Quantification of free sugars, fructan, pungency and sweetness indices in onion populations by FT-MIR spectroscopy.

Background: To facilitate faster phenotyping of onions (Allium cepa L.), Fourier-transform mid infrared (FT-MIR) spectroscopy with partial least squares (PLS) regression modelling was evaluated for the determination of pungency (pyruvate), sweetness (free sugars) and fructan in juice samples (n = 605) expressed from bulbs from breeding populations.

Results: Fourier-transform infrared (FTIR) spectra (range 1700-900 cm ) were obtained from droplets (30 μL) of unprocessed juice.

Expression and purification of the antimicrobial peptide GSL1 in bacteria for raising antibodies.

Background: The Gibberellin Stimulated-Like (GSL) or Snakin peptides from higher plants are cysteine-rich, with broad spectrum activity against a range of bacterial and fungal pathogens. To detect GSL peptides in applications such as western blot analysis and enzyme-linked immunosorbent assays (ELISA), specific antibodies that recognise GSL peptides are required. However, the intrinsic antimicrobial activity of these peptides is likely to prevent their expression alone in bacterial or yeast expression systems for subsequent antibody production in animal hosts.

Measurement of the distribution of non-structural carbohydrate composition in onion populations by a high-throughput microplate enzymatic assay.

Background: Non-structural carbohydrate (NSC; glucose, fructose, sucrose and fructan) composition of onions (Allium cepa L.) varies widely and is a key determinant of market usage. To analyse the physiology and genetics of onion carbohydrate metabolism and to enable selective breeding, an inexpensive, reliable and practicable sugar assay is required to phenotype large numbers of samples.

Purification and cloning of a gamma-glutamyl transpeptidase from onion (Allium cepa).

Gamma-glutamyl transpeptidase (E.C. 2.