Isolation and characterization of Avenin-like protein type-B from durum wheat

Proteomic techniques were applied for the investigation of “avenin-like protein type-B” in tetraploid wheat. Protein was extracted from endosperm, according to a classical chromatographic procedure and its identity confirmed by liquid chromatography-tandem mass spectrometry analysis. The characterization of avenin-like protein type-B was in good agreement with the gene-derived sequence, with the exception of glutamine as N-terminus. The presence in the glutenin extract and the high number of cysteine residues suggested that avenin-like protein type-B is integrated into gluten polymers via inter-chain disulphide bonds. This raises the question of whether the protein could play a role in determining the functional properties of gluten.     

Fire intensity and serotiny: response of germination and enzymatic activity in seeds of Pinus halepensis Mill. from southern Italy

? Context

The Mediterranean Basin is a fire-prone area. Pinus halepensis Mill. is a naturally growing conifer which is frequently used for reforestation and restoration as it displays some degree of adaption to fire. One of the traits conferring tolerance to fire is the frequent presence of serotinous cones that are thought to protect seeds from fire damage.

? Aim

We checked for the physiological responses of seeds to different intensities of fire and related them to the degree of serotiny of the cones.

? Methods

Germination percentage, mean germination rate and enzymatic activity (??-amylase and protease) were recorded for seeds burned either free or enclosed in cones. We included as experimental factors the following: fire intensity, serotiny and time during which seeds were stored in cones after harvesting and germination stage.

? Results

Burned seeds (released and enclosed) developed in serotinous cones exhibited higher heat insulation. In released seeds, germination was decreasing according to increasing fire intensity, although we found differences depending on site, serotiny and time stored after harvesting. The enzymatic activity was also found to be related to serotiny and fire intensity.

? Conclusion

Serotiny is an adaptive trait increasing the tolerance to fire which should be promoted in natural and restored populations.     

Segregation distortion in doubled haploid lines of barley (Hordeum vulgare L.) detected by simple sequence repeat (SSR) markers

A total of 147 simple sequence repeat (SSR) markers (including86 barley and 61 wheat microsatellite markers) were tested for their segregation in a doubled haploid (DH) and an F₂ population of barley. The DH population consisted of 71 doubled haploid lines, developed from F₁ plants of a cross between Tadmor and WI2291using isolated microspore culture technique. A genetic linkage map consisting of 43 microsatellite markers was constructed using the DH population. Particularly on chromosome 4H microsatellite markers showed distorted segregation ratios. Segregation of DH lines based on molecular markers were compared with segregation of 92 F₂ lines from the same cross. The proportion of loci deviating from the expected monogenic segregation ratios in the DH population was significantly higher (19/43loci, 44%) than in the F₂ population (7/43 loci, 16%). The deviation was biased towards the WI2291 parent alleles. In line with this observation, WI2291 was found to perform better than Tadmor in regenerating green plantlets with the isolated microspore-culture technique. This revised version was published online in July 2006 with corrections to the Cover Date.