Biology subjects

Avin-Wittenberg, T.

Publications and source records attributed to Avin-Wittenberg, T..

6 recordsLinked to original sources

bioRxiv2025

MATERNAL AUTOPHAGY CONTRIBUTES TO GRAIN YIELD IN MAIZE

Maize is an important crop species that is cultivated worldwide, and increasing maize yield is one of the major goals of plant breeding. The subcellular degradation and recycling pathway known as autophagy is involved in many plant developmental processes including vegetative growth, reproductive development, seed development, and senescence. Here, we demonstrate that maize autophagy-defective atg10 mutants have delayed flowering and reduced kernel size, weight and number, leading to reduced grain yield. Reciprocal crosses between mutant and parental lines indicate that the maternal plant is the major contributor to the kernel phenotype in atg10 mutants, rather than the seed genotype. We hypothesize that this may be due to detrimental effects on nutrient remobilization from maternal tissue to seeds during kernel development, leading to reduced yield.

plant biology↗

bioRxiv2024

Raffinose induces autophagy to promote plant growth

Plant growth is governed by the integration of environmental cues and nutritional status. Under stress conditions, growth is usually attenuated in favor of stress response, creating a trade-off between growth and stress. Autophagy is a vital process in eukaryotes, maintaining cellular balance by degrading and recycling cellular components. It is triggered by various nutrient-deprivation conditions and both biotic and abiotic stresses in plants. Surprisingly, over-expressing autophagy-related genes across multiple plant species resulted in increased plant size, yield, and stress resistance, posing autophagy as a regulator of the stress-growth balance. Yet, the molecular mechanisms governing its induction remain partially understood. In the current work, we identified raffinose-a plant-derived sugar known for its role in stress responses-as a novel plant autophagy inducer. Raffinose treatment resulted in increased biomass and yield in an autophagy-dependent manner in several plant species. We also show that raffinose activates autophagy through the SnRK1 kinase complex, independent of TOR signaling, and that raffinose treatment results in increased expression of ATG5 and ATG7. We also point to possible downstream candidates operating autophagy-related biomass accumulation. Our findings offer new perspectives on the role of autophagy in maintaining a balance between plant growth and stress responses, underscoring the significance of raffinose in its regulation. SIGNIFICANCE STATEMENTThe intricate balance between plant growth and stress responses is crucial for agricultural productivity, particularly as climate change intensifies environmental stressors such as drought and extreme temperatures. Usually, there is a trade-off between growth and stress response. Autophagy--a cellular recycling process essential for maintaining cellular homeostasis--plays a pivotal role in this balance. Yet, the molecular mechanisms modulating it are partially understood. Raffinose treatment enhances biomass and yields in various plant species by inducing autophagy. By elucidating the molecular mechanisms of raffinose-mediated autophagy induction, our findings provide valuable insights into potential strategies for enhancing plant resilience against climate-induced stress.

plant biology↗

bioRxiv2024

Autophagy at Crossroads: Modulating Responses to Combined Stresses, Unveiling Metabolic Shifts and Bacterial Dependencies

Plants face diverse stresses in natural environments, necessitating complex responses for survival. Abiotic and biotic stress responses are typically counteractive, posing challenges for breeding crops resilient to multiple stresses. Autophagy, a cellular transport process, plays a vital role in plant stress response, facilitating the degradation of cellular components and enabling nutrient recycling. Here, we asked what the role of autophagy is in combined abiotic (heat) and biotic (bacterial infection by Xanthomonas campestris pv. vesicatoria) stress. We introduce a conceptual framework based on assays monitoring autophagy activation, bacterial infection, and metabolic profiling. We observed that heat stress facilitates bacterial growth in an autophagy-dependent manner. Bacterial effectors facilitate this phenomenon. We also demonstrate the engagement of the autophagy-related 8 (ATG8) protein family members in stress-specific activation. Metabolic profiling highlights effector-dependent shifts in nutrient availability during stress, influencing bacterial performance. Our study challenges the assumption that combined stresses are simply the sum of individual responses as exemplified by activation of the autophagic pathway. Instead, it establishes autophagy as a link connecting environmental factors and plant-microbe interactions. Insights for our study can present a novel perspective for designing strategies to enhance crop resilience in the face of multifaceted challenges.

plant biology↗

bioRxiv2023

Autophagy in maternal tissues contributes to Arabidopsis thaliana seed development.

