Philippe Etienne

• MCF HDR
• Professor (Assistant) at University of Caen Normandy

The association of legumes with other non-legume plants, such as Brassica napus L., has been reported as an agro-ecological alternative for reducing the nitrogen (N) inputs required for B. napus growth, thanks in particular to the transfer of N compounds from the legume to B. napus. Moreover, recent studies have evidenced that silicon (Si) supply c...

Introduction Numerous studies have reported the beneficial effects of silicon (Si) in alleviating biotic or abiotic stresses in many plant species. However, the role of Si in Fabaceae facing environmental stress is poorly documented. The aim of this study is to investigate the effect of Si on physiological traits and nodulation efficiency in Trifol...

Root senescence remains largely unexplored. In this study, the time-course of the morphological, metabolic, and proteomic changes occurring with root aging were investigated, providing a comprehensive picture of the root senescence program. We found novel senescence-related markers for the characterization of the developmental stage of root tissues...

Background and Aims Numerous studies have reported the beneficial effects of silicon (Si) in alleviating biotic or abiotic stresses in many plant species. However, the role of Si in Fabaceae facing environmental stress is poorly documented. The aim of this study is to investigate the effect of Si on physiological traits and nodulation efficiency in...

In many crops species, sulfur (S) deprivation negatively affects growth, seed yield quality and plant health. Furthermore, silicon (Si) is known to alleviate many nutritional stresses but the effects of Si supply on plants subjected to S deficiency remain unclear and poorly documented. The objective of this study was to evaluate whether Si supply w...

One of the main limiting factors of plant yield is drought, and while the physiological responses to this environmental stress have been broadly described, research addressing its impact on mineral nutrition is scarce. Brassica napus and Triticum aestivum were subjected to moderate or severe water deficit, and their responses to drought were assess...

Silicon (Si) is known to alleviate many nutritional stresses. However, in Brassica napus, which is a highly S-demanding species, the Si effect on S deficiency remains undocumented. The aim of this study was to assess whether Si alleviates the negative effects of S deficiency on Brassica napus and modulates root sulfate uptake capacity and S accumul...

While it is generally acknowledged that drought is one of the main abiotic factors affecting plant growth, how mineral nutrition is specifically and negatively affected by water deficit has received very little attention, other than being analyzed as a consequence of reduced growth. Therefore, Brassica napus plants were subjected to a gradual onset...

While the benefit of silicon (Si) is often reported in cultivated plants, and particularly in those experiencing stress conditions, the underlying mechanisms are poorly described and controversial [1]. For a long time the mechanical role of Si in the cell wall has been considered as the main explanation for its beneficial effects in alleviating pla...

The early and specific diagnosis of a macronutrient deficiency is challenging when seeking to better manage fertilizer inputs in the context of sustainable agriculture. Consequently, this study explored the potential for transcriptomic and metabolomic analysis of Brassica napus roots to characterize the effects of six individual macronutrient depri...

The specific variation in the functional ionome was studied in Brassica napus and Triticum aestivum plants subjected to micronutrient or beneficial mineral nutrient deprivation. Effects of these deprivations were compared to those of macronutrient deprivation. In order to identify early events, plants were harvested after 22 days, i.e., before any...

The composition of the functional ionome was studied in Brassica napus and Triticum aestivum with respect to the response of 20 elements under macronutrient deprivation. Analysis of relative root contents showed that some nutrients, such as Fe, Ni, Cu, Na, V, and Co, were largely sequestered in roots. After 10 days of deprivation of each one of the...

The composition of the functional ionome was studied in Brassica napus and Triticum aestivum with respect to the response of 20 elements under macronutrient deprivation. Analysis of relative root contents showed that some nutrients, such as Fe, Ni, Cu, Na, V, and Co, were largely sequestered in roots. After 10 days of deprivation of each one of the...

While the benefit of silicon (Si) is often reported in cultivated plants, and particularly in those experiencing stress conditions, the underlying mechanisms are poorly described and controversial [1]. For a long time the mechanical role of Si in the cell wall has been considered as the main explanation for its beneficial effects in alleviating pla...

Main conclusion Specific combinations of physiological and molecular parameters associated with N and S remobilization measured at the onset of flowering were predictive of final crop performances in oilseed rape. Abstract Oilseed rape (Brassica napus L.) is a high nitrogen (N) and sulphur (S) demanding crop. Nitrogen- and S-remobilization process...

