Gene expression can be modulated at DNA, RNA, or protein levels, with targeted protein degradation (TPD) representing a well-established and effective strategy for manipulating protein function. TPD enables the selective elimination of proteins, protein condensates, or organelles via cellular degradation pathways, such as the ubiquitin-proteasome system, autophagy, or endocytosis, through induced proximity mechanisms. While TPD has had a transformative impact in biomedical research over the past two decades, its applications in plant science research has lagged behind. This gap stems from the dominance of RNA interference and CRISPR technologies, as well as the complexity and cost of chemical, macromolecular, and recombinant degrader platforms in plants. The recent development of genetically encoded chimeric protein degraders (GE-CPDs) offers a timely and promising alternative. These transgene-based systems offer a plant-adaptable, precise, tunable, and conditional means for controlling endogenous protein levels, opening new avenues for studying dynamic biological processes and engineering complex traits in crops. As genome engineering technologies continue to advance, GE-CPDs are poised to become a versatile and scalable platform for plant biology research and agricultural applications. In this review, we highlight five key opportunities—Selective-Targeting, Co-Targeting, Organelle-Targeting, Conditional-Targeting, and Synthetic Engineering (SCOCS)—that illustrate the emerging importance of TPD technologies, especially GE-CPDs, in advancing plant science. We argue that the field is well-positioned to harness the full potential of TPD for next-generation crop improvement.

Auxin regulates numerous aspects of plant growth and development, featuring polar auxin transport mediated by auxin efflux and influx carriers. AUX1 is the major auxin importer that actively takes up natural and synthetic auxins. However, the precise mechanisms underlying AUX1-mediated auxin recognition and transport remain elusive. Here, we present cryoelectron microscopy structures of Arabidopsis thaliana AUX1 in both apo and auxin-bound states, revealing the structural basis for auxin recognition. Structural analyses show that AUX1 assumes the LeuT-like fold in an inward-facing conformation and the auxin analog 2,4-D is recognized by polar residues located in the central cavity of AUX1. Furthermore, we identify a putative cation-binding site that contributes to stabilizing the inward-facing conformation. Interestingly, we reveal that His249 undergoes a substantial conformational shift, and its mutation completely abolishes transport activity, suggesting a crucial role for His249 in AUX1 gating. Collectively, this study provides a structural foundation for a deeper understanding of auxin influx by AUX1-like carriers.

Modern agricultural practices rely on herbicides to reduce yield losses. Herbicide-resistant weeds threaten herbicide utility and, hence, food security. New herbicide modes of action and integrated pest-management practices are vital to mitigate this threat. As the antimalarials that target the bifunctional enzyme dihydrofolate reductase-thymidylate synthase (DHFR-TS) have been shown to be herbicidal, DHFR-TS might represent a mode-of-action target for the development of herbicides. Here, we present the crystal structure of a DHFR-TS (AtDHFR-TS1) from the model dicot Arabidopsis thaliana. It shows a divergent DHFR active site and a linker domain that challenges previous classifications of bifunctional DHFR-TS proteins. This plant-conserved architecture enabled us to develop highly selective herbicidal inhibitors of AtDHFR-TS1 over human DHFR and identify inhibitors with unique scaffolds via a large-library virtual screen. These results suggest that DHFR-TS is a viable herbicide target.

Cell-to-cell communication is fundamental to multicellular life. In plants, plasmodesmata—cytoplasmic channels that connect adjacent cells—enable the transport of molecules between cells. In roots, such transport is thought to play a central role in nutrient acquisition and delivery across the multiple cell layers. In this study, we demonstrate that plasmodesmatal transport persists in fully differentiated Arabidopsis roots, even after the establishment of apoplastic barriers such as Casparian strips and suberin lamellae in the endodermis. This persistence highlights plasmodesmata as a critical pathway for intercellular trans-port in mature roots. We also identify a developmental switch in plasmodesmatal function: while transport is bidirectional in young roots, it becomes unidirectional toward the vasculature in differentiated roots. Through a genetic screen, we identified mutants with impaired directionality that maintain persistent bidirectional transport. These mutants show enlarged plasmodesmatal apertures due to defects in pectin composition and cell wall organization, highlighting the critical role of pectin in plasmodesmatal formation and function. Our findings reveal that plasmodesmata-mediated transport is dynamically regulated during root development and provide new insights into the cellular mechanisms underlying intercellular communication in plants.

