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Currently, seed priming is reported as an efficient and low-cost approach to increase crop yield, which could not only promote seed germination and improve plant growth state but also increase abiotic stress tolerance. Salinity represents one of the most significant abiotic stresses that alters multiple processes in plants. The accumulation of polyamines (PAs) in response to salt stress is one of the most remarkable plant metabolic responses. This paper examined the effect of osmopriming on endogenous polyamine metabolism at the germination and early seedling development of Brassica napus in relation to salinity tolerance. Free, conjugated and bound polyamines were analyzed, and changes in their accumulation were discussed with literature data. The most remarkable differences between the corresponding osmoprimed and unprimed seeds were visible in the free (spermine) and conjugated (putrescine, spermidine) fractions. The arginine decarboxylase pathway seems to be responsible for the accumulation of PAs in primed seeds. The obvious impact of seed priming on tyramine accumulation was also demonstrated. Moreover, the level of ethylene increased considerably in seedlings issued from primed seeds exposed to salt stress. It can be concluded that the polyamines are involved in creating the beneficial effect of osmopriming on germination and early growth of Brassica napus seedlings under saline conditions through moderate changes in their biosynthesis and accumulation.

Salinity is a growing global concern that affects the yield of crop species, including tomato (Solanum lycopersicum). Its wild relative Solanum chilense was reported to have halophyte properties. We compared salt resistance of both species during the reproductive phase, with a special focus on sodium localization in the flowers. Plants were exposed to NaCl from the seedling stage. Salinity decreased the number of inflorescences in both species but the number of flowers per inflorescence and sepal length only in S. lycopersicum. External salt supply decreased the stamen length in S. chilense, and it was associated with a decrease in pollen production and an increase in pollen viability. Although the fruit set was not affected by salinity, fruit weight and size decreased in S. lycopersicum. Concentrations and localization of Na, K, Mg, and Ca differed in reproductive structures of both species. Inflorescences and fruits of S. chilense accumulated more Na than S. lycopersicum. Sodium was mainly located in male floral organs of S. chilense but in non-reproductive floral organs in S. lycopersicum. The expression of Na transporter genes differed in flowers of both species. Overall, our results indicated that S. chilense was more salt-resistant than S. lycopersicum during the reproductive phase and that differences could be partly related to dissimilarities in element distribution and transport in flowers.

Cultivated yam (D. rotundata) is a staple tuber crop in West Africa whose sexual reproduction control remains largely unknown despite its importance for plant breeding programs. In this paper, we compared self-pollination, intracultivar cross-pollination and intercultivar cross-pollination in three monoecious cultivars (Amoula, Heapala and Yassi). Results showed that pollen viability (49%) and stigma receptivity (40%) were similar in monoecious and dioecious plants, suggesting that autogamy could occur in monoecious plants. However, fruit and seed sets were significantly lower after self-pollination compared to cross-pollination. Overall, autogamy reached 11% and pollen lability was almost zero (<1%). The low percentage of pollen grains germinating on the stigma (37%) and pollen tubes reaching the ovules (25%) after self-pollination partly explained the low seed set. Strong inbreeding depression was observed after self-pollination and almost all fruits and about 75% of the seeds resulting from self-pollination showed malformations. Seed germination was also 20 times lower after self-pollination compared to cross-pollination. Sexual reproduction remained low in D. rotundata even after cross-pollination as fruit and seed set did not exceed 18% and 13% respectively. Moreover, comparison between intracultivar cross-pollination and self-pollination revealed intravarietal genetic diversity inside the analyzed yam cultivars. Overall, our results showed that D. rotundata has a very low tolerance to autogamy in monoecious cultivars and has developed pre- and postzygotic mechanisms to limit selfing.

Salinity is a growing global concern that affects the yield of crop species, including tomato (Solanum lycopersicum). In contrast to S. lycopersicum, its wild relative Solanum chilense was reported to have halophyte properties. We compared salt resistance of both species during vegetative and reproductive phases and investigated Na and Cl accumulation in the different organs. Plants were exposed to NaCl (0, 60, 120 mM) from the seedling stage up to flowering (85 days after stress). Overall, S. chilense accumulated more Na than S. lycopersicum while Cl concentration was similar in both species under salt stress. Sodium accumulated mainly in roots in S. lycopersicum and in stems in S. chilense, showing that S. lycopersicum had an excluder behavior and S. chilense an includer behavior regarding Na accumulation while such a difference was not observed regarding Cl accumulation. Both species limited the accumulation of Na and Cl in the inflorescences. The concentration of Na and Cl in the inflorescences were respectively lower and higher in S. lycopersicum compared to S. chilense under salt stress. Na localization in the flowers was analyzed by laser ablation ICP-MS. Na was mainly located in male floral organs of S. chilense but in non-reproductive floral organs of S. lycopersicum under salinity. Na and Cl accumulation and repartition could be partly explained by gene expression of transporters involved in Na and Cl distribution. Overall, our results indicated that S. chilense was more salt-resistant than S. lycopersicum and that both species differed towards strategies of Na and Cl accumulation.

The use of orphan crops could mitigate the effects of climate change and improve the quality of food security. We compared the effects of drought, high temperature, and their combination in 12 varieties of Tartary buckwheat (Fagopyrum tataricum). Plants were grown at 21/19 °C or 28/26 °C under well-watered and water-stressed conditions. Plants were more discriminated according to environmental conditions than variety, with the exception of Islek that was smaller and produced fewer leaves, inflorescences, and seeds than the other varieties. The combination of high temperature and water stress had a stronger negative impact than each stress applied separately. The temperature increase stimulated leaf and flower production while water stress decreased plant height. Leaf area decreased with both temperature and water stress. High temperature hastened the seed initiation but negatively affected seed development such that almost all seeds aborted at 28 °C. At 21 °C, water stress significantly decreased the seed production per plant. At the physiological level, water stress increased the chlorophyll content and temperature increased the transpiration rate under well-watered conditions. High temperature also increased the polyphenol and flavonoid concentrations, mainly in the inflorescences. Altogether, our results showed that water stress and temperature increase in particular negatively affected seed production in F. tataricum.

Pear (Pyrus communis) is the main fruit crop in Belgium and ‘Conférence’ accounts for 90% of the pear production. ‘Conférence’ is self-incompatible and thus requires cross-pollination to produce fruits by fertilization. Hives could be settled in the orchards to facilitate pollination and to allow a better fruit size production. However, blooming occurs early in the spring and climatically unfavorable conditions (frost, low temperatures, rain, etc.) could prevent the pollination by insects. To overcome this inconvenience, parthenocarpy induction by spraying gibberellins is a common practice in ‘Conférence’ orchards. However, whether gibberellin treatment affects fruit set and quality of fruits produced by fertilization has not been investigated. We therefore compared the impact of gibberellin spraying on the development of parthenocarpic fruits and fruits obtained by fertilization. Un-pollinated, open-pollinated and hand-pollinated flowers were sprayed or not with 10 mg L-1 GA4/7 at the balloon, full bloom and petal fall stages and the resulting fruit production and quality were assessed. Compatible hand-pollination increased fruit size and fruit weight by respectively 9 and 8% and decreased fruit length by 10% compared to parthenocarpic fruits whatever the gibberellin treatment. Treatment with GA4/7 increased the fruit set at harvest compared to untreated fruits. The time of GA4/7 spraying significantly affected fruit parameters and treatment was more efficient when applied at the balloon stage. Regarding fruits produced by fertilization, GA4/7 treatment decreased seed development by respectively 12, 13 and 36% when applied at the balloon, full bloom and petal fall stages compared to untreated fruits. Consequently, fruit size decreased by 2 and 5% and fruit weight by 8 and 13% when GA4/7 was sprayed at full bloom and petal fall stages compared to untreated fruits. However, treatment at the balloon stage did not affect fruit size and weight. Thus, our results showed

