Biologists of IISER-Pune decode ‘cellular secret talk’ that helps plants regenerate lost parts

During this process, some of the callus cells organise themselves in a functional fashion that supports the full regeneration of the complete plant system within a month.

Professor Kalika Prasad and lead co-workers in his group, Vijina VP, Mabel Maria Mathew and Anju PS  at the Indian Institute of Science Education and Research (IISER), Pune, have been studying this complex regeneration abilities using the plant model of Arabidopsis thaliana, which is a weed.

Experts shared that only a few cells within this callus go on to mature and grow into parts like leaves, stem, root, flowers and fruits or the entire plant.

These cells are scientifically called progenitors.

“Under a laboratory set-up, we identified and tracked potent cells which had arranged themselves to specific polarity in real-time. We observed the manner in which the cells got polarised. After several years of continuous observations, it was clear that there were two kinds of progenitors, both of which were located deep within the callus,” said Prasad.

The scientists could conclude that only one type of the progenitor,  known as productive progenitor,  could regenerate plant parts.

“Genomic screening revealed the presence of an elastic shell on the outside which was holding and keeping all the progenitor cells together in the desired orientation,” said Mabel Maria Mathew, a fourth-year doctoral student at IISER-Pune and co corresponding author of the paper published in the journal Developmental Cells.

The biologists further dug deep to understand and establish the relation between the shell and the progenitor, which revealed a new fact.

The shell was found exerting an inward force onto the cells whereas the progenitor cells were responding with equal external forces onto the shell. “During this mechanical exchange of forces, the cell growth is marked by division growing whereas the shell was growing through expansion. This means, both the shell and the cells had differential growth but the forces were in collaboration,” explained Prasad.

As days passed, the scientists arrived at a point when they found that the progenitor cells were forcefully breaking open the shell. “This was facilitated mainly due to flexible and loose cell walls of the shell,” Mathew said.

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A progenitor cell, the biologists said, took anywhere between 7 to 10 days to show initial growing parts of a plant when observed under a microscope. “The full growth is achieved within 25 to 30 days and the part can be  seen through naked eyes,” said Prasad.

Stem cells are essential but they alone will not help in regeneration. It is the presence of suitably oriented cells surrounded  by a shell with loose walls that will eventually help the development of flawless and natural regenerated parts in plants, Prasad noted.

IISER Pune scientists said this know-how of the science behind regeneration in

plants could be applied in preserving some highly endangered plant species, for preserving slow regenerating trees and for the creation of repositories of such plant species in the future.