The effects of olive wastewater on the early growth of fababean and Rhizobium nodulation

Olive processing waste (OPW) is a by-product of olive oil production. Most of the studies about olive processing waste are carried-out in cotton, sunflower, wheat etc. However, there is little research performed on the effects of OPW on legumes. Therefore, the effect of OPW on growth of fababean and Rhizobium bacteria was studied in this research. It was used in doses of 0 (control), 18, 30 and 42 grams per pot, which is equivalent to doses of 3, 5 and 7 kg m-2. Increasing concentration of OPW improved the root fresh weight, nodule area, nodule diameter, root nodules scale value and the number of Rhizobium in one gram nodules. The results showed that the optimum OPW dose was 30 g pot-1 according to plant growth, nodules and Rhizobium. It was concluded that the OPW concentrations of 3% and it’s below can be used for fababean growing.

Widespread variation in NSP1, a gene involved in rhizobium nodulation, across species of Acmispon (Fabaceae) from diverse habitats

GRAS proteins comprise a large family of genes that play important roles in regulating gene expression throughout all stages of plant development. The physiological and phylogenetic breadth of GRAS proteins known among model species suggests that they may be useful as molecular genetic markers in non-model species. For example, GRAS genes involved in regulating legume–rhizobium symbioses may reveal ecological and evolutionary variation in these relationships. In this study, we collected sequences from Nodulation Signaling Protein 1 (NSP1), a gene involved in the development of an infection thread through which rhizobia enter roots, in five species of Acmispon Raf. to quantify genetic variation within and between closely related species and to compare sequence divergence in NSP1 from Acmispon with other legumes. We found a high degree of similarity of NSP1 from Acmispon with homologues in other angiosperms. Thirty-two unique alleles were identified within Acmispon, and much of this variation reflects spatial and geographic variation of sampled populations. There was no evidence of selection at the molecular level. Given the strong genetic structure found among Acmispon species, especially in a microsatellite region of the N-terminus, and the existence of homologues, NSP1 could be a useful phylogenetic marker across angiosperms.

Efecto de rastrojos de malezas y herbicidas preemergentes en el control de malezas en frijol.

In the Fabio Baudrit Experiment Station, Alajuela, Costa Rica from September of 1998 to February of 1999, the effects of stubbles from Ixophorus unisetus, Digitaria spp., Cynodon dactylon and Rottboellia cochinchinensis were evaluated to judge the efficacy of the herbicide pendimetalin, alachlor and imazetapir, Rhizobium nodulation and the growth of bean. It was found that the presence of stubbles on the surface of the soil (4.5 t dry matter/ha) was not effective in reducing the growth of weeds in bean crop under no tillage management. The efficacy of the herbicides pendimetalin, imazetapir and alachlor was not affected by the presence of stubbles on the surface of the soil. The stubbles of Ixophorus unisetus negatively affected the growth and production of bean. Stubbles of Digitaria spp.and Cynodon dactylon had a positive effect on the crop.

Microarray-Based Detection and Typing of the Rhizobium Nodulation Gene nodC: Potential of DNA Arrays To Diagnose Biological Functions of Interest

ABSTRACT Environmental screening of bacteria for the presence of genes of interest is a challenging problem, due to the high variability of the nucleotide sequence of a given gene between species. Here, we tackle this general issue using a particularly well-suited model system that consists of the nodulation gene nodC, which is shared by phylogenetically distant rhizobia. 41mer and 50mer oligonucleotides featuring the nucleotide diversity of two highly conserved regions of the NodC protein were spotted on glass slides and cross hybridized with the radioactive-labeled target genomic DNA under low-stringency conditions. Statistical analysis of the hybridization patterns allowed the detection of known, as well as new, nodC sequences and classified the rhizobial strains accordingly. The microarray was successfully used to type the nodC gene directly from legume nodules, thus eliminating the need of cultivation of the endosymbiont. This approach could be extended to a panel of diagnostic genes and constitute a powerful tool for studying the distribution of genes of interest in the environment, as well as for bacteria identification.