Genetic diversity and genomic resources available for the small millet crops to accelerate a New Green Revolution

Abstract

Small millets are nutrient-rich food sources traditionally grown and consumed by subsistence farmers in Asia and Africa. They include finger millet (Eleusine coracana), foxtail millet (Setaria italica), kodo millet (Paspalum scrobiculatum), proso millet (Panicum miliaceum), barnyard millet (Echinochloa spp.), and little millet (Panicum sumatrense). Local farmers value the small millets for their nutritional and health benefits, tolerance to extreme stress including drought, and ability to grow under low nutrient input conditions, ideal in an era of climate change and steadily depleting natural resources. Little scientific attention has been paid to these crops, hence they have been termed “orphan cereals.” Despite this challenge, an advantageous quality of the small millets is that they continue to be grown in remote regions of the world which has preserved their biodiversity, providing breeders with unique alleles for crop improvement. The purpose of this review, first, is to highlight the diverse traits of each small millet species that are valued by farmers and consumers which hold potential for selection, improvement or mechanistic study. For each species, the germplasm, genetic and genomic resources available will then be described as potential tools to exploit this biodiversity. The review will conclude with noting current trends and gaps in the literature and make recommendations on how to better preserve and utilize diversity within these species to accelerate a New Green Revolution for subsistence farmers in Asia and Africa.

A Review of Nutrient Management Studies Involving Finger Millet in the Semi-Arid Tropics of Asia and Africa

“…Finger millet has high genetic diversity [3]. All finger millet varieties do not respond to nutrients in the same manner.…”

“…Unfortunately, there is little literature available regarding development of new finger millet varieties with high yield potential under low or high nutrient input conditions, although more papers have appeared in recent years [3]. For example, in Nepal there are only three finger millets varieties that have been released after 1990 for commercial purposes [70].…”

Drought Adaptation in Millets

“…The recent review by Goron and Naizanda [6] indicates the institutions involved in the preservation efforts and the amount of germplasm available at each institution. In general, India and China dominate the collections of millets.…”

“…Proso millet is considered to have been domesticated before rice in China, based on the extreme resistance of this millet to drought [12,13]. In addition to its resistance to drought, proso millet escapes the terminal drought that normally occurs late in the growing season since it matures in only three months; hence, proso millet is considered to be a millet with low water requirements [6].…”

“…Two recent reviews examined the health-related benefits associated with millets [19,6]. A number of leading newspapers and media have recently indicated the potential of millets particularly tef as a global lifestyle crop [30][31][32].…”