Differential cadmium stress tolerance in five Indian mustard (Brassica junceaL.) cultivars

Abstract

IntroductionAgricultural soils worldwide are slightly to moderately contaminated with toxic heavy metals that restrict the crop plants to reach their full genetic potential and cause significant loss by reducing the crop productivity. 1 Among heavy metals, Cd is a non-essential and most deleterious heavy metal pollutant commonly released into the arable soil from various industrial, mining and farming practices, 2 and has been ranked No. 7 among the top 20 toxins which affect the human health by entering in the food chain. 3,4 Although Cd is a highly phytotoxic metal, it is easily taken up by plant roots growing on Cd-contaminated soils and transported to above ground plant parts. 5-7 The regulatory limit of Cd in agricultural soils is 100 mg Cd kg -1 soil, 8 but this threshold is continuously increasing because of anthropogenic and industrial activities. Plants growing on Cd contaminated soil result in Cd accumulation in all plant parts, which inhibits plant growth, affect nutrient uptake, alters the chloroplast ultrastructure, inactivates enzymes of CO 2 fixation, inhibits photosynthesis and induces lipid peroxidation and antioxidant machinery. 4,[9][10][11] However, Cd is a non redox-active metal, but it induces the generation of reactive oxygen species (ROS) including superoxide radical (O 2•-), hydrogen peroxide (H 2 O 2 ) and hydroxyl radicalThe presence of cadmium (cd) in the agricultural soils affects horticultural cultivars and constrains the crop productivity. a pot experiment was performed using five cultivars of mustard (Brassica juncea L.) to evaluate the difference in their response to cd toxicity under greenhouse conditions. The pots containing reconstituted soil were supplied with different concentration of cdcl 2 (0, 25, 50, 100 or 150 mg cd kg -1 soil). Increasing concentration of cd in the soil resulted in decreased growth, photosynthesis and yield. Maximum significant reduction in growth, photosynthesis and yield were observed with 150 mg cd kg -1 soil in all the cultivars. Our results indicate that the cultivar alankar is found to be more tolerant to cd stress, recording higher plant dry mass, net photosynthesis rate, associated with high antioxidant activity and low cd content in the plant leaves and thus less oxidative damage. cultivar rh30 experienced maximum damage in terms of reduction in growth, photosynthesis, yield characteristics and oxidative damage and emerged as sensitive cultivar. The data of tolerance index of alankar were found to be higher among all tested mustard cultivars which indicate its higher tolerance to cd. Better coordination of antioxidants protected alankar from cd toxicity, whereas lesser antioxidant activity in rh30 resulted in maximum damage. cultivars of mustard were ranked with respect to their tolerance to cd: alankar > Varuna > Pusa Bold > Sakha > rh30, respectively.Differential cadmium stress tolerance in five indian mustard (Brassica juncea L.) cultivars

Synthesis and role of salicylic acid in wheat varieties with different levels of cadmium tolerance

“…Investigations on Indian mustard cultivars with different degrees of Cd tolerance showed that higher tolerance was due to better coordination between the antioxidant enzymes [28]. Although similar basal antioxidant enzyme activities were detected, Cd stress induced different changes in tolerant and sensitive cell lines of cucumber [29].…”

Interaction of silicon and cadmium in Brassica juncea and Brassica napus

“…Indian mustard (B. juncea) was reported among the most viable candidates for the phytoextraction of a number of metals including Cd, Cr, 137 Cs, Cu, Ni, Pb, U and Zn (Kumar et al 1995;Blaylock et al 1997;Zhu et al 1999). B. juncea Silicon and cadmium effects on Brassica species 499 cultivars showed differential tolerance to Cd stress (Gill et al 2011). This species does not belong to the hyperaccumulator species sensu stricto, but is an attractive candidate for phytoremediation due to its heavy metal tolerance (Bogs et al 2003).…”

Random amplified polymorphic DNA as a method to screen metal-tolerant barley (Hordeum vulgare L.) genotypes

“…However, the treatment with lower concentrations of cadmium, boron, or nickel could induce the root and seedling growth in plants and consequently could lead to higher biomass accumulation (Gratão et al, 2008). The growth inhibition in cadmium-treated barley seedlings may be due to the interference of vital metabolic processes such as photosynthesis, respiration, and nutrient transport Root t ssue (Gill et al, 2011). Similarly, excess copper causes injury to plants and inhibition of cell elongation and cell division, which ultimately leads to retardation of plant growth (Körpe and Aras, 2011;Kalai et al, 2014).…”

“…Indeed, there is no unique parameter to determine metal or salt tolerance of plant genotypes. For instance, the shoot and root dry weights (Bağcı et al, 2003;Gill et al, 2011), root lengths (Roy and Bhadra, 2014), shoot and root lengths (Bauddh and Singh, 2011), shoot fresh weights (Jaarsma et al, 2013), and shoot and root fresh weights (Metwally et al, 2005) have all been used to evaluate metal or salt tolerance of plant genotypes. There is no standard way to calculate tolerance index for plant species or cultivars against metal exposure.…”