Salinity is a growing global concern that affects the yield of crop species, including tomato (Solanum lycopersicum). In contrast to S. lycopersicum, its wild relative Solanum chilense was reported to have halophyte properties. We compared salt resistance of both species during reproductive phase and investigated minerals accumulation and sugar metabolism to identify the main causes of the decrease of flower production and fertility. Plants were exposed to NaCl (0, 60, 120 mM) from the seedling stage for 91 days. Inflorescence production decreased in both species under salinity while inflorescences and flowers abortion increased in S. lycopersicum only. Regarding flower fertility, the number of pollen grains per flower decreased in S. chilense. Pollen viability increased with salt in S. chilense. Both species limited the accumulation of Na and Cl in the inflorescences without affecting K concentration. The concentration of Na and K in the inflorescences was lower in S. lycopersicum than in S. chilense under salt stress while the concentration of Cl was higher in the inflorescences of S. lycopersicum. In flowers, Na was mainly located in male floral organs of S. chilense but in non-reproductive floral organs of S. lycopersicum under salinity. Sugar analysis showed that S. lycopersicum and S. chilense did not present the same composition of sugars in the inflorescences and that S. lycopersicum presented more sugars in inflorescences than S. chilense. Overall, our results indicated that both species differed towards strategies of minerals and sugars accumulation in reproductive organs.

The Old Limachino Tomato is a valuable fruit with exceptional nutritional values and organoleptic sensory properties. However, it suffers from a short shelf-life, compromising post-harvest behavior. As an attempt to improve the fruit’s qualities, Limachino (L) scion was grafted onto rootstock from the rustic landrace Poncho Negro (R). Fruits produced in this graft combination were compared with fruits produced by self-grafted plants (L/L) and from a long-shelf-life cultivar Seminis (LSL). The trials were carried out for 146 days during summer of two consecutive years. Poncho Negro rootstock increased the total number of fruits produced by Limachino scion (L/R). It did not affect the fresh weight of individual fruits but reduced their water content. It has no impact on the Limachino fruit form (quality), a typical characteristic well appreciated by consumers. Fruits produced by LSL exhibited a higher firmness but a lower titratable acidity and antioxidant capacity than L/R and L/L fruits. Panels of 104 untrained final consumers and a trained panel of 13 experts attributed the highest value to L/R fruits and the lowest one to LSL. It was concluded that Poncho Negro rootstock contributes to increasing preferences and the level of acceptability towards Limachino fruits. Further research is needed to develop local technologies in order to expand the production of local tomatoes that are highly valued by consumers.

Cultivated yam (Dioscorea rotundata) is a staple tuber crop in West Africa that is mainly propagated vegetatively. Although the majority of yam cultivars flower, the control of its sexual reproduction - in particular sexual expression - remains largely unknown despite its importance for breeding programs. Our objectives were to: 1) characterize the flowering phenology and identify the causes of sex variation in this species; 2) analyze the genetic and hormonal controls of sex determinism; and 3) study the performance of sexual reproduction in monoecious cultivars. Our histological study showed that during floral morphogenesis, stamen and carpel primordia are initiated in all flowers irrespective of sex, but while only primordia corresponding to the sex of the flower continue to develop in sex-stable plants, male and female flowers of sub-dioic populations retain remnants of organs of the opposite sex. Our results also showed that the sex variation of the offspring was more related to the sex of the parents (monoecious in this case) than to the tuber sections used as seed tubers. Our genetic study did not identify a clear genetic marker for early determination of sex identity in D. rotundata yams from Benin but supported the involvement of a genetic locus (Z-) in sex expression with a possible transition from a ZZ/ZW female heterogamous system to an XX/XY male heterogamous system. Our hormonal analyses showed that jasmonates (MeJa) had a masculinizing effect in monoecious plants and that application of MeJA and cytokinins (BAP) accelerated flowering and increased inflorescence production. Furthermore, our crossing results showed that flowers of monoecious plants were fertile and showed a reproductive performance comparable to that of dioecious plants, so that they can partially compensate for the scarcity of female flowers in breeding programs. Altogether, our study has improved our understanding of the control of sex in cultivated yam (Dioscorea rotundata)., (AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2022

Drought and high temperature significantly limit plant growth and productivity in tomato (Solanum lycopersicum). The elucidation of tolerance strategies in wild relatives is a powerful approach to understand local adaptations for potential crop improvement. Solanum chilense is able to cope with harsh environment in its area of origin and could represent an abundance of genetic diversity for tomato improvement. However, physiological basis of drought and heat tolerance in Solanum chilense has received only minor attention until now. In this study, we compared the effects of drought, high temperature, and their combination in two cultivars of S. lycopersicum and six populations of S. chilense. Plants were grown at 21/19°C or 28/26°C under well-watered and water-stressed conditions. Plant growth, physiological responses, and expression of stress-responsive genes were investigated. The effects of water stress, high temperature, and their combination differed according to the accession, suggesting differences in stress resistance between species and populations. Water stress affected plants more negatively than temperature from a morpho-physiological point of view, while the expression of stress-responsive genes was more affected by temperature. Accessions clustered in two groups regarding resistance to water stress and high temperature. The expression of stress-responsive genes was more stable in resistant accessions than in sensitive ones in response to water stress and high temperature. Altogether, our results suggest that water stress and high temperature resistance in S. chilense did not depend on single traits but on a combination of morphological, physiological, and genetic traits.

The germination of pollen is a key factor in the fertilization success of selfincompatible flowering trees such as apple (Malus domestica Borkh.). Breeding programs have a particular interest in evaluating the germinability of pollens from the male parents before performing controlled crosses. In vitro pollen germination is often considered a simple reliable method to determine the exact amount of viable pollen but the composition of the artificial medium has important implications. In this study, we evaluated the optimal concentration of sucrose (5, 10, 15 and 20%) in the agar-plate medium by testing the germination capacity of 8 apple cultivars. Over the concentrations tested, 15% sucrose solution gave the best results followed by 20%. The percentage of germination significantly varied among cultivars. In the 15% sucrose concentration, the highest percentage was found in ‘Perurico’ (95%) and the lowest in ‘Raxina Dulce’ (66%). These levels are sufficient for an effective fertilisation. Furthermore, the germination of pollen was not affected by the flowering date of the cultivars.

