Frequent changes in global climate enhance environmental cues, threaten agricultural systems, which jeopardizes food security, and impair the achievements of the United Nations Sustainable Development Goal 2 “Zero Hunger”. To achieve a sustainable path, use of biostimulants represents a new strategy to enhance plant resilience against abiotic stresses like drought, temperature, salt, waterlogging, and heavy metals. This review explores recent developments in biostimulant technologies, aiming to clarify the processes that underlie their ability to promote plant tolerance. We also highlight the versatile roles of small RNA, peptides, and hormones as emerging molecular regulators, thereby revealing their potential for use as natural biostimulants. Developing on this, transformative effects of microbial biostimulants that use microbiota to strongly regulate plant stress-responsive modules are explored. Furthermore, AI-driven early warning systems provide the opportunity to identify timely stress responses, thus enabling the discovery of multi-omics network modules, allowing rational biostimulant design. These findings are then used to guide the metabolic engineering of tailored biostimulants, where the identified key regulators and network modules become direct targets for formulation or synthetic biology approaches. This review defines a roadmap for crop stress tolerance by clarifying the mechanisms of rationally designed biostimulants, thereby paving the way for climate-resilient agriculture and sustainable food systems.

Cadmium (Cd) is a toxic heavy metal that poses serious risks to human health and the ecological environment. Perilla frutescens (L.) Britt. has important medicinal and culinary value, yet its seedlings are highly sensitive to cadmium exposure. Carbohydrates, which mediate key aspects of plant-microbe interactions, play an essential role in recruiting rhizosphere microbiota. In this study, we examined how inoculation with Oceanobacillus picturae alleviates cadmium toxicity by secreting carbohydrate metabolites that reshape the rhizosphere microbial community of perilla. Inoculation markedly reduced cadmium-induced root damage, increasing fresh and dry plant weights by 2.3-fold and 1.1-fold, and enhancing root length by 14% compared with the control. In addition, root exudate profiles showed clear changes following inoculation. Metabolomic analyses revealed that stachyose was a key exudate enriched under stress conditions and acted synergistically with Azospirillum brasilense and Acinetobacter pittii to enhance perilla growth and cadmium tolerance. These findings demonstrate that perilla recruits specific plant growth-promoting rhizobacteria through stachyose-mediated chemical signaling in response to cadmium stress. This work advances our understanding of plant-microbe interactions under heavy metal stress and provides a foundation for microbiome-based phytoremediation technologies. It also offers practical value for developing sustainable agricultural practices and supporting ecological conservation.

Seed storability is critical for crop propagation, global grain preservation, and food security. However, knowledge of the molecular biology underlying seed storability remains elusive. Here, we identified the flavonoid 3′ hydroxylase gene (F3′H) as a key gene governing seed storability in soybean through map-based cloning. Functional characterization revealed that GmF3′H not only modulates seed coat pigmentation but, more importantly, also reinforces the physical integrity of both seed coat and hilum, thereby preventing mechanical cracking. Furthermore, conserved F3′H function in soybean and Arabidopsis suggests its broad evolutionary relevance for seed storability. Our findings demonstrate that GmF3′H confers a dual-defense strategy combining structural reinforcement of seed protective layers with antioxidant enhancement for engineering seed longevity and storability. Based on these findings, we developed improved soybean germplasm with enhanced storability by selecting for favorable GmF3′H haplotypes, utilizing linked seed coat color as a visual marker. This study provides new insights for understanding plant seed longevity and offers a valuable avenue for broad-spectrum breeding applications on crop seed storability to sustain seed vigor and grain security.

Anthocyanins are a critical component influencing the quality of grape. At varying concentrations, methyl jasmonate (MeJA) shows a concentration-dependent effect on the anthocyanin content in grapes. However, its molecular mechanism is unclear. In this study, we characterized an E3 ubiquitin ligase VvPUB8 that responds to MeJA and verified its negative regulation of grape anthocyanin synthesis through overexpression and mutant vectors' transformation of “Gamay” calli. Furthermore, VvPUB8 interacted directly with the transcription factor VvbHLH93, which can positively regulated anthocyanin synthesis by activating the promoters of VvMYB15 and VvMYB5a. The stability or activity of proteins regulated by ubiquitination largely depends on the type and number of the attached ubiquitin. Here, we showed that VvPUB8 facilitated K6- and K33-linked ubiquitination of VvbHLH93, thereby promoting VvbHLH93 degradation. Exogenous MeJA accelerated VvbHLH93 protein degradation and inhibited VvMYB15 promoter activation. Consequently, the synthesis of grape anthocyanins was suppressed. This study revealed that in response MeJA, VvPUB8 regulates VvbHLH93 stability through conjugation of distinct polyubiquitin chains, thereby modulating VvMYB15 and VvMYB5a promoter activity, thus inhibiting anthocyanin synthesis.

