Study of root para-nodules formation in wheat (Triticum durum) inoculated with Frankia strain CcI3 and treated with 2, 4-dichlorophenoxyacetate (2, 4-D)

Frankia strains can induce N2-fixing root nodules on certain non-leguminous plants. It is known that exogenous application of 2,4-dichlorophenoxyacetate (2,4-D) affects root morphology. In this work, wheat roots were treated with 2,4-D and inoculated with the actinomycete Frankia. Wheat plants grew in a growth chamber with hydroponic medium. Binocular observation revealed that para-nodules were formed when wheat roots were inoculated with Frankia and the root length was enhanced. When the inoculation with Frankia was combined to 2,4-D treatment, the para-nodules formed were bigger and more numerous, while the root length was shortened.Keywords: Frankia, wheat, roots, para-nodules, 2,4-dichlorophenoxyacetateAfrican Journal of Biotechnology Vol. 12(35), pp. 5427-543

Pigments photosynthétiques, enzymes antioxydantes et potentiel osmotique foliaire de dix génotypes de blé dur (Triticum durum) : effet du stress hydrique

L’ajustement osmotique, les pigments photosynthétiques et les changements d’activités des antioxydants enzymatiques ont été évalués chez dix génotypes de blé dur (Triticum durum) soumis à des conditions de stress hydrique. Les plantules de blé ont germé en hydroponie, en chambre de culture. Le stress hydrique a été appliqué aux quatrième et cinquième stades de la feuille par l’ajout d’une solution de polyéthylène glycol (PEG 6000) (-0,49 MPa). Le potentiel osmotique ainsi que la teneur en chlorophylle totale (Chl a+b) et en caroténoïdes (Car) ont été déterminés. Des analyses électrophorétiques ont été effectuées pour trois enzymes antioxydantes, soit la superoxyde dismutase (SOD), la guaïacol peroxydase (GPOX) et la catalase (CAT), en utilisant l’électrophorèse sur gel de polyacrylamide (PAGE) en conditions natives. Les résultats obtenus montrent une réduction du potentiel osmotique foliaire et une diminution de Chl a+b et Car sous l’effet du stress hydrique. Toutefois, il existe des différences significatives entre les génotypes étudiés en réponse au traitement imposé. PAGE a permis de montrer une augmentation dans l’intensité des enzymes étudiées et une apparition d’isoformes supplémentaires, dont une de CAT et trois de SOD, en conditions de stress. Ces différences dans les réponses au stress hydrique pourraient être des indices utiles et fiables pour la sélection de génotypes tolérants de blé dur.Osmotic adjustment, photosynthetic pigments and changes in antioxidant enzyme activities were evaluated in ten durum wheat (Triticum durum) genotypes under water stress conditions. The wheat seedlings germinated in hydroponic conditions in a growth chamber. Water deficit was performed at the fourth and fifth leaf stages using a polyethylene glycol (PEG 6000) solution (-0.49 MPa). Osmotic potential as well as total chlorophyll (Chl a+b) and carotenoid (Car) contents were investigated. Electrophoretic analyses were performed for three antioxidant enzymes: superoxide dismutase (SOD), guaiacol peroxidase (GPOX) and catalase (CAT) using native polyacrylamide gel electrophoresis (PAGE). The results obtained show a reduction in leaf osmotic potential and a decrease in Chl a+b and Car contents under water stress conditions. However, there are significant differences between the genotypes studied in their response to the treatment. PAGE showed an increased intensity in the enzymes studied and the appearance of additional isoforms, including one CAT and three SOD, under stress conditions. These differences in water stress response could be useful and reliable indices for the selection of tolerant durum wheat genotypes

Impact of Two Strains of <i>Rhizobium leguminosarum</i> on the Adaptation to Terminal Water Deficit of Two Cultivars <i>Vicia faba</i>

Drought stress has become one of the most uncontrolled and unpredictable constraints on crop production. The purpose of this study was to evaluate the impacts of two different Rhizobium leguminosarum strains on terminal drought tolerance induction in two faba bean genotypes cultivated in Algeria, Aquadulce and Maltais. To this end, we measured physiological parameters—osmoprotectants accumulation, oxidative stress markers and enzyme activities—to assess the effect of R. leguminosarum inoculation on V. faba under terminal water deficiency conditions in greenhouse trials. Upregulation of anti-oxidative mechanisms and production of compatible solutes were found differentially activated according to Rhizobium strain. Drought stress resilience of the Maltais variety was improved using the local Rhizobium strain OL13 compared to the common strain 3841. Symbiosis with OL13 strain leads in particular to a much better production of proline and soluble sugar in nodules but also in roots and leaves of Maltais plant. Even if additional work is still necessary to decipher the mechanism by which a Rhizobium strain can affect the accumulation of osmoprotectants or cellular redox status in all the plants, inoculation with selected Rhizobium could be a promising strategy for improving water stress management in the forthcoming era of climate change