Metabolic changes are often described as drivers of plant development even when the evidence establishes only association or a permissive requirement. This review separates biological role from causal status and evaluates claims across seven dimensions: association, necessity, localization, transport, rescue and mediation, sufficiency, and quantitative-threshold testing. We apply a when–where–how framework to four cases. Perturbations of T6P, SnRK1, and TOR support T6P-dependent kinase regulation as a mediator of lateral-root development and are consistent with a context-dependent candidate gate, but its window and threshold remain unresolved. Circadian regulation of AHA3 and SUC2 by CCA1 provides the most complete chain, combining cell-specific perturbation, transport, and rescue. The OsARF18–OsARF2–OsSUT1 pathway supports sucrose transport as a mediator of rice fertility, although receiving-cell necessity and quantitative restoration remain unresolved. H+-ATPase perturbations identify apoplastic pH as a proximal mediator of Arabidopsis hypocotyl and cotton-fiber elongation, with context-dependent optima rather than a shared threshold. Nutrient and redox regulation, specialized metabolism, stress, and senescence provide boundary comparisons. Causal confidence depends on claim-matched evidence for responding cells and developmental windows and, where relevant, transport routes, mechanisms, and whole-plant trade-offs. The framework can guide AI-assisted breeding by prioritizing genotype-, stage-, and tissue-specific interventions for prospective perturbation and rescue.

Cotton fiber length is a crucial attribute that significantly affects yarn production and fabric quality, making it a primary focus in cotton breeding efforts. Both current and previous studies have indicated a lack of correlation between fiber length and gene expression dynamics, underscoring the importance of phenotyping fiber elongation. Traditional methods for measuring fiber length, however, tend to be impractical and labor-intensive, particularly for developing fibers that are fragile and prone to twisting. In this study, we present an innovative phenotyping method to measure the elongation of developing cotton fibers. Our key findings reveal a strong linear relationship between the total volume of fiber bundles and fiber length. This relationship allows for the straightforward estimation of the linear correlation coefficient from the final fiber length and the final volume of the fiber bundle within a boll. Upon measuring both the fiber bundle volume and fiber length, we discovered that their growth dynamics were well-represented by a logistic curve. Additionally, the expression dynamics of several newly identified genes demonstrated a significant positive correlation with the rate of fiber elongation. This research marks an important advancement in quantifying gene expression dynamics and fiber elongation. We believe that measuring the elongation of developing fibers will greatly accelerate the development of high-quality cotton varieties and enhance our understanding of plant developmental biology.

ABSTRACT The effects of overused chemical fertilizers, which threaten soil, plant, and human health, have always remained a topic of interest in theory and practice, emphasizing the judicious use of mineral nutrients. This study was aimed at reducing the harmful effects of excessive chemical fertilizer application and at exploring alternative approaches that can improve soil fertility without environmental and health damage. The experimental design involved a controlled greenhouse setup where tomato cultivars were inoculated with different AMF species under varying nitrogen (N) and phosphorus (P) doses. The tomato cultivars Rio Grande and Nadir were inoculated with arbuscular mycorrhizal fungi species, including Glomus claroideum, Glomus etunicatum, Glomus fasciculatum, and Glomus mosseae—within a commercial greenhouse. This study aimed to evaluate the potential effects of these fungi on tomato growth physiology, yield, and fruit quality when subjected to varying doses of N and P. Glomus mosseae significantly increased plant height by 14%, stem diameter by 22.25%, dry matter by 23.59%, yield by 38.57%, N uptake by 16.40%, P uptake by 37.5%, potassium (K) uptake by 18.55%, chlorophyll a (Chl a) content by 15.18%, and chlorophyll b (Chl b) content by 25.19% when compared to untreated controls. Additionally, Glomus mosseae improved fruit diameter by 9.98%, fruit firmness by 18.45%, juice content by 15.20%, titratable acidity (TA) by 10.42%, and ascorbic acid concentration by 16.75%. The interaction between the N and P levels of 140:42 mg L−1 and the arbuscular mycorrhizal fungus (AMF) species Glomus mosseae resulted in the highest improvement in growth, yield, and fruit quality‐related traits. Among the cultivars, Rio Grande exhibited the greatest root colonization, plant dry matter content, N, P, K uptake, plant height, Chl a, Chl b, and yield when compared to the control. In contrast, cultivar Nadir showed the highest stem diameter, fruit size, firmness, ascorbic acid, fruit juice contents, and TA. This study recommends that AMF inoculation in combination with a low N and P supply can be promising for improving tomato growth, productivity, and fruit quality on a commercial scale with minimum threats to the environment and human health. This study suggests the exploration of long‐term sustainability and scalability of AMF inoculation methods in diverse agricultural settings.

