A protocol for increased throughput phenotyping of plant resistance to the pollen beetle

Abstract

BACKGROUND: Improving crop resistance to insect herbivores is a major research objective in breeding programs. Although genomic technologies have increased the speed at which large populations can be genotyped, breeding programs still suffer from phenotyping constraints. The pollen beetle (Brassicogethes aeneus) is a major pest of oilseed rape for which no resistant cultivar is available to date, but previous studies have highlighted the potential of white mustard as a source of resistance and introgression of this resistance appears to be a promising strategy. Here we present a phenotyping protocol allowing midthroughput (i.e., increased throughput compared to current methods) acquisition of resistance data, which could then be used for genetic mapping of QTLs.RESULTS: Contrasted white mustard genotypes were selected from an initial field screening and then evaluated for their resistance under controlled conditions using a standard phenotyping method on entire plants. We then upgraded this protocol for mid-throughput phenotyping, by testing two alternative methods. We found that phenotyping on detached buds did not provide the same resistance contrasts as observed with the standard protocol, in contrast to the phenotyping protocol with miniaturized plants. This protocol was then tested on a large panel composed of hundreds of plants. A significant variation in resistance among genotypes was observed, which validates the large-scale application of this new phenotyping protocol.CONCLUSION: The combination of this mid-throughput phenotyping protocol and white mustard as a source of resistance against the pollen beetle offers a promising avenue for breeding programs aiming to improve oilseed rape resistance.

Integrated pest control in oilseed crops—new advances from the rapeseed research community

“…A new protocol for increased throughput compared to current methods was developed for pollen beetle and shows promise to increase the speed of acquiring resistance data needed for these breeding programs. 21 Society and EU policy are now requiring new insecticides to be less environmentally damaging than conventional synthetic toxicants. RNA interference (RNAi) technology offers highly specific control of target pest insects via sequence-specific suppression of gene expression by double-stranded (ds)RNA, leading to mortality or severe sublethal effects due to the disruption of critical cellular processes.…”

“…Use of OSR cultivars that are resistant to herbivorous insects should negate the need for insecticides but development of resistant (or tolerant) varieties has been hampered by the difficulty of phenotyping resistance traits. A new protocol for increased throughput compared to current methods was developed for pollen beetle and shows promise to increase the speed of acquiring resistance data needed for these breeding programs 21 …”