During the last three decades, concentration of ozone in the lower troposphere of the Northern hemisphere has increased considerably. In many regions of the world there is an incontrovertible evidence that O3 levels are high enough to reduce crop yields, to cause shift in the genetic composition of natural and seminatural vegetation and to contribute to forest decline. These data explain the interest towards the damaging action of this pollutant on plants, particularly on molecular mechanisms, which are the basis of this kind of stress. An expression profile of genes up- and down-regulated by an acute ozone treatment (a single pulse of 150 ppb for five hours) in two hybrid poplar clones (Populus deltoides x maximowiczii, Eridano clone, and Populus x euoramericana, I-214 clone, sensitive and tolerant to O3, respectively) was obtained by sequencing 42 PCR clones belonging to four subtractive cDNA libraries obtained using suppression subtractive hybridisation (SSH). With the information gathered from different databases we were able to identify and assign a putative function to 31% of sequenced clones. The remain clones, classified as unknown, have presented an insufficient nucleotidic or deduced amino acidic similarity to proteins and/or genes of known function. Some of identified sequences presented high similarity with genes related to ozone stress already described in other species. Most of differentially expressed cDNA sequences can be classified as rarely transcribed. Indeed, almost half of the known sequences presented a meaningful similarity with genes not associated to ozone stress so far. Expression analysis of several sequenced up-regulated cDNA clones with known identity have showed that the level of all analyzed transcripts was increased by ozone treatment in both tolerant and sensitive poplar clones. By contrast, wall associated kinase (Ft32C clone) was induced by ozone stress in I-214 clone only. The Ft35A clone, isolated in I-214 poplar clone, was identified on the basis of high sequence similarity to Arabidopsis thaliana cytoplasmic ascorbate peroxidase (APX) cs1. This kind of APX result up-regulated by acute ozone treatment in tolerant poplar. By contrast, the cytosolic APX cs2, isolated by RT-PCR, was not induced by ozone treatment neither in tolerant nor in sensitive poplar clones.
Ozone-modulated genes in Populus spp.: identification of up- and down-regulated genes upon acute ozone exposure
BERNARDI, RODOLFO;NALI, CRISTINA;LORENZINI, GIACOMO;
2004-01-01
Abstract
During the last three decades, concentration of ozone in the lower troposphere of the Northern hemisphere has increased considerably. In many regions of the world there is an incontrovertible evidence that O3 levels are high enough to reduce crop yields, to cause shift in the genetic composition of natural and seminatural vegetation and to contribute to forest decline. These data explain the interest towards the damaging action of this pollutant on plants, particularly on molecular mechanisms, which are the basis of this kind of stress. An expression profile of genes up- and down-regulated by an acute ozone treatment (a single pulse of 150 ppb for five hours) in two hybrid poplar clones (Populus deltoides x maximowiczii, Eridano clone, and Populus x euoramericana, I-214 clone, sensitive and tolerant to O3, respectively) was obtained by sequencing 42 PCR clones belonging to four subtractive cDNA libraries obtained using suppression subtractive hybridisation (SSH). With the information gathered from different databases we were able to identify and assign a putative function to 31% of sequenced clones. The remain clones, classified as unknown, have presented an insufficient nucleotidic or deduced amino acidic similarity to proteins and/or genes of known function. Some of identified sequences presented high similarity with genes related to ozone stress already described in other species. Most of differentially expressed cDNA sequences can be classified as rarely transcribed. Indeed, almost half of the known sequences presented a meaningful similarity with genes not associated to ozone stress so far. Expression analysis of several sequenced up-regulated cDNA clones with known identity have showed that the level of all analyzed transcripts was increased by ozone treatment in both tolerant and sensitive poplar clones. By contrast, wall associated kinase (Ft32C clone) was induced by ozone stress in I-214 clone only. The Ft35A clone, isolated in I-214 poplar clone, was identified on the basis of high sequence similarity to Arabidopsis thaliana cytoplasmic ascorbate peroxidase (APX) cs1. This kind of APX result up-regulated by acute ozone treatment in tolerant poplar. By contrast, the cytosolic APX cs2, isolated by RT-PCR, was not induced by ozone treatment neither in tolerant nor in sensitive poplar clones.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
