Auxin-mediated growth of rice in cadmium-contaminated soil

Abstract

Pollution from heavy metals is a global problem that is very dangerous to the environment. Among the heavy metals, cadmium is receiving more and more attention because it is one of the most ecotoxic, making it very harmful for biological activity in soil, biodiversity, plant metabolism, and human and animal health. Phytohormones, produced by plants, control or regulate germination, growth, metabolism, or other physiological activities, and they can alleviate the toxic effects of heavy metals on plant growth. Auxin is the most abundant natural growth hormone, controlling apical dominance, tropism, elongation of shoots, and initiation of roots in plants. However, cadmium stress causes the degradation of indigenous auxin. To cope with this, auxin may be applied exogenously. To evaluate the role of auxin in cadmium -contaminated soil, different levels of the auxin precursor L-TRP were applied to plants growing in contaminated soil. Rice seedlings were dipped in a L-TRP solution for 2 h and transplanted into potted soil contaminated with 30 mg kg -1 cadmium. The results showed that the exogenous application of L-TRP improved the growth and yield of treated plants both in normal and contaminated soil. The data of different parameters showed that L-TRP enhanced plant height (12.54%), the number of tillers (25.53%), the number of panicles (19.04%), the 1000 grain weight (19.28%), and the paddy yield (11.78%) in cadmiumcontaminated soil, as compared to plants grown in the absence of L-TRP with the same level of contamination. L-TRP increased the uptake of cadmium in rice straw while decreasing the translocation of cadmium towards grains, as compared to plants grown in contaminated soil without L-TRP. This experiment revealed the possibility of using L-TRP to improve plant growth and soil health in contaminated soil.

Determination of selected dynamic quantities of growing intact seeds of maize

“…3 behave in an almost perfectly opposite manner and this stimulatory behaviour for IAA and the opposite inhibitory behaviour for CdCl 2 are well known in the literature, e.g. Hu et al (2013), Farooq et al (2015), see also Discussion. This stimulatory/inhibitory behaviour is clearly visible when comparing the fitting parameters C and D for the different growth factors applied at the same concentrations, see Supplementary Information and Fig.…”

“…Indeed, this fact is well known in the literature, e.g. in Farooq et al (2015), the researchers studied the influence of cadmium on plant growth and development with or without the addition of the auxin precursor L-TRP to the incubation medium. The addition of L-TRP significantly improved plant growth and yield under cadmium stress.…”

Combined Action of Copper with IAA on Individual Amino Acids and Microelement in Pods of Two Broad Bean Cultivars

“…Exogenous supply of IAA also improved the growth of Brassica juncea exposed to As [76]. In the same way, the application of different levels of L-TRP (a precursor of auxin) to the roots of rice seedlings growing in contaminated soil enhanced plant growth and yield under Cd stress, when compared to untreated seedlings in Cd-contaminated pots without this auxin precursor [80]. Some recent approaches showed that this synergistic or additive interaction between heavy metal and auxin can be used as a protective mechanism against toxicity in water environment.…”

Interactions between plant hormones and thiol-related heavy metal chelators

“…Its homeostasis (synthesis, distribution, metabolism and transport) within the plant is regulated by various environmental factors and may be disturbed by heavy metals (Hu et al 2013). However, application of tryptophan, a precursor of auxin to the roots of rice seedlings, enhanced plant growth and yield under Cd stress (Farooq et al 2015). It has been also revealed that under optimum growth conditions, root growth dependence on glutathione is linked to auxin transport in Arabidopsis (Koprivova et al 2010).…”