Uso sustentable de pastizales naturales como fuente de bioenergía

Uso sustentable de pastizales naturales como fuente de bioenergíaFil: Feldman, Susana. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentin

Desmodium mottle virus, the first legumovirus (genus Begomovirus) from East Africa

A novel bipartite legumovirus (genus Begomovirus, family Geminiviridae), that naturally infects the wild leguminous plant Desmodium sp. in Uganda, was molecularly characterized and named Desmodium mottle virus. The highest nucleotide identities for DNA-A, obtained from two field-collected samples, were 79.9% and 80.1% with the legumovirus, soybean mild mottle virus. DNA-B had the highest nucleotide identities (65.4% and 66.4%) with a typical non-legumovirus Old World begomovirus, African cassava mosaic virus. This is the first report of a legumovirus in East Africa and extends the known diversity of begomoviruses found infecting wild plants in this continent

Une wakefieldite-(Ce) non plombifère : nouvelles données sur l'espèce minérale correspondant à l'orthovanadate de cérium

A mineral, incorrectly called wolframite, from Tifemine (Morocco), was identified as nonplumboan wakefieldite-(Ce). This is the second occurrence of wakefieldite-(Ce) in the world and the first one which is Pb-free. The mineral occurs as black to brownish black bundles of veinlets, exhibiting a perfect cleavage, in massive white quartz. Electron microprobe anal. gave: (Ce0.52La0.18Nd0.15Y0.07Pr0.05Sm0.02)Σ0.99(V0.92As0.08)Σ1.00O4. Crystal structure refinement in space group I41/amd confirmed the hypothesis of a zircon-type structure with a 7.354(3) and c 6.488(4) Å. X-ray powder diffraction data are given. The measured and calcd. d. values are 4.76 and 4.80 g/cm3, resp. The mineral has hardness 250 kg/mm2, is stable at least up to 1050°, and is uniaxial pos. with nω 1.97(2) (translucent pale brown), nε 2.16 (almost opaque hazel brown)

OsttaSBEIII expression alters granule size and increases starch levels and its degradability in Arabidopsis

The physicochemical properties of starches from different botanical origin, such as viscosity, gelatinization temperature, solubility and degradability depend on the amylose/amylopectin ratio and the length and frequency of the α-1,6-glycosidic bonds in amylopectin. These branches depend on the action of the starch branching enzymes (SBEs), which are highly structurally conserved in plants. We recently identified a novel gene from Ostreococcus tauri (OsttaSBEIII) which codes for a protein showing starch branching activity (OsttaSBEIII) and with a different structure than other known SBEs from plants, containing two in-tandem carbohydrate binding modules (CBM41-CBM48) at its N-terminus. OsttaSBEIII overexpression in A. thaliana plants resulted in a higher starch content and smaller granules with an increased degradability. OEOsttaSBE lines showed also an increase in the expression and activity of starch degradative enzymes and a higher content of glucose and inorganic phosphate, which suggests a remodeling of the granule structure in response to the expression of OsttaSBEIII. These results allow us to propose the use of OsttaSBEIII as a new strategy to obtain starches with greater degradability that would be useful for different biotechnological applications

Development of co-dominant amplified polymorphic sequence markers for resistance of sunflower to downy mildew race 730

The inheritance of the reaction of sunflower to downy mildew was investigated using resistant and susceptible near isogenic lines (NILs) and their F-3 families. Resistance to race 730 was evaluated using the whole seedling inoculation technique. Seventy-three F-3 families were inoculated, among which 54 families were resistant and 19 susceptible, fitting a 3 : 1 segregation ratio. F-3 families were also studied using several PCR markers. Ten markers at the Pl6 locus, specific for the resistant line, also segregated in F-3 families with a 3 : 1 ratio. The same segregation ratio occurred for microsatellite haplotypes that resembled the resistant parent, and were amplified with ORS 166 and ORS 1043. The only common fragment that was observed between resistant and susceptible parental lines was one of the TIR-NBS-LRR resistance gene analogue markers, having a restriction site. Two co-dominant cleaved amplified polymorphic sequence (CAPS) markers were obtained. The mapping data indicate that several dominant markers and two CAPS markers, developed here, completely co-segregate with the Pl6 gene conferring resistance to race 730. CAPS markers will facilitate efficient marker-assisted selection for sunflower resistance to downy mildew race 730

A plant-specific TGS1 homolog influences gametophyte development in sexual tetraploid Paspalum notatum ovules

Aposporous apomictic plants form clonal maternal seeds by inducing the emergence of non-reduced (2n) embryo sacs in the ovule nucellus and the development of embryos by parthenogenesis. In previous work, we reported a plant-specific TRIMETHYLGUANOSINE SYNTHASE 1 (TGS1) gene (PN_TGS1-like) showing expression levels positively correlated with sexuality rates in facultative apomictic Paspalum notatum. PN_TGS1-like displayed contrasting in situ hybridization patterns in apomictic and sexual plant ovules from premeiosis to anthesis. Here we transformed sexual P. notatum with a TGS1-like antisense construction under a constitutive promoter, in order to produce lines with reduced transcript representation. Antisense plants developed prominent trichomes on the adaxial leaf surface, a trait absent from control genotypes. Reproductive development analysis revealed occasional formation of twin ovules. While control individuals typically displayed a single meiotic embryo sac per ovule, antisense lines showed 12.93-15.79% of ovules bearing extra nuclei, which can be assigned to aposporous-like embryo sacs (AES-like) or, alternatively, to gametophytes with a misguided cell fate development. Moreover, around 8.42-9.52% of ovules showed what looked like a combination of meiotic and aposporous-like sacs. Besides, 32.5% of ovules at early developmental stages displayed nucellar cells with prominent nuclei resembling apospory initials (AIs), which surrounded the megaspore mother cell (MMC) or the MMC-derived meiotic products. Two or more concurrent meiosis events were never detected, which suggest a non-reduced nature for the extra nuclei observed in the mature ovules, unless they were generated by proliferation and misguided differentiation of the legitimate meiotic products. The antisense lines produced a similar amount of viable even-sized pollen with respect to control genotypes, and formed an equivalent full seed set (similar to 9% of total seeds) after self-pollination. Flow cytometry analyses of caryopses derived from antisense lines revealed that all full seeds had originated from meiotic embryo sacs (i.e. by sexuality). A reduction of 25.55% in the germination percentage was detected when comparing antisense lines with controls. Our results indicate that PN_TGS1-like influences ovule, gametophyte and possibly embryo development