BACKGROUND:Cotton is an important crop that provides a natural fiber source for the textile industry. Polyphenol oxidase (PPO) is a type of ubiquitous metalloproteinase in plants, which play crucial roles in regulating plant growth and development, as well as plant resistance against biotic and abiotic stresses. Although the whole genome sequence of Gossypium hirsutum L. (G. hirsutum) has long been published, this gene family has not yet been well studied in cotton. RESULTS:In the present paper, we have identified the 51 PPO genes in cotton, and deeply analyzed 15 PPO genes in G. hirsutum, which are named GhPPOs. We found that three conserved domains - tyrosinase, DWL, and KFDV, were present in all 15 GhPPOs. We also analyzed the molecular characterization, phylogenetic relationships, gene structure, chromosome locations, 3D structure, and expression profiles of all the PPO genes identified. Based on the phylogenetic analysis, these PPO genes were classified into five groups (I, II, III, IV and V). The 15 GhPPO genes are distributed across eight chromosomes, and gene structure analysis showed that nine GhPPOs are devoid of introns. Analysis of cis-acting elements in GhPPOs promoters indicated their potential fundamental roles in response to plant growth, development, and stresses. Transcript profiling and RT-qPCR analysis revealed that GhPPO3/11 showed high expression levels during cotton fibre elongation, and GhPPO3/5 can be induced in response to cotton bollworm infestation. Moreover, the 3-dimensional structures of GhPPO3/ 11 and GhPPO3/ 5 were predicted by homolog modeling, and we found that all of them possess similarity spatial structures, with two independent domains, which could be the structural basis for performing biological functions. CONCLUSIONS:These findings not only provide valuable insights into the phylogenetic relationships, gene structure, cis-acting elements, and functional characteristics of upland cotton PPOs, but also shed light on their potential roles in cotton fibre elongation and response to biotic stresses.

Cotton (Gossypium spp.), a major global fiber crop, serves as an ideal model for research on plant cell development. According to the acid growth theory, plasma membrane (PM) H +-ATPase (HA) regulates cell wall acidification, thereby promoting cell elongation and providing a mechanistic framework for understanding this process. However, its application to cotton fiber cells has remained limited. In this study, the acid growth theory was utilized to investigate the elongation of cotton fibers. Comparative genomics revealed an expansion in the number of gene family members associated with acid growth, including PM HA and transmembrane kinase (TMK) genes, in tetraploid cotton. Transcriptomic analysis highlighted the co-expression of these genes during fiber elongation. Functional validation using chemical modulators and CRISPR-Cas9-mediated knockout mutants demonstrated that PM HA activity is essential for apoplastic acidification and fiber elongation. Specifically, GhHA4A and GhTMK3A were identified as potential regulators of proton extrusion; their loss-of-function mutants exhibited elevated apoplastic pH and reduced fiber length. Furthermore, the results indicated that an optimal apoplastic pH is required for fiber elongation, whereas insufficient or excessive acidification inhibits growth. Spatiotemporal modulation of PM HA activity in trans-genic cotton plants enhanced fiber length without affecting other fiber-and seed-related traits, demonstrating the potential of the acid growth theory for fiber improvement. These findings not only extend the acid growth theory beyond conventional model systems but also provide an innovative strategy for increasing fiber length in cotton breeding.

