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

In the biodiversity hotspot Western Ghats, researchers have found 62 species of plants that can withstand harsh environments . The discovery of the species, called desiccation-tolerant (DT) vascular plants, has potential applications in agriculture, particularly in areas where water is scarce. 

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, Mandar Datar, one of the authors of the research, told Down To Earth.

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“Futuristically speaking, 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 mass,” Datar said. The new inventory opens new avenues for research and the need to explore more DT plants elsewhere. 

Some plant species — ranging from algae to angiosperms — thrive in harsh environments and are termed as extremophytes, he explained. 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,” Datar said.

Out of the 62 species identified, 16 are endemic to India while 12 are exclusive to Western Ghats outcrops, said Aboli Kulkarni, another author of the study. “The findings only underline the importance of Western Ghats and as a global desiccation tolerant hotspot,” she added.

Hydration and desiccation-tolerance are two commonly studied strategies for plants in extreme habitats, he added.

“Hydration is a condition where plant tissues can tolerate more than 30 per cent 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,” he said.

The findings, Desiccation-tolerant vascular plants from Western Ghats, India: review, updated checklist, future prospects and new insights, were published in Nordic Journal of Botany in June. 

The paper said: 

Some bryophytes, ferns, lycophytes and angiosperms growing in seasonally dry and semi-arid habitats have evolved a mechanism known as desiccation-tolerance by which plants can tolerate a loss of 80–95 per cent of their relative water content and resurrect back.

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, according to the study.

The understanding of DT plants is poor in India, said Kulkarni. “Because this is such a vastly diverse country with a variety of habitats, such as forests, grasslands and outcrops, the species have received less research,” she said.

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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 researchers visited 17 sites between 2017 and 2020 to collect 26 random species samples during monsoon and post-monsoon.

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. 

“The Northern Western Ghats (NWG) cliff habitat is otherwise dominated by the grass genus Tripogon, along with ferns that desiccate for eight months and revive during monsoon,” the paper stated.

Species like Indopoa paupercula and Dimeria preferred boulders, gravelly patches, cryptogamic crusts, shallow and deep soil depressions.

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,” Kulkarni said.

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.

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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. 

However, this was not the same for all species. 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, the researchers found, underlining the need for more studies into DT plants. 

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