Impact of polyploidy on plant tolerance to abiotic and biotic stresses.

Polyploidy, defined as the coexistence of three or more complete sets of chromosomes in an organism's cells, is considered as a pivotal moving force in the evolutionary history of vascular plants and has played a major role in the domestication of several crops. In the last decades, improved cultivars of economically important species have been developed artificially by inducing autopolyploidy with chemical agents. Studies on diverse species have shown that the anatomical and physiological changes generated by either natural or artificial polyploidization can increase tolerance to abiotic and biotic stresses as well as disease resistance, which may positively impact on plant growth and net production.

A bioassay for brassinosteroid activity based on the in vitro fluorimetric detection of nitric oxide production.

Recent studies have shown that low concentrations of brassinolide induce a rapid generation of nitric oxide in mesophyll cells of maize leaves, which can be easily detected by fluorimetric methods. In this work we describe a series of natural and synthetic brassinosteroids that are able to trigger in vitro NO production in tomato cells that exhibits dose-response behavior. We propose that this effect can be used to develop a new rapid and very sensitive bioassay for brassinosteroid activity that offers several advantages when compared to the current methodologies.