Genomic DNA structure of a gene encoding cytosolic ascorbate peroxidase from Arabidopsis thaliana

AbstractA genomic DNA clone encoding cytosolic ascorbate peroxidase was isolated from a genomic library of Arabidopsis thaliana, using a cDNA for the enzyme as a probe. Nucleotide sequence and primer extension analyses of this gene (APX1) revealed nine exons split by eight introns, one of which is inserted in the 5'-untranslated region. The exon/intron organization of the APX1 gene differs from that of the guaiacol peroxidase genes

Overexpression of the RADICAL-INDUCED CELL DEATH1 (RCD1) Gene of Arabidopsis Causes Weak rcd1 Phenotype with Compromised Oxidative-Stress Responses

rcd1 is a mutant of Arabidopsis thaliana that is more resistant to methyl viologen, but more sensitive to ozone than the wild type. rcd1-2 is caused by a single nucleotide substitution that results in a premature stop codon at Trp-332. The rcd1-2 mRNA level does not change significantly with the mutation. Since overexpression of rcd1-1 cDNA has been shown to bring about an rcd1-like phenotype, we created and examined the overexpression lines of RCD1 by the use of the cauliflower mosaic virus 35S promoter. The transgenic lines exhibited a weak rcd1-like phenotype, although no resistance to methyl viologen was observed. Further, they fully complemented the aberrant rcd1-2 phenotype. Subcellular localization of RCD1 was examined by transiently expressing green fluorescent protein (GFP) fused with RCD1 in onion epidermal cells. GFP signals are observed as aggregated foci in the inner nuclear matrix-like region

Monitoring the occurrence of genetically modified oilseed rape growing along a Japanese roadside: 3-year observations

Monitoring for escape of genetically modified (GM) oilseed rape (Brassica napus) during transport can be performed by means of roadside evaluations in areas where cultivation of this GM crop is not conducted, such as in Japan. We performed a survey of oilseed rape plants growing along a 20-km section of Japan's Route 51, one of the main land transportation routes in central Japan for imports of GM oilseed rape from the Port of Kashima into Keiyo District. Oilseed rape plants were found each year, but the number of plants varied substantially during the three years of our study: 2162 plants in 2005, 4066 in 2006, and only 278 in 2007. The low number in 2007 was probably caused by roadwork. Herbicide-resistant individuals were detected in the three consecutive years (26, 8, and 5 individuals with glyphosate resistance), but glufosinate-resistant plants (9 individuals) were detected only in 2005. The roadside plants occurred mainly along the inbound lane from Kashima to Narita. These plants are likely to have their origin in seeds spilled during transportation of cargo from the port, since there are no potential natural seed source plants for B. napus near Route 51. This is the first detailed report on the transition and distribution of herbicide-resistant oilseed rape plants following loss and spillage along Japanese roads

A Methyl Viologen-Resistant Mutant of Arabidopsis, Which Is Allelic to Ozone-Sensitive rcd1, Is Tolerant to Supplemental Ultraviolet-B Irradiation

To better understand the role of active oxygen species (AOS) in acquired resistance to increased levels of ultraviolet (UV)-B irradiation in plants, we isolated an Arabidopsis mutant that is resistant to methyl viologen, and its sensitivity to UV-B was investigated. A complementation test revealed that the obtained mutant was allelic to the ozone-sensitive radical-induced cell death1-1 (rcd1-1). Therefore, this mutant was named rcd1-2. rcd1-2 was recessive and nearly 4-fold more resistant to methyl viologen than wild type. It exhibited a higher tolerance to short-term UV-B supplementation treatments than the wild type: UV-B-induced formation of cyclobutane pyrimidine dimers was reduced by one-half after 24 h of exposure; the decrease in quantum yield of photosystem II was also diminished by 40% after 12 h of treatment. Furthermore, rcd1-2 was tolerant to freezing. Steady-state mRNA levels of plastidic Cu/Zn superoxide dismutase and stromal ascorbate peroxidase were higher in rcd1-2 than in wild type, and the mRNA level of the latter enzyme was enhanced by UV-B exposure more effectively in rcd1-2. UV-B-absorbing compounds were more accumulated in rcd1-2 than in wild type after UV-B exposure for 24 h. These findings suggest that rcd1-2 methyl viologen resistance is due to the enhanced activities of the AOS-scavenging enzymes in chloroplasts and that the acquired tolerance to the short-term UV-B exposure results from a higher accumulation of sunscreen pigments. rcd1 appears to be a mutant that constitutively shows stress responses, leading to accumulation of more pigments and AOS-scavenging enzymes without any stresses

Detection of feral transgenic oilseed rape with multiple-herbicide resistance in Japan

Repeated monitoring for escaped transgenic crop plants is sometimes necessary, especially in cases when the crop has not been approved for release into the environment. Transgenic oilseed rape (Brassica napus) was detected along roadsides in central Japan in a previous study. The goal of the current study was to monitor the distribution of transgenic oilseed rape and occurrence of hybridization of transgenic B. napus with feral populations of its closely related species (B. rapa and B. juncea) in the west of Japan in 2005. The progenies of 50 B. napus, 82 B. rapa and 283 B. juncea maternal plants from 95 sampling sites in seven port areas were screened for herbicide-resistance. Transgenic herbicide-resistant seeds were detected from 12 B. napus maternal plants growing at seven sampling sites in two port areas. A portion of the progeny from two transgenic B. napus plants had both glyphosate-resistance and glufosinate-resistance transgenes. Therefore, two types of transgenic B. napus plants are likely to have outcrossed with each other, since the double-herbicide-resistant transgenic strain of oilseed rape has not been developed intentionally for commercial purposes. As found in the previous study, no transgenic seeds were detected from B. rapa or B. juncea, and more extensive sampling is needed to determine whether introgression into these wild species has occurred