Seleção de novos clones de mandioca para mesa, pela toxicidade e paladar de suas raízes «in natura»

Cassava roots contain cyanogenic glucosides. Malawian farmers classify cultivars into two groups based on the perceived danger of eating raw roots that they associate with bitterness. In the vernacular, cultivars that produce roots with bitter taste are called vyakubaba (bitter), whereas those yielding non-bitter roots are called vyakuzizra (cool). In the scientific literature they are distinguished as 'bitter' or 'sweet'. Roots from 'bitter' cultivars are processed prior to consumption. We studied the ability of farmers to predict the cyanogenic glucoside levels of 492 roots from the 10 most commonly grown cultivars. Twenty-eight farmers predicted the taste of each of the cultivars that they grew, and scored bitterness on a five-point scale by tasting the root tip. Thereafter cyanogenic glucosides were determined on half of the root, while a taste panel scored the taste of the other half. The mean cyanogenic glucoside level in 132 roots from 'cool' cultivars was 29 mg HCN eq kg −1 fresh weight (CI 25-33, range 1-123) and in 360 roots from 'bitter' cultivars was 153 mg HCN eq kg −1 fresh weight (CI 143-163, range 22-661). Farmers' distinction of 'cool' and 'bitter' cultivars predicts glucoside levels. The tasting of the tip of the root improved the farmers' prediction of toxicity. Scoring of bitterness by a trained taste panel showed a stronger correlation with glucoside levels (r 2 = 0.67). This suggests that cyanogenic glucosides confer the bitter taste, notwithstanding the probability of additional modifying intrinsic factors.

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“…In contrast to their earlier findings, 17,18 they found no association between HCN yield and taste in this later study.…”

Section: Correlation Between Taste and Cyanogenic Glucoside Levelcontrasting

confidence: 99%

Bitter taste in cassava roots correlates with cyanogenic glucoside levels

et al. 2004

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“…Esta separação poderia ser resultado de diferentes vias de domesticação das mandiocas bravas e de mesa (Rogers & Fleming, 1973;McKey & Beckerman, 1993;Dufour, 1988;Renvoize, 1972;Mkumbira et al, 1998aMkumbira et al, , 1998bRosling, 1996;Nye, 1991;Dufour & Wilson, 1996;Emperaire et al, 1998;Pereira & Pinto, 1962;Pereira et al, 1965;Normanha, 1956;Sinha & Nair, 1968;Colombo & Valle, 1998).…”

Section: Introductionunclassified

Variabilidade genética de etnovariedades de mandioca, avaliada por marcadores de DNA

Mühlen¹,

Martins

Ando

2000

Sci. agric. (Piracicaba, Braz.)

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GENETIC DIVERSITY OF CASSAVA FOLK VARIETIES ASSESSED BY DNA MARKERSABSTRACT: The objective of this work was to quantify the genetic diversity among cassava folk varieties as well as to examine the distribution of the genetic diversity among varieties of different origin and type. Fifty-four cassava varieties were chosen from 4 Brasilian regions: 45 of the Amazon basin (23 from River Negro, 6 of the River Branco and 16 of the River Solimões) and 9 of the south coast of the São Paulo State, Brazil. The modern variety Mantiqueira was also included as a reference. Among these, 38 were bitter varieties and 17 sweet. Three different types of DNA markers were used: RAPD (randomly amplified polymorphic DNA), AFLP (amplified fragment length polymorphism) and microsatellites. Analysis of the results consisted of a description of band patterns, a calculation of similarity indexes (Nei & Li) and a principal coordinate analysis (PCoA) for each marker type. Heterozygosity, diversity indexes (DI, Weir) and genetic differentiation coefficients (G ST ) were calculated for the microsatellite loci.Genetic variability was more concentrated within regions, then among regions (G ST = 0.07). Mean heterozygosity was 56%. Mean similarity indexes were dependent on the marker used: S = 0.89 for RAPD, S = 0.85 for AFLP and S = 0.59 for microsatellites. PCoA analysis revealed groups, distinguishing bitter from sweet varieties.

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“…No entanto, é necessário considerar-se que mandiocas bravas não sofreram pressão de seleção para consumo in natura e podem conter genes desfavoráveis para características peculiares em mandioca de mesa como paladar atípico e qualidades culinárias desfavoráveis. Genótipos com baixo teor de HCN também podem, em raríssimas exceções, apresentar sabor amargo porque essas características parecem não ter o mesmo controle genético, embora sejam altamente correlacionadas fenotipicamente nas variedades nativas (PEREIRA e PIN- TO, 1962;PEREIRA et al, 1965).…”

Section: Cruzamentosunclassified

Conteúdo cianogênico em progênies de mandioca originadas do cruzamento de variedades mansas e bravas

et al. 2004

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CYANIDE ACID CONTENT IN PROGENIES FROM CROSSES OF BITTER ANDSWEET CASSAVA CULTIVARS Cassava varieties are popularly separated by taste as bitter or sweet cultivars. Roots of bitter cultivars have a high HCN content (over 100 mg HCN equivalent/kg fresh roots) and are consumed only after processing, as flour, starch and other products. Sweet cultivars have low HCN content and can be consumed without any kind of processing. With the purpose of studing the possibility of using bitter varieties in the breeding of sweet cassava varieties, crosses were made between the different types of varieties to verify the cyanogenic profile of the segregating progenies. Two sweet varieties and a bitter variety (SRT-1330 Xingu) were pollinated by a sweet variety (SRT-797 Ouro do Vale). Crosses

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Seleção de novos clones de mandioca para mesa, pela toxicidade e paladar de suas raízes «in natura»

Cited by 9 publications

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Bitter taste in cassava roots correlates with cyanogenic glucoside levels

Bitter taste in cassava roots correlates with cyanogenic glucoside levels

Variabilidade genética de etnovariedades de mandioca, avaliada por marcadores de DNA

Conteúdo cianogênico em progênies de mandioca originadas do cruzamento de variedades mansas e bravas

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