Over 60 species of plants that can survive extreme dehydration found in Western Ghats

Over 60 species of plants that can survive extreme dehydration found in Western Ghats

Subject : Environment

Section: Species in news

Context:

• In the biodiversity hotspot Western Ghats, researchers have found 62 species of plants that can withstand harsh environments .

Details:

• The discovery of the species, called desiccation-tolerant (DT) vascular plants, has potential applications in agriculture, particularly in areas where water is scarce.
• Out of the 62 species identified, 16 are endemic to India while 12 are exclusive to Western Ghats outcrops.
• Hydration and desiccation-tolerance are two commonly studied strategies for plants in extreme habitats.
  • Hydration is a condition where plant tissues can tolerate more than 30 percent of water content. But in desiccation, plants undergo longer dry days during which the moisture content of the leaves is the same as in the air.
• India now has nine new generic records for the global list. They are identified as Pyrrosia, Aleuritopteris, Corallodiscus, Arundinella, Bhidea, Bothriochloa, Danthonidium, Dimeria and Glyphochloa.
• The findings revealed that Indian desiccation tolerant plants are spread mainly in rock outcrops and partially shaded tree trunks inside the forests. Ferricretes (layers of sedimentary rock) and basaltic plateaus seemed to be the preferred habitats.
• Glyphochloa goaensis, Glyphochloa ratnagirica and Glyphochloa santapaui were found only on ferricretes, while the rest of the species were found in both ferricretes and basaltic plateaus. The dominant genus was Glyphochloa, with mostly annual species occurring on plateaus.

About the desiccation-tolerant (DT) plants:

• DT plants can withstand extreme dehydration, losing up to 95 per cent of their water content.
• They are usually found in rocky outcrops in the tropics and can recover quickly when water supplies are restored.
• Some species were found to survive at increasing temperatures, which is crucial for the warming planet.
• DT plant varieties are found in both flowering and non-flowering species and in both temperate and tropical climates. The global population of these species ranges between 300 and 1,500.
• Colour changes and morphological characteristics were also observed in the species.
  • It was found that Tripogon species changed colours from greyish in dry conditions to green in hydrated situations, while turning orange to brownish yellow in the beginning of greening.
  • In another species, Oropetium thomaeum, the leaf cloud changed from green in hydrated phase to dark purple or orange and ranged from greyish to ash colour during the period of desiccation.
  • Ferns (fronds) displayed a variety of characteristics, including curling inwards towards the costa, exposing spores at the start of the dry season and during brief dry spells.
  • In the case of C lanuginosus, its leaves folded and shrank inward to protect the chlorophyllous part, not directly exposing them to sunlight during the desiccation phase.
• Utility of the discovery:
  • The genes of these plants could be used to create a high-temperature tolerant variety of crops to improve climate resilience and ensure food security for the masses.

Characteristics:

Extremophytes:

• Some plant species — ranging from algae to angiosperms — thrive in harsh environments and are termed as extremophytes.
• These species are found in extreme habitats, like hot and cold deserts, estuaries, rock outcrops, glaciers and other arid and semi-arid regions.
• Organisms living in such habitats face consistent droughts, but some experience cycles of desiccation. “To adapt to extreme conditions, these plant species develop adaptive strategies to survive through morphological and physiological traits.

Types of Extremophiles

• Acidophile: low pH; optimally 3 or below
• Alkaliphile: high pH; optimally 9 or above
• Anaerobe: little to no oxygen needed for growth
• Halophile: high salt, at least 0.2M, needed for growth
• Hyperthermophile: high heat, 80-122 C
• Hypolith: lives under rocks in cold deserts
• Metallotolerant: tolerating high levels of metal concentrations
• Oligotroph: can grow in nutritionally limited environments
• Osmophile: can grow in high sugar concentrations
• Psychrophile: very low heat, temperatures of less than -15 C
• Radioresistant: extreme radioactivity
• Xerophile: grow in very dry condition

Biodiversity Hotspots

• Biodiversity hotspots are regions that contain a high level of species diversity, many endemic species and a significant number of threatened or endangered species.
• These are heavily threatened by habitat loss and other human activities.
• Endemic species are those species which are limited/restricted to a particular region and are not found in other parts/areas of the world.
• This concept of hotspots was introduced in the late 1980s.
• A total of 36 regions across the globe are considered as Biodiversity Hotspots, which represent 2.5% of Earth’s land surface.
• These support more than half of the world’s plant species as endemics and more than 40% Mammals / birds / reptiles species as endemics.

Criteria for a Biodiversity Hotspot :

• It must have at least 1,500 vascular plants as endemics — which is to say, it must have a high percentage of plant life found nowhere else on the planet. A hotspot, in other words, is irreplaceable.
• It must have 30% or less of its original natural vegetation. In other words, it must be threatened.

Biodiversity Hotspots in India

• India has 4 Biodiversity Hotspots which are –
  • Himalayas
  • Indo-Burma region
  • Western Ghats
  • Sundaland