16 research outputs found
Small rubber particle proteins from Taraxacum brevicorniculatum promote stress tolerance and influence the size and distribution of lipid droplets and artificial poly(cis-1,4-isoprene) bodies
Natural rubber biosynthesis occurs on rubber particles, i.e. organelles resembling small lipid droplets localized in the laticifers of latexâcontaining plant species, such as Hevea brasiliensis and Taraxacum brevicorniculatum. The latter expresses five small rubber particle protein (SRPP) isoforms named TbSRPP1â5, the most abundant proteins in rubber particles. These proteins maintain particle stability and are therefore necessary for rubber biosynthesis. TbSRPP1â5 were transiently expressed in Nicotiana benthamiana protoplasts and the proteins were found to be localized on lipid droplets and in the endoplasmic reticulum, with TbSRPP1 and TbSRPP3 also present in the cytosol. Bimolecular fluorescence complementation confirmed pairwise interactions between all proteins except TbSRPP2. The corresponding genes showed diverse expression profiles in young T. brevicorniculatum plants exposed to abiotic stress, and all except TbSRPP4 and TbSRPP5 were upregulated. Young Arabidopsis thaliana plants that overexpressed TbSRPP2 and TbSRPP3 tolerated drought stress better than wildâtype plants. Furthermore, we used rubber particle extracts and standards to investigate the affinity of the TbSRPPs for different phospholipids, revealing a preference for negatively charged head groups and 18:2/16:0 fatty acid chains. This finding may explain the effect of TbSRPP3â5 on the dispersity of artificial poly(cisâ1,4âisoprene) bodies and on the lipid droplet distribution we observed in N. benthamiana leaves. Our data provide insight into the assembly of TbSRPPs on rubber particles, their role in rubber particle structure, and the link between rubber biosynthesis and lipid dropletâassociated stress responses, suggesting that SRPPs form the basis of evolutionarily conserved intracellular complexes in plants
Molecular cloning of a novel Gα subunit gene and a GÎČ subunit gene from the gray mold fungus Botrytis cinerea
The Sesquiterpene Synthase from the Botrydial Biosynthetic Gene Cluster of the Phytopathogen Botrytis cinerea
The fungus Botrytis cinerea is the causal agent of the economically
important gray mold disease that affects more than 200 ornamental and agriculturally
important plant species. B. cinerea is a necrotrophic plant pathogen that secretes
nonspecific phytotoxins, including the sesquiterpene botrydial and the
polyketide botcinic acid. The region surrounding the previously characterized
BcBOT1 gene has now been identified as the botrydial biosynthetic gene cluster.
Five genes including BcBOT1 and BcBOT2 were shown by quantitative reverse
transcription-PCR to be co-regulated through the calcineurin signaling pathway. Inactivation
of the BcBOT2 gene, encoding a putative sesquiterpene cyclase, abolished
botrydial biosynthesis, which could be restored by in trans complementation.
Inactivation of BcBOT2 also resulted in overproduction of botcinic acid that
was observed to be strain-dependent. Recombinant BcBOT2 protein converted
farnesyl diphosphate to the parent sesquiterpene of the botrydial biosynthetic
pathway, the tricyclic alcohol presilphiperfolan-8 -ol
Characterization of a new, nonpathogenic mutant of Botrytis cinerea with impaired plant colonization capacity
International audienceBotrytis cinerea is a necrotrophic pathogen that attacks more than 200 plant species.Here, the nonpathogenic mutant A336, obtained via insertional mutagenesis, was characterized.Mutant A336 was nonpathogenic on leaves and fruits, on intact and wounded tissue, while still able to penetrate the host plant. It grew normally in vitro on rich media but its conidiation pattern was altered. The mutant did not produce oxalic acid and exhibited a modified regulation of the production of some secreted proteins (acid protease 1 and endopolygalacturonase 1). Culture filtrates of the mutant triggered an important oxidative burst in grapevine ( Vitis vinifera ) suspension cells, and the mutantâplant interaction resulted in the formation of hypersensitive response-like necrosis. Genetic segregation analyses revealed that the pathogenicity phenotype was linked to a single locus, but showed that the mutated gene was not tagged by the plasmid pAN7-1.Mutant A336 is the first oxalate-deficient mutant to be described in B. cinerea and it differs from all the nonpathogenic B. cinerea mutants described to date