Biology subjects

Manishankar, P.

Publications and source records attributed to Manishankar, P..

3 recordsLinked to original sources

bioRxiv2026

A constitutively active cortical nitrate-uptake cell state underlies nitrogen-use efficiency in perennial ryegrass

Perennial ryegrass (Lolium perenne) is the most widely sown forage grass of temperate agriculture and a major sink for fertiliser nitrogen, yet the cellular basis of its nitrogen-use efficiency (NUE) is unknown. We built a single-nucleus atlas of 76,684 root nuclei from a high- and a low-NUE genotype under matched nitrogen resupply. High-affinity nitrate uptake is concentrated in one cortical cell state that co-expresses nine NRT2 transporters and all three NAR2 partner proteins, a state that whole-root RNA-seq of the same tissue cannot resolve. Under reduced nitrogen the low-NUE genotype induces this state, whereas the high-NUE genotype does not; it expresses NRT2.3 at a higher baseline and uses different NRT2 paralogs, with one array member nearly silent. Across 44 annual and perennial Pooideae genomes, the same gene families show no life-history difference in copy number, evolutionary rate or selection intensity. Their regulation, however, varies in the same direction as between the two genotypes: the perennial Brachypodium sylvaticum expresses the NRT2.3 ortholog at the level that the annual B. distachyon reaches only under nitrogen deprivation, and an N-efficient barley genotype does not induce the transporters that an N-sensitive genotype induces. NUE differences are therefore associated with constitutive versus inducible deployment of a conserved toolkit, and the expression and presence/absence variants we identify are candidate breeding markers. The atlas, the first for a forage grass, is released as an open web resource.

plant biology↗

bioRxiv2024

AI-assisted decoding of molecular signatures essential for condensation and function of NON-PHOTOTROPIC HYPOCOTYL3

The plasma membrane-associated protein NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3) is a key component of plant phototropism. Blue light induces the release of NPH3 into the cytosol, where it dynamically transitions into membrane-less biomolecular condensates. Here, we combine experimental data with the power of AI-based protein structure prediction to uncover a bipartite C-terminal motif that enables self-interaction of NPH3. We further demonstrate its importance for both the association of NPH3 with the plasma membrane and the assembly of condensates in the cytosol, with a different part of the bipartite motif playing the key role in each case. However, the formation of cytosolic condensates additionally requires the co-operative action of an N-terminal NPH3 signature. We propose that NPH3 forms a crosslinked 3D network in the cytosol based on distinct molecular determinants that simultaneously self-associate. NPH3 variants incapable of condensation are non-functional, suggesting a fundamental role of NPH3 phase separation for phototropism. This structural snapshot could have direct implications for future analyses of the plant-specific NPH3/RPT2-Like protein family.

plant biology↗

bioRxiv2021

Light-triggered and phosphorylation-dependent 14-3-3 association with NONPHOTOTROPIC HYPOCOTYL 3 is required for hypocotyl phototropism

NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3) is a key component of the phototropic response, acting downstream of the primary photoreceptor phototropin and upstream of auxin redistribution. Despite the obvious physiological significance of the blue light-induced differential growth process, the molecular mode of NPH3 action is poorly understood. Light-triggered dephosphorylation of NPH3, however, is thought to constitute a major signaling event. Here, we show that NPH3 directly binds to polyacidic phospholipids via a polybasic motif in its C-terminal domain, allowing for plasma membrane association in darkness. We further demonstrate that blue light induces phosphorylation of a C-terminal 14-3-3 binding motif in NPH3. Subsequent binding of 14-3-3 to the phosphorylated NPH3 in turn is required for light-triggered release of NPH3 from the plasma membrane. In the cytosol, NPH3 undergoes a dynamic transition from a dilute to a condensed state. Intriguingly, the dephosphorylated state of the 14-3-3 binding site as well as NPH3 plasma membrane association are recoverable in darkness. Given that NPH3 variants constitutively localizing either to the plasma membrane or to cytosolic condensates are non-functional, the phototropin-triggered and 14-3-3 mediated dynamic change in the subcellular localization of NPH3 seems to be crucial for its function. Taken together, our data demonstrate a fundamental role for 14-3-3 members in regulating NPH3 localization and auxin-dependent phototropic responses.

plant biology↗