Genetic and metabolic diversity of pink-pigmented facultative methylotrophs in phyllosphere of tropical plants

Diversity of Pink-Pigmented Facultative Methylotrophs (PPFMs) in phyllosphere of cotton, maize and sunflower was determined based on differential carbon-substrate utilization profile and Random Amplified Polymorphic DNA data. Results indicate that six diversified groups of PPFMs are found in these crops. Sunflower and maize phyllosphere harbor four different groups of methylobacteria while cotton has only two groups.

A diversidade de microrganismos metilotróficos facultativos pigmentados (PPFMs) na filosfera de algodão, milho e girassol foi determinada baseada no perfil diferencial de utilização de substratos de carbono e em dados de RAPD. Os resultados indicaram a existência de seis grupos diferentes de PPFMs nessas plantas. As filosferas de girassol e milho apresentaram quatro grupos diferentes de metilobactérias enquanto a de algodão apresentou apenas dois grupos.

Inter-conversion of free sugars and accumulation of galactomannan in response to supplied metabolic mediators during pod filling in guar.

Detached inflorescences of guar (Cyamopsis tetragonoloba), each bearing 4 uniformly-developing pods at 42 days post anthesis (DPA), were cultured for 6 days in complete liquid medium manipulated with a fixed concentration of mannose and varying concentration of myo-inositol. Such inflorescences, but with 2 pods, were also maintained in the solutions of (i) glucose(U-14C) containing myo-inositol or phytohormones, and (ii) mannose(U-14C) containing galactose for 36 hr. Effect of such exogenously supplied metabolic mediators on interconversion of free sugars in pod wall, endosperm and cotyledons and galactomannan accumulation in endosperm was studied. Myo-inositol decreased, over control, the relative proportion of invert sugars in pod wall, endosperm and cotyledons and at lower concentration (27.75 mM) it decreased the level of free sugars in pod wall and galactomannan in endosperm. In all pod tissues, 14C from both glucose and mannose got incorporated into myo-inositol as well as various sugars and maximum incorporation occurred in sucrose. High concentration of total free sugars and their 14C activity in pod wall indicated that this pod tissue was a potent accumulator of free sugars. With myoinositol, the relative proportion of 14C from glucose into raffinose sugars of pod wall and endosperm increased with a simultaneous decrease in this incorporation into galactomannan of the latter. Accompanying this, relative proportion of 14C into hexoses and myo-inositol decreased in pod tissues. Galactose increased 14C incorporation from mannose into total free sugars, sucrose and galactomannan with a concomitant decline in the labelling of hexoses. IAA and ABA enhanced 14C incorporation from glucose into total free sugars and this enhancement was much higher with IAA than ABA. The latter inhibited 14C incorporation into galactomannan. Based on these results, it was suggested that myo-inositol at lower concentration was inadequate to mediate the metabolism of sugars and, thereby, galactomannan synthesis. Galactose and mannose exhibited a mutual beneficial effect on their transportation to pods. Phytohormones stimulated the accumulation of sucrose in pod wall for its obligatory unloading into the seed.

influcnce of naphthalic anhydride and I-Aminobenzotriazole on maize resistance to herbicides-Secondary metabolism responses

Dry weight of maize shoots was significantly decreased following treatments with alachlor, metolachlor and atrazine; more reduction was observed with atrazine. The presence of naphthalic anhydride [NA] relieved these reductions whilst I-aminobenzotriazole [ABT] showed cumulative effects. Meanwhile activities of phenylalanine ammonia lyase [PAL,], tyrosine ammonia lyase [TAL] and chalcone isomerase [CI] were significantly increased; alachlor seemed the most inductive. The presence of NA counterbalanced the enhanced activities whereas ABT showed much reduction. Phenolic compounds and anthocyanin significantly increased by alachlor and metolachlor while atrazine had no effect. These increased levels became comparable to that of controls by NA but significantly diminished by ABT. The responses of PAL, TAL, and Cl preceded that of phenolics and anthocyanin confirming the controlling role of these enzymes. Moreover, these findings reveal the occurrence of an induced stress status. The counterbalancing action of NA on herbicide effects indicates the retraction of these conditions, might be due to herbicide detoxification. In contradistinction, ABT reduced these levels suggesting more decreases in enzyme concentrations probably because of the sinking of herbicide degradation through the inhibition or P450s. So a protraction of herbicide persistence, and consequently increased the phytotoxicity, could occur within the plant

Valor biológico de la proteína foliar de Atriplex suberecta / Biological value of foliar protein of Atriplex suberecta

Dentro de nuestra línea de trabajo "Atriplex - Calidad Biológica de la Proteína Foliar", hemos incluido el estudio del concentrado proteínico obtenido de las hojas de Atriplex subercta. Este comprendió: identificación química, calidad biológica de la proteína, perfil aminoacídico, y cálculo de cómputo químico (CQ). Para avaluar la retención nitrogenada se determinaron: utilización proteínica neta (NPU), digestibilidad verdadera (DV), y cálculo de valor biológico (VB). El incremento de peso se siguió mediante la relación proteínica neta (NPR) y relación proteínica neta relativa (RNPR). Los resultados revelaron: CQ = 96 calculado para aminoácidos azufrados; NPU = 60 ñ 4.00; DV = 76 ñ 5.20; VB = 87; NPR= 3.34 + 2.50 y RNPR = 88%. Estos permiten inferir que la proteína es de buena calidad, lo que indicaría que el producto sometido a estudio podría ser utilizado como complemento de cereales, dado su alto contenido de lisina (CQ, que es superior a 100)