CHANGE OF SOME OSMOLYTES ACCUMULATION IN WATER-STRESSED COLZA (BRASSICA NAPUS L.) AS AFFECTED BY 24-EPIBRASSINOLIDE*

Document Type: Regular Paper

Authors

1 1International Center for Science, High Technology and Environmental Science, Kerman, I. R. Iran 2Department of Biology, Shahid Bahonar University, Kerman, I. R. Iran

2 Department of Biology, Shahid Bahonar University, Kerman, I. R. Iran

Abstract

Brassinosteroids are phytohormones possessing a wide spectrum of antistress activity. To see
whether this hormone is able to ameliorate the effects of water stress, the effects of 24-epibrassinolise on
plant growth, accumulation of osmolytes (proline, sugars and ions), lipid peroxidation and electrolyte leakage
were investigated in Colza (Brassica napus L. cv. Fusia) plants which were under water stress. The seeds
were sown in plastic pots containing sand, clay and peat (in a proportion of 1:1:1). Solution of 24-epibrassinolid
at 10-7 M concentration containing 0.01% Tween-20 (polyoxyethylene sorbitan) was sprayed on
leaves at intervals of 1, 2 and 3 weeks after sowing. Control plants were sprayed with 0.01% Tween-20, and
water treatment was applied 26 days after germination, withholding water for 3 or 4 days. One month after
sowing, plants were harvested. Lipid peroxidation and electrolyte leakage significantly increased under water
stress, but when plants were pretreated with 24-epibrassinolid and put under water stress these parameters
decreased, revealing that less oxidative damage occurred in this group. Proline and reduced sugars content
was increased when 24-epibrassinolide were applied. FW and DW were significantly decreased under water
stress. Water stress also increased the uptake of K and Ca, but the uptake of Na significantly decreased. 24- epibrassinolide considerably increased ions uptake by plants. Taken together, these results showed that 24- epibrassinolide alleviated the effects of water stress and increased the tolerance of plants to stress by
increasing osmolytes accumulation and therefore could be used to improve crops in harsh conditions.

Keywords