Adaptability and stability of early carioca beans by mixed models / Adaptabilidade e estabilidade de feijão carioca precoce via modelos mistos

The genotype x environment interaction represents one of the major selection challenges due to the difficulty in identifying effectively superior genotypes. The present study aimed at estimating genetic parameters and selecting genotypes of early Carioca beans by analyzing simultaneous attributes, including yield, adaptability, and stability. In the agricultural year of 2015 and 2016, three trials were conducted, using a randomized block design, with three repetitions each, in the Agreste and Sertao regions of Pernambuco State. The genetic parameters were estimated using the mixed model procedure, and the selection was based on the harmonic mean of the relative performance of genetic values (MHPRVG, abbreviation in Portuguese) method. The environments influenced the phenotypic expression of the bean genotypes during both years, setting a specific adaptation. The mean heritability of the genotypes regarding yield exhibited low magnitude values in the trials of 2015 (5.78%) and 2016 (13.77%), indicating costly conditions for the selection of the improved genotypes. Genotype CNFC 15856 was selected, considering the genetic gain predicted for yield, by the average and specific performance in the three environments, and by the simultaneous attributes of yield, adaptability, and stability. The MHPRVG method enables the optimized selection of genotypes considering yield, stability, and adaptability; therefore, it should be included in the recommended selective criteria for agronomically superior genotypes in commercial plantations.

A interação genótipos x ambientes representa um dos maiores desafios da seleção por dificultar a identificação de genótipos efetivamente superiores. O objetivo desta pesquisa foi estimar os parâmetros genéticos e, pelos atributos simultâneos de produtividade, adaptabilidade e estabilidade, selecionar genótipos de feijão carioca precoce. No ano agrícola de 2015 e 2016, foram conduzidos três ensaios sob o delineamento de blocos casualizados com três repetições no Agreste e Sertão de Pernambuco. Os parâmetros genéticos foram estimados pelo procedimento de modelos mistos, e a seleção baseou-se no método da média harmônica do desempenho relativo dos valores genéticos. Os ambientes influenciaram na expressão fenotípica dos genótipos de feijão nos dois anos, configurando adaptação específica. A herdabilidade média dos genótipos para produtividade apresentou valores de baixa magnitude nos ensaios de 2015 (5,78%) e 2016 (13,77%), indicando condições dispendiosas para seleção dos genótipos melhorados. O genótipo CNFC 15856 foi selecionado considerando o ganho genético predito para produtividade pelo desempenho médio e específico nos três ambientes e pelos atributos simultâneos de produtividade, adaptabilidade e estabilidade. O método MHPRVG proporciona seleção otimizada de genótipos quanto à produtividade, à estabilidade e à adaptabilidade e, portanto, deve fazer parte dos critérios seletivos de recomendação de genótipos agronomicamente superiores para plantios comerciais.

Characterization of rhizobia isolates obtained from nodules of wild genotypes of common bean

Abstract This study aimed to evaluate the tolerance to salinity and temperature, the genetic diversity and the symbiotic efficiency of rhizobia isolates obtained from wild genotypes of common bean cultivated in soil samples from the States of Goiás, Minas Gerais and Paraná. The isolates were subjected to different NaCl concentrations (0%, 1%, 2%, 4% and 6%) at different temperatures (28 °C, 33 °C, 38 °C, 43 °C and 48 °C). Genotypic characterization was performed based on BOX-PCR, REP-PCR markers and 16S rRNA sequencing. An evaluation of symbiotic efficiency was carried out under greenhouse conditions in autoclaved Leonard jars. Among 98 isolates about 45% of them and Rhizobium freirei PRF81 showed a high tolerance to temperature, while 24 isolates and Rhizobium tropici CIAT899 were able to use all of the carbon sources studied. Clustering analysis based on the ability to use carbon sources and on the tolerance to salinity and temperature grouped 49 isolates, R. tropici CIAT899 and R. tropici H12 with a similarity level of 76%. Based on genotypic characterization, 65% of the isolates showed an approximately 66% similarity with R. tropici CIAT899 and R. tropici H12. About 20% of the isolates showed symbiotic efficiency similar to or better than the best Rhizobium reference strain (R. tropici CIAT899). Phylogenetic analysis of the 16S rRNA revealed that two efficient isolates (ALSG5A1 and JPrG6A8) belong to the group of strains used as commercial inoculant for common bean in Brazil and must be assayed in field experiments.