Avec l’avènement de la médecine vétérinaire moderne, les pratiques traditionnelles vétérinaires sont reléguées au second plan dans la gestion zoosanitaire des animaux d’élevage. Toutefois, la médecine vétérinaire moderne n’a pas pu faire face à tous les problèmes sanitaires des exploitations d’élevage, surtout dans les milieux ruraux où l’accès aux médicaments et services vétérinaires pose un problème. A cela s’ajoute le faible pouvoir d’achat des éleveurs. Ces derniers sont obligés de recourir aux pratiques et connaissances traditionnelles pour traiter leurs animaux. La médecine ethnovétérinaire a joué un rôle primordial dans la gestion des exploitations d’élevage depuis la domestication jusqu’à nos jours. Les auteurs retracent l’évolution des pratiques ethnovétérinaires puis examinent la contribution de la recherche scientifique à la connaissance et l’amélioration de la médecine traditionnelle vétérinaire. Les raisons qui expliquent aujourd’hui l’engouement autour des pratiques traditionnelles vétérinaires sont discutées. Des mesures sont proposées sous forme de perspectives pour pérenniser la médecine ethnovétérinaire. Il s’agit principalement d’oeuvrer pour la disponibilité des plantes médicinales et autres ressources naturelles utilisées dans les pratiques ethnovétérinaires, mais aussi de prouver scientifiquement l’efficacité de ces plantes et de transmettre aux éleveurs les informations les plus pertinentes. L’intégration des pratiques et des connaissances traditionnelles dans la médecine vétérinaire moderne apparait comme une alternative prometteuse pour une meilleure gestion de la santé des animaux d’élevage. Les conditions de cette intégration sont évoquées. La recherche scientifique a encore un grand rôle à jouer dans la vérification de l’efficacité des traitements ethnovétérinaires.

Salinity is an important environmental constraint which strongly reduces crop yield in several areas in the world. Rice (Oryza sativa) is considered as a salt-sensitive species and improvement of salt resistance is a major goal for plant breeders. Some species in the Oryza genus may constitute an interesting source of genes for rice improvement. Comparatively to the classical Asian rice species (Oryza sativa), the African rice Oryza glaberrima is poorly described for its response to salt stress. Our aims were 1-) to identify salt-tolerant varieties of O. glaberrima, 2-) to discriminate between the osmotic and the ionic components of salt stress and 3) to precise the impact of individual ions on salt deleterious impact. Plants were exposed to stress in nutrient solution or in soil culture. Then, a set of parameters related to photosynthesis, mineral nutrition, plant water status, yield, and antioxidative properties were recorded. Our results showed that one accession such as the cultivar TOG5307 was able to maintain a higher net photosynthesis under salt conditions and exhibited a higher level of tolerance to accumulated Na+ ions and a higher capacity for osmotic adjustment comparatively to the salt-sensitive cultivar TOG5949. The salt-resistant cultivar TOG5307 was also less affected by salinity than TOG5949 for yield-related parameters. Na+ ions appeared more toxic than Cl-, although an additive effect was recorded when both ions were simultaneously present in NaCl. The use of non-penetrating osmotic agent PEG demonstrated that osmotic and ionic components of salt stress acted in an additive way in the salt-sensitive cultivar but not in the salt-resistant one where an antagonist action was recorded for several parameters. Data were analyzed in relation to the expression of genes coding for ions transporters., (SC - Sciences) -- UCL, 2021

Pear (Pyrus communis L.) is the most important fruit crop in Belgium and ‘Conférence’ represents 90% of the pear production. ‘Conférence’ is self-incompatible and requires cross-pollination to develop fertilized fruits. Hives could be settled in the orchards to facilitate pollination and allow a better fruit size production. However, blooming occurs early in the spring and climatically unfavorable conditions (frost, low temperatures, rain, etc) could prevent the pollination by insects. In this case, parthenocarpy induction by spraying gibberellins is a common practice in ‘Conference’ orchards. However, whether gibberellin treatment affect fruit set and quality of fertilized fruits has not been investigated. We therefore compared the impact of gibberellin spraying on the development of parthenocarpic and fertilized fruits. Un-pollinated, open-pollinated and hand-pollinated flowers were sprayed or not with 10 mg/L GA4/7 at balloon, anthesis and wilted stages and the resulting fruit production and quality were assessed. Hand-pollination increased fruit size and fruit weight by respectively 9% and 8% but decreased fruit length by 10% compared to parthenocarpic fruits whatever the gibberellin treatment. Treatment with GA4/7 increased the fruit set at harvest (28% vs. 22%) compared to untreated fruits. The time of GA4/7 spraying significantly affected fruit parameters and treatment was more efficient when applied at balloon stage. Regarding fertilized fruits, GA4/7 treatment decreased seed development by respectively 12%, 13% and 36% when applied at balloon, anthesis and wilted stages compared to untreated fruits. Consequently, fruit size decreased by 2% and 5% and fruit weight by 8% and 13% when GA4/7 was sprayed at anthesis and wilted stages compared to untreated fruits. However, treatment at balloon stage did not affect fruit size and weight. Thus, our results showed that GA4/7 treatment might negatively affect the development of pollinated fruits depending on the timi

Cannabis sativa L. is a promising species for non-food production on moderate heavy metal (HM)-contaminated farmland soils and considered as a potential crop for cleaning the soil from HM because of its high biomass production, its long root system and its capacity to absorb and accumulate HM. However, until now, “soil remediation” is usually considered independently of “soil production”, and there is an obvious lack of information regarding the possibility to conciliate phytomanagement and obtaining valuable marketable products. The global aim of the present thesis is to contribute to fil this gap, with specific attention to hemp fibres, the most economically valuable part of the plant. Using two different growing systems (nutrient solution or contaminated agricultural soil), we investigated the contaminant concentration and distribution in hemp raw material, hemp HM tolerance, and the impact of HM on fibre production and quality, considering for the first time industrial standards. We showed that C. sativa is suited for fibre production associated with HM management due to its extraction potential. However, this strategy should be limited to soils with a moderate content of HM, considering that high HM bioavailability negatively impacted plant growth and development. The management of moderately HM-contaminated soils with hemp can contribute to reduce the dispersion of HM in the environment through its high biomass yield and its important root system. Besides, HM impacted fibre elongation and thickening, but not their mechanical properties, and were mainly accumulated in trichomes rather than in fibres. Fibres could thus be used in special products like insulating material and cements, with a specific attention to the stability of these material regarding the erosion of the final product. To devise agricultural strategies aimed at improving crop yield, the effect of silicon (Si) on plants’ stress resistance was also considered. Overall, we demonstrated that the ad, (AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2021

Background Tartary buckwheat (Fagopyrum tataricum) is a nutritionally balanced and flavonoid-rich crop plant that has been in cultivation for 4000 years and is now grown globally. Despite its nutraceutical and agricultural value, the characterization of its genetics and its domestication history is limited. Results Here, we report a comprehensive database of Tartary buckwheat genomic variation based on whole-genome resequencing of 510 germplasms. Our analysis suggests that two independent domestication events occurred in southwestern and northern China, resulting in diverse characteristics of modern Tartary buckwheat varieties. Genome-wide association studies for important agricultural traits identify several candidate genes, including FtUFGT3 and FtAP2YT1 that significantly correlate with flavonoid accumulation and grain weight, respectively. Conclusions We describe the domestication history of Tartary buckwheat and provide a detailed resource of genomic variation to allow for genomic-assisted breeding in the improvement of elite cultivars.

