Protein and enzymes regulations towards salt tolerance of some Indian mangroves in relation to adaptation

Abstract

Elevated substrate salinity and anthropogenic impulse are the major threat to the mangrove ecosystem. In the Indian subcontinent, Sundarbans have the richest mangrove species diversity. Due to geomorphic characteristics and unplanned management, the elevated salinity prevails in the western part and that has direct impact on vegetation. Seven mangrove taxa were examined, of which four (Aegialitis rotundifolia, Heritiera fomes, Xylocarpus granatum, and X. mekongensis) were considered as degrading and three (Bruguiera gymnorrhiza, Excoecaria agallocha, and Phoenix paludosa) were considered as natural control. The targeted taxa were collected from five different islands and were selected on the basis of increasing salinity gradient. As salinity increased from site I to V (11.76-15.2 ppt), the amount of total leaf proteins decreased in all the targeted species and ranged between 5.67 and 25.23%. The percentage of protein depletion was less in Aegialitis, Heritiera, and Xylocarpus than the other three taxa in higher salinity that pointed out their less adaptability, as degradation of protein may be essential for efficient stress management. Two antioxidative (peroxidase and superoxide dismutase) and two hydrolyzing (acid phosphatase and esterase) enzymes showed a positive correlation with salinity. In four degrading taxa, the percentage of enzyme increment was less than those of their natural control taxa. Salinity imposed increment of antioxidant enzymes facilitate ROS scavenging, which is an inevitable elevated byproduct during photo-inhibition. Lower amount and number of isoforms in higher salinity indicated towards less suitability of Aegialitis rotundifolia, Heritiera fomes, Xylocarpus granatum, and X. mekongensis in increased salinity level of western Sundarbans.

Role of Secondary Metabolites and Radical Scavenging Aptitude for Better Adaptability of Mangroves in Varying Salinity of Sundarbans, India

“…The soil salinities of these places were 11.77 ± 2.1, 12.25 ± 1.96, 12.4 ± 1.18, 13.98 ± 2.29 and 15.23 ± 2.16 ppt respectively (Dasgupta et al 2012). A controlled mesophytic (at the premises of Indian Statistical Institute, Kolkata where the soil salinity is 2 ppt, (Nandy et al, 2009)) replicas of the studied taxa of well matured up to 12 -15 years old, were also taken for comparative study (Table 1).…”

“…In the Indian subcontinent, Sundarbans mangrove swamp is the world's largest and having richest floral diversity (21°31' -22° 30' N and 88°10' -89°51' E), formed by two major rivers -the Ganga and the Brahmaputra and with their numerous tributaries (Dasgupta et al, 2012). Environmental (tectonic upliftment in north-western part, India and subsidence in the east, Bangladesh) and demographic compulsion (damming on river, urban sewage and industrial wastes expedite siltation in the riverbed) are interrupting the fresh water discharge through river systems, leading to salinity elevation of this zone.…”

RAPD and ISSR marker mediated genetic polymorphism of two mangroves Bruguiera gymnorrhiza and Heritiera fomes from Indian Sundarbans in relation to their sustainability

“…For each island or site, sampling was done from 6 locations with a minimum distance of 10 ft. The substrate salinity of these sites were in increasing gradient and measured as 11.77±2.1, 12.25±1.96, 12.4±1.18, 13.98±2.29 and 15.23±2.16 ppt respectively (Dasgupta et al 2012). The controlled mesophytic replicas of the studied taxa, well matured up to 15-17 years old, collected from the premises of Indian Statistical Institute, Kolkata, where the soil salinity was 2 ppt (Dasgupta et al 2012) were also taken for comparative study.…”

Molecular markers assisted DNA polymorphism: Implications in mangrove research

“…The authors commented that the high levels of the antioxidant enzymes enhanced the defensive ability of the plants against reactive oxygen species (ROS) which in turn avoids lipid peroxidation during salt stress. Dasgupta et al (7,28) worked with some mangrove species from Indian Sundarbans and reported an increase in concentration of two antioxidant enzymes PRX and SOD; and two stress-related hydrolyzing enzymes, Acid phosphatase and Esterase with the Horizon e-Publishing Group ISSN: 2348-1900 rise of salinity in in situ condition. Qualitative study with gel electrophoresis also indicated the density and/or number of bands increase (isoforms) for all the four enzymes with increased salinity.…”

“…According to a report, the mangrove forest area loss in the south Asia is approximately 1% every year (5). Sea level rise and increase in substrate salinity are the two major abiotic factors initiating the natural depletion of mangroves all over the world (6,7).…”