Analysis on the arcelin expression in bruchid pest resistant wild pulses using real time RT-qPCR.

Arcelin, the antimetabolic protein from wild pulses is a known natural insecticidal molecule. Wild pulses with high arcelin content could serve as potential source to increase the levels of insect resistance in cultivated pulse crops. In this study, arcelin (Arl) gene expression was screened in seven stored product insect pest resistant wild pulse varieties using real time RT-qPCR. Arcelin gene specific real time PCR primers were synthesized from arcelin mRNA sequence of the wild pulse variety, Lablab purpureus. The results revealed different levels of arcelin gene expression in the tested varieties. Canavalia virosa registered significantly high content indicating its suitability for utilization of arcelin gene in developing stored product insect pest resistance with other cultivated pulses.

Natural selection for efficiency in the use of nitrogen in common bean identified by analysis of microsatellites and grain yield

This study was carried out in order to verify whether natural selection acts on segregating common bean populations grown in the presence and absence of N, and to verify that natural selection affects the frequency of microsatellite alleles specifically, and in order to identify those that can assist in selection. Four populations from the crosses Ouro Negro x CI-107 and VC-5 x IAPAR-81 were carried forward in bulk to F8 at both levels of N. Ouro Negro and VC-5 are considered stress tolerant to nitrogen and IAPAR-81 and CI-107 responsive. One hundred progenies were obtained from each cross and grown in the presence and absence of N. DNA was extracted from 400 progenies, of which 194 were evaluated in the rainy season and 79 in the winter crop for grain yield. These progenies were evaluated in two separate experiments with and without N, in a 14 x 14 lattice design during rainy season and 9 x 9 in the winter season. We selected 35 pairs of polymorphic primers from the parents, with 20 being common from the two crosses. Using DNA of the 400 progenies, it was found that natural selection acted in 33 loci, in at least one environment and cross, and that alleles of the four parents were favoured by natural selection. QTLs were identified for the response rate of N and for grain yield and the linked markers are potential for assisted selection, especially the two most stable; BMD-20, in response to the use of N and PVBR-93 for grain yield.

Genetic diversity analysis of common beans based on molecular markers

A core collection of the common bean (Phaseolus vulgaris L.), representing genetic diversity in the entire Mexican holding, is kept at the INIFAP (Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias, Mexico) Germplasm Bank. After evaluation, the genetic structure of this collection (200 accessions) was compared with that of landraces from the states of Oaxaca, Chiapas and Veracruz (10 genotypes from each), as well as a further 10 cultivars, by means of four amplified fragment length polymorphisms (AFLP) +3/+3 primer combinations and seven simple sequence repeats (SSR) loci, in order to define genetic diversity, variability and mutual relationships. Data underwent cluster (UPGMA) and molecular variance (AMOVA) analyses. AFLP analysis produced 530 bands (88.5 percent polymorphic) while SSR primers amplified 174 alleles, all polymorphic (8.2 alleles per locus). AFLP indicated that the highest genetic diversity was to be found in ten commercial-seed classes from two major groups of accessions from Central Mexico and Chiapas, which seems to be an important center of diversity in the south. A third group included genotypes from Nueva Granada, Mesoamerica, Jalisco and Durango races. Here, SSR analysis indicated a reduced number of shared haplotypes among accessions, whereas the highest genetic components of AMOVA variation were found within accessions. Genetic diversity observed in the common-bean core collection represents an important sample of the total Phaseolus genetic variability at the main Germplasm Bank of INIFAP. Molecular marker strategies could contribute to a better understanding of the genetic structure of the core collection as well as to its improvement and validation.

