Diversity in Surface Microstructures of Trichomes, Epidermal Cells, and Stomata in Lentil Germplasm

To develop crops capable of withstanding challenges posed by climate change, breeding strategies must focus on addressing multiple stresses occurring concurrently in plants. Leaf epidermal structures such as trichomes, stomata, and epidermal cells play an important role in mediating plant defense and could be essential traits that impart wide-ranging tolerance to biotic and abiotic stresses. Consequently, it is important to inform on the underlying diversity in these traits in lentil germplasm (Lens spp.). In this study, we characterized foliar microstructures of 12 genotypes belonging to seven wild and cultivated Lens species. We performed scanning electron microscopy on leaflet and pod surfaces for their qualitative characterization. For quantitative characterization, we observed surface imprints via light microscopy and quantified trichome density (TD), trichome length (TL), stomatal density (SD), epidermal cell density (ECD), and stomatal index (SI) on adaxial and abaxial leaflet surfaces for each genotype. We also assessed the heritability of trichome traits by evaluating interspecific recombinant inbred lines (RILs) derived from the cross Lens culinaris CDC Redberry × Lens tomentosus IG 72805. Comparing foliar microstructures, we found that TD and TL varied widely among cultivated and wild lentil genotypes. However, in most lentil genotypes, the adaxial leaflet surface had lower TD and longer trichomes compared to the abaxial surface. Pubescence on pods comprised five major phenotypes: no trichomes or glabrous pods, very short trichomes at low density, short trichomes at high density, medium-length trichomes at high density, and long trichomes at high density. Leaves of all species were amphistomatous, and SI, SD, and ECD were all higher on the adaxial compared to the abaxial surface. Adaxial surfaces had slightly sunken stomata, which might be an adaptive trait to conserve water. Quantifying TD and TL on the leaflets of interspecific RILs revealed transgressive segregation of these traits, suggesting that TD and TL are quantitative in nature. While taxonomic implications of this study are limited, a detailed description of agronomically relevant morphophysiological traits presented in this paper along with the mode of inheritance of trichomes may serve as a resource for scientists developing lentil adapted to concurrent biotic and abiotic stresses of the future.

Starting material for the breeding of easily producible lentil varieties

Materials and methods. As of January 1, 2021, the National Center for Plant Genetic Resources of Ukraine has a collection comprising 1,101 lentil specimens from 54 countries, including 90 Ukrainian specimens. Of these, 17% are breeding varieties, 45% are breeding lines, 37% are trivially bred varieties and forms, and about 1% are five wild lentil species. The collection specimens were evaluated in accordance with valid methods. Our objective was to evaluate the collection for the traits that determine ease of production and to offer starting material for breeding. Our purpose was to identify sources of valuable economic characteristics for the breeding of easily producible lentil varieties. Results and discussion. Basing on the multi-year results, we selected and proposed the starting material to create easily producible lentil varieties with the following characteristics: high yields of seeds (11 macrosperma sources (Krasnohradska 5 originating from Ukraine [1000-seed weight = 73 g]; 1913 T 15 from Canada [66 g]; UD0600141 from Spain [91 g]; and others) and 25 microsperma sources (UD0600707 from Ukraine [34 g]; Miledi from Russia [38 g]; CDC Redcap from Canada [38 g]; and others)); suitability for mechanized harvesting (6 macrosperma sources (Mistseva 5 from Ukraine, Ilina from Slovakia, 1921 T 11 from Canada, and others) and 18 microsperma sources (Novourenskaya 3565 from Russia, Pozdnyaya from the Czech Republic, CDC Redwing from Canada, and others)); improved biochemical composition and high cooking qualities of seeds (3 macrosperma sources (local accessions: UD0600141 from Spain, UD0600329 from Syria, UD0600151 from Mexico) and 10 microsperma sources (local accessions: UD0600451 from Bulgaria, UD0600017 from Afghanistan, UD0600979 from Israel, and others)). Conclusions. For 30 years of intensive work of the National Center for Genetic Resources of Plants of Ukraine, divers and original staring material of lentil has been collected and studied; sources of valuable economic characteristics have been identified for breeding programs of research institutions of Ukraine and other countries

