Epibrassinolide regulated synthesis of polyamines and auxins in Raphanus sativus L. seedlings under Cu metal stress

Abstract

The effects of various conc of (10-11, 10-9 and 10-7 M) 24-epibrassinolide (24-epiBL) on polyamines and auxins contents was analyzed in 7days old seedlings of Raphanus sativus L. cv. Pusa chetki under copper metal stress. Cu metal (0.2mM) treatment significantly increased endogenous levels of putrescine, spermidine and spermine when compared with control values. Cadaverine content got decreased under metal stress. Endogenous polyamines showed varying levels in seedlings when applying 24-epiBL treatment only. Maximum increase was found in putrescine, cadaverine and spermidine in 10-11, 10-9 and 10-7 M conc of 24-epiBL respectively when applied alone to R. sativus seedlings. However, metal treatment supplemented with 24-epiBL revealed small increase in polyamines. Putrescine and cadaverine got enhanced in combination of Cu metal and 10-7 M (24-epiBL) in comparison to metal treatment alone, whereas decrease in spermidine and spermine levels were recorded in combinations of Cu metal and 10-9 and 10-7 M 24-epiBL respectively. Endogenous contents of Indole-3-acetic acid (IAA) and Naphthalene acetic acid (NAA) were significantly affected by 24-epiBL when applied alone or along with Cu metal. Both free and bound forms of NAA were not detected in untreated seedlings, but were recorded in seedlings treated with metal stress. Decreased IAA contents observed in metal treatment got enhanced significantly in seedlings with 24-epiBL supplementation. To the best of our knowledge the present investigation is the first one to explain the effects of 24-epiBL on endogenous contents of polyamines, indole acetic acid and naphthalene acetic acid under copper metal stress.