Chromosome identification in the Andean common bean accession G19833 (Phaseolus vulgaris L, Fabaceae)

Characterization of all chromosomes of the Andean G19833 bean genotype was carried out by fluorescent in situ hybridization. Eleven single-copy genomic sequences, one for each chromosome, two BACs containing subtelomeric and pericentromeric repeats and the 5S and 45S ribosomal DNA (rDNA) were used as probes. Comparison to the Mesoamerican accession BAT93 showed little divergence, except for additional 45S rDNA sites in four chromosome pairs. Altogether, the results indicated a relative karyotypic stability during the evolution of the Andean and Mesoamerican gene pools of P. vulgaris.

Comportamento de genótipos de feijoeiro ao ataque de Bemisia tabaci (Genn) biótipo B (Hemiptera: Aleyrodidae) / Behavior of bean genotypes to attack by Bemisia tabaci (Genn) biotype B (Hemiptera: Aleyrodidae)

Avaliou-se o comportamento de genótipos de feijoeiro sob infestação de Bemisia tabaci (Genn.) biótipo B em condições de campo, nas épocas de cultivo "da seca" e "das águas". Utilizaram-se os genótipos IAC-Tybatã, IAC-Una, FT-Nobre, Pérola, LP 98-122, LP 02-130, LP 01-38, LP 9979, BRS-Pontal, BRS-Requinte, BRS-Triunfo, BRS-Grafite, CV-48 e Z-28. Adotou-se o delineamento de blocos casualizados com 14 tratamentos e três repetições. As avaliações foram realizadas semanalmente, contando-se o número de ovos e de ninfas de B. tabaci biótipo B em dez folíolos por parcela. Na safra "da seca" os genótipos menos ovipositados por B. tabaci biótipo B foram IAC-Una e LP 02-130 e os mais ovipositados foram os genótipos Z-28 e Pérola. As menores presenças de ninfas de mosca-branca foram observadas em LP 98-122 e FT-Nobre e as maiores em LP 01-38, Pérola e Z-28. Para a safra "das águas" os genótipos não diferiram entre si em relação ao ataque de B. tabaci biótipo B. Os fatores da produção apresentaram diferença estatística somente na safra das secas.

Bean genotypes were evaluated under the infestation of Bemisia tabaci (Genn.) biotype B under field conditions in the dry and rainy season. The genotypes used were IAC-Tybatã, IAC-Una, FT-Nobre, Pérola, LP 98-122, LP 02-130, LP 01-38, LP 9979, BRSPontal, BRS-Requinte, BRS-Triunfo, BRS-Grafite, CV-48 and Z-28. The experiment was arranged in randomized blocks with 14 treatments and 3 replications. The evaluations were made on a weekly basis by counting B. tabaci biotype B eggs and nymphs on 10 leaflets per plot. In the dry season the least oviposited genotypes by B. tabaci biotype B were IAC-Una and LP 02-130, while the most oviposited were Z-28 and Pérola. The least presence of nymphs of whitefly was observed on LP 98-122 and FT-Nobre, and the most on LP 01-38, Perola and Z-28. For the rainy season the genotypes did not differ in relation to the attack of B. tabaci biotype B. The yield factors presented a statistical difference only in the dry season.

