EPISTASIS PARA PRODUCCI 3N DE GRANOS Y CARACTERES DE LA PLANTA EN UNA POBLACI 3N DE MA\ucdZ TROPICAL

En ma\uedz, estudios sobre la importancia de la epistasis en la herencia de caracteres cuantitativos han mostrado resultados contradictorios; por lo tanto, es de gran relevancia determinar la influencia de los efectos epist\ue1ticos involucrados en la herencia de esos caracteres en el cultivo. En tal sentido, esta investigaci\uf3n fue desarrollada para (a) detectar la presencia de epistasis, (b) confirmar la importancia de la interacci\uf3n epistasis por ambientes y (c) estimar los efectos epist\ue1ticos en plantas F2 para producci\uf3n de granos y caracteres de la planta utilizando el dise\uf1o triple test cross en una poblaci\uf3n de ma\uedz tropical formada a partir de dos l\uedneas gen\ue9ticamente divergentes. Cien progenies F2:3 retrocruzadas a ambas l\uedneas parentales y a la F1 fueron evaluadas en once ambientes. La epistasis fue detectada para todos los caracteres, con excepci\uf3n del acame total. Para producci\uf3n de granos, altura de planta e intervalo entre florecimientos la epistasis del tipo aditiva x dominante y/o dominante x dominante fue m\ue1s importante que la epistasis aditiva x aditiva; mientras, para altura de mazorca, posici\uf3n relativa de la mazorca y floraci\uf3n masculina y femenina, ambos tipos de epistasis fueron importantes. La interacci\uf3n epistasis con ambientes fue significativa para la floraci\uf3n femenina e intervalo entre florecimientos. Fueron identificados efectos epist\ue1ticos no-unidireccionales significativos en plantas F2 para todos los caracteres. Los resultados sugieren que, en la poblaci\uf3n estudiada, la epistasis constituye un componente importante de la varianza gen\ue9tica; por consiguiente, el modelo aditivo dominante no es suficiente para describir la variaci\uf3n gen\ue9tica de los caracteres estudiados. Palabras clave adicionales: Caracteres cuantitativos, interacciones no al\ue9licas, triple test cross, Zea mays ABSTRACT Epistasis for grain yield and plant traits in a tropical maize population In maize, studies on the importance of epistasis in the inheritance of quantitative traits have shown contradictory results; therefore, is of great importance to determine the influence of epistatic effects involved in the inheritance of these characters in the crop. Thus, this research was conducted to (a) to verify the presence of epistasis, (b) to verify the importance of epistasis by environment interaction and (c) to estimate epistatic effects in plants F2 for grain yield and plant traits using the triple test cross design in a tropical maize population developed from two inbred lines genetically divergent. One hundred F2:3 progenies backcrossed to both parental lines and F1 were evaluated in eleven environments. Epistasis was detected for all traits, except for root and stalk lodging. For grain yield, plant height and anthesis-silking interval the additive x dominance and/or dominance x dominance epistasis were more important than additive x additive epistasis; however, for ear height, ear placement, days to anthesis and days to silk emergence, both types of epistasis were important. Epistasis by environment interaction was significant for days to silk emergence and anthesis-silking interval. Significant epistatic non-unidirectional effects were identified in F2 plants for all traits. The results suggest that, in the studied population, epistasis is an important component of genetic variance; therefore, the dominant additive model is not sufficient to describe the genetic variation of the studied traits. Additional key words: Non allelic interactions, triple test cross, quantitative traits, Zea mays<br

Influence of initial pH of the growing medium on the activity, production and genes expression profiles of laccase of Pleurotus ostreatus in submerged fermentations

Background: Enzymatic activity and laccase isoenzymes number of Pleurotus ostreatus grown in different pH values of the growing medium in submerged fermentation and incubated in buffer solutions of different initial pH values were determined. The expression profiles of five laccase genes (Lacc1, Lacc4, Lacc6, Lacc9 and Lacc10) in these cultures were also studied. Results: The highest laccases activity was obtained in cultures grown at initial pH of 4.5 and the lowest in cultures grown at initial pH of 8.5. Isoenzyme profiles were different in all the cases. Lacc1, Lacc4, Lacc6 and Lacc10 were expressed in all the cultures. Conclusions: The initial pH of the growing medium is an important factor for regulating the expression of laccase genes, having an effect on the activity and on the laccase isoenzymes number produced by P. ostreatus in SmF. This is the first report on the influence of different initial pH values of the growing medium on the laccases activity, laccase isoenzymes number and laccases expression profiles of P. ostreatus grown in submerged fermentation