Effectiveness of the Classification for the Phosphorus Use Efficiency Traits at the Seedling Stage in Lentil

Background: Understanding the morphology of the root system in lentils is critical for the identification of root characteristics for breeding cultivars with enhanced phosphorus use efficiency (PUE) to better adapt to poor P environments. PUE and variability in root morphological characteristics at the early vegetative stage were investigated among 40 indigenous and exotic lentil genotypes in a hydroponic phenotyping system.Results: A prerequisite for developing P-efficient crop cultivars is to categorise existing germplasm. In this experiment, 40 lentil genotypes were grown for 24 days under P deficit (3 μm KH2PO4) and P adequate (250 μm KH2PO4) conditions in hydroponics. Lentil genotypes exhibited significant variability for root, biomass, and P efficiency traits. Different techniques have identified various genotypes of lentils based on the efficiency of phosphorus uptake (PUPE) and the efficiency of phosphorus utilization (PUTE). IG 568229 showed the highest PUPE, while the wild ILWL-15 lentil showed the lowest PUPE in both media. The wild lentil ILWL-95 showed maximum PUTE under P adequate medium. The IC 560135, IG 334, IG 560157 and IG 568229 genotypes were found to be highly efficient at both P levels and to be ideal for a large range of P levels without having a drastic impact on biomass output.Conclusions: The primary step for breeding more P-efficient crop plants is the classification of the germplasm. IC 560135 and IC 268238 contrasting lentil lines may be useful for mapping population development, mapping and tagging of gene(s), QTLs for PUE in lentil. These efficient P crops also ensure food and nutritional security, in addition to reducing the cost of cultivation.

Lack of effective resistance to the virulent race of Colletotrichum lentis in Lens culinaris Medikus subsp. culinaris

Anthracnose caused by Colletotrichum lentis is an important fungal disease of lentil in western Canada. Two known pathogenic C. lentis races, race 0 and race 1 have been identified and current cultivars of lentil have little or no resistance to the virulent race 0. Seven Lens culinaris subsp. culinaris landrace accessions were previously reported to have resistance to C. lentis race 0. In this study, accession VIR-2633, with reported resistance to both races of C. lentis, and seven accessions were assessed for race 0 resistance relative to LR-59-81, an interspecific line derived from a L. culinaris subsp. culinaris × Lens ervoides cross. The results showed a lack of effective resistance to race 0 among the tested L. culinaris accessions when compared to that of LR-59-81. A few sublines displayed modest improvements in resistance compared to the susceptible check ‘Eston’, but were significantly more susceptible than LR-59-81. Moreover, screening of the sublines of accession VIR-2633 identified 12 sublines with resistance to race 1, but all VIR-2633 sublines were susceptible to race 0. The study underlined the importance of wild lentil germplasm for broadening the genetic base of cultivated lentil and their usefulness in disease screening experiments as positive checks.

Can wild lentil genotypes help improve water use and transpiration efficiency in cultivated lentil?

Climate change forecasts point to increased frequency of droughts which may affect plant growth. For protein crops such as lentil, genetic improvement of both water use and drought tolerance is necessary. Wild lentil species are known to have evolved in drought prone areas and can be introgressed into cultivated lentil, making them candidates for the evaluation of high transpiration efficiency (TE) and drought tolerance. We assessed TE, water use and drought tolerance at the plant level for five wild lentil species and in cultivated lentil. Under fully watered and moderate drought conditions, wild lentil genotypes consumed significantly less water to fix similar or more dry matter compared with their cultivated counterparts. Under severe drought conditions, the wild lentil genotype L. ervoides IG 72815 had significantly higher TE compared with L. culinaris Eston. Lens ervoides L-01-827A, had significantly higher yield compared with all other species in the presence or absence of drought and showed significantly higher (α = 5%) TE under moderate drought. Drought susceptibility index was identified as a tool to identify drought-tolerant lentil genotypes grown under severe drought. The numerous small seeds of wild lentil made it difficult to estimate drought indices that are weight based and require formulae that incorporate seed numbers.