Characterization of trichomes in Lens spp. and their effect on drought resistance, herbicide efficacy, and pea aphid fecundity
Date
2020-07-07
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Journal ISSN
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ORCID
Type
Thesis
Degree Level
Masters
Abstract
Drought, weeds, and increasing insect pressure are imminent threats to lentil production in the Canadian prairies. This research characterized trichomes (surface hairs) in wild and cultivated lentil and explored their role in imparting resistance to drought, herbicides, and the pea aphid.
In a growth chamber study, 20 wild and cultivated lentil genotypes from seven species were subjected to fully watered and moderate drought conditions. Microstructures on adaxial leaf surfaces were characterized and transpiration rate in 12 genotypes across all species was determined. Drought response of trichomes across species was inconsistent and differed with genotype: While some genotypes increased their trichomes under drought, others decreased them. Similar results were observed upon measuring traits of trichome length, epidermal cell density, and stomatal index. Among the 12 genotypes in which transpiration rate was determined, most genotypes reduced transpiration under drought and this decrease was associated with an increase in trichome density. However, some genotypes responded to drought by increasing transpiration and reducing trichomes, indicating that response to drought is unique to each genotype and other mechanisms are responsible for drought tolerance in lentil.
Greenhouse experiments were conducted to test trichome influence on glyphosate tolerance and spray droplet retention using water and water + non-ionic surfactant solution. A set of recombinant inbred lines using L. culinaris CDC Redberry and L. tomentosus IG 72805 as parents were selected based on varying trichome characteristics on adaxial leaf surfaces. While glyphosate tolerance studies proved inconclusive, surface spray retention decreased with increasing trichome density upon addition of non-ionic surfactant. Results indicate that trichomes might improve herbicide resistance by preventing surface droplet retention.
Lastly, pea aphid performance was monitored on lentil cultivars CDC Redberry and CDC Maxim, and L. tom. IG 72805, which exhibit low, intermediate, and high trichome density on adaxial leaf surfaces, respectively. Pea aphids had the least mortality, largest adult size and least maturity time on L. tom. IG 72805. Their biosis was lowest on CDC Maxim and intermediate on CDC Redberry, suggesting that cultivated lentil has antibiosis potential.
Altogether, this research shows that the role of trichomes in imparting drought resistance in lentil is complex and genotype dependent. While trichomes are not beneficial in imparting pea aphid resistance, they might help in the development of herbicide tolerant lentil cultivars.
Description
Keywords
Lentil, trichomes, drought tolerance, herbicide resistance, pea aphid, wild lentil, cultivated lentil
Citation
Degree
Master of Science (M.Sc.)
Department
Plant Sciences
Program
Plant Sciences