Mineral Composition of the Palms Leaflets of the Date Palm

This work was realized in two Tunisian continental palm plantations (Deglet Nour). It aimed at studying the mineral composition of date palms' leaflets to base recommendations for foliar diagnosis on.

At pollination, three palms per palm tree were taken at the median position, the lower green palm, and the last open palm. Leaflets were analyzed on the entire palm split into 4 zones. A broad variation of the palm portions leaflets' mineral composition is shown. The median zone leaflet nitrogen (N) and magnesium (Mg) contents were the highest for all of the palm positions. A similar nitrogen and magnesium determination was noticed along each palm.

The highest calcium (Ca) content was at the base of the youngest palm and at the apex of the oldest palm; phosphorus (P) content was the reverse. The highest potassium (K) content was determined in the base palm leaflets.

For foliar diagnosis, median zone leaflet sampling of median palm at pollination is recommended.     

Characterization of the antigenic and functional domains of a Mycoplasma synoviae variant vlhA gene

The Mycoplasma synoviae haemagglutinin gene, vlhA, encodes two major immunodominant and surface-exposed membrane proteins, MSPB and MSPA. Both products are antigenically variable but only MSPA mediates binding to erythrocytes. Previously we have shown that M. synoviae type strain WVU 1853 could express a variant vlhA gene, referred to as MS2/28.1, with a considerably shorter and divergent MSPA region. A finding that prompted detailed characterization of its antigenic and functional properties. Here we mutagenized each of the six opal codons of the variant MS2/28.1 vlhA member into tryptophan, thus allowing its expression in Escherichia coli as well as its cleavage products, MSPB and MSPA. In addition, we expressed 5 contiguous regions of MS2/28.1 extending from the last part of MSPB to the C-terminus of MSPA. Colony immunostaining with region-specific antisera mapped antigenic variation to the N-terminal half of MS2/28.1 MSPA. No haemagglutinating activity was observed for MSPB, but consistent haemadsorption inhibition was mapped to the region extending from amino acid 325 to 344. Inhibition of both haemagglutination and haemadsorption activities were obtained with sera directed against the C-terminal region of MSPA, with the highest titers (1/320 and 1/160, respectively) being recorded for its last 60 residues. Importantly, antibodies to this region also yielded the highest metabolic inhibition titer of 1/1280. Overall, aside from mapping the functional domains of a M. synoviae highly divergent haemagglutinin gene, this study shows that the C-terminal half of its MSPA region induced the highest titers of antibodies inhibiting haemagglutination, haemadsorption, and metabolism.     

Genotypic lipoxygenase variation in soybean seeds and response to nitrogen nutrition

Decreasing the lipoxygenase content of soybean (Glycine max (L.) Merr.) seed is a prerequisite for its increased use in human foods. These investigations aim to analyse the variation of lipoxygenase contents in relation to the genotype or the nitrogen nutrition of the plant. Four genotypes from a divergent selection for N₂ fixation and the recurrent parent, Weber, were grown in pots, and two Bradyrhizobium japonicum strains (G.49 and SMGS1) were used. Dinitrogen fixation was estimated in situ using the acetylene–reduction assay. The lipoxygenase activity was determined polarographically on seeds taken from plants grown under controlled conditions in the presence or absence of symbiotic N₂ fixation. The large genotypic variation observed for the lipoxygenase contents was enhanced by high N₂ fixation. The variation range of lipoxygenase contents, which was obtained through the combination of the genotypic variation and the N₂ fixation activity, was relatively large with a ratio of 2 on a seed dry–weight basis and a ratio of 2.6 when the total proteins were considered. Decreased lipoxygenase content and increased total protein content can thus be considered in parallel in a genetic context, together with more efficient N₂ fixation.