The global yield of cottonseed could meet the annual protein requirements of approximately half a billion people if gossypol were absent from the seeds. Here, we characterize the molecular mechanism by which the Gl2e mutation exerts a dominant-negative effect on gland development, providing a mechanistic basis for engineering seed-specific gossypol-free (SSGF) cotton. We show that Gl2/Gl3 form multimers-likely tetramers-that function as master regulators within the transcriptional network controlling gossypol gland development. Further analyses demonstrate that Gl2e, a dominant mutant allele of Gl2, induces a glandless phenotype through its dominant-negative effect. In addition, multimers composed of Gl2e and Gl2/Gl3 retain E-box binding activity but lack transcriptional activation capacity, thereby inhibiting gland organogenesis. Guided by these insights, we engineered SSGF cotton by driving Gl2e expression specifically during seed development, effectively suppressing gossypol gland formation in seeds. Multi-year, multi-location field trials of the SSGF cotton confirmed the stable production of gossypol-free seeds without compromising fiber yield or other key agronomic traits. Notably, completely gossypol-free oil and flour can be produced directly from SSGF seeds without the need for degossypolization. This work establishes a mechanistic foundation for understanding gland development and offers a sustainable path toward enhancing global plant-derived protein and oil resources.

Cotton (Gossypium spp.) is considered a major cash crop in agriculture, food, and textile industries all over the world. The foremost focus of scientists and farmers is to meet global food security needs, but unfortunately, evolving weather conditions have significantly reduced the overall production. Latest genome sequence of Gossypium hirsutum enables us to understand the molecular mechanisms and identify development-related and stress-responsive genes. The Reproductive Meristem (REM) gene family, a subfamily of B3 DNA-binding superfamily of transcription factors, is characterized in model plants including Arabidopsis and Chickpea, but no study reported in G. hirsutum. In current study, 33 members of REM gene family were predicted and confirmed to possess the conserved REM-related domains in G. hirsutum. The phylogenetic analysis revealed that REM family members are divided into six sub-groups consistent with Arabidopsis, further confirming the evolutionary relationship across species. The pattern of introns, exons, and conserved motifs also indicated evolutionary conservation. Gene duplication analysis suggested segmental duplication as a reason for the expansion of REM gene family. RNA-seq and real-time qPCR assisted expression analysis in root, leaf and stem under multiple abiotic stresses (drought, salt, low and high temperature) collectively suggesting GhREM1 and GhREM5.4 as potential regulators under low and high temperature stress which is supported with the presence of temperature responsive cis-elements. Furthermore, GhREM1-OE and GhREM5.4-OE revealed the significant regulation of peroxidase (POD) under both low and high temperature stress indicating the potential involvement in temperature tolerance. Green fluorescent protein GFP revealed that both genes were localized in the nucleus. Our findings elucidate the ground work for co-regulatory relationship of REM genes and antioxidant activity in cotton under temperature stress.

The investigation into cysteine-rich receptor-like kinases (CRLKs) holds pivotal significance as these conserved, upstream signalling molecules intricately regulate fundamental biological processes such as plant growth, development and stress adaptation. This study undertakes a comprehensive characterisation of CRLKs in Solanum tuberosum (potato), a staple food crop of immense economic importance. Employing comparative genomics and evolutionary analyses, we identified 10 distinct CRLK genes in potato. Further categorisation into three major groups based on sequence similarity was performed. Each CRLK member in potato was systematically named according to its chromosomal position. Multiple sequence alignment and phylogenetic analyses unveiled conserved gene structures and motifs within the same groups. The genomic distribution of CRLKs was observed across Chromosomes 2-5, 8 and 12. Gene duplication analysis highlighted a noteworthy trend, with most gene pairs exhibiting a Ka/Ks ratio greater than one, indicating positive selection of StCRLKs in potato. Salt and drought stresses significantly impacted peroxidase and catalase activities in potato seedlings. The presence of diverse cis-regulatory elements, including hormone-responsive elements, underscored their involvement in myriad biotic and abiotic stress responses. Interestingly, interactions between the phytohormone auxin and CRLK proteins unveiled a potential auxin-mediated regulatory mechanism. A holistic approach combining transcriptomics and quantitative PCR validation identified StCRLK9 as a potential candidate involved in plant response to heat, salt and drought stresses. This study lays a robust foundation for future research on the functional roles of the CRLK gene family in potatoes, offering valuable insights into their diverse regulatory mechanisms and potential applications in stress management.

