Effects of physicochemical characteristics and lipid distribution in Algerian Durum Wheat semolinas on the technological quality of Couscous

Corresponding author. E-mail: [email protected] audienceSemolinas milled from 18 Algerian durum wheat cultivars cropped over a two-year period (1999-2000) were used for making couscous. This study was designed to determine the impact of lipid components of durum wheat semolina on the quality of the couscous end product. Lipids were extracted from semolina by various techniques and classified as free or bound lipids, polar or apolar lipids, and glycolipids or phospholipids. An analysis of the overall results clearly revealed that the cooking quality of couscous made from different durum wheat semolinas was partially dependent on the semolina free lipid content and composition. We have shown that this is mainly a varietal characteristic (53.4%). The surface state of the couscous, i.e., caking index (r = -0.48) and cooking loss (r = -0.54), thus depends on the apolar lipid content. Polar lipids, and especially glycolipids, affect couscous texture in terms of firmness (r = 0.57 and r = 0.63, respectively). Polar bound lipids also contribute to couscous swelling (r = 0.53) and caking index (r = 0.70). Moreover, we obtained no correlation between cooked couscous quality and the semolina total lipid content (r < 0.3). We also showed that couscous characteristics were not significantly related to the semolina protein and dry gluten contents or gluten index (r < 0.3)

Are phosphatases involved in the regulation of symbiotic nitrogen fixation under phosphorus deficiency?

In this study, we highlight the differential expression of phosphatases (APases) within the nodules of Phaseolus vulgaris under phosphorus (P) deficiency and address whether this expression might influence the nodule conductance to O2 diffusion and the subsequent respiration that supports N2 fixation in legumes. The identification of APases genes expression was performed with in situ RT-PCR methodology in nodules of two P. vulgaris recombinant inbred lines; RIL115 (Pefficient) and RIL147 (P-inefficient) grown in hydroaeroponic culture under deficient versus sufficient P supply. Our results brought the first evidence that phytase, trehalose 6-P phosphatase and fructose 1,6 bisphosphatase were differentially expressed among nodule tissues of the RIL115 and RIL147 and suggested that the abundance of their transcripts in infected cells at the vicinity of inner cortex and in outer cortex cells to be considered as new mechanism by which nodules acclimate to P deficiency. This overexpression under P deficiency coupled with increased correspondent enzyme activities and improved rhizobial use efficiency, N2 fixation and is therefore likely to play an important role in tolerance to low P availability. It is suggested that APases are involved in the osmoregulation of nodule conductance to O2 diffusion that is associated with the adaptation to environmental constraints of nitrogenase activity in the infected N2 fixing central tissues of the nodule

Is the contrast between nodulated recombinant imbred lines of common bean ([i]Phaseolus vulgari[/i]s L.) linked with available phosphorus in soil? A multi-local field test in Mediterranean conditions

In order to assess the relation between symbiotic nitrogen fixation and soil phosphorus, a multi-local test was proposed to producers of Tizi Ouzou area in Algeria, without modification of their cultivation practises. The nodulation and growth of the cultivar traditionally used by farmers, was studied with seven potentially interesting recombinant inbred lines selected among the crossing of BAT 477 and DOR 364 in addition. The sampling was performed at the flowering stage. The major finding in this work is that nodule biomasss were positively correlated with Olsen-P. Although, the curvilinear regressions of nodule biomass and shoot biomass as a function of Olsen-P suggest the existence of 2 ranges of Olsen-P among studied sites that are separated by critical P values. It is concluded that the low nodulation of the RILs was partly compensated by increasing the efficiency in use of the rhizobial symbiosis

Variability of N2 fixation in cowpea under phosphorus deficiency is related to phosphorus use efficiency

Low availability of phosphorus (P) is a major constraint to legumeproduction, and efforts are being made to identify legume genotypeswith tolerance to low P and greater P use efficiency (PUE). Cowpea(Vigna unguiculata L.) genotypes vary in their adaptation to low-Psoils. In order to investigate to what extent this variation may berelated to PUE for symbiotic nitrogen fixation (SNF), five genotypes,Adrar, El Kala, Djenet, Tizi Ouzou and Bejaia, were grown in semihydroponicculture with sufficient versus deficient P supply. At theflowering stage, the biomass of plants and nodules and their Pcontents was determined after measuring the quantity of N2 fixed.The results showed that nodule and shoot biomass were less when Pwas deficient. The genotypes that presented the maximum growthduring the experiment presented a high efficiency in use of therhizobial symbiosis calculated as the slope of plant biomass regressionas a function of nodulation. Under P-deficiency, efficiency in use of Pfor SNF was significantly increased in the genotypes El Kala, Djenetand Adrar and accompanied with an increase of the efficiency in useof the rhizobial symbiosis. Hence the large differences show thattraits for more P uptake-efficient plants exist in the tested cowpeagenotypes. This opens the possibility to breed for more P uptakeefficientvarieties as a way to bring more sparingly soluble soil P intocycling in crop production and obtain capitalisation of soil P reserves

Adaptation de la symbiose rhizobienne chez le haricot à la déficience en phosphore (détermination de la réponse de la plante en terme d'échanges gazeux et de flux minéraux échangés avec la rhizosphère)

