How nitric oxide down-regulates cryptochrome 1 from canola in blue but not red light, and reduces hypocotyl dwarfism in lead and drought stress

Abstract

Pollution of the environment and agricultural lands by lead and also drought stress is one of the important factors in reducing the production and quality of crops, including canola (Brassica napus L.). Expression of one key gene called cryptochrome 1 (CRY1) for reducing the hypocotyl dwarfism was analyzed in canola seedlings (Hyola 401 cultivar). We have studied the CRY1 gene on canola 5-day-old seedlings after exposure to sodium nitroprusside as the nitric oxide (NO) donor (100 μM), lead (100 μM), polyethylene glycol 6000 (PEG-6000) for imposed drought (5%) and their combination (100 μM lead + PEG 5%). The blue and red lights were irradiated for 2, 4 and 8 hours (h). A protocol for real-time quantitative PCR (RT-qPCR) analysis of this gene was developed using the β-actin gene as an internal standard. The CRY1 gene significantly up-regulated in drought and simultaneous lead and drought stresses in 8 h blue light irradiation. NO interaction considerably down-regulated the CRY1 gene in controlled seedlings and in all blue-light irradiations except for lead stress in 8 h. This light in synchronous lead and drought stress led to significant hypocotyl dwarfism by CRY1, especially at 8 h. Using NO interplay, hypocotyl dwarfism by CRY1 gene was reduced in all treatments except for red light and lead stress in 4 and 8 h of blue light.