Marker-assisted backcrossing using microsatellites and validation of SCAR Phs marker for resistance to white mold in common bean

Molecular markers may accelerate selection through the identification of plants with higher proportion of recurrent parent genome, as well as identifying those plants bearing target alleles like quantitative traits loci (QTLs) for white mold resistance. The objectives of this work were: 1) to employ microsatellite markers (SSR) in order to accelerate the recovery of recurrent parent genome 2) to validate sequence characterized amplified region (SCAR) Phs associated with a QTL that confers resistance to white mold, as previously identified in bean populations. Lines G122 and M20 were crossed, which generated 267 F1 plants from backcross (BC) BC1 and 113 plants from backcross BC2.SSR polymorphic markers were adopted. The relationship between BC plants and the recurrent parent was estimated based on the recurrent genome proportion (PR) in each BC plant, and the Sorensen-Dice genetic similarity (sg ir). To determine how much the phenotypic variation is explained by SCAR Phs, 56 F1:2BC1 progenies were evaluated on the field following a random block design with two replications through the straw test method. SSR markers are efficient in identifying individuals with a greater proportion of the recurrent genome. SCAR Phs was not efficient for the indirect selection of common beans for white mold resistance.

Allele frequency and selection efficiency in cross populations of Andean x Mesoamerican common beans (Phaseolus vulgaris L. Fabales, Fabaceae)

Strategies were investigated for improving efficiency in the use of segregating common bean (Phaseolus vulgaris) populations using crosses between the Andean cultivar BRS-Radiante and the Mesoamerican parent cultivar Carioca-MG by developing populations with 12.5%, 25%, 50%, 75% and 87.5% of the allele frequency of one of the parents. For each of the five populations we evaluated for two traits, the number of days to the beginning of flowering and grain yield (g plot-1), in the F2:3 (sown in February 2006) and F2:4 (sown in July 2006) generation progenies using 15 x 15 lattice design experiments, with 44 progenies (n = 220 plants) plus the two parents and three controls being evaluated for each generation. In terms of variability release, the populations with different parental allele frequencies presented no consistent tendency of alteration. In general, genetic variance was stated among progenies in all populations, indicating success with selection. For grain yield, the lowest mean was observed in the populations with 50% of the alleles of both parents. If, for instance, the objective is to develop earlier flowering lines, the best strategy is to perform two, or at least one, backcross with the earliest parent. The most suitable allele frequency is to be determined according to the desired grain type.

The impact of local extinction on genetic structure of wild populations of lima beans (Phaseolus lunatus) in the Central Valley of Costa Rica: consequences for the conservation of plant genetic resources

Plant populations may experience local extinction and at the same time new populations may appear in nearby suitable locations. Species may also colonize the same site on multiple occasions. Here, we examined the impact of local extinction and recolonization on the genetic structure of wild populations of lima beans (Phaseolus lunatus) in the Central valley of Costa Rica. We compared genetic diversity from the samples taken from the populations before and after extinction at 13 locations using microsatellite markers. Locations were classified according to the occurrence of extinction episodes during the previous five years into three groups: 1) populations that experienced extinction for more than one year, and were later recolonized (recolonized), 2) populations that did not experience local extinction (control), and 3) populations that did not experience local extinction during the study, but were cut to experimentally simulate extinction (experimental). Our data did not show a clear tendency in variation in allele frequencies, expected heterozygosity, and effective number of alleles within and between groups of populations. However, we found that the level of genetic differentiation between samples collected at different times at the same location was different in the three groups of populations. Recolonized locations showed the highest level of genetic differentiation (mean Fst= 0.2769), followed by control locations (mean Fst= 0.0576) and experimental locations (mean Fst= 0.0189). Similar findings were observed for Nei’s genetic distance between samples (di,j= 0.1786, 0.0400, and 0.0037, respectively). Our results indicate that genetic change in lima beans depends on the duration and frequency of local extinction episodes. These findings also showed that control populations are not in equilibrium. Implications of these results for the establishment of conservation strategies of genetic resources of lima beans are discussed. Rev. Biol. Trop. 56 (3): 1023-1041. Epub 2008 September 30.

