'Reining In Ripening'

Regarding Sarah Everts' fine article on understanding the role plant hormones play in regulating ripening in fruits and vegetables (C&EN, Oct. 29, page 10), the same plant signaling chemicals that regulate ripening also regulate all crop and forest plants' growth and development and plant responses to environmental stress (drought, salinity, heat, and pathogen attack).

This subject is a hot topic for plant physiologists. A number of chemists worldwide are working on plant hormone action and are contributing to systems biology approaches for improving plant production. From a chemistry point of view, there are significant challenges: plant hormones act at micromolar or lower concentrations and are present in a background of abundant primary and secondary metabolites; hormones are rapidly turned over. There are also multiple active compounds in the individual hormone families and many are still unknown.

In our lab at the National Research Council in Saskatoon, Saskatchewan, we are developing sensitive analytical methods to profile a broad spectrum of plant hormones and their metabolites in a single plant tissue sample. Using high-performance liquid chromatography coupled to a tandem mass spectrometer and employing stably labeled hormone analogs of each hormone and metabolite as internal standards, we can obtain profiles quantitating more than 20 compounds in one analysis (www.nrc-cnrc.gc.ca/highlights/2007/0702plantprofiling_e.html; Plant J. 2003, 35, 405).

We are working with plant biologists studying ripening of grapes and growth of canola, pine trees, and other species, and we are interested in collaborating with chemists and biologists in this area.

By the way, the structure of the biologically active ABA molecule has a cis double bond conjugated to the acid. The trans compound shown in your article is an inactive photoisomerization product (J. Plant Growth Regul. 2005, J24, 274).

Suzanne R. Abrams
Saskatoon, Saskatchewan