Effect Of Cd On Nutrient Elements And Free Amino Acids Of Kandelia Candel Seedlings

Kandelia candel is a common woody plant in mangrove forest. Because of its special environment and the growth of their physiological characteristics, it has the capacity of the heavy metal pollution tolerance and purification. Current research on mangrove plants mainly in three areas: the first is on field surveys and sampling, analysis of heavy metals in mangrove plants and their habitat in the accumulation and distribution; the second is physical aspect, mainly study mangrove plant antioxidant enzymes and photosynthetic enzyme system analysis; the third is molecular context, mainly study heavy metal tolerance genes. Few researchers have investigated attention to heavy metal Cd on the mangrove plant nutrients and free amino acids. The study is focused on two aspects from the above, revealed the Kandelia candel seedlings in Cd stress, nutrient elements and free amino acids change.The impacts of cadmium (Cd) stress, at five levels ranging from 0.25 to 200 mg/ L, on 1-month old seedlings of Kandelia candel were studied through analyzing the concentrations of nutrient elements, free amino acids in the seedlings after two-week treatment . The results show that:(1) Although some stress symptoms, including leaf yellowing, inhibition of the increments of plant height and fresh weight, were observed when Cd concentration higher than 10 mg L-1, the root of Kandelia candel. could still adsorb/absorb and fix significant amounts of Cd up to 36.02 mg g-1 DW at 200 mg L-1 Cd treatments.(2) Cd treatments at concentrations higher than 10 mg L-1 would inhibit the growth of Kandelia candel. However, no dead case was observed for two-week treatment at any Cd level.(3) Macro-nutrient elements such as potassium (K), calcium (Ca) and magnesium (Mg) in roots significantly decreased when Cd concentration was higher than 10 mg L-1. Micro-nutrient elements Iron (Fe), zinc (Zn), monel (Mn) and copper (Cu) in roots are similar to the changes, Cd stress may make ZIP family proteins increased, so increased their levels in cells.(4) Cd stress affected the free amino acid content of Kandelia candel, and this is on the N metabolism of impact. Proline (Pro), alanine (Ala), cysteine (Cys), methionine (Met), lysine (Lys), valine (Val) and leucine (Leu), they were accumulated in Kandelia candel seedlings, which was high related with Cd stress.(5) Cd stress did not result in changes in morphological and anatomical features of K. candel seedlings after two weeks treatment.