Buckwheat is a pseudocereal with high nutritional and nutraceutical properties. Although common buckwheat (Fagopyrum esculentum) is the main cultivated species, Tartary buckwheat (Fagopyrum tataricum) is gaining interest. In this paper, we compared plant growth, yield-related parameters and seed nutritional qualities of two varieties of F. esculentum and F. tataricum under field conditions in Belgium. Fagopyrum esculentum flowered earlier, produced less nodes, less branches, less inflorescences, but more flowers per inflorescence than F. tataricum. The yield was higher in F. tataricum, while the thousand-grain weight was higher in F. esculentum. Yield ranged between 2037 kg/ha and 3667 kg/ha depending on the species and year. Regarding nutritional qualities, seeds of F. esculentum contained more proteins (15.4% vs. 12.8%) than seeds of F. tataricum although their amino acid profile was similar. Seeds of F. esculentum contained also more Mg (1.36 vs. 1.15 mg/g dry weight (DW)) and less Fe (22.9 vs. 32.6 µg/g DW) and Zn (19.6 vs. 24.5 µg/g DW) than F. tataricum. The main difference between seed nutritional quality was the concentration of flavonoids that was 60 times higher in F. tataricum than in F. esculentum. Both species grow well under Belgian conditions and showed good seed quality.

Drought and higher temperatures caused by climate change are common stress conditions affecting plant growth and development. The reproductive phase is particularly sensitive to stress, but plants also need to allocate their limited resources to produce floral traits and resources to attract pollinators. We investigated the physiological and floral consequences of abiotic stress during the flowering period of Impatiens glandulifera, a bee-pollinated species. Plants were exposed to three temperatures (21, 24, 27 °C) and two watering regimes (well-watered, water stress) for 3 weeks. Not all parameters measured responded in the same manner to drought and/or heat stress. Drought stress induced leaf senescence, decreasing leaf number by 15–30% depending on growth temperature. Drought also reduced photosynthetic output, while temperature rise affected stomatal conductance. The number of flowers produced dropped 40–90% in response to drought stress, while higher temperatures shortened flower life span. Both stresses affected floral traits, but flower resources diminished in response to higher temperatures, with lower nectar volume and pollen protein content. We conclude that increased temperatures and drought stress, which are becoming more frequent with climate change, can negatively affect flowering, even if plants deploy physiological resistance strategies.

Buckwheat is a pseudocereal with high nutritional and nutraceutical properties. Although common buckwheat (Fagopyrum esculentum) is the main cultivated species, Tartary buckwheat (Fagopyrum tataricum) is gaining interest. In most western European countries, buckwheat production has declined during the 20th century with the development of more productive crops, but it is currently receiving renewed attention for its nutritional and environmentally friendly qualities. Both species were cultivated under field conditions in Belgium and showed good yield (2037 kg/ha - 3667 kg/ha) and good seed quality (Aubert et al., 2021). Fagopyrum esculentum flowered earlier, produced less nodes, less branches, less inflorescences, but more flowers per inflorescence than F. tataricum. The yield was higher in F. tataricum, while the thousand-grain weight was higher in F. esculentum. Both species differed by their reproduction: F. esculentum is a heterostylous and self-incompatible species mainly pollinated by insects while F. tataricum produces one type of flower that can self-fertilize. However, we observed that insects visited both species: F. esculentum was twice as visited and attracted a greater diversity of insects than F. tataricum, which generally attracted smaller insects. In the context of ongoing climate change, expected temperature rise and increase of drought periods may significantly limit plant growth and productivity of crop species. We investigated the effects of a sub-optimal temperature (27°C vs. 21°C) and of water stress (<20% vs. 40-50% soil water content) on F. esculentum and F. tataricum under controlled conditions (Aubert et al., 2020a, b). High temperature increased leaf production mainly in F. tataricum but decreased leaf area in both species. Water and photosynthesis-related parameters were affected by high temperature but our results suggested that although transpiration rate was increased, adaptive mechanisms were developed to limit the negative impact on p

Most apple trees (Malus domestica Borkh.) are self-incompatible and fruit yield depends on cross-pollination between genetically compatible cultivars with synchronous flowering. Flowering intensity can vary strongly among years due to the biennial bearing habit of the cultivars. The knowledge of the phenological stages and floral and pollen characteristics is essential to select suitable pollen donors. We evaluated the phenotypic variability of flowering-related traits (i.e., flowering phenology, flowering intensity, pollen production and pollen quality) in 45 apple cultivars over two successive flowering seasons. Large phenotypic variability was found among the studied cultivars indicating that the local germplasm collection provides a good source of genetic and phenotypic diversity. However, low correlations were observed between floral biology traits and, consequently, the improvement in one trait seems not to affect other traits. Some of the cultivars such as ‘Perurico’ and ‘Raxila Dulce’ regularly produced copious amounts of high-quality pollen which can improve the pollen load dispersion leading to a most effective pollination process. We did not identify statistically significant correlations between pollen attributes and the biennial bearing phenomenon. The large variation in bloom dates from year-to-year observed under a typical Oceanic climate makes it advisable to combine cultivars in new plantings.

In temperate regions, climate change is leading to more frequent droughts and higher average temperatures, impacting all ecosystems. Most flowering plants in temperate zones depend on insect pollinators for their reproduction. Insect pollinators collect floral resources, pollen and nectar, which they sometimes rely exclusively on it for food. Plants attract pollinators through floral signals (flower size, quantity of floral resources, etc.). If these signals are altered, the mutualistic relationship between plants and pollinators can be compromised. My thesis aims to investigate climate change-induced changes in floral signals and their potential impact on pollinator behaviour. Plants, during their flowering period, were subjected to combined stresses (increased temperatures and drought) under controlled conditions. Collectively, the results of the research conducted in this thesis confirm that these stresses negatively impact the floral signals and resources of the plants. When pollinators were exposed to a binary choice between 'unstressed' and 'stressed' flowers, 75% of them chose the unstressed flowers. These results indicate that the change in floral signals of stressed plants is perceived by insects, which may compromise pollinator attractiveness and potentially plant reproductive success., Dans les régions tempérées, les changements climatiques induisent des sécheresses plus fréquentes ainsi qu’une température moyenne plus élevée, impactant l’ensemble des écosystèmes. La majorité des plantes en zone tempérée dépendent des insectes pollinisateurs pour assurer leur reproduction. Les pollinisateurs, en butinant, récoltent des ressources florales, du pollen et du nectar, dont ils dépendent parfois exclusivement pour leur alimentation. Les plantes attirent les pollinisateurs grâce à des signaux floraux (taille de la fleur, quantité de ressources florales, etc.). Si ces signaux sont modifiés, la relation mutualiste entre les plantes et les pollinisateurs peut être compromise. Ma thèse vise à étudier les modifications des signaux floraux induites par les changements climatiques ainsi que les répercussions potentielles sur le comportement des pollinisateurs. Les plantes, durant leur période de floraison, ont été soumises à des stress combinés (hausse de températures et sécheresse) en conditions contrôlées. Collectivement, les résultats des recherches menées dans le cadre de cette thèse confirment que ces stress impactent négativement les signaux floraux des plantes. Quand les pollinisateurs ont été soumis à un choix binaire entre des fleurs « non stressées » et « stressées », 75% d’entre eux se sont orientés vers des fleurs non stressées. Ces résultats indiquent que la modification des signaux floraux des plantes stressées est perceptible par les insectes, ce qui peut compromettre l'attrait des pollinisateurs et potentiellement le succès reproducteur des plantes., (AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2021

Les sécheresses et les vagues de chaleur sont de plus en plus fréquentes durant ces saisons, qui sont cruciales pour les plantes. En pleine période de croissance et de reproduction, celles-ci subissent ou tolèrent plus ou moins bien ces conditions météorologiques. mais que la plante doit en plus attirer des insectes pour sa pollinisation, cela se complique.

