The Genetic Makeup of a Global Barnyard Millet Germplasm Collection

Barnyard millet (Echinochloa spp.) is an important crop for many smallholder farmers in southern and eastern Asia. It is valued for its drought tolerance, rapid maturation, and superior nutritional qualities. Despite these characteristics there are almost no genetic or genomic resources for this crop in either cultivated species [E. colona (L.) Link and E. crus-galli (L.) P. Beauv.]. Recently, a core collection of 89 barnyard millet accessions was developed at the genebank at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). To enhance the use of this germplasm and genomic research in barnyard millet improvement, we report the genetic characterization of this core collection using whole-genome genotyping-by-sequencing. We identified several thousand single-nucleotide polymorphisms segregating in the core collection, and we use them to show patterns of population structure and phylogenetic relationships among the accessions. We determine that there are probably four population clusters within the E. colona accessions and three such clusters within E. crus-galli. These clusters match phylogenetic relationships but by and large do not correspond to classification into individual races or clusters based on morphology. Geospatial data available for a subset of samples indicates that the clusters probably originate from geographic divisions. In all, these data will be useful to breeders working to improve this crop for smallholder farmers. This work also serves as a case study of how modern genomics can rapidly characterize crops, including ones with little to no prior genetic data

Collection of Kaura, Fara-Fara and Guineense sorghums in Northern Nigeria

Sorghum is the principal food crop grown in northern Nigeria. Although sorghum germplasm has been extensively collected in Nigeria, very few Kauras, Fara-faras and Guinéense types are presently available in the world collection at Icrisat. In view of a pressing need by breeders for sorthums with drought tolerance, high yield and grain quality a collection was launched to collect these land races. Kauras (mostly durra-caudatum) are high yielding sorghums, partially adapted to low moisture conditions. Fara-faras (mostly guinea-caudatum) are early-maturing and high yielding. Guinéense sorghums (guinea, subrace guinéense) have white flinty grain with weathering resistance. Landraces from northern Nigeria are potentially good parents in breeding programs for the semi-arid tropics. The collected material was rejuvenated and are being maintained in the Icrisat germplasm bank.Le sorgho est la principale culture vivrière de la région nord du Nigeria. Bien qu'une grande partie de la variabilité génétique du sorgho ait été collectée au Nigeria, très peu des types Kaura, Fara-fara, et Guinéense sont actuellement disponibles dans la collection mondiale à l'ICRISAT. Suite à une demande pressante des sélectionneurs du sorgho, une collection spécifique de ces types a été entamée. Les types Kaura, (surtout des durra-caudatum), sont des sorghos à rendement élevé qui s'adaptent quelque peu aux conditions hydriques faibles. Les types Fara-fara (surtout des guinée-caudatum) sont des variétés hâtives à rendement élevé, dont les grains blancs sont appréciés par la plupart des paysans. Les sorghos de type Guinéense (Race : Guinée, sous-race : Guinéense) ont des grains blancs cornés résistants aux altérations. Les pieds de type Guinéense observés ont été presque exempts des dégâts causés par des insectes ravageurs ou par des maladies par rapport au type Kaura qui est sensible aux maladies et aux attaques des insectes ravageurs. Les populations locales originaires du Nigeria du nord s'avèrent prometteuses dans les programmes de l'amélioration pour les zones tropicales semi-airdes en Afrique de l'Ouest. Le matériel prélevé a été amené à I'Icrisat, rajeuni et conservé dans la banque des ressources génétiques de l'Institut.Prasada Rao K.E., Obilana A.T., Mengesha Melak H. Collection of Kaura, Fara-Fara and Guineense sorghums in Northern Nigeria. In: Journal d'agriculture traditionnelle et de botanique appliquée, 32ᵉ année,1985. pp. 73-81

Systematics and domestication of Panicum sumatrense (Graminae)

Panicum sumatrense Roth. ex Roem. & Schult. (Indian millet, sama) is widely cultivated as a cereal across India, Nepal and western Burma. It is particularly important in the Eastern Ghats of India, where it forms an important part of tribal agriculture. The species is divided into P. sumatrense subsp. sumatrense to include cultivated sama, and subsp. psilopodium (Trin.) de Wet comb. nov. to include the wild progenitor of sama. These two subspecies cross where they are sympatric to produce fertile hybrids, derivatives of which are often weedy in sama fields. Two races of cultivated sama are recognized. Race nana includes plants with decumbent to almost prostrate culms that become erect at time of flowering. Inflorescences are large and open with the upper branches sometimes clumped and curved at time of maturity. Race robusta includes erect plants with large, strongly branched, open or compact inflorescences. This race is grown in northwestern Andhra Pradesh and adjacent Orissa of India where it crosses with race nana.Le Panicum sunwtrense est une céréale très cultivée en Inde, au Népal et en Birmanie occidentale. 11 est spécialement important dans la région des Ghat orientaux, en Inde, où il occupe une place considérable dans l'agriculture tribale. Cette espèce est divisée en deux sous-espèces, le P. sumatrense subsp. sumatrense qui inclut le « sama » cultivé et la sous-espèce P. psilopodium (Trin.) de Wet comb. nov. qui inclut l'ancêtre sauvage du « sama ». Ces deux sous-espèces se croisent quand elles sont sympatriques pour donner des hybrides fertiles dont les dérivés deviennent souvent les mauvaises herbes des champs de « sama ». On reconnait deux races de « sama » cultivées. La race « nana » comprend les plantes à stipes presque couchés qui se dressent lors de la floraison. Les inflorescences sont longues et ouvertes avec les branches supérieures parfois en touffe et recourbées lors de la maturité. La race « robusta » comprend des plantes dressées avec des branches longues et fortes et des inflorescences ouvertes et compactes. Cette race est cultivée dans le nord-ouest de l'Andhra Pradesh et dans l'Orissa, état voisin, où il se croise avec la race « nana ».de Wet J.M.J., Prasada Rao K.E., Brink D.E. Systematics and domestication of Panicum sumatrense (Graminae). In: Journal d'agriculture traditionnelle et de botanique appliquée, 30ᵉ année, bulletin n°2, Avril-juin 1983. pp. 159-168

Assessment of genetic diversity in three subsets constituted from the ICRISAT sorghum collection using random vs non-random sampling procedures : A. Using morpho-agronomical and passport data

A large collection, such as sorghum (#Sorghum bicolor$ (L.) Moench) landrace collection held at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), represents a challenge for the maintenance of both the accessions of and the information documented for the germplasm collection. The accessibility and knowledge of the landrace collection are the essential factors for an efficient utilization of the genetic resources by both breeders and farmers. Different sampling strategies, either random or non-random, were proposed to obtain subsets of reduced size (core collection). Three subsets were established ; a random sampling within a stratified collection (logarithmic strategy : L) ; a sample based upon morpho-agronomic diversity (principal component score strategy : PCS) ; and a sample based upon an empirical knowledge of sorghum (taxonomic strategy : T). Comparisons of these three samples for morpho-agronomic characterization and passport information were assessed to determine their impact on phenotypic diversity. For their overall diversity, the three subsets did not differ, as shown with the two-dimensional representation of the morpho-agronomic diversity and the Shannon-Weaver diversity indices. When comparisons for morpho-agronomic and passport data were considered, the PCS subset looked similar to the entire landrace collection. The L subset showed differences for characters associated with the photoperiod reaction that was considered in the stratification of the collection. The T subset was the most distinct from the entire landrace collection as it over-represented the landraces selected by farmers for specific uses and covered the widest range of geographical adaptation and morpho-agronomic characteristics. (Résumé d'auteur