To limit the environmental pollution associated with intensive nitrogen (N) fertilizer usage, alternative cultural practices must be considered for crops requiring high N inputs such as rapeseed. In this context, the effects of silicon (Si) supply on the agronomic performance of rapeseed cultivated under field conditions with two N fertilizer level...

Main conclusion Modulation of gene expression in roots of Brassica napus by silicon (Si) supply could allow plants to cope with future stresses. The origin of the beneficial effects of silicon (Si) in plants, especially when they are subject to stress, remains poorly understood. Some authors have shown that Si alleviates plant stress and consider t...

Senescence associated gene (SAG) 12, which encodes a cysteine protease is considered to be important in nitrogen (N) allocation to Arabidopsis thaliana seeds. A decrease in the yield and N content of the seeds was observed in the Arabidopsis SAG12 knockout mutants (sag12) relative to the wild type (Col0) under limited nitrogen nutrition. However, l...

SAG12 is the most widely used senescence-associated reference gene for characterizing leaf senescence, and the increase in SAG12 protein during leaf senescence is remarkable. However, the role of this cysteine protease in N remobilization and the leaf senescence process remains unclear. The role of SAG12 has been poorly investigated and the few rep...

Oilseed rape (Brassica napus L.) is a crop requiring high inputs. In a context of sustainable agriculture especially by inputs reduction (including N), it becomes necessary to decipher the physiological mechanisms related to N management in plant. B. napus is characterized by a Low Nitrogen Use Efficiency due to a low Nitrogen Remobilization Effici...

Determination of S status is very important to detect S deficiency and prevent losses of yield and seed quality. The aim of this study was to investigate the possibility of using the ([Cl⁻]+[NO3⁻]+[PO4³⁻]):[SO4²⁻] ratio as an indicator of S nutrition under field conditions in Brassica napus and whether this could be applied to other species. Differ...

Silicon (Si) is the second most abundant element in soil and has several beneficial effects, especially in plants subjected to stress conditions. However, the effect of Si in preventing nitrogen (N) starvation in plants is poorly documented. The aim of this work was to study the effect of a short Si supply duration (7 days) on growth, N uptake, pho...

Effect of Si treatment on SPAD values of mature leaf from Zea mays L. Plants were pretreated with (+Si) or without (-Si) during 1 week and supplied with (+N) or without N (-N) for 21 days (D21). Data are means ± SE (for n = 4). ∗ indicates significant differences between -Si (control) and +Si plants with p < 0.001.

Control quality of total RNAs extracted from mature leaf of N (-N) deprived plants treated with (+Si) or without (-Si). At each time (Day 0, 3, 6, 9, 12, and 21 only for +Si-N), three biological repetitions have been performed. 1 μg of total RNAs were separated on agarose gel (1%) containing 0.5 μg/ml of ethidium bromide (0.5 μg/ml). After separati...

Detail of cytokinin contents [expressed in pg mg-1 dry weight (DW)] in roots and shoots (D0) and in mature leaf and roots (D12) of Brassica napus L. Plants were pretreated with (+Si) or without (-Si) silicon for 1 week and supplied with (-Si+N; +Si+N) or without (-Si-N; +Si-N) N for 12 days (from D0 to D12). Data are means ± SE (for n = 3). ∗ and ∗...

Phenotype of Brassica napus L. plants cultivated without (-Si+N; A) or with silicon (+Si+N; B) during 1 week (D0) and grown without N for 12 days (-Si-N and +Si-N; C,D). The black arrows indicate the mature leaf identified at the beginning of the N starvation (D0) and used to follow the time of course of photosynthetic activity, SPAD measurements s...

Human mineral malnutrition or hidden hunger is considered a global challenge, affecting a large proportion of the world’s population. The reduction in the mineral content of edible plant products is frequently found in cultivars bred for higher yields, and is probably increased by intensive agricultural practices. The filling of grain with macro an...

Rapeseed (Brassica napus L.) is a crop requiring high levels of nitrogen (N) fertilizer for growth and to optimize yield and seed quality. To limit the environmental pollution associated with intensive N fertilizer use, rapeseed–clover (Trititcum incarnatum L.) mixtures were grown in lysimeters under low N conditions (100 kg N ha−1). Considering th...

