Amaranthus deflexus L.

Nota de alcance

PARTE UTILIZADA=Used part: Semillas y hojas. 

ACCIÓN FARMACOLÓGICA= Pharmacological action: Diurético, laxante. 

COMPOSICIÓN QUÍMICA= Chemical composition: 3.2. Composición aminoacídica de las proteínas de las semillas de amaranto En general se considera que los amarantos cultivados constituyen una fuente de proteínas bastante equilibrada respecto a la composición aminoacídica. La composición de aminoácidos de las proteínas de las semillas es bastante homogénea en todas las especies estudiadas siendo los aminoácidos más abundantes aspártico, glutámico, serina, glicina y leucina (Tabla 1). Estudios previos indican que la calidad nutricional de las semillas de los amarantos cultivados es mejor que en muchos cereales, ya que el contenido en aminoácidos en las especies de este género se aproxima más a los valores mínimos establecidos por la FAO/WHO (1991) como óptimos en una dieta para humanos (Bressani y García-Vela, 1990; Gorinstein et al., 1991). Así, el balance de aminoácidos esenciales es bastante mejor que el de muchas proteínas vegetales. Por ejemplo, presentan mayores contenidos de aminoácidos azufrados (metionina más cisteina) que las leguminosas. Así, los contenidos en aminoácidos azufrados oscilan entre el 1.6% en A. muricatus y A. cruentus y el 3.6% en A. deflexus. Si se comparan con las proteínas de cereales, los amarantos estudiados presentan mayores contenidos de treonina, arginina, triptófano y lisina que las proteínas de cereales (Lorenz, 2003), aunque peores contenidos de ramificados, principalmente valina e isoleucina (Tabla 1). Hay que destacar que estas proteínas son una fuente rica en triptófano, como puede verse en la Tabla 1, aminoácido que no es muy abundante en el mundo vegetal y que, sin embargo, en la mayoría de las especies estudiadas supera ampliamente el valor establecido por la FAO/WHO (1991). Atendiendo a los estudios previos, los aminoácidos más escasos en este género son leucina, treonina e isoleucina (Bressani y García-Vela, 1990). Sin embargo, los resultados obtenidos en el presente trabajo indican que la cantidad de treonina es óptima, ya que en todas las especies estudiadas está por encima del 4%, superando el valor del 3,4% recomendado por la FAO/WHO (1991). De las especies estudiadas A.muricatus y A. deflexus presentan la composición aminoacídica que más se aproxima a los valores recomendados por la FAO/WHO (1991). Por el contrario las especies más deficitarias son A. hypochondriacus, que es deficitario en histidina, tirosina, triptofano, fenilalanina y lisina y A. graecizans deficitario en tirosina, isoleucina, leucina, fenilalanina y lisina. Es destacable que entre las especies más equilibradas, en lo que respecta a su composición aminoacídica, se encuentren las consideradas como malas hierbas, como A. muricatus o A. deflexus, mientras que entre las peores esté una de las más cultivadas, como es A. hypochondriacus. Dada la facilidad de hibridación observadas en este género, estas plantas silvestres pueden representar una buena fuente de aminoácidos esenciales para mejorar la composición química de las cultivadas mediante hibridación. O también plantearse la introducción como cultivo de estas especies silvestres que tienen una mejor composición aminoacídica. 

Nota de alcance

DIVERSIDAD GENÉTICA Y MEJORAMIENTO DE PLANTAS MEDICINALES= Medicinal plants and improvement of medicinal herbs
:

Genetic diversity and relationships of 23 cultivated and wild Amaranthus species were examd. using both isoenzyme and RAPD markers. A total of 30 loci encoding 15 enzymes were resolved, and all were polymorphic at the interspecific level. High levels of inter-accessional genetic diversity were found within species, but genetic uniformity was obsd. within most accessions. In the cultivated grain amaranths (A. caudatus, A. cruentus, and A. hypochondriacus), the mean value of HT was 0.094, HS was 0.003, and GST was 0.977 at the species level. The corresponding values in their putative wild progenitors (A. hybridus, A. powellii, and A. quitensis) were 0.135, 0.004, and 0.963, resp. More than 600 RAPD fragments were generated with 27 arbitrary 10-base primers. On av., 39.9% of the RAPD fragments were polymorphic among accessions within each crop species; a similar level of polymorphism (42.8%) was present in the putative progenitors, but much higher levels of polymorphism were found in vegetable (51%) and other wild species (69.5%). The evolutionary relationships between grain amaranths and their putative ancestors were investigated, and both the RAPD and isoenzyme data sets supported a monophyletic origin of grain amaranths, with A. hybridus as the common ancestor. A complementary approach using information from both isoenzymes and RAPDs was shown to generate more accurate ests. of genetic diversity, and of relationships within and among crop species and their wild relatives, than either data set alone. 

