Heavy metals in ecosystem threat for plant, crop growth: Banaras Hindu University study

VARANASI: A study conducted by the researchers from the department of Botany, Institute of Science, Banaras Hindu University, Bhabha Atomic Research Center (BARC) and department of Atomic Energy, Government of India, discovered that increased concentration of heavy metals like Cadmium is a threat for growth of plants and crops, increasing the concerns of food security.The study, led by an assistant professor Yogesh Mishra and his research scholars Akanksha Srivastava and Subhankar Biswas, tried to understand how cyanobacteria maintain photosynthesis under stressful conditions, particularly in the presence of heavy metals. Other members of the research team include Hema Rajaram and Arvind Kumar from BARC.
The latest finding has been published in the globally reputed scientific journal BBA-Proteins and Proteomics (January 2023).
“Growing human activities have resulted in a significant increase in the concentration of heavy metals in different ecosystems. Experts believe that this poses a serious threat to the growth of living organisms, especially photosynthetic organisms, as the structural and functional aspects of photosynthesis are extremely sensitive to heavy metals,” said Mishra, adding that the enhanced stress of Cadmium adversely impacts the productivity of plants/crops and could add to concerns of food security, already escalated by climate change situations. Interestingly, cyanobacteria (blue green algae), a significant class of photosynthetic prokaryotes that first appeared on earth at least 2.6 billion years ago when environmental conditions were harsh, are comparatively resistant to heavy metals.
He said that the process of photosynthesis has two modes -linear electron flow and cyclic electron flow. The enhanced accumulation of cadmium concentration adversely affects the linear electron flow. The research team observed that in case of highly toxic heavy metal cadmium stress in a model cyanobacterium, Anabaena sp. PCC 7120, linear electron flow gets affected while the cyclic electron flow gets activated to maintain the photosynthetic process. Another breakthrough finding revealed that LexA protein regulates these photosynthetic responses by regulating related key photosynthetic genes. This is the first such discovery so far in this direction.
Mishra said the finding is a result of a detailed study carried out over the years. The finding is expected to pave the way for further research to address the challenges of heavy metal toxicity in the ecosystem and also help in developing stress tolerant crops with improved photosynthesis efficiency, helping in dealing with the question of food security, he added. “Since photosynthesis is one of the vital processes that is affected by heavy metal stress, our findings are promising for the development of recombinant cyanobacteria with improved photosynthetic efficiency and heavy metal tolerance capacity,” said Mishra. Previous works of the series were published in reputed peer-reviewed journals Environmental and Experimental Botany (2022) and Algal Research (2021), he added.
Mishra also worked as a post-doctoral fellow at the Max Plank Institute in Cologne, Germany, and the Umea Plant Science Center in Sweden, from 2008 to 2013. His area of interest is molecular stress biology of cyanobacteria and plants.