Plastic pots were filled with 1 kg of soil to sand mixture (1:3) and were pre-treated with 200 ml’s of deionised water (controls), deionised water containing methylglyoxal, deionised water containing 1 mM zirconium and deionised water containing methylglyoxal and 1 mM zirconium, separately. Brassica rapa cv. Nooitgedacht seeds were surface sterilized and allowed to germinate to completion (9 days) under each separate treatment. After scoring the germination percentage, plants were left to grow for an additional 14 days and during this period, plants were treated twice a week with the four separate treatments. Seedling shoots were harvested and fresh material was dried to assess dry weights. Fresh material was also used to determine cell viability and superoxide content. The rest of the seedling shoots were snap frozen in liquid nitrogen and ground into fine powder for storage at -80°C. The frozen material was used to determine contents of chlorophyll, methylglyoxal, hydrogen peroxide, conjugated diene, hydroxyl radical and zirconium. The rest of the frozen material was used for total protein extraction for subsequent assessment of enzymatic activities such as superoxide dismutase, ascorbate peroxidase, catalase, and glyoxalase I. Methylglyoxal treatment increased the germination percentage as well as overall seedling shoot growth of B. rapa when compared to the controls. This increase could be attributed to the regulation of reactive oxygen species (ROS) by antioxidant enzymes. Zirconium treatment decreased the germination percentage of B. rapa as well as the seedling shoot growth possibly through overproduction of toxic ROS. However, when seeds were treated with a combination of methylglyoxal and zirconium, we observed an increased in germination percentage as well as seedling shoot growth when compared to the zirconium only treatment.
Link: https://doi.org/10.1016/j.sajb.2017.01.030
DOI: https://doi.org/10.1016/j.sajb.2017.01.030
