Rapid identification of lettuce seed germination mutants by bulked segregant analysis and whole genome sequencing.

Lettuce (Lactuca sativa) seeds exhibit thermoinhibition, or failure to complete germination when imbibed at warm temperatures. Chemical mutagenesis was employed to develop lettuce lines that exhibit germination thermotolerance. Two independent thermotolerant lettuce seed mutant lines, TG01 and TG10, were generated through ethyl methanesulfonate mutagenesis.

Genome sequence of the biocontrol strain Pseudomonas fluorescens F113.

Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR) that has biocontrol activity against fungal plant pathogens and is a model for rhizosphere colonization. Here, we present its complete genome sequence, which shows that besides a core genome very similar to those of other strains sequenced within this species, F113 possesses a wide array of genes encoding specialized functions for thriving in the rhizosphere and interacting with eukaryotic organisms.

Evolutionary history of the phl gene cluster in the plant-associated bacterium Pseudomonas fluorescens.

Pseudomonas fluorescens is of agricultural and economic importance as a biological control agent largely because of its plant association and production of secondary metabolites, in particular 2,4-diacetylphloroglucinol (2,4-DAPG). This polyketide, which is encoded by the eight-gene phl cluster, has antimicrobial effects on phytopathogens, promotes amino acid exudation from plant roots, and induces systemic resistance in plants. Despite its importance, 2,4-DAPG production is limited to a subset of P.

Genetic and functional characterization of the gene cluster directing the biosynthesis of putisolvin I and II in Pseudomonas putida strain PCL1445.

Pseudomonas putida PCL1445 secretes two cyclic lipopeptides, putisolvin I and putisolvin II, which possess a surface-tension-reducing ability, and are able to inhibit biofilm formation and to break down biofilms of Pseudomonas species including Pseudomonas aeruginosa. The putisolvin synthetase gene cluster (pso) and its surrounding region were isolated, sequenced and characterized. Three genes, termed psoA, psoB and psoC, were identified and shown to be involved in putisolvin biosynthesis.

Size does matter: cre-mediated somatic deletion efficiency depends on the distance between the target lox-sites.

Cre/lox recombination in vivo has become an important tool to induce chromosomal rearrangements like deletions. Using a combination of Ds transposition and Cre/lox recombination in two independent experiments on chromosomes 6 and 7 of tomato, two sets of somatic deletions up to a size of 200 kb were obtained. The efficiency of somatic deletion decreased with increasing deletion size.

Cre recombinase expression can result in phenotypic aberrations in plants.

The cre recombinase gene was stably introduced and expressed in tomato, petunia and Nicotiana tabacum. Some plants expressing the cre gene driven by a CaMV 35S promoter displayed growth retardation and a distinct pattern of chlorosis in their leaves. Although no direct relation can be proven between the phenotype and cre expression, aberrant phenotypes always co-segregate with the transgene, which strongly suggests a correlation.