Las poblaciones de plantas pueden experimentar extinción local, y al mismo tiempo, pueden surgir a sus alrededores nuevas poblaciones. Algunas especies pueden colonizar el mismo sitio en múltiples ocasiones. Aquí examinamos el impacto de la extinción local y recolonización en la estructura genética de poblaciones silvestres del frijol lima (Phaseolus lunatus) en el valle Central de Costa Rica. Comparamos la diversidad genética de muestras tomadas en poblaciones, antes y después de la extinción, en 13 sitios, usando marcadores de microsatélite. Según los episodios de extinción durante los cinco años previos, clasificamos los sitios así: 1) poblaciones que han experimentado extinción por más de un año, y después han recolonizado (recolonizado), 2) poblaciones que no han experimentado extinción local (control), y 3) poblaciones que no han experimentado extinción local durante el estudio, pero fueron cortadas experimentalmente, simulando una extinción (experimental). Nuestros datos no mostraron una clara tendencia en la variación de las frecuencias alélicas, heterozigosidad, o número efectivo de alelos en y entre grupos de poblaciones. Los niveles de diferenciación genética entre muestras recolectadas en diferentes momentos en el mismo sitio fueron diferentes en los tres grupos de poblaciones. Los sitios recolonizados mostraron el mayor nivel de diferenciación genética (Fst = 0.2769), seguidos de los sitios control (Fst= 0.0576) y sitios experimentales (Fst= 0.0189). Obtuvimos resultados similares en la distancia genética Neis entre muestras (d i,j = 0.1786, 0.0400, y 0.0037, respectivamente). Los cambios genéticos en los frijoles lima dependen de la duración y frecuencia de los episodios de extinción local. Las poblaciones "control" no están en equilibrio. Las implicaciones de estos resultados para el establecimiento de estrategias de conservación de los recursos genéticos de habas se encuentran en discusión.

Genetic mapping of a new set of microsatellite markers in a reference common bean (Phaseolus vulgaris) population BAT93 x Jalo EEP558

The present study describes a new set of 61 polymorphic microsatellite markers for beans and the construction of a genetic map using the BAT93 x Jalo EEP558 (BJ) population for the purpose of developing a reference linkage map for common bean (Phaseolus vulgaris). The main objectives were to integrate new microsatellites on the existing framework map of the BJ population, and to develop the first linkage map for the BJ population based exclusively on microsatellites. Of the total of 264 microsatellites evaluated for polymorphism, 42.8% showed polymorphism between the genitors. An integrated map was created totaling 199 mapped markers in 13 linkage groups, with an observed length of 1358 cM and a mean distance between markers of 7.23 cM. For the map constructed exclusively with microsatellites, 106 markers were placed in 12 groups with a total length of 606.8 cM and average distance of 6.8 cM. Linkage group designation and marker order for BM microsatellites generally agreed with previous mapping, while the new microsatellites were well distributed across the genome, corroborating the utility of the BJ population for a reference map. The extensive use of the microsatellites and the availability of a reference map can help in the development of other genetic maps for common bean through the transfer of information of marker order and linkage, which will allow comparative analysis and map integration, especially for future quantitative trait loci and association mapping studies.

Effect of natural selection on common bean (Phaseolus vulgaris) microsatellite alleles

The effect of natural selection on microsatellite simple sequence repeat (SSR) alleles was investigated in two distinct common bean (Phaseolus vulgaris) generations (F8 and F24) derived from the cross between the P. vulgaris cultivars Carioca MG x ESAL 686. The F2 segregant population was propagated by the bulk method and 107 plants were sampled in two generations (F8 and F24). Each plant generated one family which was replicated by the bulk method to F8:11 and F24:27 families from which DNA was extracted. Thirty pairs of microsatellite primers were polymorphic for the parents and the bulk of the F24:27 families. Out of 30 loci selected by natural selection, 29 microsatellite alleles came from the Carioca MG parent and one allele came from the ESAL 686 parent. Natural selection affected all the generations and its intensity was specific for each locus and generation. Therefore all the alleles selected at each locus must be important for adaptation in a breeding program.