European pear requires inter-cultivar cross-pollination by insects to develop fertilized fruits. However, some European pear cultivars such as ‘Conference’ naturally produce parthenocarpic seedless fruits. To better understand the hormonal regulation of fruit set and early fruit development in this European pear cultivar, the phytohormone and polyamine profiles in ‘Conference’ flowers and fruits resulting from both fertilization and parthenocarpic processes were analyzed. The expression of genes involved in phytohormone metabolism and signaling were also investigated. Phytohormone profiles differed more at flower stage 3 days after treatment than in 15 day- and 30-day-old fruits in response to fertilization and parthenocarpy. An increase in auxins, abscisic acid, ethylene precursor, and spermine, and a decrease in putrescine were recorded in the fertilized flowers as compared to the parthenocarpic flowers. Fertilization also upregulated genes involved in gibberellin synthesis and down-regulated genes involved in gibberellin catabolism although the total gibberellin content was not modified. Moreover, exogenous gibberellin (GA3, GA4/7) and cytokinin (6BA) applications did not increase parthenocarpic induction in ‘Conference’ as observed in other European and Asian pear cultivars. We hypothesize that the intrinsic parthenocarpy of ‘Conference’ could be related to a high gibberellin level in the flowers explaining why exogenous gibberellin application did not increase parthenocarpy as observed in other pear cultivars and species.

Seed priming is a pre-sowing method successfully used to improve seed germination. Since water plays a crucial role in germination, the aim of this study was to investigate the relationship between better germination performances of osmoprimed Brassica napus seeds and seed water status during germination. To achieve this goal, a combination of different kinds of approaches was used, including nuclear magnetic resonance (NMR) spectroscopy, TEM, and SEM as well as semi-quantitative PCR (semi-qPCR). The results of this study showed that osmopriming enhanced the kinetics of water uptake and the total amount of absorbed water during both the early imbibition stage and in the later phases of seed germination. The spin–spin relaxation time (T2) measurement suggests that osmopriming causes faster water penetration into the seed and more efficient tissue hydration. Moreover, factors potentially affecting water relations in germinating primed seeds were also identified. It was shown that osmopriming (i) changes the microstructural features of the seed coat, e.g., leads to the formation of microcracks, (ii) alters the internal structure of the seed by the induction of additional void spaces in the seed, (iii) increases cotyledons cells vacuolization, and (iv) modifies the expression pattern of aquaporin genes.

Pear (Pyrus communis) is the most important fruit crop in Belgium and ‘Conférence’ represents 90% of the pear production. ‘Conférence’ is self-incompatible and requires cross-pollination to develop fertilized fruits. We therefore compared seven pear cultivars (‘Dicolor’, ‘Doyenné du Comice’, ‘Joséphine de Malines’, ‘Seigneur Espéren’, ‘Sweet Sensation’, ‘Triomphe de Vienne’, ‘Williams Bon Chrétien’) adapted to Belgian conditions in order to identify valuable pollinizer cultivars for ‘Conférence’. These cultivars were used as male parent in hand pollination experiments with ‘Conférence’ and the resulting number of fruits was assessed. Fruit size and weight were measured at harvest. Moreover, to evaluate the pollination efficiency of these cultivars and their attractiveness for bees, we analyzed their pollen and nectar production and composition. Pollen is one of the prime nutrient resources used for bee larvae and nectar represents the major source of sugars for bees. Regarding fruit production, the mean weight and size reached 103-154 g and 50-61 mm respectively depending on the crossings. The largest fruits resulted from the pollination of ‘Conférence’ with ‘Triomphe de Vienne’ or ‘Doyenné du Comice’. The cultivars differed in their pollen and nectar quantities and compositions. The mean number of pollen grains per anther ranged from 2,200 for ‘Dicolor’ to 4,600 for ‘Williams Bon Chrétien’. Pollen viability was high whatever the cultivar (60-92%). Pollen polypeptide concentration was variable (31-107 µg mg-1) while amino acid concentration was high and stable (346-390 µg mg-1) among cultivars. The nectar sugar content per flower varied between 52 µg for ‘Seigneur Espéren’ to 255 µg for ‘Conférence’. Pear cultivars produced therefore pollen of high quality regarding amino acid content while their nectar production was poor in sugars. Bee attractiveness might differ among cultivars and needs further research to optimize orchard management.

Pear belongs to the Rosaceae family as most of the cultivated fruit trees. It is the second fruit tree crop in terms of production after apple. Its production has increased these last decades to reach a world production of more than 27 megatons for almost 1,600,000 ha. Pears have been cultivated in Europe and in Asia for more than 5,000 years. Of all known and reported pear species and interspecific hybrids, five are mainly cultivated. These include the European pear, Pyrus communis, and the Asian pears P. pyrifolia, P. ×bretschneideri, P. ussuriensis, and P. sinkiangensis. Fruits of European pears are elongated and have a full-bodied texture, while those of Asian pears are round and have a sandy texture. The Pyrus genus belongs to the Amygdaloideae subfamily and the Malinae tribe, and consists of about 75 to 80 species and interspecific hybrid species. As several hybridizations are observed among Pyrus species, this renders the distinction among some pear species rather difficult. The origin of the Pyrus genus dates back to the Oligocene Epoch, about 33.35 to 25.23 Mya. It is a genus of mainly deciduous trees and shrubs spread throughout temperate Eurasia, reaching the Atlas Mountains in North Africa, and extending to Japan and South China. Pyrus species produce generally simple leaves alternately arranged. Leaves are glossy green on some species, densely silvery-hairy in some others. Pyrus flowers are white, borne in corymbs on short spurs or lateral branchlets, and are composed of five sepals, five petals, numerous stamens, and usually a five-locular ovary with free styles. The Pyrus fruit is a pseudo-fruit composed of the receptacle or the calyx tube, greatly dilated, enclosing the true fruit, and consisting of five cartilaginous carpels, known as the core. Morphological characters of the leaf, fruit, and calyx are commonly used to differentiate among Pyrus species. There are thousands of pear cultivars over the world with wide diversity for fruit shape, taste

Coastal areas in the world are not only suffered from salinization but are also contaminated with high amounts of heavy metals resulting from human activities. Kosteletzkya pentacarpos is a promising wetland halophyte plant species for phytomanagement of heavy metal-contaminated salt areas. However, in previous work, K. pentacarpos was exposed to one single heavy metal, and was cultivated in nutrient solution only. Hence the global aim of the present study is to assess the response of K. pentacarpos to a complex heavy metal pollution implying the simultaneous presence of Cd and Zn excess, to understand the putative influence of NaCl on the plant physiological and biochemical behaviour, and to compare the plant behaviour in nutrient solution and in contaminated soil. In our study, combination of Cd and Zn increases heavy metal concentrations in all organs with accumulation of Cd mainly in the cell walls and even distribution of Zn between symplasm and apoplasm. Heavy metal accumulation reduces net photosynthesis, leading to a heavy metal-induced oxidative stress. Combined treatment also induces a specific plant hormonal status in K. pentacarpos which could not be fully explained by an additive effect of Cd and Zn. Heavy metal stress reduces osmotic potential through osmolytes (proline and glycinebetaine) accumulation and modified metabolism. The addition of NaCl reduces the heavy metal absorption, resulting in alleviation of oxidative stress and modification of phytohormoneal status. In contaminated soil, combination of heavy metal affects plant growth, development and flowering. Cultivation of K. pentacarpos changes the bioavailability of heavy metal and reduces the volume of leachate as well as their heavy metal concentration in response to NaCl. It is concluded that K. pentacarpos is a promising candidate for revegetation of multiple heavy metals contaminated areas, especially under salt stress conditions., (AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2019