Soybean is a major crop that produces high-quality seed oil for global consumption. However, the regulatory mechanisms underlying seed oil content remain poorly understood. In this study, GmGT-2F, a trihelix transcription factor, was identified as a positive regulator of seed oil content. It was observed that GmGT-2F expression gradually increased during seed development. Furthermore, GmGT-2F overexpression elevated seed oil content and increased the proportion of oleic and linoleic acids in fatty acid composition. However, knocking out GmGT-2F improved seed protein content and seed size. We demonstrated that GmGT-2F binds to the GmAGAL promoter and activates its transcription. Moreover, knockout of GmAGAL and GmGT-2F/GmAGAL reduced α-galactosidase activity and decreased seed oil content. The metabolomic and seed sucrose content analyses of the gmagal and wild-type (WT) plants showed that GmGT-2F affects the transcription of GmAGAL to regulate the activity of α-galactosidase and may control the oil content by influencing the generation and distribution of sucrose in the seed. In addition, GmCYP2 interacts with GmGT-2F, reducing its promoter-binding activity and inhibiting GmAGAL transcription. Haplotype diversity analyses of GmGT-2F, GmCYP2, and GmAGAL revealed combinations associated with increased oil or protein content. This study elucidates the regulatory mechanism by which GmGT-2F regulates seed oil content, expands understanding of trihelix transcription factor function in seed quality trait regulation, and provides new insights for high-quality soybean breeding.

Leaf angle is a key agronomic trait for improving planting density and yield in lettuce, particularly in controlled-environment agriculture and high-density field cultivation. Leaf angle regulation is well studied in monocots; however, the genetic and molecular mechanisms in dicots remain largely unknown. Here, we genetically clone and functionally characterize LsOFP6a, an OVATE family protein gene, as a key regulator of leaf angle in lettuce. A nonsense mutation in LsOFP6a in large-leaf-angle cultivars produces a truncated protein with impaired function. CRISPR/Cas9 knockout and complementary tests confirmed that LsOFP6a negatively regulates leaf angle in lettuce. LsOFP6a physically interacts with the BELL-like homeodomain transcription factor LsBLH2. Genetic analyses revealed that LsOFP6a regulates leaf angle through an LsBLH2-dependent pathway, and LsBLH2 is recessive-epistatic to LsOFP6a. LsBLH2 directly upregulates the expression of the cytokinin oxidase gene LsCKX5a. LsOFP6a represses the transcriptional activity of LsBLH2 on LsCKX5, leading to elevated cytokinin levels and small leaf angle. Furthermore, LsOFP6a inhibits the effects of LsBLH2 on repressing abaxial gene LsYAB1, leading to enhanced abaxial cell elongation and erect leaves. Loss of function of LsOFP6a decreases the cytokinin level and represses abaxial cells, resulting in large leaf angles. In summary, the LsOFP6a–LsBLH2 module orchestrates cytokinin catabolism and leaf dorsiventrality to regulate lettuce leaf angle. Our study suggests potential novel strategies for the breeding of lettuce with compact architecture and suitable for high-density planting in the open field and plant factories.

Auxin plays a pivotal role in regulating crop nitrogen (N)-use efficiency (NUE), coordinating both N-responsive root development and the expression of N metabolism genes. In our previous work, we identified DULL NITROGEN RESPONSE1 (DNR1) as a repressor within the auxin-mediated NUE network in rice. Here, we further delineate this pathway by identifying the SUMO E3 ligase OsSIZ1 as a key upstream regulator of DNR1. Contrary to its canonical role, we discovered that OsSIZ1 exhibits ubiquitin E3 ligase activity toward DNR1, facilitating its polyubiquitination at lysine 314 and subsequent degradation. This degradation promotes auxin accumulation, thereby enhancing NUE and grain yield. Notably, the yield advantage driven by OsSIZ1 is most pronounced under low-N conditions, underscoring its potential as a breeding target for developing resilient crops that require less N fertilizer, enabling a more sustainable agriculture.

