Induction of the expression of defence genes in Carica papaya fruit by methyl jasmonate and low temperature treatments

The defence mechanisms that are activated by methyl jasmonate (MJ) in fruits are not well understood. In this work, we studied the expression of defence genes in papaya fruit that are induced by the exposure to MJ and/or low temperatures. The papaya fruits ‘Maradol’ were randomly divided into two groups: one group was the untreated control and the other was treated with 10-4 M of MJ. Half of the fruits from each of the two groups were stored after treatment for 5 days at 5ºC and 2 days at 20ºC. We studied the expression levels of the pdf1.1 and pdf1.2 genes by amplification from expression libraries created from the pulp and skin tissues of the papaya fruit. As a reference, the mRNA level of the 18s ribosomal gene was used. In the skin tissue, the expression levels of the pdf1.1 and pdf1.2 genes were higher immediately after MJ treatment compared to the control. Furthermore, the expression of pdf1.2 remained high after MJ treatment and subsequent storage compared to the control. It was therefore concluded that the activation of the pdf1.1 and pdf1.2 genes forms part of the molecular defence mechanism in fruits that is activated by exposure to MJ. To our knowledge, this is the first study that analyzes the gene expression in papaya fruit that is induced by the exogenous application of methyl jasmonate and cold treatment.

La biotecnología en plantas y aspectos biotecnológicos del mango / Plant biotechnology and biotechnological aspects of mango

El presente trabajo analiza aspectos biotecnológicos generales para el mejoramiento de características agronómicas de plantas hortofrutícolas, utilizando la tecnología del ADN recombinante. Mediante la misma se ha logrado obtener plantas transgénicas resistentes a insectos, hongos, bacterias y herbicidas, con mejores características de calidad durante poscosecha y con alto contenido nutricional. Se ha dado un enfoque especial a los aspectos biotecnológicos para el mejoramiento del mango, dado que durante las pasadas dos décadas muy pocos cultivares han sido mejorados. En algunos ensayos, los principales aspectos estudiados son la eficiencia en la inducción de embriones durante la embriogénesis somática y en la recuperación de plantas, la inducción al azar de mutantes para obtener plantas resistentes a agentes selectivos y la transformación con genes que regulan ciertas características agronómicas. La biotecnología tiene un alto potencial para proveer soluciones alternativas a problemas que demandan no sólo los productores de mango, sino también para los demás productores agrícolas