Brassinosteroids and Water Stress Response

Brassinosteroids (BRs), a group of plant hormone first identified in 1973 in oilseed rape, is known to play  key roles in  numerous plant developmental processes such as fruit ripening, cell elongation and pollen tube formation. These phytohormones have also been suggested to increase the resistance of plants to a variety of stresses, including chilling and drought stress. Spraying plants with BRs have been shown to improve the plants’ response to water stress. However, it is not known whether changes in the endogenous BR levels mediate plants’ response to water deficit.

Scientists from the University of Tasmania in Australia, using peas with mutation in the BR genes, found out that the level of biologically active BRs is not significantly altered during water stress. This suggests that plants’ response to drought is not mediated by changes in the levels of BRs. The researchers also observed that absence of the BR genes does not affect the production of the plant stress hormone ABA as well as growth parameters, including water potential, leaf size and height.

The full paper published by Physiologia Plantarum is available to subscribers at http://www.blackwell-synergy.com/action/showPdf?submitPDF=Full+Text+PDF+%28150+KB%29&doi=10.1111%2Fj.1399-3054.2008.01057.x