Glyceollin is an Important Component of Soybean Plant Defense Against Phytophthora sojae and Macrophomina phaseolina

The response of soybean transgenic plants, with suppressed synthesis of isoflavones, and nontransgenic plants to two common soybean pathogens, Macrophomina phaseolina and Phytophthora sojae, was studied. Transgenic soybean plants of one line used in this study were previously generated via bombardment of embryogenic cultures with the phenylalanine ammonia lyase, chalcone synthase, and isoflavone synthase (IFS2) genes in sense orientation driven by the cotyledon-preferable lectin promoter (to turn genes on in cotyledons), while plants of another line were newly produced using the IFS2 gene in sense orientation driven by the Cassava vein mosaic virus constitutive promoter (to turn genes on in all plant parts). Nearly complete inhibition of isoflavone synthesis was found in the cotyledons of young seedlings of transgenic plants transformed with the IFS2 transgene driven by the cotyledon-preferable lectin promoter compared with the untransformed control during the 10-day observation period, with the precursors of isoflavone synthesis being accumulated in the cotyledons of transgenic plants. These results indicated that the lectin promoter could be active not only during seed development but also during seed germination. Downregulation of isoflavone synthesis only in the seed or in the whole soybean plant caused a strong inhibition of the pathogen-inducible glyceollin in cotyledons after inoculation with P. sojae, which resulted in increased susceptibility of the cotyledons of both transgenic lines to this pathogen compared with inoculated cotyledons of untransformed plants. When stems were inoculated with M. phaseolina, suppression of glyceollin synthesis was found only in stems of transgenic plants expressing the transgene driven by a constitutive promoter, which developed more severe infection. These results provide further evidence that rapid glyceollin accumulation during infection contributes to the innate soybean defense response.

Mannose-Binding Lectin Promoter Polymorphisms and Gene Variants in Pulmonary Tuberculosis Patients from Cantabria (Northern Spain)

Mannose-binding lectin is a central molecule of the innate immune system. Mannose-binding lectin 2 promoter polymorphisms and structural variants have been associated with susceptibility to tuberculosis. However, contradictory results among different populations have been reported, resulting in no convincing evidence of association between mannose-binding lectin 2 and susceptibility to tuberculosis. For this reason, we conducted a study in a well genetically conserved Spanish population in order to shed light on this controversial association. We analysed the six promoter and structural mannose-binding lectin 2 gene variants in 107 patients with pulmonary tuberculosis and 441 healthy controls. Only D variant and HYPD haplotype were significantly more frequents in controls which would indicate that this allele could confer protection against pulmonary tuberculosis, but this difference disappeared after statistical correction. Neither the rest of alleles nor the haplotypes were significantly associated with the disease. These results would indicate that mannose-binding lectin promoter polymorphisms and gene variants would not be associated with an increased risk to pulmonary tuberculosis. Despite the slight trend of the D allele and HYPD haplotype in conferring protection against pulmonary tuberculosis, susceptibility to this disease would probably be due to other genetic factors, at least in our population.

Spatial and temporal regulation of a soybean (Glycine max) lectin promoter in transgenic cotton (Gossypium hirsutum)

The activity of a soybean (Glycine max L. Merrill) lectin gene promoter was investigated in transgenic cotton plants (Gossypium hirsutum L.) with the view to using this promoter for the seed-specific alteration of gossypol, a secondary metabolite in cotton that has adverse effects on the nutritional value of cottonseed products like oil and protein-rich meal. Agrobacterium-mediated transformation generated stable transformants containing a construct with the lectin promoter fused to the β-glucuronidase reporter gene (pLeGUS). Fluorometric GUS assays and northern hybridization detected strong promoter activity during embryo development. GUS activity in developing embryos was detected as early as 10 d post-anthesis (dpa), peaking late in embryo maturation. Enzyme activity persisted in imbibed mature seed, and negligible activity remained detectable in the roots and cotyledons of 7-d-old seedlings. No GUS activity was detected in leaves and squares of mature plants. GUS transcripts increased during embryo development to peak about 35 dpa, declining to a low level in imbibed mature seed. No transcripts were detected in roots, cotyledons, leaves or squares. Histochemical GUS activity staining indicated promoter activity in all cells of the cotyledons, including the flattened cells of the gossypol glands, the presumed site of synthesis of gossypol. This study concluded that the soybean lectin gene promoter is a useful tool for the seed-specific expression of transgenes in cotton.

Control of Ferredoxin and Gal/GalNAc Lectin Gene Expression in Entamoeba histolytica by acis-Acting DNA Sequence

ABSTRACT The ferredoxin (fdx) and lectin (hgl5) promoters of Entamoeba histolytica contain the DNA sequence motif TATTCTATT (URE3). Previously we showed that mutation of the URE3 motif in the hgl5 lectin promoter results in an increase in promoter reporter activity. Mutation of this motif in the fdx promoter led to a 40-to-50% decrease in fdx promoter activity as measured by reporter gene activity and abundance of mRNA. E. histolytica nuclear proteins exhibited sequence-specific binding to the URE3 motif in electrophoretic mobility shift assays. These results support the regulation of both ferredoxin and lectin promoters by a nuclear protein(s) which recognizes the URE3 motif.