Arbuscular mycorrhizal fungi (AMF) promote water and mineral nutrients uptake by plant roots, which can reduce the chemical fertilizer inputs in crop production. To gain better insight into the comparative effect of different strains of AMF in improving tomato performance at morphological and physiological levels, seedlings of two tomato cultivars (i.e., Better Boy and Roma) were inoculated with four strains of Glomus mosseae (i.e., HS 1–2 , BEG 12 , BEG 55 , and BEG 54 ) under greenhouse conditions. Results showed that tomato growth and yield varied largely depending on the mycorrhizal strain and tomato cultivar, with wide variations in root colonization ranging from 5.30 to 78.63%. Overall, mycorrhization with BEG 54 showed significantly better tomato performance when compared to the BEG 55, HS 1–2 and BEG 12 strains. In the case of cultivars, Better Boy performed better than Roma cultivar in terms of growth, physiological traits, yield, and fruit quality. The highest plant height, dry matter, nitrogen, phosphorus, potassium, chlorophyll a, chlorophyll b, AMF colonization, yield, fruit juice, ascorbic acid, and titratable acidity contents were recorded in Better Boy cultivar while the highest stem diameter was found in Roma cultivar. Taken together, AMF colonization suggested a promising approach for large-scale tomato production by efficient absorption and utilization of nutrients, and encouraging plants’ symbiotic relationships with soil microorganisms.

Cucumber (Cucumis sativus L.) is a widely cultivated crop with rich germplasm resources, holding significant nutritional value. It also serves as an important model for studying epidermal cell fate and sex determination. Cucumbers are covered with multicellular and unbranched trichomes, including a specific type called spines found on the surface of the fruit. The presence and density of these fruit spines determine the visual quality of cucumber fruits. However, the key regulatory genes and mechanisms underlying cucumber fruit spine development remain poorly understood. In this study, we identified a WUSCHEL-related homeobox (WOX) family gene CsWOX3, which functioned as a typical transcriptional repressor and played a negative role in fruit spine development. Spatial-temporal expression analysis revealed that CsWOX3 exhibited a relatively high expression level in the cucumber female floral organs, particularly in the fruit exocarp. Knockout of CsWOX3 using CRISPR/Cas9 resulted in a significant 2-to-3-fold increase in the diameter of fruit spines base, while overexpression led to a 17% decrease in the diameter compared to the wild-type. A SQUAMOSA PROMOTER BINDING PROTEIN-LIKE transcription factor CsSPL15 could directly bind and activate the expression of CsWOX3, thereby suppressing the expression of downstream auxin-related genes, such as CsARF18. Additionally, the RING-finger type E3 ubiquitin ligase CsMIEL1-like interacted with the HD domain of CsWOX3, which might result in the ubiquitination and subsequent alteration in protein stability of CsWOX3. Collectively, our study uncovered a WOX transcription factor CsWOX3 and elucidated its expression pattern and biological function. This discovery enhances our comprehension of the molecular mechanism governing cucumber fruit spine morphogenesis.

