Tuesday 09 may
Xuemei Chen ‘microRNAs as signals in cell-cell communication’
She talks about microRNA moving across cells through plasmodesmata. Shows published work unveiling miRNAs produced in shoots that end up in the root, such as https://pubmed.ncbi.nlm.nih.gov/34707241. The first part of the talk is mostly about their work on discovering how a particular miRNA moves across cell layers in the root and how its activity is controlled by a protein (KTN1) that mediates its loading into AGO1. The second part is about the role of miR156 in thermomorphogenesis in Arabidopsis thaliana, a process where PIF4 plays a signaling role. She terminates by saying her lab is recruiting postdocs.
Stephen P. Long ‘More productive future-proofed crops via manipulation of photosynthesis to address global food security in 2050’
Light conversion efficiency is the least optimized aspect of plant productivity during the green revolution (https://pubmed.ncbi.nlm.nih.gov/18374559), and likely the only one with room for improvement. For two decades the have modelled the photosynthesis as diff equation digital twin. By numerical integration they are looking for bottlenecks. They are testing future 2060 conditions to test their predictions at https://soyface.illinois.edu, finding that increases in [CO2] increase yield at the cost on spending more water (due to open stomata), but with large variability among cultivars. They use tobacco to optimize photosynthesis focusing on three subprocesses (1yr from transformation to field trial, see https://www.annualreviews.org/doi/abs/10.1146/annurev-arplant-070221-024745). All three interventions improved efficiency. Engineered, transgenic cowpea seeds are already being sawn in Nigeria and Puerto Rico. They are now doing multi-location field trials.
Cristina Ferrándiz ‘Don’t stop me now: the end of reproduction in annual plants‘
Fruits feedback to flowering buds to arrest flowering at the right time (arrest ~bud dormancy according to RNAseq). Fruits export auxin, which probably has a role, as well as cytokinins (https://pubmed.ncbi.nlm.nih.gov/34963064) and ABA (https://www.nature.com/articles/s41467-018-03067-5). They show the potential of mutants in gene FUL to boost fruit production in A. thaliana and pea (two seasons, two locations in Canada; in other trials with elite bg it had a + effect one season, - the next one).
Daniel Van Damme ‘Mechanistic insight into plant endocytosis ‘
Endocytosis plays a role in shutting down membrane proteins that help communicate with the outside world. Jotnarlogs are genes/proteins absent in (human/yeast) species models that remain hidden until found in other orgs (https://doi.org/10.1016/j.cub.2020.03.068). They work with a TPLATE mutant which is viable but thermosensible and aggregates at 35C, and also with the nosh mutant (lacks a SH3 domain used to identify the cargo, such as ubiquitenable protein BRI1). Recent work investigate the role of disorder regions in other EH-domain proteins that take part in vesicles and recognize specific lipids and bind to clathrin (https://www.biorxiv.org/content/10.1101/2022.03.17.484738v2).
Rosa Lozano-Durán ‘Chasing geminiviruses to understand plant biology’
The most divergent protein in geminiviruses is C4, due to positive selection and its role in pathogenicity [symptom determinant]. It has a cp transit peptide and is also found in other membranes. By following the routes of C4 she has found a plant defense mechanism against virus infection mediated by BAM1 RLK and links the membrane and the chloroplast (https://www.pnas.org/doi/full/10.1073/pnas.1715556115). https://www.biorxiv.org/content/10.1101/2022.12.16.520777v1
Cosmocaixa has a great science museum
Joy Bergelson ‘Field GWAS and experimental evolution experiments reveal genetic tradeoffs in response to temporally and spatially variable selection’
Describes 2yr of common garden experiments in 4 locations (2N, 2S) in Sweden. In 75% S experiments, N lines did best. In N sites no difference, but S lines had less overwinter survival. They also do “evolution plots” where the find that viability selectio > fecundity selection. After GWAS analysis, they conclude that fitness is complex, due to a large number of minor effect loci, with no major candidate. They did observe a “home effect”, which they measure by computing freq(SNPs) home and away and then calculating the skewness of their effect on fitness. They used this approach to short list SNPs for local adaptation, with modest success apparantely.
Olivier Hamant ‘How transcriptional noise and mechanical conflicts contribute to organ shape reproducibility‘
Mechanical fluctuation drives cell/organ development (https://doi.org/10.1073/pnas.2008895117). Cell microtubules are good sensors of stress levels. Somehow mechanical tensions is reflected in gene expression.
The same as fluctuation is the key word of the climate reports of IBCC. For breeding it means we should aim at robustness, not only efficiency. Stephen Long argues they are not incompatible. Some ideas: mixed varieties by default (in France about 40% of wheat, not sure in which areas?, seed companies are already selling in France mixes apparently), understand hardiness, is biofuel really the way to go? Not much sense, precision agriculture? Very fragile, best “imprecision agriculture”, participatory research. He invites papers on these ideas for the journal https://www.cambridge.org/core/journals/quantitative-plant-biology
Liam Dolan ‘De novo development of polarity in plant cells’
Polarity is inherited after cell division in Marchantia. How does polaritity appear in a non-polar cell? Their current model is that initially the nucleous is at the center, a few hours later it moves to a pole pulled by actin microfilaments. The division plate seems to be oriented by blue light, not gravity. This is impaired by phototropin mutants, which encode a protein that accumulates in the membrane.
