Plant Lipoxygenases (LOXs) are a class of dioxygenases which display diverse functions in several physiological processes such as growth, development and response to biotic and abiotic stresses. Even if LOXs have been characterised from several plant species, the physiological role of seed LOXs is still unclear. With the aim to better clarify the occurrence of LOXs and their influence on hazelnut seed quality, we carried out the biochemical and molecular characterisation of the main LOX isoforms expressed during seed development. With this aim a genomic clone containing a complete LOX gene was isolated and fully characterised. The 9887 bp sequence reported contains an open reading frame of 5334 bp encoding a putative polypeptide of 99 kDa. Semi quantitative RT-PCR carried out from RNAs extracted from seeds at different maturation stages showed that LOXs are mainly expressed at early developmental stages. These results were confirmed by LOX activity assays. Biochemical characterisation of the reaction products of the hazelnut LOX indicated that it is a 9-LOX. Two cDNAs were isolated by RT-PCR carried out on total RNA from immature hazelnut seeds. Sequence analysis indicated that the two cDNAs are highly homologous (91.9 % degree of identity) and one of these corresponded exactly to the genomic clone. The deduced amino acidic sequences of the hazelnut LOXs showed that they are closely related to a previously reported almond LOX (79.5 % identity) and, to a less extent, to some LOXs involved in plant response to pathogens (cotton and tobacco LOXs, 75.5 and 74.6 % identity respectively). The physiological role of hazelnut LOXs and their role in influencing seed quality are also discussed.
Biochemical and molecular characterization of hazelnut (Corylus avellana) seed lipoxygenase
Santino A;De Paolis A;Gallo A;Mita G
2003
Abstract
Plant Lipoxygenases (LOXs) are a class of dioxygenases which display diverse functions in several physiological processes such as growth, development and response to biotic and abiotic stresses. Even if LOXs have been characterised from several plant species, the physiological role of seed LOXs is still unclear. With the aim to better clarify the occurrence of LOXs and their influence on hazelnut seed quality, we carried out the biochemical and molecular characterisation of the main LOX isoforms expressed during seed development. With this aim a genomic clone containing a complete LOX gene was isolated and fully characterised. The 9887 bp sequence reported contains an open reading frame of 5334 bp encoding a putative polypeptide of 99 kDa. Semi quantitative RT-PCR carried out from RNAs extracted from seeds at different maturation stages showed that LOXs are mainly expressed at early developmental stages. These results were confirmed by LOX activity assays. Biochemical characterisation of the reaction products of the hazelnut LOX indicated that it is a 9-LOX. Two cDNAs were isolated by RT-PCR carried out on total RNA from immature hazelnut seeds. Sequence analysis indicated that the two cDNAs are highly homologous (91.9 % degree of identity) and one of these corresponded exactly to the genomic clone. The deduced amino acidic sequences of the hazelnut LOXs showed that they are closely related to a previously reported almond LOX (79.5 % identity) and, to a less extent, to some LOXs involved in plant response to pathogens (cotton and tobacco LOXs, 75.5 and 74.6 % identity respectively). The physiological role of hazelnut LOXs and their role in influencing seed quality are also discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