Cotton (Gossypium spp.) has evolved pigment glands (PGs) that accumulate toxic terpenoids, such as gossypol, which serve as a defence mechanism against pests (Gadelha et al., 2014). Laboratory experiments and field trials have confirmed that PGs are essential for tolerance to chewing pests in cotton (Benedict et al., 1977; Mao et al., 2007). Altering the ability of PGs to synthesize and accumulate secondary metabolites is a promising strategy for pest resistance. The discovery of PG development-related genes, such as Gl2/Gl3, CGF1 and CGF2, has preliminarily revealed the genetic mechanisms involved in PG biogenesis and the gossypol synthesis pathway (Janga et al., 2019; Ma et al., 2016). However, few studies have focused on the regulation of PG size. Here, we isolated a PG-specific valine glutamine (VQ) gene, GhVQ22 (GH_A12G0470/GH_D12G0482), regulates PG size and affects the composition and content of secondary metabolites in PGs. GhVQ22 has potential applications in novel anti-pest strategies for cotton. Comparative transcriptome analyses between the PG tissues (PGT) and the PG-adjacent tissues (PGAT) in embryos at 18 days post-anthesis (DPA) were performed through laser-capture microdissection (Figure S1). We detected 506 differentially expressed genes (DEGs) in PGT compared with PGAT (Figure 1a). The 20 DEGs with the highest fold changes were selected for preliminary gland phenotype screening by virus-induced gene silencing (Table S1). GhVQ22-silenced plants (TRV2:GhVQ22) showed significantly enlarged PGs compared to the wild-type (WT) (Figure S2a). GhVQ22 expression was barely detected in PGAT (Figure 1b) and glandless cotton Z12YW (gl2gl2gl3gl3) (Figure 1c), β-Glucuronidase (GUS) reporter expression driven by the GhVQ22 promoter was limited to PGs in stable transgenic G. hirsutum (Figure 1d). These results confirmed that GhVQ22 expression is PG-specific. The Ghvq22 mutant exhibited significant increase in PG size across most tissues (Figure 1e), and PG diameter was approximately 2.7 times larger as compared to WT (Figure S3a). In true leaves of the Ghvq22 mutant, the PG size was significantly larger than that of the WT across the pseudo-developmental trajectory (Figure 1f, Figure S3b). In Ghvq22 mutant, mature PGs exhibited 3–5 sheath cell layers, whereas in WT, there were only 1–3 sheath cell layers (Figure 1g, Figure S3c). Similarly, the cavity diameter was correspondingly increased (Figure 1h, Figure S3c), meanwhile its PG density was half as compared to WT (Figure 1i). But the PG diameter and density were significantly reduced in gl2gl2Gl3Gl3 and Gl2Gl2gl3gl3 mutants with lower GhVQ22 expression (Figure S4b–d). The total secondary metabolites extracted from Ghvq22 leaves were significantly different from the WT (Figure S5). Liquid chromatography–mass spectrometry revealed that 2193 and 1879 metabolites were up-regulated and down-regulated, respectively, in Ghvq22 mutant compared with the WT (Figure 1k). The gossypol content was decrease approximately 50% as compared to WT (Figure 1j). The kaempferol and catechin content was significantly increased and decreased compared with the WT, respectively (Figure 1l,m, Figures S6 and S7). These results suggested that GhVQ22 might regulate secondary metabolite synthesis in PGs. The regulatory relationship between GhVQ22 and PG development-related genes was investigated to determine how GhVQ22 regulates PG development. As PG development progressed with embryo development from 13 to 30 DPA, GhVQ22 expression lagged behind that of Gl2/Gl3 (Figure 1n). Gl2 and Gl3, the core factors that redundantly regulate PG development, activate target gene expression by binding to the G-box (5′-CACGTG-3′) cis-regulatory element (Lin et al., 2023). The GhVQ22 promoter contains a G-box at −234 to −229 bp (Figure S8). Through conducting an electrophoretic mobility shift assay (EMSA) (Figure 1o) and yeast one-hybrid analysis (Figure S9), we confirmed that Gl2 can bind to the GhVQ22 promoter. In addition, Gl2 could activate its transcriptional activity as indicated by a dual-luciferase reporter assay in leaves of Nicotiana benthamiana (Figure 1p). The comparative transcriptome of 18 DPA embryos revealed that 1464 and 1370 genes were up-regulated and down-regulated, respectively, in Ghvq22 (Figure S10). Gene Ontology (GO) enrichment analysis demonstrated that the up-regulated DEGs enriched in cell division, secondary metabolite and flavonoid biosynthesis (Figure 1q). The expression level of PG development-related genes, such as Gl2/Gl3, CGF1, CGF2, JUB1 and ERF105, was significantly enhanced in Ghvq22 mutant (Figures S11 and S12a). These results suggested that GhVQ22 regulation of PG development might depend on the genetic networks of Gl2/Gl3 and are involved in cell division and secondary metabolite pathway. Our hypothesis suggests that Gl2/Gl3 not only activates the expression of genes involved in PG development but also triggers the expression of the negative regulator GhVQ22 (Figure 1r). These two opposing mechanisms form a delicate balance in regulating PG development and secondary metabolite synthesis. Our study revealed that GhVQ22 as a downstream target of Gl2/Gl3, negatively regulates PG size and affects secondary metabolic accumulation. We speculate that the significant changes in PG development-related genes and gland morphogenesis might affect secondary metabolic synthesis. We also observed the stem trichome density of the Ghvq22 mutant was significantly lower than that of the WT (Figure S13b), suggesting that the PGT and PGAT might influence each other by the signal molecular communications. In general, the present results lay a foundation for further research on the regulation of PG development. This work was financially supported by the National Natural Science Foundation of China (grant no. U21A20213) and the Natural Science Foundation of Henan Province, China (grant no. 232300421007). None declared. C.