From zero to hero: the past, present and future of grain amaranth breeding

Abstract

Grain amaranth is an underutilized crop with high nutritional quality from the Americas. Emerging genomic and biotechnological tools are becoming available that allow the integration of novel breeding techniques for rapid improvement of amaranth and other underutilized crops. Out of thousands of edible plants, only three cereals-maize, wheat and rice-are the major food sources for a majority of people worldwide. While these crops provide high amounts of calories, they are low in protein and other essential nutrients. The dependence on only few crops, with often narrow genetic basis, leads to a high vulnerability of modern cropping systems to the predicted climate change and accompanying weather extremes. Broadening our food sources through the integration of so-called orphan crops can help to mitigate the effects of environmental change and improve qualitative food security. Thousands of traditional crops are known, but have received little attention in the last century and breeding efforts were limited. Amaranth is such an underutilized pseudocereal that is of particular interest because of its balanced amino acid and micronutrient profiles. Additionally, the C photosynthetic pathway and ability to withstand environmental stress make the crop a suitable choice for future agricultural systems. Despite the potential of amaranth, efforts of genetic improvement lag considerably behind those of major crops. The progress in novel breeding methods and molecular techniques developed in model plants and major crops allow a rapid improvement of underutilized crops. Here, we review the history of amaranth and recent advances in genomic tools and give a concrete perspective how novel breeding techniques can be implemented into breeding programs. Our perspectives are transferable to many underutilized crops. The implementation of these could improve the nutritional quality and climate resilience of future cropping systems.

Potential of Amaranth in Alleviating Malnutrition in Indonesia

“…However, phylogenetic and population genetic analysis suggested a clear geographic grouping of A. hybridus from South America with A. quitensis and A. caudatus and A. hybridus from central America with the two northern crop species. This suggests separate domestication events in the different regions [15].…”

“…The three most representing are A. cruentus, A. caudatus, and A. hypochondriacus. Since 1980, it has been rediscovered due to its extra ordinary nutritional characteristics, particularly as an alternative crop when cereals and vegetables can't be grown due to abiotic challenges [24]. The protein content found in the grain amaranth was relatively high, namely, 13-19% DM; thus, this is close to the optimum required in the human diet as described by the World Health Organization (WHO) and the Food and Agriculture Organization (FAO) [26].…”

“…Later on, it was divided into three sections, and more recently, the genus has been distinguished into three sub-genera and nine sections, based on inflorescence and flower characters [14]. The most recent finding has separated it into three sub-genera, namely, Acnida, Amaranthus, and Albersia, by using genome-wide molecular markers [15].…”

“…Since 1980, Amaranthus has been rediscovered as potential crop for the twentyfirst century with promising food ingredients that can substitute cereal proteins [24]. Generally, the three major crops (rice, wheat, and maize) provide the largest proportion of daily nutrition and calories for billions of people, but they lack of essential minerals and vitamins for a balanced nutrition.…”

Amaranth as a Pseudocereal in Modern Times: Nutrients, Taxonomy, Morphology and Cultivation

“…The initial evidence of Amaranth cultivation dates back to the mid-Holocene period (8000-7000 BP) [24]. In Central America, seeds of A. hypochondriacus and A. cruentus were found which date back 1500 and 6000 years, respectively, from Mexico [25]. The three main grain Amaranth species cultivated throughout different regions in America are A. cruentus, which is cultivated throughout North America, particularly in and around Southern Mexico and Guatemala, A. hypochondriacus, which is cultivated through the western part of America, particularly from southwestern America to central Mexico, as well as A. caudatus, which is cultivated closer to Southern America, particularly near the Andes and Northern Argentina [17].…”