Santosh G. Rajput's research while affiliated with University of Nebraska at Lincoln and other places

Proso millet ( Panicum miliaceum L.) is a short‐season annual crop known for high water‐use efficiency and drought tolerance. The low water requirement makes this ancient grain an excellent rotational crop for the winter wheat‐based dryland cropping system in the High Plains of the United States. The genetic base of the commonly grown US cultivars is very narrow. Assessment of proso millet germplasm for agronomic traits is essential for its efficient utilization in the genetic improvement of this crop. The objectives of this study were to (1) characterize the US proso millet germplasm based on nine important morpho‐agronomic traits and (2) classify the germplasm into clusters based on these morpho‐agronomic traits. A total of 77 genotypes from 24 different countries were evaluated in the field during 2014 and 2015 at Scottsbluff and Sidney, NE. The genotypes showed significant variations for all the traits across locations. Many traits showed genotype × environment interactions and were highly correlated. Several genotypes were identified as sources of desired traits, such as maturity, lodging, and grain shattering. The genotypes formed six clusters based on morpho‐agronomic data. Principal component analysis revealed that these nine traits explained maximum phenotypic variance and could be used as selection indices in proso millet breeding. This is the most comprehensive study of the US proso millet core collection based on morpho‐agronomic traits and would be useful for developing improved proso millet cultivars.

Proso millet (Panicum miliaceum L.) is the best rotational crop in most dryland production areas in the semiarid US High Plains because of the highest water use efficiency among all cereal crops and short growing season. In the United States, it is used for birdseed, but it is used mostly for human consumption in Asia and Europe. Genomic resources and genetic research of this crop are limited. There is no report of molecular marker-based genetic diversity analysis of the US germplasm, which is important for its genetic improvement. The objective of this study was to evaluate genetic diversity of US proso millet germplasm based on DNA markers. A set of 90 proso millet genotypes (landraces and cultivars) and 100 simple-sequence repeat (SSR) markers were used. Cluster analysis was based on unweighed pair-group method with arithmetic average (UPGMA) and principal component analysis (PCA) using NTSYSpc software. A total of 1287 alleles with size range from 40 to 1500 bp were amplified by the 100 SSR markers. The US proso millet germplasm used in this report is highly genetically diverse. The genotypes formed one major and two minor groups, which correspond to their geographic origin, pedigree, and morphoagronomic traits with few exceptions. All the cultivars developed in the United States remained together in a subcluster within Group 2. Many of these SSR markers with high resolving power were very informative and could be useful for further genetic diversity studies of proso millet. This study would have significant implications for future proso millet genetic improvement.

Proso millet (Panicum miliaceum L.) is the cereal crop with the low water requirement and increasingly being used for human consumption. It is the most common rotational crop within wheat-based dryland production systems in the semiarid High Plains of the USA. However, there is no published genetic map for this species, which prevents the identification of quantitative trait loci (QTL). The objectives of the present study were (1) construction of a genetic linkage map and (2) identification of DNA markers linked to QTLs for morpho-agronomic traits. A total of 93 recombinant inbred lines derived from a single F1 (“Huntsman” × “Minsum”) were genotyped with GBS-SNP markers and phenotyped for nine morpho-agronomic traits in the field during 2013 and 2014 at Scottsbluff and Sidney, NE. IciMapping v.4.0.6.0 was used for constructing a genetic linkage map and mapping QTL. The RILs exhibited significant variation for a wide range of traits, and several traits showed evidence of genotype × environment interactions. A total of 833 GBS-SNP markers formed 18 major and 84 minor linkage groups, whereas 519 markers remained ungrouped. A total of 117 GBS-SNP markers were distributed on the 18 major linkage groups spanning a genome length of 2137 cM of proso millet with an average distance of 18 cM between markers. The length and number of markers in each of the 18 major linkage groups ranged from 54.6 to 236 cM and 4 to 12, respectively. A total of 18 QTLs for eight morpho-agronomic traits were detected on 14 linkage groups, each of which explained 13.2–34.7 % phenotypic variance. DNA markers flanking the QTLs were identified, which will aid in marker-assisted selection of these traits. To our knowledge, this is the first genetic linkage map and QTL mapping in proso millet, which will support further genetic analysis and genomics-assisted genetic improvement of this crop.