Tesis doctoral de MarÁ§al Soler Del Monte
The periderm is a complex structure that protects plant mature (secondary) organs and wounded tissues from water loss, injuries and pathogens. This barrier capacity is accomplished by the cork layer of the periderm, a tissue made of dead cells with suberin deposited into cell walls. Although cork and suberin are critical for the survival of land plants, very few is known about the molecular processes involved in their biosynthesis and differentiation, probably due to the lack of appropriate plant models. Here we developed a strategy to identify and characterize cork candidate genes using a combination of two model plants for periderm studies. The bark of cork oak (quercus suber) was used to identify candidate genes and to analyze the seasonal behaviour of some of these genes. The potato (solanum tuberosum) tuber was used to demonstrate the role of some selected candidates in the regulation of cork by reverse genetic analyses. we isolated and identified 142 cork candidate genes, mainly up-regulated in the cork of cork oak in comparison to wood and somatic embryo, which suggest a specific role in the periderm. Most of these candidate genes, such as cytochromes p450, abc transporters, acytransferases and fatty acid elongases, encode enzymes which have been previously hypothesized as possible members of the suberin biosynthetic pathway. In addition, other candidate genes encode stress responsive and regulatory proteins, which are related to cork and suberin for the first time. Of note that transcript accumulation in cork of genes encoding nam, myb, hd-zipiii, knox and kanadi transcription factors suggests that some regulatory mechanisms may be conserved between the formation of wood and cork. to contribute to a better understanding of cork formation and phenology, we analyzed the expression pattern during the growing season of twelve selected candidate genes in the cork of cork oak. Our results showed that many genes, such as the enzymes cyp86a1, gpat and hcbt and the transcription factors nam and wrky, showed their highest expression in june, the month when cork growth rate is maximal. In contrast, the expression of genes encoding the enzymes f5h and fat and the stress proteins hsp17.4 and ann was correlated with temperature and relative humidity. to shed some light on the role of the regulatory proteins nam, rik, dem2 and rev in the cork tissue we performed a reverse genetic approach in potato periderm, obtaining in all cases kanamycin resistant lines indicating correct insertion of foreign dna. Up- and down-regulated lines have been confirmed for the nam transcription factor, and it is planned to confirm the rest of the lines and to perform phenotypic analyses in brief. If differences are detected between transgenic and wild-type plants, this will be, as far as we know, the first demonstration of the function of regulatory genes in the periderm.
Datos académicos de la tesis doctoral «Molecular genetics of cork formation«
- Título de la tesis: Molecular genetics of cork formation
- Autor: MarÁ§al Soler Del Monte
- Universidad: Girona
- Fecha de lectura de la tesis: 09/06/2008
Dirección y tribunal
- Director de la tesis
- llosera Figueras Vall
- Tribunal
- Presidente del tribunal: pere Puigdomenech rosell
- lukas Schreiber (vocal)
- isabel Allona alberich (vocal)
- michel Delseny (vocal)