil Kashkush

doi:10.1371/journal.pone.0198394

Abstract

Pearl millet [Pennisetum glaucum (L.) R. Br.] is an important “orphan” cereal and the most widely grown of all the millet species worldwide. It is also the sixth most important cereal in the world after wheat, rice, maize, barley, and sorghum, being largely grown and used in West Africa as well as in India and Pakistan. The present study was carried out in the frame of a program designed to increase benefits and reduce potential health problems deriving from the consumption of pearl millet. The specific goal was to provide a database of information on the variability existing in pearl millet germplasm as to the amounts of phytate, the most relevant antinutrient compound, and the goitrogenic compounds C-glycosylflavones (C-GFs) accumulated in the grain.Results we obtained clearly show that, as indicated by the range in values, a substantial variability subsists across the investigated pearl millet inbred lines as regards the grain level of phytic acid phosphate, while the amount of C-GFs shows a very high variation. Suitable potential parents to be used in breeding programs can be therefore chosen from the surveyed material in order to create new germplasm with increased nutritional quality and food safety. Moreover, we report novel molecular data showing which genes are more relevant for phytic acid biosynthesis in the seeds as well as a preliminary analysis of a pearl millet orthologous gene for C-GFs biosynthesis. These results open the way to dissect the genetic determinants controlling key seed nutritional phenotypes and to the characterization of their impact on grain nutritional value in pearl millet.

Highlights

With the purpose to contribute to the knowledge needed for breeding programs regarding nutritional traits of pearl millet, here we analysed the content of the major antinutrient phytic acid and of the goitrogenic C-glycosylflavones of the grain and provide information on genes involved in their biosynthesis
The research described in the present paper was the first phase of a program designed to improve pearl millet—derived food by accomplishing the following objectives: 1) reduction of the level of phytic acid accumulated in the grain; 2) reduction of the potential health problems derived from the presence in the grain of the goitrogenic C-glycosylflavones
For what concerns the second objective, the results we presented here clearly show that a high variability exists across the panel of investigated pearl millet inbred lines as to the seed levels of the six C-GFs that were analysed and quantified by HPLC

Summary

Introduction

Pearl millet is an important cereal in arid and semi-arid regions both in India and subSaharan Africa where it contributes to food security, but it has other uses, such as source of feed and fodder for livestock, fuel and construction materials [2,3]. It is mostly grown in areas with limited agronomic potential characterised by low rainfall (300–500 mm) and marginal soils. Pearl millet food is gluten free, has a low glycemic index, and is a significant source of micronutrients such as iron and zinc (contents are higher than those in other cereals), both in India and sub-Saharan Africa where, as compared to other cereals and vegetables, it potentially represents one of the cheapest source of these micronutrients [7]

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Conclusion