In this study we tested whether legumes can improve the growth and N and S nutrition of rapeseed in an intercropping system and compared the effect of mixtures on legume N-fixation and soil N-resources. Rapeseed was cultivated in low N conditions in monocrops using one (R) or two plants (RR) per pot and in mixtures with lupine, clover or vetch. The...

Under sulfur (S) deficiency, crosstalk between nutrients induced accumulation of other nutrients , particularly molybdenum (Mo). This disturbed balanced between S and Mo could provide a way to detect S deficiency and therefore avoid losses in yield and seed quality in cultivated species. Under hydroponic conditions, S deprivation was applied to Bra...

Principal component analysis of mineral contents (N, P, K, S, Ca, Mg, Fe, Cu, Zn, Mn, Mo, B and Na) in old leaves of 45 commercial oilseed rape crops. Correlation circles on the factorial planes (A) and (B) projection of the commercial crops (numbers refer to fields/crops given in Fig 6 and SD2). S deficient in red, at risk of S deficiency in orang...

Location of 45 commercial crops in France. Location of 45 commercial crops in Francewith crops classified into three S status groups: S deficient in red, at risk of S deficiency in orange and S sufficient in green. Map of France from Institut Géographique National (IGN, 2016, free of copyrights). (TIF)

Growth conditions used for multispecies experiment. (DOCX)

Composition of the two nutrient solutions used for control and S deprivation during the treatment period of B. napus and Z. mays. Nutrient concentrations are expressed in mM. (PPTX)

S and Mo contents and [Mo]:[S] ratio in young leaves grown under field conditions. (A, B, C) S content (mg g-1 DW), (D, E, F) Mo content (μg g-1 DW) and (G, H, I) the [Mo]:[S] 104 ratio (to simplify reading the [Mo]:[S] ratio is presented with a multiplier factor of 104) in young leaves of B. napus grown under field conditions after (A, D, G) 15 an...

Sulphur (S) is a meso element in plants ranking in need next to after N, P and K. Due to its presence in a wide range of organic compounds (proteins, glucosinolates, glutathione, phytochelatins, vitamins…), it plays a central role in essential functions such as essential amino acids and hormone syntheses, defense mechanisms against (a)biotic stress...

The composition of the ionome is closely linked to a plant’s nutritional status. Under certain deficiencies, cross-talk induces unavoidable accumulation of some nutrients, which upsets the balance and modifies the ionomic composition of plant tissues. Rapeseed plants (Brassica napus L.) grown under controlled conditions were subject to individual n...

Nitrogen (N) transfer is well documented in legume-cereal intercropping but this is less often reported for legume-Brassica intercrops even though Brassica crops require higher levels of N fertilizers. The present study was carried out to quantify N transfer from legumes (Lupinus albus L., Trifolium incarnatum L. or Vicia sativa L.) to rapeseed (Br...

In order to cope with variable mineral nutrient availability, higher plants have developed numerous strategies including the remobilization of nutrients from source to sink tissues. However, such processes remain relatively unknown for magnesium (Mg), which is the third most important cation in plant tissues. Using Mg depletion of Brassica napus, w...

In coming decades, increasing temperatures are expected to impact crop yield and seed quality. To develop low input systems, the effects of temperature and sulfur (S) nutrition in oilseed rape, a high S demanding crop, need to be jointly considered. In this study, we investigated the effects of temperatures [High Temperature (HT), 33°C/day, 19°C/ni...

Winter oilseed rape is characterized by a low N use efficiency related to a weak leaf N remobilization efficiency (NRE) at vegetative stages. By investigating the natural genotypic variability of leaf NRE, our goal was to characterize the relevant physiological traits and the main protease classes associated with an efficient proteolysis and high l...

Oilseed rape is the third largest oleaginous crop in the world but requires high levels of N fertilizer of which only 50% is recovered in seeds. This weak N use efficiency is associated with a low foliar N remobilization, leading to a significant return of N to the soil and a risk of pollution. Contrary to what is observed during senescence in the...

Sulfur (S) nutrition in rapeseed (Brassica napus L.) is a major concern for this high S-demanding crop, especially in the context of soil S oligotrophy. Therefore, predicting plant growth, S plant allocation (between the plant’s compartments) and S pool partitioning (repartition of the mobile-S vs. non-mobile-S fractions) until the onset of reprodu...

Les modèles climatiques actuels prédisent une augmentation des températures en fin de printemps, au moment du remplissage des graines, ce qui pourrait avoir une incidence sur le rendement des cultures de colza et la qualité des graines. Par ailleurs, cette culture a des besoins en soufre (S) importants, en particulier en fin de cycle. Dans un conte...

