Impacts of seed priming with salicylic acid and sodium hydrosulfide on possible metabolic pathway of two amino acids in maize plant under lead stress.

Heavy metals pollution is one of the key environmental problems. In this research, the effect of seed priming with salicylic acid and sodium hydrosulfide was investigated on methionine and arginine amino acids contents and some compounds derived from their metabolism as well as ZmACS6 and ZmSAMD transcripts levels in maize plants under lead stress. For this purpose, maize seeds were soaked in salicylic acid (0.5 mM) and sodium hydrosulfide (0.5 mM) for 12 hours and then exposed to lead (2.5 mM) for 9 days. The results showed that lead stress reduced nitric oxide content and shoot ZmACS6 and ZmSAMD transcript levels while increased glycine betaine, methionine, arginine and proline amino acids contents as well as root ZmACS6 and ZmSAMD transcript levels. Salicylic acid and sodium hydrosulfide pretreatments reduced methionine, arginine and proline accumulation and increased glycine betaine and nitric oxide contents and regulated the expression of ZmACS6 and ZmSAMD genes (genes participating in methionine metabolism) under lead stress. Our data suggest that salicylic acid and hydrogen sulfide play role in regulating the methionine and arginine metabolism in maize under lead stress condition.