-S.Z., Z.-F.L. and C.-P.S. conceived and directed the project. P.-B.W., X.-F.C., X.-L.Z., L.L., P.-Y.W., C.-D.Y. and R.Z. performed the experiments and wrote the manuscript. The data that supports the findings of this study are available in the supplementary material of this article. Figure S1 a, Embryos at 18 DPA with pigment glands at different developmental stages. b, Diagram of laser-capture microdissection sampling of PG tissues and PGA tissues. Figure S2 a, Phenotype of GhVQ22-silenced cotton. TRV2:CLA, positive control; TRV2:00, empty vector; TRV2:GhVQ22, GhVQ22-silenced cotton. b, GhVQ22 expression in the leaves and stem of TRV2:00, TRV2:GhVQ22 (n =3, *** P < 0.001, Student's t-test). c, Expression of other VQ genes in the leaves of TRV2:00 and TRV2:GhVQ22 (n = 3, n.s. no significance, Student's t-test). d, Sequence analysis of GhVQ22 in the WT, Ghvq22-L2, and Ghvq22-L5. Figure S3 a, Mature PG diameter of leaves in WT and Ghvq22 (n > 30, *** P < 0.001, Student's t-test). b, Diameter of pigment glands at different developmental stages of the first true leaf. (n > 30, *** P < 0.001, Student's t-test). c, Morphological comparison of mature PGs in leaf and stem between WT and Ghvq22. Figure S4 a, Phenotype of WT, gl2gl2Gl3Gl3 and Gl2Gl2gl3gl3 mutants. b, Relative transcript levels of Gl2, GhVQ22, ERF105 and JUB1 in WT, Gl2Gl2gl3gl3 and gl2gl2Gl3Gl3 leaves (n = 3, * P< 0.05, *** P < 0.001, Student's t-test). c, Diameter of pigment glands of WT, Gl2Gl2gl3gl3 and gl2gl2Gl3Gl3 leaves (n = 25, *** P < 0.001, Student's t-test). d, PG density in WT, Gl2Gl2gl3gl3 and gl2gl2Gl3Gl3 leaves (n = 10, *** P < 0.001, Student's t-test). Figure S5 a, Total metabolites extract of WT and Ghvq22 leaves. b, Total ions current of WT and Ghvq22 mutant. Figure S6 Liquid chromatography–mass spectrometry (LC-MS) analysis of kaempferol standard. Figure S7 LC-MS analysis of catechin standard. Figure S8 The G-box (CACGTT) motif in GhVQ22 gene promoter. Figure S9 Yeast one-hybrid assays show the binding ability of Gl2 to the GhVQ22 promoter. Figure S10 Volcano plot of DEGs in 18 DPA embryos between WT and Ghvq22 mutant. Figure S11 Relative transcript levels of Gl2, ERF105, CGF1, CGF2, and JUB1 in WT and Ghvq22 leaves (n = 6, *** P < 0.001, Student's t-test). Figure S12 Heatmap of relative expression of PG development-regulated genes. Figure S13 a, Stem trichome phenotypes of WT and Ghvq22. b, Second-internode stem trichome number per mm2 of WT and Ghvq22. (n > 10, *** P < 0.001, Student's t-test). c, Second-internode stem trichome length of WT and Ghvq22. (n > 10, n.s. no significance, Student's t-test). Figure S14 Evolutionary relationships of the VQ gene family members of Arabidopsis thaliana and Gossypium hirsutum. Figure S15 Heatmap of relative expression of VQ gene family members in PGT and PGAT. Figure S16 Subcellular localization of GhVQ22 in Nicotiana benthamiana leaves. Figure S17 Gene Ontology (GO) analysis of genes that were downregulation expressed in the Ghvq22 compared with that of the wild type (P < 0.001). Table S1 Top 20 differential expression genes between PGT and PGAT. Table S2 Up metabolites. Table S3 Down-metabolites. Table S4 Primers used in this manuscript. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Due to shallow root systems, potato is a particularly drought-sensitive crop. To counteract these limitations, the application of plant growth-promoting microorganisms (PGPMs) is discussed as a strategy to improve nutrient acquisition and biotic and abiotic stress resilience. However, initial root colonization by PGPMs, in particular, can be affected by stress factors that negatively impact root growth and activity or the survival of PGPMs in the rhizosphere. In this study, perspectives for the use of commercial silicate-based soil conditioners (SCs) supposed to improve soil water retention were investigated. The SC products were based on combinations with lignocellulose polysaccharides (Sanoplant® = SP) or polyacrylate (Geohumus® = GH). It was hypothesized that SC applications would support beneficial plant–inoculant interactions (arbuscular mycorrhiza, AM: Rhizophagus irregularis MUCL41833, and Pseudomonas brassicacearum 3Re2-7) on a silty loam soil–sand mixture under water-deficit conditions (6–12 weeks at 15–20% substrate water-holding capacity, WHC). Although no significant SC effects on WHC and total plant biomass were detectable, the SC-inoculant combinations increased the proportion of leaf biomass not affected by drought stress symptoms (chlorosis, necrosis) by 66% (SP) and 91% (GH). Accordingly, osmotic adjustment (proline, glycine betaine accumulation) and ROS detoxification (ascorbate peroxidase, total antioxidants) were increased. This was associated with elevated levels of phytohormones involved in stress adaptations (abscisic, jasmonic, salicylic acids, IAA) and reduced ROS (H2O2) accumulation in the leaf tissue. In contrast to GH, the SP treatments additionally stimulated AM root colonization. Finally, the SP-inoculant combination significantly increased tuber biomass (82%) under well-watered conditions, and a similar trend was observed under drought stress, reaching 81% of the well-watered control. The P status was sufficient for all treatments, and no treatment differences were observed for stress-protective nutrients, such as Zn, Mn, or Si. By contrast, GH treatments had negative effects on tuber biomass, associated with excess accumulation of Mn and Fe in the leaf tissue close to toxicity levels. The findings suggest that inoculation with the PGPMs in combination with SC products (SP) can promote physiological stress adaptations and AM colonization to improve potato tuber yield, independent of effects on soil water retention. However, this does not apply to SC products in general.

