Dosis altas de radiación gamma (Cobalto60) disminuyen la expresión fenotípica de caracteres en caña de azúcar (Saccharum officinarum L.): High doses of gamma radiation (Cobalt60) decrease the phenotypic expression of characters in sugarcane (Saccharum officinarum L.)

La mutagénesis inducida es una técnica para crear variabilidad genética de manera rápida, directa y fácil en plantas de propagación vegetativa. A través de un agente mutagénico se provocan cambios en una o varias características morfológicas y fisiológicas que se transmiten a su progenie. En México no existe información sobre mutagénesis inducida en el cultivo de caña de azúcar. Por tal motivo, el objetivo del trabajo fue determinar el efecto de la radiación gamma a base de Cobalto60 en la expresión de caracteres fenotípicos en dos variedades comerciales de caña de azúcar. Fueron irradiadas 100 yemas de cada variedad, CP 72-2086 y MEX 69-290, con seis diferentes dosis de radiación gamma: 0, 50, 70, 80, 90 y 100 Grey con Cobalto60. Se sembraron en maceta bajo malla sombra y después se trasplantaron a campo. Los caracteres evaluados fueron emergencia de yemas, caracteres morfológicos y componentes de rendimiento. En general, a mayor dosis de radiación gamma, mayor afectación en la expresión fenotípica de las variables evaluadas, resultando diferentes interacciones entre los factores involucrados. Las dosis de 90 y 100 Grey causaron mayor efecto en la disminución de la expresión fenotípica de los caracteres y demoraron el crecimiento de las plantas. En las interacciones, la variedad CP 72-2086 fue más sensible en la emergencia de yemas, altura de planta, número de macollos y longitud del entrenudo, y la MEX 69-290 en área foliar, los que nos indica que, existe diferente grado de sensibilidad en los caracteres y las variedades evaluadas. Por lo tanto, las dosis altas de radiación gamma causan disminución en diferente proporción en la expresión fenotípica de caracteres y demora el crecimiento de las plantas en caña de azúcar. De igual manera, existe diferente grado de sensibilidad a la radiación gamma en los caracteres y genotipos

Popping patterns in F2 segregant progenies from popcorn × non-popcorn crosses

The most important commercial feature in popcorn (Zea mays L.) is the expansion of the starch contained in the endosperm; however, little has been studied about the underlying genetic basis of this quantitative trait, for which the development of segregating populations is required. The first step is the selection of the most appropriate contrasting parents for popping capacity to create these populations. The objectives of this study were, 1) to analyze the popping patterns of F2 populations derived from crosses between popcorn × nonpopcorn inbred lines to identify the most divergent cross for future molecular analysis in search of alleles-related to popping capacity,  and 2) to estimate the number of genes responsible for popping expansion volume based on the tails of segregation. Seven biparental crosses of popcorn × non-popcorn were performed to obtain F2 populations, and those were phenotypedfor popping expansion volume. Phenotypes were analyzed by the H test, Lilliefors normality-test, Fisher’s coefficient of skewness, and kurtosis level. The number of genes estimation was made with X2 and (1/4)n tests. The popping patterns indicated that popcorn × flint corn was the most divergent cross, with the most symmetrical distribution, and therefore, the best suitable population to be used for molecular analysis. Results indicated the existence of three to five major genes related to popping expansion volume. Transgressive segregation was present in all populations, showing individuals whit a popping expansion volume higher or lower than the parental ones, suggesting that non-popcorn lines contain variation for alleles that promote popping.Keywords: Popcorn, popping expansion volume, popping patterns, transgressive segregation, Zea mays L

Popping patterns in F2 segregant progenies from popcorn × non-popcorn crosses

The most important commercial feature in popcorn (Zea mays L.) is the expansion of the starch contained in the endosperm; however, little has been studied about the underlying genetic basis of this quantitative trait, for which the development of segregating populations is required. The first step is the selection of the most appropriate contrasting parents for popping capacity to create these populations. The objectives of this study were, 1) to analyze the popping patterns of F2 populations derived from crosses between popcorn × nonpopcorn inbred lines to identify the most divergent cross for future molecular analysis in search of alleles-related to popping capacity,  and 2) to estimate the number of genes responsible for popping expansion volume based on the tails of segregation. Seven biparental crosses of popcorn × non-popcorn were performed to obtain F2 populations, and those were phenotypedfor popping expansion volume. Phenotypes were analyzed by the H test, Lilliefors normality-test, Fisher’s coefficient of skewness, and kurtosis level. The number of genes estimation was made with X2 and (1/4)n tests. The popping patterns indicated that popcorn × flint corn was the most divergent cross, with the most symmetrical distribution, and therefore, the best suitable population to be used for molecular analysis. Results indicated the existence of three to five major genes related to popping expansion volume. Transgressive segregation was present in all populations, showing individuals whit a popping expansion volume higher or lower than the parental ones, suggesting that non-popcorn lines contain variation for alleles that promote popping.Keywords: Popcorn, popping expansion volume, popping patterns, transgressive segregation, Zea mays L