Louis Pasteur first reported that living cells switch from aerobic to anaerobic metabolism under low-oxygen conditions, but the underlying regulatory mechanism remains to be fully elucidated. ALCOHOL DEHYDROGENASE 1 (ADH1) encodes a key enzyme in ethanolic fermentation and is upregulated under hypoxia. In this study, we searched for Arabidopsis thaliana mutants with defects in hypoxia-induced ADH1 expression and identified the IQ DOMAIN containing protein 22 (IQD22) as a crucial regulator of ADH1-mediated hypoxia tolerance. The iqd22 mutant plants were hypersensitive to submergence and hypoxic stress as compared with the wild-type plants, whereas IQD22 overexpressors were more tolerant. We showed that under hypoxia, IQD22 enhances the interaction between the calcium-dependent protein kinase CPK12 and the ETHYLENE RESPONSE FACTOR (ERF)-VII-type transcription factor RELATED TO AP2.12 (RAP2.12) to upregulate hypoxia-responsive genes, including ADH1. Moreover, we found that IQD22 interacts with calmodulins (CaMs) in vivo and facilitates their association with ADH1, stimulating its abundance in response to hypoxia. Metabolic profiling revealed that hypoxia causes significant increase in glycolytic metabolites but greatly lower ethanol accumulation in the iqd22-2 mutant. Genetic analysis showed that disruption of ADH1 suppresses the improved hypoxia-tolerance phenotype of IQD22 overex-pressors. Taken together, these results indicate that IQD22 functions in the CaM-ADH1 and CPK12-RAP2.12 regulatory modules, which coordinately mediate calcium-dependent activation of anaerobic respiration to control metabolic flux during hypoxia.

Broad-spectrum resistance (BSR) is highly sought after for the effective management of crop diseases. However, genes suitable for developing BSR remain scarce. In this study, we demonstrate the development of BSR to wheat yellow rust (YR), powdery mildew (PM), and leaf rust (LR) diseases elicited by three biotrophic fungal pathogens using a newly defined module, namely, RFEL1-NPR3. RFEL1 is an active RING-finger E3 ubiquitin ligase identified in diploid and polyploid wheat species, which ubiquitinates and promotes the degradation of wheat NPR3 (TaNPR3), an important negative immune regulator conserved in higher plants, via the 26S proteasome system. Downregulation of TaNPR3 by either overexpressing RFEL1 or knocking out TaNPR3 confers strong resistance against four different YR races as well as the PM and LR diseases without adverse effects on wheat growth and yield traits. Notably, the enhanced disease resistance exhibited by RFEL1-overexpressing and TaNPR3-knockout lines is correlated with increased expression of defense related genes and elevated stability of NPR1, a pivotal positive regulator of plant immune signaling. Our findings underscore the importance of ubiquitination-dependent NPR3 degradation in plant immunity and advocate for the application of the RFEL1-NPR3 module in engineering BSR against biotrophic fungal pathogens in wheat and other crops.

Extracellular vesicles (EVs) facilitate cross-kingdom communication by delivering bioactive molecules between cells. Although the role of fungal EVs in cross-kingdom RNA trafficking is well documented, whether and how they deliver pathogen-derived virulence effectors into host plants to facilitate infection remains largely unknown. Here, we report that the fungal pathogen Rhizoctonia solani secretes vesicles enriched with the EV marker R. solani tetraspanin 2 (RsTsp2) and the effectors R. solani necrosis-promoting protein 8 (RsNP8) and R. solani serine protease (RsSerp). These proteins are upregulated during infection and are critical for fungal virulence. Notably, clathrin-coated vesicles accumulate at the fungal infection sites, and RsTsp2, RsSerp, and RsNP8 are detectable within these vesicles, indicating their entry into plant cells via clathrin-mediated endocytosis. RsNP8 is translocated into the chloroplast, where it interacts with NP8-interacting chloroplast protein 1 (NICP1) in Arabidopsis. NICP1 contributes to plant immunity by regulating the reactive oxygen species burst during infection, whereas RsNP8 suppresses this immune response. Silencing of RsTsp2, RsSerp, and RsNP8 in R. solani attenuates sheath blight disease progression in rice. Taken together, these findings demonstrate that fungal EVs enable cross-kingdom delivery of effectors into plant cells, revealing a previously unrecognized mechanism by which eukaryotic pathogens invade host plants.

Drought stress severely limits rice productivity. Understanding of drought-response mechanisms in rice is essential for developing climate-resilient varieties. While cysteine-rich receptor-like kinases (CRKs) are primarily implicated in plant development and immunity, their role in drought response remains poorly understood. In this study, we identified a CRK, OsCRK14, as a key positive regulator of drought resistance in rice. We demonstrated that plasma membrane-localized OsCRK14 phosphorylates the receptor-like cytoplasmic kinase OsRLCK57 under drought stress, leading to activate a mitogen-activated protein kinase(MAPK) cascade (OsMKKK10-OsMKK4-OsMPK6). Activated OsMPK6 directly phosphorylates the abscisic acid-responsive transcription factor OsbZIP66 at conserved Serine-Proline/Threonine-Proline motifs, enhancing its stability and promoting drought-responsive gene expression. Furthermore, we found that natural variations in the OsCRK14 promoter influence its transcript levels due to the altered OsMYB72 binding affinities, which are correlated with drought-resistance differences among rice varieties. Collectively, our study discovers a novel CRK-RLCK-MAPK-bZIP signaling pathway that connects membrane signal sensing to transcriptional regulation in drought response, providing both mechanistic insights and genetic resources for breeding drought-resistant rice.