Long-term soil mining with extensive cultivation practices and traditional breeding methods have declined the flavor and nutritional value of tomatoes. Apart from important mineral nutrients (i.e., nitrogen, phosphorus, and potassium), fungi known as arbuscular mycorrhizae (AM) can considerably improve the quality of agricultural production through higher phosphate uptake. Using hydroponically cultured commercially available tomato cultivars, we investigated the possible effects of mycorrhizae in improving the nutritional quality of tomato fruit. Funneliformis mosseae (syn. Glomus mosseae)-inoculated tomato plants were grown on a 1:1 mixture of peat and vermiculite, and different phosphorus levels were applied. RNAseq and metabolites were studied to confirm the relative gene expression and metabolites in fruit tissues. The results showed that AM inoculation with low phosphorus can significantly improve important fruit-quality traits such as free amino acids, lycopene (47.9%), and β-carotene (29.6%) without compromising the yield. Further, differentially expressed genes (DEGs) were identified by comparing the nutritional and ripening potential of fruits produced by mycorrhizal and non-mycorrhizal plants. Notably, carotenoids and sugars (BRIX values) were found to be higher in mycorrhized plants in contrast to non-mycorrhized plants. Therefore, the current study suggests mycorrhization as a promising approach for the production of high-quality tomato fruit for human consumption.