La déficience en phosphore est l un des facteurs limitant la production de légumineuses à graines, dont le haricot (Phaseolus vulgaris). La diversité génétique de cette espèce en Amérique latine a permis d'identifier avec le CIAT, des lignées recombinantes du croisement de DOR364 et BAT477 à fort pouvoir fixateur d'azote (FSN) et à forte efficacité d'utilisation de phosphore (EUP). Les résultats obtenus au cours de ce travail nous ont permis de répondre à notre objectif principal de thèse qui consistait à vérifier la pertinence des critères d'adaptation de la fixation symbiotique de l'azote chez le haricot à la disponibilité de P que nous avons déterminé. Nous avons démontré, d'une part, en milieu hydroaéroponique, que les racines nodulées du haricot, excrètent dans leur rhizosphère une quantité de H+ qui est corrélée à la perméabilité nodulaire. Ce qui laisse penser qu'une part d'H+ excrétée par les racines nodulées est liée à la fixation symbiotique de N2. D'autre part, nous avons démontré que sous déficience en P les lignées tolérantes acidifient plus leur rhizosphère que les sensibles. En multisites les facteurs les plus déterminants de la hiérarchisation des sites sont N-total et P-total. Deux groupes de lignées se distinguent, les tolérantes versus les sensibles à la faible fertilité des sols en P. La lignée locale se distingue des groupes précédents. Elle est capable de croître dans différents sols, notamment les contraignants avec une grande capacité à noduler, par conséquent, à compenser la déficience en N. Nous avons également pu démontrer que les biomasses nodulaire et aérienne sont corrélées au P Olsen du solPhosphorus deficiency is one of the limiting factor for grain legume production like bean (Phaseolus vulgaris). The results obtained during this work enabled us to confirm our main aim of this work which is checking the relevance of the criteria of adaptation of the symbiotic nitrogen fixation of bean to P availability. We showed, in controlled conditions that the nodulated roots of bean, release in their rhizosphere a quantity of H+ which is correlated with the nodul permeability. What lets think that a share of H+ released is related to the symbiotic N2 fixing. In addition, we showed that under P deficiency the tolerant lines acidify more their rhizosphere that the sensitive ones. Into multisite trial the most determining factors of the hierarchisation of the sites are total-N and total-P. Two groups of lines are distinguished: tolerant versus sensitive to P deficiency. The local farmer line is distinguished from the studied lines. It is able to grow in various soil fertility, in particular the constraining soils. ones with a great capacity with noduler, consequently, to compensate for deficiency in NR. We also could show that shoot and nodule biomass are correlated with the Olsen-P Olsen of the soilMONTPELLIER-SupAgro La Gaillarde (341722306) / SudocSudocFranceF

P-deficiency increases phytase activity and O2 uptake per N2 reduced in [i]Phaseolus vulgaris[/i] L.

To understand the mechanisms used by legumes to improve their PUE for SNF under P-deficiency, six RILs of P. vulgaris were inoculated with Rhizobium tropici CIAT899, and grown at two levels of P supply. Our results have revealed that the increases of APases and phytases activities under P-deficiency varied among RILs of P. vulgaris and were positively correlated with increases both of the nodule conductance to O2 diffusion and the EURS. This may represent an adaptive mechanism for N2-fixing legumes to respond to low P availability, by increasing the utilization and the uptake of P for SNF

Discrimination against 15N among recombinant inbred lines of [i]Phaseolus vulgaris[/i] L. contrasting in phosphorus use efficiency for nitrogen fixation

Although isotopic discrimination processes during nitrogen (N) transformations influence the outcome of 15N based quantification of N2 fixation in legumes, little attention has been given to the effects of genotypic variability and environmental constraints such as phosphorus (P) deficiency, on discrimination against 15N during N2 fixation. In this study, six Phaseolus vulgaris recombinant inbred lines (RILs), i.e. RILs 115, 104, 34 (P deficiency tolerant) and 147, 83, 70 (P deficiency sensitive), were inoculated with Rhizobium tropici CIAT899, and hydroaeroponically grown with P-sufficient (250 μmol P plant−1 week−1) versus P-deficient (75 μmol P plant−1 week−1) supply. Two harvests were done at 15 (before nodule functioning) and 42 (flowering stage) days after transplanting. Nodulation, plant biomass, P and N contents, and the ratios of 15N over total N content (15N/Nt) for shoots, roots and nodules were determined. The results showed lower 15N/Nt in shoots than in roots, both being much lower than in nodules. P deficiency caused a larger decrease in 15N/Nt in shoots (−0.18%) than in nodules (−0.11%) for all of the genotypes, and the decrease in shoots was greatest for RILs 34 (−0.33%) and 104 (−0.25%). Nodule 15N/Nt was significantly related to both the quantity of N2 fixed (R2 = 0.96***) and the P content of nodules (R2 = 0.66*). We conclude that the discrimination against 15N in the legume N2-fixing symbiosis of common bean with R. tropici CIAT899 is affected by P nutrition and plant genotype, and that the 15N/Nt in nodules may be used to screen for genotypic variation in P use efficiency for N2 fixation

Advantage of intercropping maize [i](Zea mays[/i] L.) and common bean ([i]Phaseolus vulgaris[/i] L.) on yield and nitrogen uptake in Northeast Algeria

Legume-cereal intercropping, is a productive and sustainable system by its nutrients facilitation, and its effect to increase N uptake for intercropped cereal; via symbiotic nitrogen (N2) fixation. The aim of this work was to test effect of maize-common bean intercropping system on the growth, nodulation, yield and N uptake. This field study was conducted in Setif region, North of Algeria. The study was carried out using intercropping system with one Cvs of common bean and one maize CV which were cultivated locally by the farmers of the region. The results showed a positive correlation between the nodule and shoot dry weight, this correlation is more significant in the intercropping than sole crop. However intercropping increase maize yield by more than 12.5%, the N concentration in shoot (20.8%) and seed (33.5%); as consequence N concentration in rhizosphere soil was significantly enhanced for intercropped common bean. Intercropping advantage was observed especially; at low concentration of nitrogen in indigenous soil. We conclude that nitrogen symbiotic fixation was contributes to facilitate N uptake for intercropped maize