Finger millet (Eleusine coracana (L.) Gaertn. subsp. coracana) is the most important millet in eastern Africa and perhaps the oldest domesticated cereal grain in Africa. One of the major factors limiting finger millet production is blast disease caused by the fungus Magnaporthe grisea. Crop wild relatives and landraces present a potential source of novel genes. This study investigated the response of cultivated and wild relatives of finger millet to an isolate of blast disease from western Kenya. Previous germplasm collections were purified through two generations of single‐seed descent before screening alongside improved and farmer‐preferred varieties (FPVs) under a screen house across three seasons. Farmer‐preferred varieties were identified through participatory varietal selection (PVS). The plants were inoculated twice during each growth period using hand‐spraying method and data on disease incidence recorded at grain‐filling stage. Genotypic data was generated using diversity arrays technology (DArT) sequencing and data analysis done using Genstat 18.2 and TASSEL 5.2.58. We observed high heritability (81%), indicating that the variation observed was predominantly genetic. Wild accessions were generally more resistant to the disease in comparison to the cultivated accessions. Preliminary genome‐wide association study (GWAS) using general linear model with principal component analysis led to the identification of 19 markers associated with blast disease that will be be developed into assays for genotype quality control and trait introgression. Wild accessions and landraces of finger millet present a good reservoir for novel genes that can be incorporated into crop improvement programs.

Finger millet is a key food security crop widely grown in eastern Africa, India and Nepal. Long considered a ‘poor man’s crop’, finger millet has regained attention over the past decade for its climate resilience and the nutritional qualities of its grain. To bring finger millet breeding into the 21st century, here we present the assembly and annotation of a chromosome-scale reference genome. We show that this ~1.3 million years old allotetraploid has a high level of homoeologous gene retention and lacks subgenome dominance. Population structure is mainly driven by the differential presence of large wild segments in the pericentromeric regions of several chromosomes. Trait mapping, followed by variant analysis of gene candidates, reveals that loss of purple coloration of anthers and stigma is associated with loss-of-function mutations in the finger millet orthologs of the maize R1/B1 and Arabidopsis GL3/EGL3 anthocyanin regulatory genes. Proanthocyanidin production in seed is not affected by these gene knockouts.

Tritrophic interactions allow plants to recruit natural enemies for protection against herbivory. Here we investigated genetic variability in induced responses to stemborer egg-laying in maize Zea mays (L.) (Poaceae). We conducted a genome wide association study (GWAS) of 146 maize genotypes comprising of landraces, inbred lines and commercial hybrids. Plants were phenotyped in bioassays measuring parasitic wasp Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) attraction to volatiles collected from plants exposed to stemborer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) eggs. Genotyping-by-sequencing was used to generate maize germplasm SNP data for GWAS. The egg-induced parasitoid attraction trait was more common in landraces than in improved inbred lines and hybrids. GWAS identified 101 marker-trait associations (MTAs), some of which were adjacent to genes involved in the JA-defence pathway (opr7, aos1, 2, 3), terpene biosynthesis (fps3, tps2, 3, 4, 5, 7, 9, 10), benzoxazinone synthesis (bx7, 9) and known resistance genes (e.g. maize insect resistance 1, mir1). Intriguingly, there was also association with a transmembrane protein kinase that may function as a receptor for the egg elicitor and other genes implicated in early plant defence signalling. We report maize genomic regions associated with indirect defence and provide a valuable resource for future studies of tritrophic interactions in maize. The markers identified may facilitate selection of indirect defence by maize breeders.