Title: Regulatory role of Ca2+ and NO in
salicylic acid (SA) induced signaling against
Ni2+-induced toxicity in Anabaena sp. PCC 7120
Running Head: Ca2+ and NO in SA signaling
against Ni2+- toxicity
Authors: Nidhi Verma†, Parul
Parihar†, Rachana Singh*, Sheo Mohan Prasad*, Aparna
Pandey
Affiliation: Ranjan Plant Physiology and Biochemistry
Laboratory, Department of Botany, University of Allahabad, Prayagraj-
211002 India.
Emailing addresses:nidhi111verma@gmail.com
(N. Verma),
parulprhr336@gmail.com
(P. Parihar)
*Corresponding authors’ email:rachanaranjansingh@gmail.com
(R. Singh),
profsmprasad@gmail.com
(S.M. Prasad)
†Contributed equally
Abstract: Present study deals with the regulation of SA induced
Ca2+-mediated NO signaling in cyanobacteriumAnabaena PCC 7120. Nickel (Ni2+)-toxicity
strongly inhibited growth (DW), exopolysaccharides, photosynthetic
pigments, PSII photochemistry (OJIP transient parameters:Fm , Fv ,Fm/Fo ,Fv/Fo , Ψo ,ФPo , ФEo , Area ,N , and PIABS were suppressed; whileFo , Fo/Fm ,Fo/Fv , Sm ,ФDo , ABS/RC ,TRo/RC , ETo/RC andDIo/RC were raised), nitrogen metabolism status
and non-enzymatic antioxidant system by increasing intracellular
Ni2+ accumulation and excessive ROS production.
However, salicylic acid (SA), calcium (CaCl2) and sodium
nitroprusside (SNP) addition to the culture medium counteracted on
negative impact of Ni2+ thereby improving the growth.
Further, to investigate the relation between Ca2+ and
NO, when c-PTIO was supplemented to Ni+SA+Ca and EGTA to Ni+SA+NO
treated culture medium, the recovery on above studied traits caused due
to Ca2+ and NO was arrested even in presence of SA to
Ni2+-stressed Anabaena cells thereby suggesting
the signaling behavior of Ca2+ and NO in SA induced
pathway; however, the impact was worsened under c-PTIO supplemented
Ni+SA+Ca than EGTA supplemented Ni+SA+NO treatment thereby suggesting
key role of NO in SA-induced Ca2+-mediated signaling.
Additionally, NO accumulation, intracellular Ni2+accumulation, ROS and indices, and non-enzymatic antioxidant system were
also examined that showed varied results.