Identification of early sulphur (S) deficiency indicators is important for species such as Brassica napus, an S-demanding crop in which yield and the nutritional quality of seeds are negatively affected by S deficiency. Because S is mostly stored as SO4 (2-) in leaf cell vacuoles and can be mobilized during S deficiency, this study investigated the...

In coming decades, increasing temperatures are expected to impact crop yield and seed quality. To develop low input systems, the effects of temperature and sulfur (S) nutrition in oilseed rape, a high S demanding crop, need to be jointly considered. In this study, we investigated the effects of temperatures [High Temperature (HT), 33°C/day, 19°C/ni...

Oilseed rape, a crop requiring a high level of nitogen (N) fertilizers, is characterized by low N use efficiency. To identify the limiting factors involved in the N use efficiency of winter oilseed rape, the response to low N supply was investigated at the vegetative stage in 10 genotypes by using long-term pulse-chase (15)N labelling and studying...

Background and aims In the coming decades, increasing spring temperatures are expected to impact crop yield and grain quality. Therefore, in a context of developing low input systems, the effects of temperature and sulfur (S) nutrition in rapeseed which is a high S demanding crop, should be jointly considered. Materials and Methods In this study,...

Our current knowledge about sulfur (S) management by winter oilseed rape to satisfy the S demand of developing seeds is still scarce, particularly in relation to S restriction. Our goals were to determine the physiological processes related to S use efficiency that led to maintain the seed yield and quality when S limitation occurred at the bolting...

The importance of zinc (Zn) has been of little concern in human nutrition despite a strong decrease of this element in crops since the rise of high yielding varieties. For better food quality, Zn biofortification can be used, but will be optimal only if mechanisms governing Zn management are better known. Using Zn deficiency, we are able to demonst...

During the last 40 years, crop breeding has strongly increased yields but has had adverse effects on the content of micronutrients, such as Fe, Mg, Zn and Cu, in edible products despite their sufficient supply in most soils. This suggests that micronutrient remobilization to edible tissues has been negatively selected. As a consequence, the aim of...

Brassica napus L. is an important crop plant, characterised by high nitrogen (N) levels in fallen leaves, leading to a significant restitution of this element to the soil, with important consequences at the economic and environmental levels. It is now well established that the N in fallen leaves is due to weak N remobilisation that is especially re...

Despite its worldwide economic importance for food (oil, meal) and non-food (green energy and chemistry) uses, oilseed rape has a low nitrogen (N) use efficiency (NUE), mainly due to the low N remobilization efficiency (NRE) observed during the vegetative phase when sequential leaf senescence occurs. Assuming that improvement of NRE is the main lev...

Background Oilseed rape (Brassica napus L.) is facing an increasing demand to meet worldwide needs for food and biofuel industries. Its high sulfur (S) requirements have led to consider S limitation before the onset of pod formation as a major concern to maintain high yield and to reach good oil quality (Postma et al., 1999). Therefore, the predic...

Oilseed rape (Brassica napus L.) is a crop with a complex aerial architecture that can cause self-shading leading to a vertical light gradient over the foliage. Mutual shading between neighboring plants at a high sowing density also results in an alteration of photosynthetically active radiation (PAR) absorption by lower leaves. The aim of this stu...

Oilseed rape (Brassica napus L.) is the third worldwide oleaginous crop and requires high level of nitrogen (N) fertilizer which only 50% is found in seeds (Schjoerring et al. 1995) revealing a low N Use Efficiency (NUE). This weak NUE is mainly related to a low leaf N Remobilization Efficiency (NRE). In order to improve NRE, our goals were to (i)...

The main aim of this communication is to discuss the current knowledge about the potential direct mechanisms that are involved in the beneficial action of humic substances on plant development. To this end, we present and discuss here recent results obtained in our laboratory, along with other findings published by other authors. Finally, we propos...

Different strategies, known as crop biofortification, can be used to increase micronutrient concentrations in harvested parts to reduce nutrient deficiencies in the human diet. Apart from fertilization and genetic selection, a more environmentally friendly, less expensive, and more immediate solution could rely on the use of biostimulants derived f...

