Endophyte-Mediated Reinforcement of Morpho-Physiology of Brassica juncea Under Cadmium Toxicity

The present study was conducted to test the efficacy of Serendipita indica in Brassica juncea against cadmium (Cd) stress. Cd is a trace element that enters into plants through contaminated soil. Serendipita indica is a fungal endophyte which colonizes and benefits exceptionally large group of plants. Roots of 3-days old B. juncea seedlings were inoculated with S. indica and raised in toxic Cd concentrations (10 mu M, 30 mu M and 50 mu M Cd) till 12 days after inoculation in plant growth chamber with conditions of 16-h light/8-h dark photoperiod, temperature 25 degrees C (+/- 2 degrees C) and 80% relative humidity. The seedlings were tested for various morpho-physiological parameters like seed germination, plant biomass and %age heavy metal tolerance index. Also, various non-enzymatic antioxidants like vitamin A, vitamin C, phenols, flavonoids, total soluble sugars, reducing and non-reducing sugars were analyzed. Cd led to reduction in the % age germination of B. juncea seeds. Serendipita indica inoculation incremented the growth parameters like fresh weight, dry weight, root length, shoot length which were diminished by Cd stress. Enhancement of 20.66% in root length was observed in inoculated and Cd stressed seedlings. The content of phenols increased under unstressed conditions by 26.6% and by 55.29% under Cd stressed conditions in S. indica inoculated seedlings along with increasing contents of vitamin A and C. Overall, the content of carbohydrates was enhanced with S. indica inoculation. The study suggests that S. indica endophyte has great potential in boosting growth and physiological parameters which help in managing Cd stress in B. juncea.