Transgene elimination in genetically modified dry bean and soybean lines

Transgene elimination is a poorly studied phenomenon in plants. We made genetic and molecular studies of a transgenic dry bean line immune to bean golden mosaic geminivirus and a soybean line. In both lines, the transgenes were stable during the vegetative phase but were eliminated during meiosis. Due to its potential biotechnological value, this transgenic line was micropropagated by grafting and the vegetative copies were studied for more than two years. More than 300 plants of progeny were obtained during this period, demonstrating that the phenomenon of elimination was consistently repeated and offering an opportunity for detailed study of transgene elimination, including the characterization of the integration sites. Cloning and sequencing of the transgenic loci, reciprocal crosses to untransformed plants, genomic DNA blots, and GUS assays were performed in the transgenic lines. Based on the molecular and genetic characterization, possible mechanisms involved in transgene elimination include intrachromosomal recombination, genetic instability resulting from the tissue culture manipulations, and co-elimination of transgenes, triggered by a process of genome defense.

Identification of SSR and RAPD markers linked to a resistance allele for angular leaf spot in the common bean (Phaseolus vulgaris) line ESAL 550

The objective of this study was to identify RAPD and SSR markers associated with a resistant allele for angular leaf spot (Phaeoisariopsis griseola) from the line 'ESAL 550', derived from the Andean 'Jalo EEP 558' cultivar, to assist selection of resistant genotypes. The resistant line 'ESAL 550' and the susceptible cultivar 'Carioca MG' were crossed to generate F1 and F2 populations. One hundred and twenty F2:3 families were evaluated. The DNA of the 12 most resistant families was bulked and the same was done with the DNA of the 10 most susceptible, generating two contrasting bulks. One RAPD and one SSR marker was found to be linked in coupling phase to the resistant allele. The SSR marker was amplified by the primer PV-atct001(282C), and its distance from the resistant allele was 7.6 cM. This is the most useful marker for indirect selection of resistant plants in segregating populations. The RAPD marker was amplified by the primer OPP07(857C) linked in coupling phase to the resistant allele, and distant 24.4 cM. Therefore, this RAPD marker is not so useful in assisting selection because it is too far from the resistant allele.

Isolation of (GA)n microsatellite sequences and description of a predicted MADS-box sequence isolated from common bean (Phaseolus vulgaris L. )

The isolation of (GA)n microsatellites using a highly microsatellite-enriched library is described for the first time in common bean (Phaseolus vulgaris L.). A relatively simple and effective method to isolate DNA repeats from microsatellite-enriched libraries based on hybridization-capture of repeat regions using biotin-conjugated oligonucleotids and non-radioactive colony hybridization was carried out. PCR products from 200 to 800 bp were obtained and cloned. Of the 60 clones sequenced, 21 yielded (GA)n microsatellites with n values equal or higher than six. These (GA)n microsatellite-containing loci could be useful for further genetic mapping studies. A (GA)n microsatellite linked to a putative MADS-box gene was identified. This sequence, which represents the first MADS-box locus described to date in common bean, showed a very high similarity with other known MADS-box sequences and was grouped within the AGL2 subfamily cluster of the Arabidopsis MADS-box genes. The vicinity of microsatellites to some genes is also discussed

Prediction of seed-yield potential of common bean populations

Earliest possible prediction of seed-yield potential of autogamous crop populations increases breeding program efficiency by saving time and resources. Alternatives for obtaining seed-yield predictions were compared by evaluating four common-bean populations in F1 and F2 generations together with the parents. Mean components (m + a' and d) and variances were estimated. The potential of each population was predicted by using both these and the Jinks and Pooni (1976) procedure, which allows probability estimation of each population of originating lines surpassing a determined standard. Estimate efficiency was determined by evaluating performances of 62 F5:7 families from each population. Mean component m + a' estimates obtained for the F1 and F2 generations proved efficient in predicting seed yield of F7 generation lines as did d for estimate variance among F7 generation families. In addition, the Jinks and Pooni (1976) procedure proved efficient in early prediction of common bean population genetic potentials, especially when using the m + a' estimate

