Novel sources of resistance to blast disease in finger millet

Abstract

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.

Genetics and breeding for climate change in Orphan crops

“…More recently, DArT has been combined with NGS in a procedure called DArT-sequencing (DArT-seq) (Sansaloni et al 2011) that enables high throughput genotyping for rapid SNP discovery in many orphan crops. DArT sequencing is now being used in the characterization of many climate-resilient orphan crops including Bambara groundnut (Redjeki et al 2020), finger millet (Dida et al 2020 Aside from DArT-sequencing, other restriction-associated DNA sequencing (RADseq) (Davey et al 2011) genotyping methods including genotyping-by-sequencing (GBS) (Elshire et al 2011) have also been exploited in the characterization and linkage mapping of orphan crops, especially where a reference genome is available as was done in white Guinea yam (Dioscorea rotundata) (Tamiru et al 2017). These sequence-based genotyping platforms are the future of genotyping in all crops including orphan crops with no reference genomes.…”

“…More recently, DArT has been combined with NGS in a procedure called DArT-sequencing (DArT-seq) (Sansaloni et al 2011 ) that enables high throughput genotyping for rapid SNP discovery in many orphan crops. DArT sequencing is now being used in the characterization of many climate-resilient orphan crops including Bambara groundnut (Redjeki et al 2020 ), finger millet (Dida et al 2020 ), Kersting’s groundnut ( Kerstingiella geocarpa ) (Kafoutchoni et al 2020 ), lupin ( Lupinus albus ) (Raman et al 2014) and grass pea (Almeida et al 2016 ).…”

Genomic and phenotypic characterization of finger millet indicates a complex diversification history

“…However, again the accessions and/or molecular markers involved were generally limited to small numbers, and studies did not have available a finger millet genome assembly to map markers to chromosome positions. These studies include those of Dida et al (2021) who used a medium-sized panel of SNPs but only 52 East African accessions to search for blast disease resistance MTAs; Puranik et al (2020) who used a large panel of SNPs but assessed only 190 genotypes to search for grain nutrient-content-related MTAs; Sharma et al (2018) who applied a medium-sized panel of SNPs to only 113 accessions to search for MTAs in 14 agro-morphological traits; and Tiwari et al (2020) who, beginning with the same SNPs and germplasm panel of Sharma et al (2018), explored marker associations with grain protein content. Despite their limited scope, these previous studies indicated some MTAs.…”

Crop Science special issue: Adapting agriculture to climate change: A walk on the wild side

“…spontaneum accessions and in lines derived from interspecific crosses with wild Hordeum species for enhancing barley breeding efforts," who show that high levels of resistance to the net form of net blotch, scald, leaf rust and powdery mildew were identified in CWR-derived barley lines, including some that were resistant to all four diseases. In "Novel sources of resistance to blast disease in finger millet," Dida et al (2021) show that wild finger millet was generally more resistant to the blast disease caused by Magnaporthe grisea compared to cultivated finger millet. In "Wild Lathyrus species as a great source of resistance for introgression into cultivated grass pea (Lathyrus sativus L.) against broomrape weeds (Orobanche crenata Forsk.…”

“…In ” Novel sources of resistance to blast disease in finger millet ,” Dida et al. (2021) show that wild finger millet was generally more resistant to the blast disease caused by Magnaporthe grisea compared to cultivated finger millet. In " Wild Lathyrus species as a great source of resistance for introgression into cultivated grass pea (Lathyrus sativus L.) against broomrape weeds (Orobanche crenata Forsk.…”