Context

Scientists at the DBT-Institute of Life Sciences, Bhubaneswar have reported for the first time a reference-grade whole genome sequence of a highly salt-tolerantand salt-secreting true-mangrove species, Avicennia marina.

About

About the salt secreting 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.

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.

The genome sequence

• This study reports the assemblage of a 456.6 Mb of the estimated 462.7 Mb A. marina genome (98.7% genome coverage) in 31 chromosomes derived from 88 scaffolds and 252 contigs.
• The percentage of genomes in gaps was 0.26%, thereby proving it to be a high-level assembly.
• This study employed the latest genome sequencing and assembling technologies and identi?ed 31,477 protein-coding genes and a “salinome” consisting of 3246 salinity-responsive genes and homologs of 614 experimentally validated salinity tolerance genes.
• The study reported identi?cation of 614 genes, including 159 transcription factors, which are homologous to the genes that were functionally validated for salinity tolerance in transgenic systems.

Significance of study

• 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 signi?cant challenge to crop production in dryland areas.
• 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.

Mangroves in India India has about 3% of the total Mangrove cover in South Asia” “Mangrove cover in the country has increased by 54 sq km (1.10%) as compared to the previous assessment.” “The current assessment shows that mangrove cover in the country is 4,975 sq km [(1.2 million acres)], which is 0.15% of the country’s total geographical area.” West Bengal has 42.45% of India’s mangrove cover, followed by Gujarat 23.66% and A&N Islands 12.39%.  Gujarat shows maximum increase of 37 sq km in mangrove cover.