The scientific community has recently made a significant breakthrough in the field of genomics. For the first time, researchers have successfully unveiled the reference-grade whole genome sequence of the highly salt-tolerant mangrove species, Avicennia marina. The research was spearheaded by the Department of Biotechnology (DBT)-Institute of Life Sciences, based in Bhubaneswar.
About Avicennia Marina
Avicennia Marina is among the most prominent mangrove species found all across India, often referred to as the grey or white mangrove. Apart from its unique ability to thrive optimally in 75% seawater, it can also tolerate greater than 250% seawater. Few plants possess the extraordinary ability of this species to excrete up to 40% of salt through leaf-based glands and prevent salt entry at the roots.
The Importance of This Study
Global agricultural productivity is increasingly compromised by abiotic stressors like limited water availability and soil and water salinization. This study holds immense relevance in addressing these challenges.
Dryland areas, constituting 40% of the world’s total land, face significant hurdles in crop production due to water scarcity. Moreover, saline conditions impact around 900 million hectares globally, including an estimated 6.73 million ha in India, causing an annual financial loss of 27 billion USD.
As a result of the study, genomic resources were developed. These will enable scientists to explore the potential of identified genes for creating drought and salinity-resistant crop strains. This could revolutionize farming in coastal regions, which is of particular significance for India with its 7,500m coastline and two substantial island systems.
Mangroves: An Overview
Mangroves are small trees or shrubs that grow along coastlines in salty sediments, sometimes even underwater. They belong to the Rhizophoraceae, Acanthaceae, Lythraceae, Combretaceae and Arecaceae families.
Mangroves have several peculiar characteristics. They can survive harsh conditions like high salt levels and low oxygen availability. They have special roots called pneumatophores, which absorb oxygen from the air due to minimal soil oxygen. Moreover, these trees store fresh water in thick, succulent leaves to minimize evaporation, and their seeds germinate while still on the parent tree.
Threats to Mangroves
Despite their environmental importance, mangroves face several threats. Coastal development activities like constructing shrimp farms and hotels lead to widespread mangrove deforestation. The trees are also harvested unsustainably for firewood, construction wood, charcoal production, and animal fodder. Overfishing, pollution, and rising sea levels further threaten mangrove ecosystems.
Mangroves: A Global and Indian Perspective
Mangroves are found in over 118 countries in the tropical and subtropical regions. Asia boasts the largest mangrove coverage worldwide, followed by Africa, North and Central America, Oceania, and South America.
In the context of India’s State of Forest Report 2019, mangroves cover 4,975 sq km, accounting for 0.15% of its total geographical area. Several major river deltas, as well as Kerala’s backwaters, have dense mangrove forests. West Bengal’s Sundarbans is the largest mangrove region globally and a UNESCO World Heritage Site. West Bengal has 42.45% of India’s mangrove cover, followed by Gujarat at 23.66%, and Andaman & Nicobar Islands at 12.39%.