Many plants require animal pollinators for successful reproduction; these plants provide pollinator resources in pollen and nectar (rewards) and attract pollinators by specific cues (signals). In a seeming contradiction, some plants produce toxins such as alkaloids in their pollen and nectar, protecting their resources from ineffective pollinators. We investigated signals and rewards in the toxic, protandrous bee-pollinated plant Aconitum napellus, hypothesizing that male-phase flower reproductive success is pollinator-limited, which should favour higher levels of signals (odours) and rewards (nectar and pollen) compared with female-phase flowers. Furthermore, we expected insect visitors to forage only for nectar, due to the toxicity of pollen. We demonstrated that male-phase flowers emitted more volatile molecules and produced higher volumes of nectar than female-phase flowers. Alkaloids in pollen functioned as chemical defences, and were more diverse and more concentrated compared to the alkaloids in nectar. Visitors actively collected little pollen for larval food but consumed more of the less-toxic nectar. Toxic pollen remaining on the bee bodies promoted pollen transfer efficiency, facilitating pollination.

European pear requires inter-cultivar cross-pollination by insects to develop fertilized fruits. However, some European pear cultivars such as ‘Conference’ naturally produce parthenocarpic seedless fruits. To better understand the hormonal regulation of fruit set and early fruit development in this European pear cultivar, the phytohormone and polyamine profiles in ‘Conference’ flowers and fruits resulting from both fertilization and parthenocarpic processes were analyzed. The expression of genes involved in phytohormone metabolism and signaling were also investigated. Phytohormone profiles differed more at flower stage 3 days after treatment than in 15 day- and 30-day-old fruits in response to fertilization and parthenocarpy. An increase in auxins, abscisic acid, ethylene precursor, and spermine, and a decrease in putrescine were recorded in the fertilized flowers as compared to the parthenocarpic flowers. Fertilization also upregulated genes involved in gibberellin synthesis and down-regulated genes involved in gibberellin catabolism although the total gibberellin content was not modified. Moreover, exogenous gibberellin (GA3, GA4/7) and cytokinin (6BA) applications did not increase parthenocarpic induction in ‘Conference’ as observed in other European and Asian pear cultivars. We hypothesize that the intrinsic parthenocarpy of ‘Conference’ could be related to a high gibberellin level in the flowers explaining why exogenous gibberellin application did not increase parthenocarpy as observed in other pear cultivars and species.

Pear (Pyrus communis) is the most important fruit crop in Belgium and ‘Conférence’ represents 90% of the pear production. ‘Conférence’ is self-incompatible and requires cross-pollination to develop fertilized fruits. We therefore compared seven pear cultivars (‘Dicolor’, ‘Doyenné du Comice’, ‘Joséphine de Malines’, ‘Seigneur Espéren’, ‘Sweet Sensation’, ‘Triomphe de Vienne’, ‘Williams Bon Chrétien’) adapted to Belgian conditions in order to identify valuable pollinizer cultivars for ‘Conférence’. These cultivars were used as male parent in hand pollination experiments with ‘Conférence’ and the resulting number of fruits was assessed. Fruit size and weight were measured at harvest. Moreover, to evaluate the pollination efficiency of these cultivars and their attractiveness for bees, we analyzed their pollen and nectar production and composition. Pollen is one of the prime nutrient resources used for bee larvae and nectar represents the major source of sugars for bees. Regarding fruit production, the mean weight and size reached 103-154 g and 50-61 mm respectively depending on the crossings. The largest fruits resulted from the pollination of ‘Conférence’ with ‘Triomphe de Vienne’ or ‘Doyenné du Comice’. The cultivars differed in their pollen and nectar quantities and compositions. The mean number of pollen grains per anther ranged from 2,200 for ‘Dicolor’ to 4,600 for ‘Williams Bon Chrétien’. Pollen viability was high whatever the cultivar (60-92%). Pollen polypeptide concentration was variable (31-107 µg mg-1) while amino acid concentration was high and stable (346-390 µg mg-1) among cultivars. The nectar sugar content per flower varied between 52 µg for ‘Seigneur Espéren’ to 255 µg for ‘Conférence’. Pear cultivars produced therefore pollen of high quality regarding amino acid content while their nectar production was poor in sugars. Bee attractiveness might differ among cultivars and needs further research to optimize orchard management.

Climate change alters the abiotic constraints faced by plants, including increasing temperature and water stress. These changes may affect flower development and production of flower rewards, thus altering plant–pollinator interactions. Here, we investigated the consequences of increased temperature and water stress on plant growth, floral biology, flower-reward production, and insect visitation of a widespread bee-visited species, Borago officinalis. Plants were grown for 5 weeks under three temperature regimes (21, 24, and 27°C) and two watering regimes (well-watered and water-stressed). Plant growth was more affected by temperature rise than water stress, and the reproductive growth was affected by both stresses. Vegetative traits were stimulated at 24°C, but impaired at 27°C. Flower development was mainly affected by water stress, which decreased flower number (15 ± 2 flowers/plant in well-watered plants vs. 8 ± 1 flowers/plant under water stress). Flowers had a reduced corolla surface under temperature rise and water stress (3.8 ± 0.5 cm2 in well-watered plants at 21°C vs. 2.2 ± 0.1 cm2 in water-stressed plants at 27°C). Both constraints reduced flower-reward production. Nectar sugar content decreased from 3.9 ± 0.3 mg/flower in the well-watered plants at 21°C to 1.3 ± 0.4 mg/flower in the water-stressed plants at 27°C. Total pollen quantity was not affected, but pollen viability decreased from 79 ± 4% in the well-watered plants at 21°C to 25 ± 9% in the water-stressed plants at 27°C. Flowers in the well-watered plants at 21°C received at least twice as many bumblebee visits compared with the other treatments. In conclusion, floral modifications induced by abiotic stresses related to climate change affect insect behavior and alter plant–pollinator interactions.

To investigate whether Tilia trees are poisonous or valuable resources for bee visitors, we determined the nectar and pollen quantities and composition of the four main Tilia species planted in Western Europe (T. cordata , T. platyphyllos , T. tomentosa, and T. × europaea ). We developed a new method to detect nicotine in nectars.We observed insect visitor diversity and abundance.We also assessed bumblebee death when individuals were only fed with Tilia flowers. No traces of mannose or nicotine, incriminated in the Tilia toxicity, have been detected in the nectars of the studied species. Huge numbers of insect visitors, mainly bees and syrphids, visited the trees which offer large numbers of flowers, plenty of sugar rich nectar, and protein-rich pollen. Bumblebees only fed with Tilia flowers did not present any particular mortality. We discuss the different hypotheses of the supposed toxicity and propose future research to solve this debate.