IntroductionPost-stroke depression (PSD), one of the most common complications following stroke, affects approximately one-third of stroke patients and is significantly associated with increased disability and mortality as well as decreased quality of life, which makes it an important public health concern. Treatment of PSD significantly ameliorates depressive symptoms and improves the prognosis of stroke.Areas coveredThe authors discuss the critical aspects of the clinical application of prediction and preventive treatment of PSD. Then, the authors update the biological factors associated with the onset of PSD. Furthermore, they summarize the recent progress in pharmacological preventive treatment in clinical trials and propose potential treatment targets. The authors also discuss the current roadblocks in the preventive treatment of PSD. Finally, the authors put postulate potential directions for future studies so as to discover accurate predictors and provide individualized preventive treatment.Expert opinionSorting out high-risk PSD patients using reliable predictors will greatly assist PSD management. Indeed, some predictors not only predict the incidence of PSD but also predict prognosis, which indicates that they might also aid the development of an individualized treatment scheme. Preventive application of antidepressants may also be considered.

Phosphate is one of the essential mineral nutrients. Phosphate transporter genes (PHTs) play an important role in Pi acquisition and homeostasis in tomato plants. However, basic biological information on PHT genes and their responses of symbiosis with arbuscular mycorrhizal in the genome remains largely unknown. We analyzed the physiological changes and PHT gene expression in tomatoes (Micro-Tom) inoculated with arbuscular mycorrhizal (AM) fungi (Funneliformis mosseae) under different phosphate conditions (P1: 0 µM, P2: 25 µM, and P3: 200 µM Pi). Twenty-three PHT genes were identified in the tomato genomics database. Protein sequence alignment further divided the 23 PHT genes into three groups, with similar classifications of exons and introns. Good colonization of plants was observed under low phosphate conditions (25 µM Pi), and Pi stress and AM fungi significantly affected P and N accumulation and root morphological plasticity. Moreover, gene expression data showed that genes in the SlPHT1 (SlPT3, SlPT4, and SlPT5) gene family were upregulated by Funneliformis mosseae under all conditions, which indicated that these gene levels were significantly increased with AM fungi inoculation. None of the analyzed SlPHT genes in the SlPH2, SlPHT3, SlPHT4, and SlPHO gene families were changed at any Pi concentration. Our results indicate that inoculation with AM fungi mainly altered the expression of the PHT1 gene family. These results will lay a foundation for better understanding the molecular mechanisms of inorganic phosphate transport under AM fungi inoculation.

Arbuscular mycorrhizal fungi (AMF) form mutualistic symbiotic relationships with many land plants and play a key role in nitrogen (N) acquisition. NO3−-N and NH4+-N are the main sources of soil mineral N, but how extraradical mycelial transfer affects the different N forms and levels available to tomato plants is not clear. In the present study, we set up hyphal compartments (HCs) to study the efficiency of N transfer from the extramycelium to tomato plants treated with different N forms and levels of fertilization. Labeled 15NO3−-N or 15NH4+-N was placed in hyphal compartments under high and low N application levels. 15N accumulation in shoots and the expression of LeNRT2.3, LeAMT1.1, and LeAMT1.2 in the roots of tomato were measured. According to our results, both 15NO3−-N and 15NH4+-N were transported via extraradical mycelia to the shoots of plants. 15N accumulation in shoots was similar, regardless of the N form, while a higher 15N concentration was found in shoots with low N application. Compared with the control, inoculation with AMF significantly increased the expression of LeAMT1.1 under high N and LeNRT2.3 under low N. The expression of LeAMT1.1 under high N was significantly increased when NO3—N was added, while the expression of LeNRT2.3 was significantly increased when NH4+-N was added under low N. Taken together, our results suggest that the N transfer by extraradical mycelia is crucial for the acquisition of both NO3−-N and NH4+-N by the tomato plant; however, partial N accumulation in plant tissue is more important with N deficiency compared with a higher N supply. The expression of N transporters was influenced by both the form and level of N supply.

Verticillium wilt, caused by Verticillium dahliae, seriously restricts the yield and quality improvement of cotton. Previous studies have revealed the involvement of WRKY members in plant defense against V. dahliae, but the underlying mechanisms involved need to be further elucidated. Here, we demonstrated that Gossypium hirsutum WRKY DNA-binding protein 33 (GhWRKY33) functions as a negative regulator in plant defense against V. dahliae. GhWRKY33 expression is induced rapidly by V. dahliae and methyl jasmonate, and overexpression of GhWRKY33 reduces plant tolerance to V. dahliae in Arabidopsis. Quantitative RT-PCR analysis revealed that expression of several JA-associated genes was significantly repressed in GhWRKY33 overexpressing transgenic plants. Yeast one-hybrid analysis revealed that GhWRKY33 may repress the transcription of both AtERF1 and GhERF2 through its binding to their promoters. Protein-protein interaction analysis suggested that GhWRKY33 interacts with G. hirsutum JASMONATE ZIM-domain protein 3 (GhJAZ3). Similarly, overexpression of GhJAZ3 also decreases plant tolerance to V. dahliae. Furthermore, GhJAZ3 acts synergistically with GhWRKY33 to suppress both AtERF1 and GhERF2 expression. Our results imply that GhWRKY33 may negatively regulate plant tolerance to V. dahliae via the JA-mediated signaling pathway.