Doru Pamfil

Fatty acid composition of lipids in pot marigold (Calendula officinalis L.) seed genotypes

BackgroundCalendula officinalis L. (pot marigold) is an annual aromatic herb with yellow or golden-orange flowers, native to the Mediterranean climate areas. Their seeds contain significant amounts of oil (around 20%), of which about 60% is calendic acid. For these reasons, in Europe concentrated research efforts have been directed towards the development of pot marigold as an oilseed crop for industrial purposes.ResultsThe oil content and fatty acid composition of major lipid fractions in seeds from eleven genotypes of pot marigold (Calendula officinalis L.) were determined. The lipid content of seeds varied between 13.6 and 21.7 g oil/100 g seeds. The calendic and linoleic acids were the two dominant fatty acids in total lipid (51.4 to 57.6% and 28.5 to 31.9%) and triacylglycerol (45.7 to 54.7% and 22.6 to 29.2%) fractions. Polar lipids were also characterised by higher unsaturation ratios (with the PUFAs content between 60.4 and 66.4%), while saturates (consisted mainly of palmitic and very long-chain saturated fatty acids) were found in higher amounts in sterol esters (ranging between 49.3 and 55.7% of total fatty acids).ConclusionsAll the pot marigold seed oils investigated contain high levels of calendic acid (more than 50% of total fatty acids), making them favorable for industrial use. The compositional differences between the genotypes should be considered when breeding and exploiting the pot marigold seeds for nutraceutical and pharmacological purposes.

The evolutionarily conserved multifunctional glycine-rich RNA-binding proteins play key roles in development and stress adaptation.

The class IV glycine-rich RNA-binding proteins are a distinct subgroup within the heterogenous superfamily of glycine-rich proteins (GRPs). They are distinguished by the presence of an RNA-binding domain in the N-terminus; generally in the form of an RNA-recognition motif (RRM) or a cold-shock domain (CSD). These are followed by a C-terminal glycine-rich domain. Growing evidence suggests that these proteins play key roles in the adaptation of organisms to biotic and abiotic stresses including those resulting from pathogenesis, alterations in the osmotic, saline and oxidative environment and changes in temperature. Similar vertebrate proteins are also cold-induced and involved in, e.g. hibernation, suggesting evolutionarily conserved functions. The class IV RNA-binding GRPs are likely to operate as key molecular components of hormonally regulated development and to work by regulating gene expression at multiple levels by modifying alternative splicing, mRNA export, mRNA translation and mRNA degradation.

Identification of new adventitious rooting mutants amongst suppressors of the Arabidopsis thaliana superroot2 mutation

Summary Auxin is a major regulator of adventitious rooting and, to better understand its role, we identified suppressor mutants of superroot2-1. This provides new resources for the discovery of genetic players involved in auxin signalling or auxin crosstalk with other hormones.

Transgenic plums expressing Plum pox virus coat protein gene do not assist the development of virus recombinants under field conditions.

SUMMARY The serological and genetic variability of Plum pox virus (PPV) isolates from transgenic plum trees expressing the PPV coat protein gene and conventional plums was analyzed. PPV isolates were characterized serologically by TAS-ELISA using PPV-D and PPV-M specific monoclonal antibodies and by molecular typing across three genomic regions as well as RFLP analysis of the 3’ terminus of the CP gene. PCR products spanning the (Cter)CP and (Cter)NIb-(Nter)CP regions were sequenced. Sequence information revealed no significant difference between serological and molecular features of PPV isolates from transgenic and conventional plums that were growing together in experimental orchards for 6-8 years. These results show that transgenic plums do not promote the emergence of new PPV variants under field conditions.

Development of a novel inducible bioluminescent and antibiotic resistance tagging system and its use to investigate the role of antibiotic production by Pectobacterium carotovorum ssp. carotovorum during potato tuber infection

We report the construction of a novel Tn7 vector for the tagging and enumeration of target bacteria from complex microbial communities. The system utilises a cassette for inducible bioluminescence and tetracycline resistance that integrates at a defined neutral position present in most Gram-negative species. We used this approach to chromosomally tag Pectobacterium such that it could be enumerated in mixed consortia without placing a significant bioburden on the tagged strain. Two Pectobacterium strains, a carbapenem antibiotic producer and an isogenic knock-out strain were tagged using this system. The modified Pectobacterium strains were used to compare the extent to which potato tuber-associated and endophytic bacteria can gain advantage and multiply in planta, utilising the nutrients released by a Pectobacterium infection, when the infecting Pectobacterium is either an antibiotic producer (Car+) or a carbapenem knock-out (Car−) strain. We show that the ability to synthesise carbapenem has a significant effect upon Pectobacterium numbers throughout the course of the infection. Whilst limiting the number of other bacterial species, carbepenem production allows the Pectobacterium to replicate to higher titres in the rotting tuber. We anticipate that the Tn7 tagging vector will be of use to other researchers studying ecological interactions in complex environments.

THE SEGREGATION OF TREE HABIT ON PEAR SEEDLINGS IN SIX HYBRID COMBINATIONS

Trees habit is an important trait in pear breeding and pear culture (1, 2, 3). The segregation for trees habit of F1 pear hybrids belonging from six combinations was analysed. The seedlings originate in incomplete diallel cross, effectuated with four genitors (Comtesse de Paris, Milenium, Virgiliu Hibernal, Cluj 89-1-81 selection), were framed in six classes of growth (after UPOV Guidelines), respectively architectural ideotype: 1. Fastigiate; 2. Upright; 3. Semi-upright; 4. Spreading; 5. Drooping; 6. Weeping. In each combination, the majority of F1 hybrids had spreading habit (between 57% in Comtesse de Paris x Milenium and 81% in Milenium x Cluj 89-1-81). The occurrence of high percentages of spreading habit seedlings in all combinations (see the table) suggests that this ideotype of tree growth is easy to obtain in pear breeding. Because a valuable type of tree habit for modern plantation is with a spurred growth habit and strong apical control, it can be appreciated that Milenium (a relative new cultivar created at Fruit Research Station Cluj-Napoca) can be used as genitor for this trait. Especially used as mother genitor in cross with Virgiliu Hibernal (another new cultivar obtained at FRS Cluj), Milenium gave birth to the highest percentage of upright seedlings (16%), and with fastigiate habit (3%)