Nota de alcance

ÚLTIMOS AVANCES EN LA QUÍMICA Y ACTIVIDADES BACTERIOLÓGICAS EN LAS PLANTAS MEDICINALES= Medicinal plants, last advances on chemistry and bacteria activities on the medicinal herbs

1) The seed protein profiles and amino acid compn. were detd. in 11 amaranth species (Amaranthus viridis, A. powellii, A. muricatus, A. deflexus, A. graecizans, A. blitoides, A. retroflexus, A. blitum, A. albus, A. cruentus, A. hypochondriacus).  Seed samples were obtained from wild plants growing in Southwest Spain.  The protein profiles were studied by gel filtration chromatog. and denaturing electrophoresis.  The protein profiles were similar in all 11 species, with small variations in mol. wts. and amts. of the main seed proteins.  The 6 main protein fractions sepd. by gel filtration chromatog. had mol. wts. 300, 180, 120, 40-50, 20-30 kDa, and <10 kDa.  The electrophoretic anal. grouped the peptides into 3 main fractions (50-64, 33-37, and 18-25 kDa).  The most balanced amino acid compns. were seen in A. muricatus, A. blitum, and A. powellii.  A. hypochondriacus and A. graecizans were the most deficient in amino acid compn., with limitations in 5 essential amino acids.  The data show the potential of wild Amaranthus species for use as crops or their use in plant breeding.

2) Genetic diversity and relationships of 23 cultivated and wild Amaranthus species were examd. using both isoenzyme and RAPD markers.  A total of 30 loci encoding 15 enzymes were resolved, and all were polymorphic at the interspecific level.  High levels of inter-accessional genetic diversity were found within species, but genetic uniformity was obsd. within most accessions.  In the cultivated grain amaranths (A. caudatus, A. cruentus, and A. hypochondriacus), the mean value of HT was 0.094, HS was 0.003, and GST was 0.977 at the species level.  The corresponding values in their putative wild progenitors (A. hybridus, A. powellii, and A. quitensis) were 0.135, 0.004, and 0.963, resp.  More than 600 RAPD fragments were generated with 27 arbitrary 10-base primers.  On av., 39.9% of the RAPD fragments were polymorphic among accessions within each crop species; a similar level of polymorphism (42.8%) was present in the putative progenitors, but much higher levels of polymorphism were found in vegetable (51%) and other wild species (69.5%).  The evolutionary relationships between grain amaranths and their putative ancestors were investigated, and both the RAPD and isoenzyme data sets supported a monophyletic origin of grain amaranths, with A. hybridus as the common ancestor.  A complementary approach using information from both isoenzymes and RAPDs was shown to generate more accurate ests. of genetic diversity, and of relationships within and among crop species and their wild relatives, than either data set   alone.

3) Population dynamics of weeds in successive maize and bean crops were evaluated in two soil management systems (conventional and no-tillage), for two maize applications (grain and silage), and in four consecutive growing seasons.  Every year, conventional tillage consisted in plowing and harrowing before sowing.  In no-tillage, chemical weed desiccation was made with the mixture glyphosate + 2.4-D.  To control weeds, the mixture fluazifop-p-butil + fomesafen was applied on the bean crop in all the planting seasons, and the herbicides nicosulfuron + atrazine on maize after crop emergence (1998--1999, 1999--2000, 2001--2002) and atrazine + metolachlor before emergence (2000--2001).  Purple nutsedge (Cyperus rotundus) was the most important species under conventional soil tillage; while in no-tillage the dicotyledonous weed species (Amaranthus deflexus, Bidens pilosa, Euphorbia heterophylla, Galinsoga parviflora Ipomoea grandifolia) were the most relevant.  Regardless of the maize use, the C. rotundus population and tuber bank, with prevailingly dormant tubers, was considerably reduced in no-tillage compared with the conventional system. 

Nota bibliográfica

1) TOURSARKISSIAN, Martín. Plantas medicinales de Argentina : sus nombres botánicos, vulgares, usos y distribución geográfica. Buenos Aires : Hemisferio Sur, 1980, p.1

2) JUAN, R., et al. Seed protein characterisation of eleven species of amaranthus: caracterización proteica de las semillas de once especies de amaranto. Grasas y Aceites. 2007, vol.58, nº1, p.49-55.  

3) CHAN, K. F.; SUN, M. Genetic diversity and relationships detected by isoenzyme and RAPD analysis of crop and wild species of Amaranthus. Theoretical and Applied Genetics.1997, vol.95, nº5-6, p.865-873.  

4) MACHADO, A., et al. Population dynamics of weeds in no-tillage and conventional crop systems. Journal of environmental science and health. Part. B, Pesticides, food contaminants, and agricultural wastes. 2005, vol.40, nº1, p.119-28.  

Amaranthus deflexus L.
Término aceptado: 27-Jul-2007