Changes in activities of antioxidant enzymes in radish (Raphanus sativus) seedlings in response to allelopathic effect of safflower (Carthamus tinctorius)

Abstract ROS (Reactive Oxygen Species) production is a usual plant reaction to environmental stresses such as allelopathy. Plants possess antioxidant enzymes to scavenge cells and resist against the ROS. This study was conducted to evaluate changes in antioxidant enzymes (CAT, GPX, APX) in radish seedlings in response to allelopathic effect of safflower root and shoot residues grown under normal irrigation and drought stress. Safflower allelopathic effect led to an increase in antioxidant enzymes activities. GPX activity increased more than CAT and APX. Radish seedlings exposed to safflower residue grown under drought stress showed more antioxidant enzymes activities. Root residues enhanced the activities of antioxidant enzymes greater than shoot. Seedlings exposed to root residues grown under drought stress had the highest level of antioxidant enzymes activities.

Analysis of deformable distortion in the architecture of leaf xylary vessel elements of Carthamus oxycantha caused by heavy metals stress using image registration.

Anatomical study of leaf xylary vessel elements of Carthamus oxycantha under various intensities of lead (Pb) and nickel (Ni) stress (200, 400, 600, and 800 mg Pb(NO3 )2 , NiCl2 ·6H2 O/kg of the soil) was conducted. The deformations caused due to metal stress were detected using point-based image registration technique. Initially, a set of corresponding feature points called landmarks was selected for warping of two-dimensional microscopic images of deformed/source vessel (stressed) to its normal/target (unstressed) counterpart. The results show that the target registration error is less than 3 mm using real plant image datasets. The stress caused alterations mainly in diameter, size, and shape of the cells. Average cell diameter and average wall diameter of vessels were measured with "Image J." The range of decrease in average cell diameter from 18.566 to 13.1 µm and the range of increase in average wall diameter was from 5.166 to 10.1 µm, with increase in stress factor through 200, 400, 600, and 800 mg Pb(NO3 )2 , NiCl2 ·6H2 O/kg of the soil. We noted large deformation in the form of shrinkage in cell size and diminution in its diameter. The diminution in diameter and the shrinkage in cell size of vessel cells may be due to the deposition of wall materials. It can be a possible strategy to limit the water flow to overcome the rapid mobility and transportation of the excess amount of metals to safeguard the cellular components from unpleasant consequences of metallic stress.