Exogenous application of salicylic acid may improve tolerance to salinity. However, the timing of its application may influence the plant response to salt toxicity. We investigated if exogenous salicylic acid application had similar protective effects when applied as a priming agent or concomitantly with NaCl. Tomato seedlings primed or not with 0.01 mM salicylic acid were further treated with 125 mM NaCl, 0.01 mM salicylic acid or combined treatments. Both priming and concomitant application of salicylic acid increased plant growth of salt-stressed plants but their positive impact was not additive. The endogenous salicylic acid concentration increased in the leaves at the end of the experiment after concomitant application but not in response to priming, suggesting that salicylic acid accumulated during priming was metabolized subsequently. Salicylic application either before or during salt exposure acts on the two main constraints induced by salinity, namely the ionic and the osmotic constraints. Regarding ion accumulation, priming increased Na+ and K+ accumulation in leaves of salt-treated plants while concomitant salicylic application had no impact on shoot Na+ and K+ accumulation. Regarding osmotic adjustment, both priming and concomitant salicylic acid decreased osmotic potential values in salt-treated plants. Carbon isotope discrimination showed that combination of both salicylic acid application methods were required to maintain a good water use efficiency in salt-treated plants. Our work demonstrates that both procedure of SA application have positive impact on salt resistance but that the underlying properties sustaining these adaptations differ between the two modes of salicylic acid application.

Background and aim Cichorium intybus is a biennal species storing inulin in taproot during the first year and flowering after vernalization. Heat impact on sugar distribution and inulin yield remains poorly documented. Methods Plants were cultivated under ambient or high (ambient+5 °C) temperature for 27 weeks. Plants were monthly harvested and morphological parameters, bolting rate, sugar translocation, soluble sugars and inulin content were determined.Results Heat reduced shoot and root growth and unexpectedly induced precocious bolting. It increased fructose contents in roots and leaves, increased root myo-inositol and reduced leaf sucrose content. At harvest, inulin content was higher in heat-treated than in control roots but total amount of inulin produced per plant was lower. Heat inhibited sugar translocation from leaves to secondary roots. Total soluble sugar content was lower in leaves but higher in roots of bolted plants compared to non-bolted ones. Bolting induced an increase in the mean degree of polymerization of inulin and root lignification. Conclusion High temperatures impaired inulin production as a result of root growth inhibition and reduced sugar translocation from the leaves to the roots. Heat induced precocious bolting on non-vernalized plants. Bolting reinforced root growth inhibition and thus inulin yield decrease.

Arsenic (As) is a toxic metalloid ubiquitously present in the environment and which threaten human health in numerous areas in the world. Atriplex atacamensis, is an endemic xero-halophyte plant species of Northern Chile found close to the Atacama Desert where arsenic contamination frequently occurs mainly due to mine waste and volcanic sediments. This region is also characterized by high salinity. The global aim of our study is to analyze the physiological behavior of A. atacamensis exposed to toxic doses of As in order to quantify its level of resistance and to decipher its mechanisms of tolerance to this toxic element. A field analysis confirmed the presence of high As doses in the soil and in the water collected from Rio Loa in North Chile. Experiments were then performed in nutrient solution on seedlings issued from seeds collected on mature plants and confirmed that young seedlings were able to cope with high As doses (up to 1000 µM). Both As(V) and As(III) were detected within plant tissues. Addition of NaCl increased As translocation from the root to the shoot and the proportion of endogenous As(V) comparatively to As(III). In contrast, phosphate deficiency reduced As translocation. Arsenic did not induce any water stress at the plant level and As was not excreted by the leaf trichomes. Beside osmoprotectant (proline, glycinebetaine), polyamines may also afford protection in response to As toxicity. External As(III) was more toxic than As(V) at both the whole plant and cell levels. As content in the roots (up 5000 µg.g-1) were at least 10 times higher than in old leaves and approximately 50 times higher than in young leaves. The root As accumulation and cell wall sequestration appeared to be efficient strategies for As resistance. Oversynthesis of phytochelatin plays a key role in plant protection against accumulated As. Atriplex atacamensis is considered as a promising tool for the phytomanagement of As-contaminated areas in arid regions., (SC - Sciences) -- UCL, 2018

Tomato (Solanum lycopersicum) is the second most highly produced vegetable crop worldwide and unfavourable environmental conditions such as drought significantly limit plant growth and productivity in this species. Although important sources of variation for drought tolerance exist in wild relatives, the mechanisms and the key genes controlling tolerance in tomato are little known. The elucidation of tolerance strategies in wild relatives living in dry zones is a powerful approach to understand local adaptations for potential crop improvement. Solanum chilense is able to cope with harsh environment in its area of origin and could represent an abundance of genetic diversity for tomato improvement. However, physiological basis of drought tolerance in Solanum chilense has received only minor attention until now. The aim of our research is to study the changes mediated by drought acclimation in Solanum chilense in order to highlight morphological and physiological basis of drought tolerance in this species during vegetative and reproductive stages. Six populations of Solanum chilense belonging to different phylogenetic groups and growing in contrasted habitats were compared. Plants were grown under greenhouse conditions in Belgium and for each population, half of the plants were regularly watered and the other half were watered each two weeks. The number of leaves produced were overall 25% lower for water-stressed plants compared with control plants and differed among population. The flowering time was also highly divergent among populations. Most physiological parameters (chlorophyll fluorescence, gaz exchanges, chlorophyll content, stomatal conductance,…) differed according to the water treatment. For physiological parameters, the main inter-population differences were observed between a coastal population in Peru and a population located in the Acatama desert. Our first results suggest local and population adaptation to drought in Solanum chilense.

European pear (Pyrus communis) requires insect pollination among compatible cultivars for fruit production. However, most commercial orchards have a limited number of cultivars arranged in monotypic blocks or rows. This can result in insufficient inter-cultivar pollination. We hypothesise that limitations in pollen transfer among cultivars could be explained by both insect behaviour and orchard design. We compared insect activity and pollination efficiency in two European pear cultivars, in orchards with different designs: (i) cultivars alternated in the same row or (ii) cultivars in separate rows. To assess limitations in pollen transfer, we also compared hand pollination with compatible pollen versus open pollination by insects. Insect visitors mainly foraged on neighbouring trees within a row, with few movements across rows (1%). Honey bees (Apis mellifera) and bumble bees (Bombus terrestris) visited significantly more flowers per tree (8.5 vs. 3) and more trees (2.1 vs. 1.3) than solitary bees (Andrena spp.) and hoverflies. Insect visitors deposited large amounts of pollen (∼500 pollen grains) on flower stigmas regardless of the insect type. Cultivar placement affected inter-cultivar pollination; less incompatibility signs were observed when cultivars alternated in the same row (5%) than when cultivars were in separate rows (38%). We observed limitations in pollen transfer as open pollination resulted in significant reduced fruit set, compared with hand pollination, in ‘Conférence’ (21% vs. 30.7%) and ‘Doyenné du Comice’ (7.2% vs. 16.8%). The foraging behaviour of the insects limited thus inter-cultivar pollen transfer in the orchards with cultivars in separate rows. Cultivars used for pollination (pollinizers) should be planted in the same rows as the main cultivar to increase inter-cultivar pollination.

Sprouted seeds of many plant species represent a kind of vegetable often produced at home. Their consumption have been increasing in recent years because they are considered a healthy food for their high content in bioactive compounds and antioxidants [1]. Many Brassica species are used for sprouting since they are known to contain vitamins (i.e., ascorbic acid), minerals, phenolics and glucosinolates (GLS), whichmay have health-promoting effects like antioxidant and anticancer activity [2–4]. On the other hand, most Brassica species, rapeseed included, may contain erucic acid (EA), which may cause heart lesions [5], and progoitrin, a glucosinolate having goitrogenic effects [6]. However, the rapeseed cultivars labelled as 00 (double zero) have close to nil EA and GLS contents and can thus be used with no restrictions for human feeding [7], while maintaining a high supply of phenolics. Phenolic compounds are important components of many fruits and vegetables where they contribute to flavor, color, and sensory properties and may have important effects on the oxidative stability. The phenolic compounds are divided into different classes: flavonoids (i.e., anthocyanins, flavan-3-ols, flavones, flavanones, flavonols, etc) and non-flavonoids (phenolic acids, stilbens, lignans).

