Piriformospora indica confers cadmium tolerance in Nicotiana tabacum

Piriformospora indica, a root-colonizing endophytic fungus of Sebacinales, promotes plant growth and confers resistance against biotic and abiotic stresses. In order to confirm the influence of P. indica on growth, proline, malondialdehyde (MDA), chlorophyll, and cadmium (Cd) amounts in Nicotiana tabacum under Cd stress, hydroponics, pot and field trials were conducted. The results showed that P. indica can store Cd in plant roots and reduce leaf Cd content, reduce the concentration of MDA, and increase the proline and chlorophyll content and the activities of catalase, peroxidase, and superoxide dismutase under hydroponic Cd stress. RT-PCR analysis showed that the relative expression level of genes Gsh2, TaPCS1, oas1, GPX, and Hsp70 in colonized plants was 4.3, 1.4, 2.9, 1.7, and 6.9 fold higher than in un-colonized plants respectively. Cd exposure significantly reduced un-colonized plants' agronomic traits compared to P. indica-colonized ones. Our results suggested that P. indica can sequester Cd in roots, so that much less cadmium was transported to leaves, and the increased concentrations of antioxidant enzymes, pigments and proline contents, as well as the higher expression of stress-related phytochelatin biosynthesis genes in P. indica-inoculated plants, may also serve to protect N. tabacum plants against oxidative damage, enhancing Cd tolerance.

Note: “−P, + P” indicate the plants un-inoculated or inoculated with P. indica, “R, L” indicate the root and leaf of N. tabacum.In order to research the influence of Piriformospora indica puts on Nicotiana tabacum cadmium (Cd) content, hydroponic, pot and field trials were carried out. The hydroponic experiment results showed that Cd content in root and leaf of plants increased with the increase of Cd treatment concentration. Cd content in P. indica-inoculated plant roots much higher than the colonized, but the leaf Cd of colonized plants was much lower compared to non-inoculated plants, indicating that the fungus possessing suitable degradation pathways or metal sequestration or chelation system, can chelate Cd or adsorb Cd to chitin in the root tissues of plant. This causes accumulation of Cd in roots, and prevents Cd translocation from roots to leaves, resulted in the Cd content in leaves reduced under Cd stress. This finding suggests that P. indica has a positive influence in reducing leaf Cd content, contributing to reduce heavy metal content in cigarettes.Figure optionsDownload as PowerPoint slide