Uncovering the Molecular Regulation of Seed Development and Germination in Endangered Legume Paubrasilia echinata Through Proteomic and Polyamine Analyses
Authors: Vettorazzi, R. G., Carrari-Santos, R., Sousa, K. R., Oliveira, T. R., Grativol, C., Olimpio, G., Venancio, T. M., Pinto, V. B., Quintanilha-Peixoto, G., Silveira, V., Santa-Catarna, C.
The study examined seed maturation and germination in the endangered legume Paubrasilia echinata using proteomic and polyamine analyses at 4, 6, and 8 weeks post-anthesis, identifying over 2,000 proteins and linking specific polyamines to developmental stages. Mature seeds (6 weeks) showed elevated proteasome components, translation machinery, LEA proteins, and heat shock proteins, while polyamine dynamics revealed putrescine dominance in early development and spermidine/spermine association with desiccation tolerance and germination. These findings uncover dynamic molecular shifts underlying seed development and provide insights for conservation and propagation.
The study provides a comprehensive proteomic analysis of seed mitochondria from white lupin, revealing fully assembled OXPHOS complexes ready for immediate energy production upon imbibition. Quantitative mass‑spectrometry identified 1,162 mitochondrial proteins, highlighting tissue‑specific transporter and dehydrogenase profiles and dynamic remodeling during early germination, while many uncharacterized proteins suggest novel legume‑specific functions.
PHO2 suppresses arbuscular mycorrhizal symbiosis in high phosphate conditions
Authors: Birch, S., Perryman, S., Ellison, E., Foreman, N., Mekjan, N., Williams, A., Bate-Weldon, M., Ralfs, T., Pucker, B., Whiting, M., Hope, M. S., Wallington, E., Field, K., Choi, J.
The study identifies the rice E2 ubiquitin‑conjugating enzyme PHO2 as a key negative regulator of arbuscular mycorrhizal (AM) colonisation under high phosphate conditions. pho2 mutants in Oryza sativa (and Nicotiana benthamiana) maintain AM fungal entry and exhibit enhanced direct and symbiotic phosphate accumulation, linked to sustained expression of AM‑related genes despite phosphate sufficiency.
Light on its feet: Acclimation to high and low diurnal light is flexible in Chlamydomonas reinhardtii
Authors: Dupuis, S., Chastain, J. L., Han, G., Zhong, V., Gallaher, S. D., Nicora, C. D., Purvine, S. O., Lipton, M. S., Niyogi, K. K., Iwai, M., Merchant, S. S.
The study examined how prior light‑acclimation influences the fitness and rapid photoprotective reprogramming of Chlamydomonas during transitions between low and high diurnal light intensities. While high‑light‑acclimated cells struggled to grow and complete the cell cycle after shifting to low light, low‑light‑acclimated cells quickly remodeled thylakoid ultrastructure, enhanced photoprotective quenching, and altered photosystem protein levels, recovering chloroplast function within a single day. Transcriptomic and proteomic profiling revealed swift induction of stress‑response genes, indicating high flexibility in diurnal light acclimation.
The study introduces a native‑condition method combining cell fractionation and immuno‑isolation to purify autophagic compartments from Arabidopsis, followed by proteomic and lipidomic characterisation of the isolated phagophore membranes. Proteomic profiling identified candidate proteins linked to autophagy, membrane remodeling, vesicular trafficking and lipid metabolism, while lipidomics revealed a predominance of glycerophospholipids, especially phosphatidylcholine and phosphatidylglycerol, defining the unique composition of plant phagophores.
Drought drives reversible disengagement of root-mycorrhizal symbiosis
Authors: Akmakjian, G. Z., Nozue, K., Nakayama, H., Borowsky, A. T., Morris, A. M., Baker, K., Canto-Pastor, A., Paszkowski, U., Sinha, N., Brady, S., Bailey-Serres, J.
The study shows that during drought, rice (Oryza sativa) downregulates nutrient acquisition and arbuscular mycorrhizal (AM) symbiosis genes, causing the fungal partner to enter metabolic quiescence and retract hyphae, but upon re-watering the symbiosis is rapidly reactivated. This reversible dynamic suggests that plant‑fungus mutualisms are fragile under fluctuating water availability.
The study employed computational approaches to characterize the SUMOylation (ULP) machinery in Asian rice (Oryza sativa), analyzing phylogenetic relationships, transcriptional patterns, and protein structures across the reference genome, a population panel, and wild relatives. Findings reveal an expansion of ULP genes in cultivated rice, suggesting selection pressure during breeding and implicating specific ULPs in biotic and abiotic stress responses, providing resources for rice improvement.
The study evaluated barley stripe mosaic virus (BSMV) and foxtail mosaic virus (FoMV) vectors for virus-induced gene silencing (VIGS) and virus-mediated overexpression (VOX) in several Oryza sativa cultivars, finding that neither vector altered gene expression despite successful assays in wheat and extensive optimization. The lack of photobleaching with BSMV-PDS and absent GFP fluorescence with FoMV suggest intrinsic resistance mechanisms in rice, highlighting species-specific limitations of virus-enabled reverse genetics and the need for alternative vectors.
The study measured flower opening time and flower exposure duration (FED) in rice cultivars and performed controlled crossing experiments under short‑day and long‑day conditions, finding that when FED overlap exceeds ~20 min, cross‑pollination frequency often exceeds 60 % and can reach 100 %. These results overturn the long‑standing view that rice cross‑pollination is <2 % and highlight the need to investigate genetic factors underlying F1 sterility.
The study demonstrates that a beta‑1,3‑glucan‑binding protein from the rice blast fungus Magnaporthe oryzae interacts with the rice thaumatin‑like protein OsPR5, which sequesters the fungal protein to trigger immunity, while the fungus secretes thaumatin‑binding proteins to counteract this defense. Additionally, a rice cell‑surface receptor kinase containing a thaumatin domain has evolved to detect the fungal GBP, highlighting a complex coevolutionary arms race in the rice apoplast.