Effects of humic acid on antioxidant defense system and senescence-related genes expression in petals of LA-Hybrid Lily

In cut flowers, increasing postharvest flower life is the most important commercial factor in all cultivars. HA is a compound derived from animal and plant decomposition. Due to hormone-like effects of HA, the effects of HA on expression of three senescence dependent genes: CYP , NAC2 and LOX were investigated in Lilium longiflorum Hybrid LA petals during bud development and onset of senescence. The SSC, soluble sugars and MDA along with activity of POD, SOD and CAT were measured at these stages. The results showed that expression of CYP and LOX genes decreased in both stages under induction of HA. The expression of these genes decreased in the senescence stage more severely. The expression of NAC2 gene also increased in treated plants with 4.1-fold. Enzymatic results showed that the effect of HA on stimulation of POD enzyme activity was more than other enzymes so that 95% of POD increased in bud development stage. These findings showed that HA is able to reduce damage of senescence by strengthening the antioxidant system. It can induce metabolic changes or expression of gene in anti-aging pathways.