Why In News?

Scientists from the MACS Agharkar Research Institute (ARI), Pune have discovered five new species of lichen-forming fungi belonging to the genus Allographa in the biodiversity-rich Western Ghats.

 

What is Allographa?

Allographa is a genus of script lichens, meaning it is a composite organism formed by a fungus pairing with algae or cyanobacteria to create a lichen.

 

The genus belongs to the family Graphidaceae and consists of more than 200 globally recognized species.

 

Characteristics

  • It exhibits robust and prominent elongated fruiting bodies known as lirellae.

  • The species has a completely carbonized excipulum, giving the fruiting bodies a distinctly dark, massive structure.

  • They feature large, colourless (hyaline) ascospores that turn a violet-blue color when exposed to iodine.

 

Which New Species Were Discovered?

  • Allographa keralensis: Named geographically after the state of Kerala.

  • Allographa nayakae: Named to honor the renowned Indian lichenologist Dr. Sanjeeva Nayaka.

  • Allographa paraconsanguinea.

  • Allographa persistinspersa.

  • Allographa semicarbonisata.

 

What are Lichens?

Composite Organism: Lichens are not a single organism. They are a symbiotic, mutualistic partnership between two distinct organisms.

 

The Partners:

  • Mycobiont (Fungi): Forms the dominant structural body (thallus). It provides protection, secures anchorage, and absorbs water and mineral nutrients from the environment. It belongs mostly to Ascomycota or Basidiomycota.

  • Photobiont (Algae/Cyanobacteria): The photosynthetic component. It contains chlorophyll to synthesize food (carbohydrates) for the association. 

 

Ecological Significance & Functions

  • Pioneer Species: Lichens are primary colonizers of bare rocks. They secrete organic acids (like oxalic acid) that chemically weather rocks into soil particles, initiating primary ecological succession. 

  • Bioindicators of Air Pollution:

    • They lack a protective cuticle or roots, absorbing water and gases directly from the atmosphere.

    • They are highly sensitive to Sulfur Dioxide (SO₂) and heavy metals.

    • Their absence or decline in an area indicates high levels of air pollution.

  • Climate & Forest Health Indicators: Recent discoveries (like the Allographa species in the Western Ghats) use molecular data to show that lichens act as highly sensitive indicators of micro-climatic shifts and forest degradation.

  • Nitrogen Fixation: Lichens containing cyanobacteria (blue-green algae) can fix atmospheric nitrogen, contributing directly to soil fertility in nutrient-poor ecosystems.  

 

Economic and Practical Uses

  • Litmus Paper: The chemical indicator dye litmus, used to test acidity (pH), is extracted from lichens like Roccella tinctoria. 

  • Food and Fodder: "Reindeer moss" serves as crucial winter food for arctic animals. In India, Parmelia perlata (known as Kalpasi or Dagad Phool) is widely used as a spice in traditional cooking.  

  • Perfumes and Medicines: Used as fixatives in the perfume industry and traditionally used to extract antibiotic compounds (like usnic acid) for wound healing. 

 

 

Source: PIB

 

 

 

PRACTICE QUESTION

Q. Consider the following statements regarding the recently discovered Allographa species:

  1. They are parasitic plants entirely dependent on tree sap for survival.

  2. They are lichen-forming fungi that establish a symbiotic relationship with algae or cyanobacteria.

  3. They are excellent bioindicators for monitoring air pollution. 

Which of the statements given above is/are correct? 

A) 1 only 

B) 2 and 3 only 

C) 1 and 3 only 

D) 1, 2, and 3

Answer: B

Explanation:

Statement 1 is incorrect: Allographa species are not parasitic plants. Instead, they belong to a diverse group of lichen-forming fungi.

Statement 2 is correct: Members of the genus Allographa are script lichens (lichen-forming fungi) that form a mutually beneficial symbiotic relationship with photosynthetic partners like algae (e.g., Trentepohlia) or cyanobacteria. 

Statement 3 is correct: Like many lichens, Allographa species are highly sensitive to air pollution, climate shifts, and habitat degradation, making them excellent bioindicators for assessing forest health and environmental quality.