Natural selection and family X location interaction in the common (dry) bean plant

Natural selection takes place while advancing generations of segregant populations of self pollinating species by the population (bulk) method. There is evidence that it maintains the individuals with greater grain yield. The question arises whether natural selection preserves the individuals which are more adapted only to the environment where the generation advance occurred, that is, if it contributes to increasing the genotype x environment interaction in the family assessment. This study was carried out to check this hypothesis in the common bean plant using families derived from a segregating population from a cross between the Carioca MG x ESAL 686 cultivars. The segregating populations increase in homozygosity was obtained by the population (bulk) method until the F14 generation, in three distinct locations in Minas Gerais state: Lavras, Lambari and Patos de Minas. Forty-seven F14:15 families were randomly taken from the population in each location and later multiplied to obtain F14:16 families. These families were jointly assessed with three controls using a triple 12 x 12 lattice design in the three locations of generation advance in the wet season of 1998/1999. All the estimated parameters showed that while advancing segregant populations by the population (bulk) method, natural selection acted to preserve the individuals which are more adapted to the environment in which they were advanced

Host plant nodule parameters associated with nitrogen fixation efficiency in French bean (Phaseolus vulgaris L) cultivars.

Two cultivars of French bean (Phaseolus vulgaris L.) viz. contender and arka komal were planted in polythene bags containing sand and grown under glasshouse conditions. The nodulation status, shoot/root biomass, activities of several nodule enzymes, total soluble protein and leghaemoglobin contents were monitored over the entire growth period. Allantoinase activity in leaves was measured to monitor the ureide degrading capacity. Significant genotype difference was observed in both the cultivars. All the parameters showed a decline after flowering except uricase, which declined before flowering. Malate dehydrogenase and isocitrate dehydrogenase showed a constant decline throughout the growth period. Degree of decline varied with the genotype for all the parameters. Leghaemoglobin content, PEP carboxylase activity and ureide degrading capacity of leaves did not show an appreciable decline in contender and were significantly higher than in arka komal. These factors can be used to increase nitrogen fixation in French bean.

Importância de compostos organossulfurados em sementes de leguminosas e em outros vegetais / Importance of organosulfur compounds in seeds of legumes and in other vegetables

Os compostos organossulfurados, representados pelos peptídeos ´GAMA`-glutamilsulfurados, são encontrados em grande quantidade em vegetais das famílias Alliaceae, Cruciferae e Leguminosae. A seus produtos de metabolização se atribui propriedades organolépticas típicas e quando são ingeridos por mamíferos, causam efeitos biológicos diversos. Estes efeitos são diferentes nestas três famílias, devido à formação de metabólitos secundários que dependem da presença ou ausência de enzimas específicas nestes vegetais. Na família Alliaceae, representada pelo alho e pela cebola, são produzidos compostos sulfurados, que além de serem precursores de aroma e de flavor característicos após a ruptura do tecido vegetal e a ação enzimática, se tornaram conhecidos pelos efeitos benéficos para a saúde humana. A via metabólica percorrida pelos compostos organossulfurados na família Cruciferae, dá origem, além do flavor, a compostos secundários diversos, incluindo o metanotiol e dissulfetos, altamente tóxicos para ruminantes, causando anemia hemolítica. Na família Leguminosae, os dipeptídeos sulfurados são encontrados principalmente nas sementes, sendo que o feijão Phaseolus vulgaris, L., dentre os gêneros estudados, os possui em maior concentração. A ´BETA’-glutamil-S-metil-L-cisteina e a S-metil-L-cisteina livre, podem em conjunto, representar ate ´50 POR CENTO1’ do conteúdo total de metionina presente no feijão, desaparecendo somente por ocasião da sua germinação...