Peroxiredoxins （Prx） catalyse the reduction of hydrogen peroxide （H2O2） and, in association with catalases and other peroxidases, may participate in signal transduction by regulating intercel ular H2O2 concentrati...Peroxiredoxins （Prx） catalyse the reduction of hydrogen peroxide （H2O2） and, in association with catalases and other peroxidases, may participate in signal transduction by regulating intercel ular H2O2 concentration that in turn can control gene transcription and cel signaling. Using virus-induced-gene-silencing （VIGS）, 2-Cys Peroxiredoxin （2CysPrx） family and type-II Peroxiredoxin B （PrxI B） gene were silenced in Nicotiana benthamiana, to study the impact that the loss of function of each Prx would have in the antioxidant system under control （22℃） and severe heat stress conditions （48 ℃）. The results showed that both Prxs, although in different organel es, influence the regeneration of ascorbate to a significant extent, but with different purposes. 2CysPrx affects abscisic acid （ABA） biosynthesis through ascorbate, while PrxIIB does it probably;through the xanthophyl cycle. Moreover, 2CysPrx is key in H2O2 scavenging and in consequence in the regulation of ABA signal-ing downstream of reactive oxygen species and PrxIIB provides an important assistance for H2O2 peroxisome scavenges.展开更多
Understanding abiotic stress responses is one of the most important issues in plant research nowadays. Abiotic stress, including excess light, can promote the onset of oxidative stress through the accumulation of reac...Understanding abiotic stress responses is one of the most important issues in plant research nowadays. Abiotic stress, including excess light, can promote the onset of oxidative stress through the accumulation of reactive oxygen species. Oxidative stress also arises when in vitro propagated plants are exposed to high light upon transfer to ex vitro. To determine whether the underlying pathways activated at the transfer of in vitro grapevine to ex vitro conditions reflect the processes occurring upon light stress, we used Vitis vinifera Affymetrix GeneChip （VvGA） and a custom array of genes responsive to light stress （LSCA） detected by real-time reverse transcriptase PCR （qRT-PCR）. When gene-expression profiles were compared, ＇protein metabolism and modification＇, ＇signaling＇, and ＇anti-oxidative＂ genes were more represented in LSCA, while, in VvGA, ＇cell wall metabolism＇ and ＇secondary metabolism＇ were the categories in which gene expression varied more significantly. The above functional categories confirm previous studies involving other types of abiotic stresses, enhancing the common attributes of abiotic stress defense pathways. The LSCA analysis of our experimental system detected strong response of heat shock genes, particularly the protein rescuing mechanism involving the cooperation of two ATP-dependent chaperone systems, Hsp100 and Hsp70, which showed an unusually late response during the recovery period, of extreme relevance to remove non-functional, potentially harmful polypeptides arising from misfolding, denaturation, or aggregation brought about by stress. The success of LSCA also proves the feasibility of a custommade qRT-PCR approach, particularly for species for which no GeneChip is available and for researchers dealing with a specific and focused problem.展开更多
基金funded by Fundao para a Ciência e Tecnologia (FCT): CBAA (Pest OE/AGR/UI0240/2011)the postdoc grants SFRH/BPD/43898/2008 to PVSFRH/BPD/85767/ 2012 to LC
文摘Peroxiredoxins （Prx） catalyse the reduction of hydrogen peroxide （H2O2） and, in association with catalases and other peroxidases, may participate in signal transduction by regulating intercel ular H2O2 concentration that in turn can control gene transcription and cel signaling. Using virus-induced-gene-silencing （VIGS）, 2-Cys Peroxiredoxin （2CysPrx） family and type-II Peroxiredoxin B （PrxI B） gene were silenced in Nicotiana benthamiana, to study the impact that the loss of function of each Prx would have in the antioxidant system under control （22℃） and severe heat stress conditions （48 ℃）. The results showed that both Prxs, although in different organel es, influence the regeneration of ascorbate to a significant extent, but with different purposes. 2CysPrx affects abscisic acid （ABA） biosynthesis through ascorbate, while PrxIIB does it probably;through the xanthophyl cycle. Moreover, 2CysPrx is key in H2O2 scavenging and in consequence in the regulation of ABA signal-ing downstream of reactive oxygen species and PrxIIB provides an important assistance for H2O2 peroxisome scavenges.
文摘Understanding abiotic stress responses is one of the most important issues in plant research nowadays. Abiotic stress, including excess light, can promote the onset of oxidative stress through the accumulation of reactive oxygen species. Oxidative stress also arises when in vitro propagated plants are exposed to high light upon transfer to ex vitro. To determine whether the underlying pathways activated at the transfer of in vitro grapevine to ex vitro conditions reflect the processes occurring upon light stress, we used Vitis vinifera Affymetrix GeneChip （VvGA） and a custom array of genes responsive to light stress （LSCA） detected by real-time reverse transcriptase PCR （qRT-PCR）. When gene-expression profiles were compared, ＇protein metabolism and modification＇, ＇signaling＇, and ＇anti-oxidative＂ genes were more represented in LSCA, while, in VvGA, ＇cell wall metabolism＇ and ＇secondary metabolism＇ were the categories in which gene expression varied more significantly. The above functional categories confirm previous studies involving other types of abiotic stresses, enhancing the common attributes of abiotic stress defense pathways. The LSCA analysis of our experimental system detected strong response of heat shock genes, particularly the protein rescuing mechanism involving the cooperation of two ATP-dependent chaperone systems, Hsp100 and Hsp70, which showed an unusually late response during the recovery period, of extreme relevance to remove non-functional, potentially harmful polypeptides arising from misfolding, denaturation, or aggregation brought about by stress. The success of LSCA also proves the feasibility of a custommade qRT-PCR approach, particularly for species for which no GeneChip is available and for researchers dealing with a specific and focused problem.
