Genome of Avicennia marina – a Salt tolerant Mangrove Species - Decoded

• 10 Jul 2021

Indian scientists have for the first time achieved to bring out reference-grade whole genome sequence of a highly salt-tolerant and salt-secreting true-mangrove species, Avicennia marina.

About Avicennia marina

• Avicennia marina is one of the most prominent mangroves species found in all mangrove formations in India.
• It is a salt-secreting and extraordinarily salt-tolerant mangrove species that grows optimally in 75% seawater and tolerates >250% seawater.
• It is among the rare plant species, which can excrete 40% of the salt through the salt glands in the leaves, besides its extraordinary capacity to exclude salt entry to the roots.

Significance of the Find

• This study assumes significance as agriculture productivity globally is affected due to abiotic stress factors such as limited water availability and salinization of soil and water.
• Availability of water is a significant challenge to crop production in dryland areas, accounting for ~40 percent of the world’s total land area. Salinity, is prevalent in ~900 million hectares globally (with an estimated 6.73 million ha in India), and it is estimated to cause an annual loss of 27 billion USD.
• The genomic resources generated in the study will pave the way for researchers to study the potential of the identified genes for developing drought and salinity tolerant varieties of important crop species of the coastal region that is significant for India with 7,500m of coastline and two major island systems.

About Mangroves

• Mangroves are a unique group of species found in marshy intertidal estuarine regions and survive a high degree of salinity through several adaptive mechanisms.
• Mangroves are important resources for the coastal region and are of great ecological and economic value.
• They form a link between marine and terrestrial ecosystems, protect shorelines, provide habitat for a diverse array of terrestrial organisms.
• Mangroves occur in the tropics and subtropics between latitudes 25° N and 25°S.
• They require high solar radiation that helps to filter saline water through their roots. This explains why mangroves are confined to only tropical and subtropical coastal waters.
• Since mangroves grow between the land and sea, they represent the best example of ecotone and are breeding ground for many commercially important fishes.
• They contain a salt filtration system to deal with salt water immersion and wave action.
• They possess pneumatophores (blind roots) to overcome the respiration problem in the anaerobic soil.
• Mangroves show Viviparity mode of reproduction which means that seeds germinate in the tree itself before falling to the ground. This is an important adaptive mechanism to overcome the problem of germination in saline water.