Mitogen-activated protein kinase (MAPK) cascades regulate growth, development, stress responses, and immunity in plants by transmitting signals from upstream regulators to downstream components. In this study, we identify a MAPK cascade composed of MAPK kinase kinase 19 (MKKK19), three MAPK kinases (MKK3/MKK5/MKK9), and MAPK 6 (or MPK6) that is involved in Arabidopsis leaf senescence. The kinase oxidative signal-inducible 1 (OXI1) functions upstream of the MKKK19–MKK3/MKK5/MKK9–MPK6 cascade to promote leaf senescence, whereas two of RESPIRATORY BURST OXIDASE HOMOLOGS (RBOHs), RBOHD and RBOHF, act downstream to mediate the accumulation of reactive oxygen species (ROS). Loss-of-function mutation of OXI1, MKKK19, MKK3/MKK5/MKK9, or MPK6 resulted in delayed leaf senescence associated with reduced ROS levels, whereas transgenic lines overexpressing OXI1, MKKK19, MKK3/MKK5/MKK9, or MPK6 displayed the opposite phenotypes. Epistatic analyses supported the involvement of OXI1, MKKK19, MKK3/MKK5/MKK9, MPK6, and RBOHD/RBOHF in the same signaling pathway for leaf senescence. In conclusion, genetic and biochemical analysis of the Arabidopsis MKKK19–MKK3/MKK5/MKK9–MPK6 cascade through OXI1 and RBOHD/RBOHF revealed a vital role for the MAPK cascade and ROS in natural leaf senescence.

Jasmonates (JAs) are vital to plant defense and stress adaptation. In Salvia miltiorrhiza, JA significantly promotes tanshinone accumulation, a class of bioactive diterpenoids. Although transcriptional regulation of JA signaling is well characterized, the post-translational mechanisms governing JA-mediated tanshinone biosynthesis remain poorly understood. Here, we identify SmWRKY2 as a critical regulator of JA-induced tanshinone accumulation, which interacts with SmCPK20. SmCPK20 positively regulates JA-induced tanshinone accumulation. JA signaling activates SmCPK20, promoting phosphorylation of SmWRKY2 at Thr-256. This phosphorylation event significantly enhances SmWRKY2's binding to the SmCPS1 promoter and its transcriptional activation capacity, thereby promoting tanshinone accumulation. Furthermore, SmWRKY2 interacts with the JA signaling repressor SmJAZ3. SmJAZ3 inhibits the SmWRKY2–SmCPK20 interaction in the absence of JA. JA-triggered degradation of SmJAZ3 releases SmWRKY2, enabling SmCPK20-mediated phosphorylation and promoting tanshinone biosynthesis. Collectively, our results demonstrate that JA and Ca²⁺ signaling pathways cooperate to regulate plant secondary metabolism.

The circadian clock is an endogenous timekeeping mechanism that coordinates diverse biological processes across diverse organisms. Emerging evidence recently underscores its critical role in modulating plant immune responses. Salicylic acid (SA) is a central phytohormone in plant immunity; however, the molecular mechanisms by which clock components influence SA signaling under biotic stress are poorly understood. Here, we report the pivotal role of the core clock components, PSEUDO-RESPONSE REGULATOR 5 (PRR5) and PRR7, in governing Arabidopsis immunity by direct suppression of SA signaling. We found that the transcriptional outputs of SA signaling showed rhythmic expression and were remarkably affected by PRR5 and PRR7. Genetic analyses revealed that PRR5 and PRR7 function genetically upstream of the SA receptor NONEXPRESSER OF PATHOGENESIS-RELATED GENES 1 (NPR1) to inhibit SA-mediated defenses. Biochemical assays confirmed physical interactions among PRR5/7, NPR1, and TGA3, highlighting a direct mechanism whereby PRR5/7 antagonize the transcriptional activity of the NPR1–TGA3 complex. The prr5 prr7 double mutant not only showed enhanced SA signaling but also boosted pathogen-associated molecular pattern-triggered immunity, highlighting their broad inhibitory function in plant immunity. These findings provide critical insights into the temporal dynamics of plant immunity and reveal key molecular targets for breeding crop varieties with an optimized balance between growth and immunity.