Effect of Salicylic acid and Methyl Jasmonate on Antioxidant systems of Haematococcus pluvialis

The influence of phytohormones, salicylic acid
(SA) and methyl jasmonate (MJ) on the antioxidant systems
in Haematococcus pluvialis was investigated. Both
SA and MJ at 500 lM concentration reduced the growth of
alga with salicylic acid, having more pronounced effect.
Carotenoid and chlorophyll contents were decreased by SA
and increased by MJ. Salicylic acid (100 lM) increased
astaxanthin content to 6.8-fold under low light
(30 lmol m-2 s-1), while MJ (10 lM) showed marginal
increase in astaxanthin. Salicylic acid (500 lM) increased
superoxide dismutase activity to 4.5- and 3.3-fold and
ascorbate peroxidase (APX) activity to 15.5- and 7.1-fold
under low and high light, respectively. Methyl jasmonate
increased catalase activity (1.4-fold) under high light and
APX activity (5.4-fold) under low light. Different mechanism
of oxidative stress induced antioxidant production
may be the plausible reason for this varied response for
salicylic acid and methyl jasmonate. Higher concentrations
of SA and MJ inhibited astaxanthin accumulation by different
mechanisms either by scavenging the free radicals or
by increasing primary carotenoids production. At lower
concentrations, these phytohormones could be used for
elicitation of secondary carotenoid production.