Work done in the lab of Dr. Divya Chandran at Regional Centre for Biotechnology, Faridabad
Akriti Sharma obtained her B.Sc. in Microbiology from the University of Delhi and her M.Sc. in Biotechnology from Guru Jambheshwar University of Science and Technology, Hisar. She is pursuing her PhD in plant cell biology under Dr. Divya Chandran at the Regional Centre for Biotechnology, Faridabad. She is investigating how the plant nuclear movement is regulated during plant-pathogen interactions and its biological significance.
Unlike in school textbooks where the nucleus is shown at the center of the cell, the nucleus in actuality is highly dynamic. It frequently changes its position in response to internal and external stimuli. This repositioning of the nucleus is controlled by the cytoskeleton, which serves as tracks along which the nucleus moves. In plants, nuclear movement has been studied during plant development as well as plant-pathogen interaction. However, how and why the plant nucleus moves upon attack by a pathogen is poorly understood. To address this, we investigated the nuclear behavior in plant cells upon pathogen attack. For this, we worked on pea, which is an important legume crop in India and is infected by powdery mildew fungi. Fungal conidia land on the plant cell and invade the plant cell wall, forming the fungal haustorium. A fungal haustorium is a specialized feeding structure through which it hijacks the plant cell and takes up its nutrients. We looked at the plant nuclear dynamics upon fungal infection and observed that when fungus tries to penetrate the plant cell wall, the host nucleus moves toward that site. After penetration when the fungus forms the haustorium, the plant nucleus becomes closely associated with it. Interestingly, as the fungus continues to grow, the plant nucleus moves away from that initial site of infection.
Also, we found that this plant nuclear movement to the site of infection upon powdery mildew attack was regulated by the actin cytoskeleton and not by microtubules. In addition, unlike microtubules, the actin cytoskeleton undergoes a change in its orientation upon fungal infection as it becomes more polarized towards the site of infection. Till now, plant actin reorganization upon fungal infection in plants was shown to be involved in hindering the fungal growth in resistant plants. However, we have shown in pea plants that are susceptible to powdery mildew that this reorganization of the actin cytoskeleton is important for fungal growth in legumes like pea.
Our study highlights the behavior of the nucleus within the plant cell attacked by powdery mildew fungi. We have shown how the plant nucleus first responds to the fungal attack by moving closer to that site and then later moving away from it. While studying plant nuclear mobility, we found that it is governed by the actin cytoskeleton rather than microtubules. Our study provides the crucial initial information on actin and nuclear dynamics that lays the framework for such studies in legume-powdery mildew interactions.
“Our study provides the crucial initial information on actin and nuclear dynamics that lays the framework for such studies in legume-powdery mildew interactions.”
Any kind of research is filled with both successes and failures. After struggling for a long time to stain the plant actin, I was able to successfully stain it. And I was completely blown away when I first observed the actin cytoskeleton under confocal microscopy for the first time. The actin cytoskeleton appeared like fine threads that immediately gave an impression of lightning and thunder in the stormy sky. This event excited me and I was able to appreciate how techniques like microscopy can help us visualize such tiny structures to unravel the mysteries within a cell.
Our research findings indicated an important role for plant nuclear movement upon powdery mildew infection. Along with the cytoskeleton, the nuclear movement is known to be regulated by nuclear envelope proteins called LINC (Linkers of Nucleoskeleton and Cytoskeleton) complex. The role of LINC complex in regulating the nuclear movement during plant development has been well studied but not in plant-pathogen interactions. Next, we will try to decipher the role of the LINC complex in regulating the nuclear movement in plants upon powdery mildew infection.
Since my school days, I have been passionate about science and curious about the hows and whys of the world around me. Also, scientific literature and interactions with scientists and colleagues have been a great source of inspiration.
Indian science has made remarkable advancements in recent years. Not only that, Indian researchers have made a big impact on the world. I would like to utilize the scientific and analytical skills that I have learned during the PhD programme to do fascinating science in the future.
Sharma, A., Chandran, D. Host nuclear repositioning and actin polarization towards the site of penetration precedes fungal ingress during compatible pea-powdery mildew interactions. Planta 256, 45 (2022). https://doi.org/10.1007/s00425-022-03959-3
Ph.D. student at inStem Bangalore
Sukanya hails from a small town, kotdwara in Uttarakhand. She completed her Masters’ degree in Biotechnology from Banasthali Vidyapith, Rajasthan. After this, she served as a graduate teacher for one year at P.G. College, Kotdwara, Uttarakhand. In 2014, she qualified for the JGEEBILS exam conducted by NCBS/TIFR and joined as a Research Scholar (Ph.D. student) in Dr. Tina Mukherjee’s lab at inStem. Currently, she continued working as a bridging post-doc in Dr. Tina Mukherjee’s lab. Besides work, she loves reading non-fiction books, enjoys gardening, and cooking delicious food.
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