Evaluation of resistance to stemphylium blight in interspecific recombinant inbred lines derived from Lens culinaris × Lens ervoides

Abstract

Cultivated lentil suffers yield loss from stemphylium blight, caused by Stemphylium botryosum Wallr. Identification of sources of stemphylium blight resistance and knowledge of the mode of inheritance of resistance are important for developing resistant cultivars. The interspecific recombinant inbred line (RIL) population developed from a cross between the moderately resistant parent Lens culinaris cv. ‘Eston’ and the resistant parent L. ervoides (Brign.) Grande accession IG 72815 was evaluated for stemphylium blight resistance under controlled conditions at the University of Saskatchewan, Saskatoon, Canada, and under field conditions at the Pulses Research Centre (PRC), Ishurdi, Bangladesh. We hypothesized that resistance from both parents will lead to transgressive segregation indicative of pyramiding of resistance genes from the same. However, no resistant transgressive segregants were observed in the RIL population. A large proportion (50%) of the RILs had disease severity levels similar to the resistant parent IG 72815 in experiments conducted under natural disease pressure in Bangladesh. Under controlled conditions in Saskatoon, 38% of RILs had resistance levels similar to IG 72815. Across all environments, 14 RILs consistently had resistance levels similar to IG 72815. The distribution of disease severity scores for all RILs indicated polygenic inheritance of stemphylium blight resistance in the population. RILs with consistent resistant reactions should prove useful for lentil improvement programmes. This will contribute to increasing the productivity of lentil crops in North America and the Indo-Gangetic region, which account for more than 68% of world lentil production.

An advanced lentil backcross population developed from a cross betweenLens culinaris×L. ervoidesfor future disease resistance and genomic studies

“…None of the LABC-01 individuals had significantly less disease than the resistant parent LR-59-81 (Supplementary Table S1). This observation is consistent with the findings of Adobor et al . (2020) who also reported the absence of resistant transgressive segregants in L. ervoides interspecific population screened for stemphylium blight resistance in the greenhouse, growth chamber and the field conditions.…”

“…None of the LABC-01 individuals had significantly less disease than the resistant parent LR-59-81 (Supplementary Table S1). This observation is consistent with the findings of Adobor et al (2020) who also reported the absence of resistant transgressive segregants in L. ervoides interspecific population screened for stemphylium blight resistance in the greenhouse, growth chamber and the field conditions. A high proportion of the LABC-01 individuals (144) had similar disease severity when compared to the resistant parental line LR-59-81, indicating that resistance genes were transferred from the resistant parent to LABC-01 individual lines ( Supplementary Table S1).…”

Mapping of genomic regions linked to stemphylium blight (Stemphylium botryosum Wallr.) resistance in lentil using linkage mapping and marker-trait association analysis

“…This was further confirmed in the interspecific L . culinaris × L. ervoides RIL population LR-26 by Adobor et al (2020). QTLs consistently detected across different environments are ideal for introgression and use in breeding programs because crops with such QTLs are more likely to display a resistant phenotype in more than one environment (El-Soda et al, 2014).…”

Optimization of inoculum production of Stemphylium botryosum for large-scale resistance screening of lentils

“…However, the pathogen has steadily increased in virulence and is currently responsible for up to 80% lentil yield losses [ 7 ]. Furthermore, over recent decades, its incidence has also increased in different regions of the world, notably in Canada [ 8 ], India, Nepal and North America [ 3 , 9 ].…”

“…The optimization of inoculum production and of the inoculation method as a whole is therefore urgently needed to allow large-scale screening of lentil germplasm and populations. Recent studies have resorted to mycelial suspensions for artificial inoculations [ 9 ]. However, a comprehensive understanding of the impact of inoculum type, inoculum concentration, growth conditions and their interaction with genotype has yet to be determined.…”