Short and Long Term Effects of Salicylic Acid on Protection to Phytoplasma Associated Stress in Potato Plants - Salicylic Acid: Plant Growth and Development - page 312

Popova 2007 ), potato microplants (Mora-Herrera et al. 2005 ), and in orange
(Huang et al. 2008 ).
Information about the SA effect on phytoplasma-induced disease is limited.
Previously, phytoplasma-damage reduction by sprayed SA was associated with
high hydrogen peroxide and ascorbic acid contents together with reduction of
peroxidase activity, favored photosynthate translocation, and improved tuber
quality, suggesting an important role of SA regulating these molecules counter-
acting pathogen effects (Sanchez-Rojo et al. 2011 ), however, the potential long
term effects of SA is poorly understood, even less is known about phytoplasma-
damage reduction in potato.
Hence, the present study evaluated the SA long-term effect on reducing phy-
toplasma-caused disease symptoms and physiological responses such as biomass
accumulation, POX activity, and AA and H 2 O 2 contents.

2 Materials and Methods

2.1 Plant Material

Virus-free Solanum tuberosum L. cv. Alpha microplants were obtained from the
in vitro Germoplasm Bank of the Instituto Nacional de Investigaciones Forestales
Agrícolas y Pecuarias at Metepec, México. The plants were also negative to C.
Liberibacter spp. Phytoplasma-infected potato plants were obtained from those
with PPT symptoms under natural conditions. Single node cuttings were in vitro
propagated in test tubes in Murashige and Skoog ( 1962 ) medium at 20 + 1C
under 16 h photoperiod (fluorescent lights, 35 lmol m -2 s -1 , 400-700 nm; Es-

pinoza et al. 1986 ).

2.2 Chemical Treatments

In vitro. Single node cuttings were obtained from in vitro phytoplasma infected
plants and subcultured in test tubes containing Murashige and Skoog ( 1962 )
medium added with SA (0, 0.1, 0.01 and 0.001 mM) and incubated at 20 + 1C
under 16 h of photoperiod (fluorescent lights, 35 lmol.m -2 s -1 , 400-700 nm).
Negative and positive phytoplasma plants were micropropagated without SA as
controls. Twenty to twenty five microplants 28-32-days-old from each treatment
were transplanted to greenhouse in pots containing peat-moss. All plants were
fertilized each 15 days and watered twice a week (Fig. 1 ).
Greenhouse. Twenty to twenty five in vitro phytoplasma infected plants 28-32-
days-old were transplanted to greenhouse in pots containing peat-moss. Negative
and positive phytoplasma plants were sprayed twice a week with SA 0, 0.1, 0.01