Biology subjects

Shanmukhan, A. P.

Publications and source records attributed to Shanmukhan, A. P..

3 recordsLinked to original sources

bioRxiv2023

Gametophytic epigenetic regulators MEA and DME synergistically suppress ectopic shoot formation in Arabidopsis

The gametophyte to sporophyte transition facilitates the alternation of generations in a plant life cycle. The epigenetic regulators DEMETER(DME) and MEDEA(MEA) synergistically control central cell proliferation and differentiation, ensuring proper gametophyte to sporo-phyte transition in Arabidopsis. Mutant alleles of DME and MEA are female gametophyte lethal, eluding the recovery of recessive homozygotes to examine their role in the sporophyte. Here, we exploited the paternal transmission of these mutant alleles coupled with CENH3-haploid inducer to generate mea-1;dme-2 sporophytes. Strikingly, the simultaneous loss of function of MEA and DME leads to the emergence of ectopic shoot meristems at the apical pole of the plant body axis. DME and MEA are expressed in the developing shoot apex and regulate the expression of various shoot-promoting factors. Chromatin immunoprecipitation(ChIP), DNA methylation and gene expression analysis revealed several shoot regulators as potential targets of MEA and DME. Knockdown of upregulated shoot-promoting factors STM, CUC2, and PLT5 rescued the ectopic shoot phenotypes. Our findings reveal a previously unrecognized synergistic role of MEA and DME in restricting the meristematic activity at the shoot apex during sporophytic development to orchestrate the plant architecture.

plant biology↗

bioRxiv2020

Regulation of touch dependant de novo root regeneration in Arabidopsis

The versatile regeneration capability of leaves enable even a detached Arabidopsis leaf to yield two kinds of regenerative responses namely, wound healing at the cut end in form of callus formation or de novo root regeneration (DNRR). Using various experimental approaches, we show that the factor favouring DNRR over callus formation seems to be a mechanical cue, possibly touch, at the cut end of the detached leaf. Here, we show that the forced expression of a PLETHORA transcription factor can bypass the need for touch to initiate DNRR. Our findings provide a genetic frame-work for touch dependant DNRR and suggest that a core PLT transcription regulatory module acts in response to mechano-sensing stimuli.

plant biology↗

bioRxiv2020

Age, wound size and position of injury - dependent vascular regeneration assay in growing leaves

BackgroundRecurring damage to aerial organs of plants necessitates their prompt repair, particularly their vasculature. While vascular regeneration assay in aerial plant parts such as stem and inflorescence stalk are well established, those on leaf vasculature remained unexplored. Recently we established a new vascular regeneration assay in growing leaf and discovered the underlying molecular mechanism. ResultsHere we describe the detailed stepwise method of incision and the regeneration assay used for studying the leaf vascular regeneration. By using a combination of micro-surgical perturbations, brightfield microscopy and other experimental approaches, our new findings show that the regeneration efficiency decreases with aging of the leaf, and increases with the nearness of the wound towards the proximal end of the leaf. ConclusionThis easy-to-master vascular regeneration assay is an efficient and rapid method to study the mechanism of vascular regeneration in growing leaves. It can be readily adapted for other plant species and can be combined with cellular and molecular biology techniques.

plant biology↗