Cadmium toxicity in Arabidopsis plants with altered polyamine metabolism

RECALDE LAURA; BENAVIDES MA. PATRICIA; VAZQUEZ, A; GROPPA MA. DANIELA

Buenos Aires

Congreso; Reunión conjunta de sociedades de biociencias; 2019

SAIB

Cadmium is a non-essential element normally present in soils atlow concentrations but now widespread due to industrial activitiesand fertilizers applications. Nitrogen is a crucial nutrient, for what nitrogen fertilization is a strategy to increase shoot biomass but also rises metal extraction from soils, adding the risk of Cd accumulation infood. Polyamines are vital nitrogen-containing compounds related toabiotic stress tolerance. To study the importance of N levels in alleviating Cd toxicity, transgenic Arabidopsis plants with increased Putlevels were used. Wild type, 7.2 and 2.1 transgenic seeds were germinated and grown for 10d in a controlled climate room at 22±2°Cin pots with a mixture of organic substrate:perlite:vermiculite (1:1:2).Thereafter, they were irrigated either with Hoagland (C) or with Hoagland added with 100 µM Cd Cl2 for 10 d. Rosettes were used forexperiments. Biomass and RWC did not change, chlorophyll contentdecreased around 30% whereas lipid peroxidation was not modifiedafter Cd treatment in all cultivars. The antioxidant enzymes catalase(CAT) and guaiacol peroxidase (GPOX) were constitutively increased in the transgenic 7.2 and 2.1 cultivars. Catalase activity wasreduced 60% in WT plants and between 30 and 40% in transgenicplants after Cd exposure. GPOX activity was not modified in WTplants but increased around 40% with Cd in both Put overproducers.Nitrate reductase (NR), a crucial enzyme in N metabolism, was 18%higher in transgenic cultivars compared to WT plants without Cd,and was reduced around 20% only in 7.2 transgenic line upon Cdexposure. Despite growth was not affected and no toxicity symptoms were observed either in WT or in transgenic cultivars after Cdtreatment, some antioxidant enzymes as well as NR were constitutively modified in Put overproducers plants and were differentiallyaffected by the metal, suggesting a relationship between Cd stress,N metabolism and the antioxidant status in plantsKeywords: cadmium, nitrogen metabolism, polyamines, Arabidopsis