Salinity is a major environmental stress limiting tomato production in arid and semi-arid conditions due to irrigation. Although cultivated tomato is quite sensitive to salinity, several of its wild relatives exhibit halophyte properties. Solanum chilense is spontaneously present in salt-affected areas of North Chile but the physiological basis of its salt-resistance has received only minor attention so far. Comparing the behaviour of the cultivated glycophyte Solanum lycopersicum with its wild-relative halophyte Solanum chilense will help to unravel the strategies of plant response to salt stress. A holistic approach was used to compare the hormonal profile of Solanum lycopersicum and Solanum chilense plants subjected to 125 mM NaCl for 7 days. Solanum chilense displayed a contrasting behaviour comparatively to Solanum lycopersicum, not only for plant growth, mineral nutrition, osmotic adjustment but also regarding phytohormonal profiling. Salinity improved plant growth in Solanum chilense. This species behaved as an includer species accumulating higher concentration of Na+ in the shoot than Solanum lycopersicum, which exhibited an excluder behaviour. Moreover, the capacity to use inorganic ions as osmotica improved salt resistance in Solanum chilense and phytohormones could be involved in this process. Most hormonal compounds were higher in Solanum chilense than in Solanum lycopersicum. Interestingly, salicylic acid, ethylene and cytokinins were positively correlated with osmotic potential in Solanum chilense under salinity while these hormones were negatively correlated with osmotic adjustment in Solanum lycopersicum. This study revealed that both species respond differently to salinity and that involvement of phytohormones in this resistance was species specific.

Several bee species are experiencing significant population declines. As bees exclusively rely on pollen for development and survival, such declines could be partly related to changes in their host plant abundance and quality. Here, we investigate whether generalist bumblebee species, with stable population trends over the past years, adapted their diets in response to changes in the distribution and chemical quality of their pollen resources. We selected five common species of bumblebee in NW Europe for which we had a precise description of their pollen diet through two time periods (‘prior to 1950’ and ‘2004–2005’). For each species, we assessed whether the shift in their pollen diet was related with the changes in the suitable area of their pollen resources. Concurrently, we evaluated whether the chemical composition of pollen resources changed over time and experimentally tested the impact of new major pollen species on the development of B. terrestris microcolonies. Only one species (i.e. B. lapidarius) significantly included more pollen from resources whose suitable area expanded. This opportunist pattern could partly explain the expansion of B. lapidarius in Europe. Regarding the temporal variation in the chemical composition of the pollen diet, total and essential amino acid contents did not differ significantly between the two time periods while we found significant differences among plant species. This result is driven by the great diversity of resources used by bumblebee species in both periods. Our bioassay revealed that the shift to new major pollen resources allowed microcolonies to develop, bringing new evidence on the opportunist feature of bumblebee in their diets. Overall, this study shows that the response to pollen resource drift varies among closely related pollinators, and a species-rich plant community ensures generalist species to select a nutrient-rich pollen diet., FLWIN, info:eu-repo/semantics/published

Several bee species are experiencing significant population declines. As bees exclusively rely on pollen for development and survival, such declines could be partly related to changes in their host plant abundance and quality. Here, we investigate whether generalist bumblebee species, with stable population trends over the past years, adapted their diets in response to changes in the distribution and chemical quality of their pollen resources. We selected five common species of bumblebee in NW Europe for which we had a precise description of their pollen diet through two time periods (‘prior to 1950’ and ‘2004–2005’). For each species, we assessed whether the shift in their pollen diet was related with the changes in the suitable area of their pollen resources. Concurrently, we evaluated whether the chemical composition of pollen resources changed over time and experimentally tested the impact of new major pollen species on the development of B. terrestris microcolonies. Only one species (i.e. B. lapidarius) significantly included more pollen from resources whose suitable area expanded. This opportunist pattern could partly explain the expansion of B. lapidarius in Europe. Regarding the temporal variation in the chemical composition of the pollen diet, total and essential amino acid contents did not differ significantly between the two time periods while we found significant differences among plant species. This result is driven by the great diversity of resources used by bumblebee species in both periods. Our bioassay revealed that the shift to new major pollen resources allowed microcolonies to develop, bringing new evidence on the opportunist feature of bumblebee in their diets. Overall, this study shows that the response to pollen resource drift varies among closely related pollinators, and a species-rich plant community ensures generalist species to select a nutrient-rich pollen diet., SCOPUS: ar.j, FLWIN, info:eu-repo/semantics/published

Bumblebees are the predominant wild pollinators for many plant species in temperate regions. A bumblebee colony requires pollen and nectar throughout its lifetime, but degraded and fragmented habitats may have gaps in the temporal and spatial continuity of floral resources.Heathlands are open biotopes that provide favourable habitat for bumblebees like Bombus jonellus, a declining species in Belgium. In heathlands, ericaceous species are the main plants that provide pollen and nectar for bumblebees. Although the nectar composition of ericaceous species has been previously studied, data on pollen composition remain scarce.We examined bumblebee diets (composition of their pollen loads) in Belgian heathlands over the course of a colony lifetime to assess the fidelity of bumblebees for ericaceous species. We compared nutritional values by investigating the chemical composition (amino acids, polypeptides and sterols) of the pollen of the ericaceous and dominant non-ericaceous species present in pollen loads. No relationship was detected between the abundance of a particular plant species in bumblebee loads and its pollen composition.The successive flowering periods and the nutritional quality of pollen of ericaceous species offer valuable resources for bumblebees. Ericaceous species represent a large part of bumblebee diets in heathlands, especially in early spring and late summer when the diversity of other flowering species was low.Bumblebee pollen loads also contained non-ericaceous flowering species that grow outside heathlands. Thus, land planning must incorporate conservation strategies for the different elements of the landscape matrix, including heathlands, peatlands, meadows and margins., SCOPUS: ar.j, FLWIN, info:eu-repo/semantics/published

Floral organogenesis requires coordinated interactions between genes specifying floral organ identity and those regulating growth and size of developing floral organs. With the aim to isolate regulatory genes linking both developmental processes (i.e., floral organ identity and growth) in the tomato model species, a novel mutant altered in the formation of floral organs was further characterized. Under normal growth conditions, floral organ primordia of mutant plants were correctly initiated, however, they were unable to complete their development impeding the formation of mature and fertile flowers. Thus, the growth of floral buds was blocked at an early stage of development; therefore, we named this mutant as unfinished flower development (ufd). Genetic analysis performed in a segregating population of 543 plants showed that the abnormal phenotype was controlled by a single recessive mutation. Global gene expression analysis confirmed that several MADS-box genes regulating floral identity as well as other genes participating in cell division and different hormonal pathways were affected in their expression patterns in ufd mutant plants. Moreover, ufd mutant inflorescences showed higher hormone contents, particularly ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and strigol compared to wild type. Such results indicate that UFD may have a key function as positive regulator of the development of floral primordia once they have been initiated in the four floral whorls. This function should be performed by affecting the expression of floral organ identity and growth genes, together with hormonal signaling pathways.