Despite its high capacity to take up nitrate from soil, winter rapeseed (Brassica napus) is characterized by a low N recovery in seeds. Thus, to maintain yield, rapeseed requires a high fertilization rate. Increasing nutrient use efficiency in rapeseed by addition of a biostimulant could help improve its agroenvironmental balance. The effects of ma...

Supplementary Table 1 List of the differentially expressed genes in shoots and roots of rapeseed after 3 days of AZAL5 supply to the roots

Supplementary Table 2 List of the differentially expressed genes in shoots and roots of rapeseed after 30 days of AZAL5 supply to the roots

The main aim of this communication is to discuss the current knowledge about the potential direct mechanisms that are involved in the beneficial action of humic substances on plant development. To this end, we present and discuss here recent results obtained in our laboratory, along with other findings published by other authors. Finally, we propos...

Winter rapeseed (Brassica napus) is characterized by a low N recovery in seeds and requires high rates of fertilization to maintain yield. Its nutrient use efficiency could be improved by addition of a biostimulant such as humic acids whose physiological effects have been described previously in some plant species. However, to our knowledge, no stu...

List of the differentially expressed genes in shoots and roots of rapeseed after 3 days of HA7 supply to the roots.

List of the differentially expressed genes in shoots and roots of rapeseed after 30 days of HA7 supply to the roots.

Sink strength for S as a major parameter to model vegetative growth in oilseed rape (Brassica napus L.) under contrasting sulfur (S) supplies

Fig. 1: Evolution of the relative allocation of (a) biomass and (b) Q N (rQ N) for the each organ (in % of total biomass and Q Ntot respectively) i.e. fallen leaves, pods, flowers, leaves, stem, secondary roots and taproot for control, SS and DS plants (n=4). Bonferroni's comparison procedure (=0.05). Lower case letters indicate rankings between tr...

N-fertilizer use efficiencies are affected by their chemical composition and suffer from potential N-losses by volatilization. In a field lysimeter experiment, 15N-labelled fertilizers were used to follow N uptake by Brassica napus L. and assess N-losses by volatilization. Use of urea with NBPT (urease inhibitor) showed the best efficiency with the...

Background and aims Urea is the major nitrogen (N) form supplied as fertilizer in agriculture. However, urease, a nickel-dependent enzyme, allows plants to use external or internally generated urea as a nitrogen source. Since a urease inhibitor is frequently applied in conjunction with urea fertilizer, the N-metabolism of plants may be affected. Th...

Oilseed rape is a crop with a complex aerial architecture which is determinant for the absorption of the Photosynthetically Active Radiation (PAR). This study aims to (i) describe the architectural modifications of shoot triggered by shading and (ii) analyze the impacts on biomass production and Nitrogen (N) fluxes and allocation patterns. Two shad...

Winter oilseed rape is sensitive to S limitation, however few studies have clearly assessed the impact of initial S reserves on the remobilization of leaf N-S compounds and senescence dynamics within the leaves in S limited plants. As a consequence, the impacts of high or low initial S reserves on these parameters, further cross-combined with eithe...

In order to optimize nitrogen (N) fertilization and to reduce the environmental impact of oilseed rape without decreasing yield, a clearer understanding of N dynamics inside the plant is crucial. The present investigation therefore aimed to study the effects of different N-application rates on the dynamics of N uptake, partitioning, and remobilizat...

How the remobilization of S and N reserves can meet the needs of seeds of oilseed rape subject to limitation of S fertilization remains largely unclear. Thus, this survey aims to determine the incidence of sulphate restriction [low S (LS)] applied at bolting [growth stage (GS) 32], visible bud (GS 53), and start of pod filling (GS 70) on source–sin...

Because it has a high demand for sulphur (S), oilseed rape is particularly sensitive to S limitation. However, the physiological effects of S limitation remain unclear, especially during the rosette stage. For this reason a study was conducted to determine the effects of mineral S limitation on nitrogen (N) and S uptake and remobilization during ve...

The impact of sulphur limitation on the remobilization of endogenous S compounds during the rosette stage of oilseed rape, and the interactions with N availability on these processes, were examined using a long-term 34SO42− labelling method combined with a study of leaf senescence progression (using SAG12/Cab as a molecular indicator) and gene expr...

Our goal was to identify the leaf proteomic changes which appeared during N remobilisation that were associated or not associated with senescence of oilseed rape in response to contrasting nitrate availability. Remobilisation of N and leaf senescence status were followed using (15)N tracing, patterns of chlorophyll level, total protein content and...