Seeds are an essential food source, providing nutrients for germination and early seedling growth. Degradation events in the seed and the mother plant accompany seed development. One degradation mechanism is autophagy, facilitating cellular component breakdown in the lytic organelle. Autophagy influences various aspects of plant physiology, specifically nutrient availability and remobilization, suggesting its involvement in source-sink interactions. During seed development, autophagy was shown to affect nutrient remobilization from mother plants and function in the embryo. Yet, these studies examined autophagy-knockout (atg mutant) plants, making it impossible to distinguish between the contribution of autophagy in the source (i.e., the mother plant) and the sink tissue (i.e., the embryo). To address this, we employed a novel approach to differentiate between autophagy in source and sink tissues. We investigated how autophagy in the maternal tissue affects seed development by performing reciprocal crosses between WT and atg mutant Arabidopsis thaliana plants. Although F1 seedlings possessed a functional autophagy mechanism, etiolated F1 plants from maternal atg mutants displayed reduced growth. This was attributed to altered protein but not lipid accumulation in the seeds, suggesting autophagy differentially regulates carbon and nitrogen remobilization. Surprisingly, F1 seeds of maternal atg mutants exhibited faster germination, resulting from different seed coat development. Our study emphasizes the significance of examining autophagy in a tissue-specific manner, revealing valuable insights into the interplay between different tissues during seed development. It sheds light on the tissue-specific functions of autophagy, offering potential for new research into the underlying mechanisms governing seed development and crop yield.

plant biology↗

bioRxiv2020

Autophagy is required for lipid homeostasis during dark-induced senescence in Arabidopsis

Autophagy is an evolutionarily conserved mechanism that mediates the degradation of cytoplasmic components in eukaryotic cells. In plants, autophagy has been extensively associated with the recycling of proteins during carbon starvation conditions. Even though lipids constitute a significant energy reserve, our understanding of the function of autophagy in the management of cell lipid reserves and components remains fragmented. To further investigate the significance of autophagy in lipid metabolism, we performed an extensive lipidomic characterization of Arabidopsis (Arabidopsis thaliana) autophagy mutants (atg) submitted to dark-induced senescence conditions. Our results revealed an altered lipid profile in atg mutants, suggesting that autophagy affects the homeostasis of multiple lipid components under dark-induced senescence. The acute degradation of chloroplast lipids coupled with the differential accumulation of triacylglycerols (TAGs) and plastoglobuli indicates an alternative metabolic reprogramming towards lipid storage in atg mutants. The imbalance of lipid metabolism compromises the production of cytosolic lipid droplets and the regulation of peroxisomal lipid oxidation pathways in atg mutants. One-sentence summaryAutophagy is required for the mobilization of membrane lipid components and lipid droplet dynamics during extended darkness in Arabidopsis.

plant biology↗

bioRxiv2019

Vacuolar processing enzyme translocates to the vacuole through the autophagy pathway to induce programmed cell death

The caspase-like vacuolar processing enzyme (VPE) is a key factor in programmed cell death (PCD) associated with plant stress responses. Growth medium lacking a carbon source and dark conditions caused punctate labeling of 35S::VPE1-GFP (StVPE1-GFP) in potato leaves. Carbon starvation of BY-2 cells induced higher VPE activity and PCD symptoms. Growing VPE-RNAi BY-2 cells without sucrose reduced VPE activity and prevented PCD symptoms. During extended exposure to carbon starvation, VPE expression and activity levels peaked, with a gradual increase in BY-2 cell death. Histological analysis of StVPE1-GFP in BY-2 cells showed that carbon starvation induces its translocation from the endoplasmic reticulum to the central vacuole, through tonoplast engulfment. Exposure of BY-2 culture to the autophagy inhibitor concanamycin A caused autophagic bodies accumulation in the cell vacuole. Such accumulation did not occur in the presence of 3-methyladenine, an inhibitor of early-stage autophagy. BY-2 cells constitutively expressing StATG8IL-RFP, an autophagosome marker, showed colocalization with the StVPE1-GFP protein in the cytoplasm and vacuole. RNAi silencing of the core autophagy component ATG4 in BY-2 cells reduced VPE activity and cell death. These results are the first to suggest that VPE translocates to the cell vacuole through the autophagy pathway, leading to PCD.\n\nOne sentence summaryCarbon starvation induced programmed cell death by trafficking vacuolar processing enzyme through the autophagy pathway to the vacuole.

plant biology↗