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Background The gibberellic acid (GA) inhibitor, uniconazole, is a plant growth regulator commonly used in banana cultivation to promote dwarfing but also enhances the cold resistance in plants. However, the mechanism of this induced cold resistance remains unclear. Results We confirmed that uniconazole induced cold tolerance in bananas and that the activities of Superoxide dismutase and Peroxidase were increased in the uniconazole-treated bananas under cold stress when compared with the control groups. The transcriptome and metabolome of bananas treated with or without uniconazole were analyzed at different time points under cold stress. Compared to the control group, differentially expressed genes (DEGs) between adjacent time points in each uniconazole-treated group were enriched in plant-pathogen interactions, MAPK signaling pathway, and plant hormone signal transduction, which were closely related to stimulus-functional responses. Furthermore, the differentially abundant metabolites (DAMs) between adjacent time points were enriched in flavone and flavonol biosynthesis and linoleic acid metabolism pathways in the uniconazole-treated group than those in the control group. Temporal analysis of DEGs and DAMs in uniconazole-treated and control groups during cold stress showed that the different expression patterns in the two groups were enriched in the linoleic acid metabolism pathway. In addition to strengthening the antioxidant system and complex hormonal changes caused by GA inhibition, an enhanced linoleic acid metabolism can protect cell membrane stability, which may also be an important part of the cold resistance mechanism of uniconazole treatment in banana plants. Conclusions This study provides information for understanding the mechanisms underlying inducible cold resistance in banana, which will benefit the production of this economically important crop.

• Seed yield, determined mainly by seed numbers and seed weight, is the primary target of soybean breeding. Identifying the genes underlying yield-related traits is of great significance. • Through joint linkage mapping and a genome-wide association study for 100-seed weight, we cloned GmGA3ox1, a gene encoding gibberellin 3β-hydroxylase, which is the key enzyme in the gibberellin synthesis pathway. • Genome resequencing identified a beneficial GmGA3ox1 haplotype contributing to high seed weight, which was further confirmed by soybean transformants. CRISPR/Cas9-generated gmga3ox1 mutants showed lower seed weight, but promoted seed yield by increasing seed numbers. The gmga3ox1 mutants reduced gibberellin biosynthesis while enhancing photosynthesis. Knockout of GmGA3ox1 resulted in the upregulation of numerous photosynthesis-related genes, particularly the GmRCA family encoding ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) activases. The basic leucine zipper transcription factors GmbZIP97 and GmbZIP159, which were both upregulated in the gmga3ox1 mutants and induced by the gibberellin synthesis inhibitor uniconazole, could bind to the promoter of GmRCAβ and activate its expression. Analysis of genomic sequences with over 2700 soybean accessions suggested that GmGA3ox1 is being gradually utilized in modern breeding. Our results elucidated the important role of GmGA3ox1 in soybean yield. These findings reveal important clues for future high-yield breeding in soybean and other crops.

Poor light stress causes lodging risks in hybrid indica rice (Oryza sativa L.) in Sichuan Basin, China. However, the effective way of improving lodging resistance of hybrid indica rice by plant regulation strategy under poor light stress has not yet been investigated. A 2‐yr field study, comparing the three foliar application uniconazole rates under normal light and shading condition, was conducted to determine the lodging resistance and its physiological mechanism by using two hybrid rice varieties (Yuxiang203 [YX203] and Cliangyouhuazhan [CLYHZ]). The results showed that shading significantly decreased grain yield, but, increased lodging index (LI) due to poor stem breaking strength (M). Also, shading increased the non‐structural carbohydrates (NSC), but reduced structural carbohydrate (SC), especially for lignin in basal culm and thus, weakened the stem stiffness. Grain yield was first increased, and then declined with increasing foliar uniconazole rates. And, LI decreased sharply owing to improvement of M while reduction of bending moment by whole plant (WP). Larger section modulus (SM) of YX203 and higher bending stress (BS) of CLYHZ were contributed to higher M. Correlation analysis showed that M was significantly correlated with culm diameter, culm wall thickness and SC content for YX203, and that with SC content for CLYHZ, respectively. The results indicated that foliar application of uniconazole increased lodging resistance of hybrid indica rice for larger M and SC accumulation in basal stem. Uniconazole foliar application at 40 mg L–1 can increase lodging resistance while maintaining grain yield of hybrid indica rice in the Sichuan Basin, China. Core Ideas Shading rapidly raised lodging risks of hybrid indica rice due to poor stem strength of basal stem. The foliar application uniconazole increased lodging resistance of hybrid indica rice. The higher stem strength of Yuxiang203 rely on section modulus and structural carbohydrates. Uniconazole rate at 40 mg L–1 rose lodging resistance and yield of hybrid indica rice in the Sichuan Basin.

Uniconazole is a widely used plant growth retardant in the agricultural field. However, toxicological effects of uniconazole in aquatic ecosystem at chiral level are still unclear. Herein, acute toxicity, oxidative stress effects, neurotoxicity, and thyroid disruption of uniconazole enantiomers were investigated through using zebrafish as a model. ( R )-Uniconazole possessed 1.16-fold greater acute toxicity to zebrafish than ( S )-enantiomer. Then, integrated biomarker response values of oxidative stress parameters in zebrafish exposed to ( R )-uniconazole were about 1.27~1.53 times greater than those treated by ( S )-uniconazole, revealing that ( R )-uniconazole could result in more significant adverse effects than ( S )-uniconazole. Subsequently, the results of acetylcholinesterase activity of experimental fish demonstrated a state of inhibition-activation-inhibition after 14-day exposure to uniconazole, and a significant enantioselective neurotoxicity of uniconazole was observed in zebrafish after exposure for 4 and 7 days ( p < 0.05). Moreover, thyroxine and triiodothyronine contents in ( R )-uniconazole-exposed zebrafish were 0.89-fold ( p =0.007) and 0.80-fold ( p =0.007) than those in ( S )-enantiomer-treated group, respectively. Furthermore, molecular docking results between uniconazole enantiomers and thyroid hormone receptors revealed that ( R )-uniconazole was more tightly bound than ( S )-uniconazole to the receptors. Briefly, our findings provide favorable information for ecological risk assessments of chiral agrochemicals in the environment and health of aquatic organisms. Graphical abstract

In this work, the enantioselective bioaccumulation and dissipation of uniconazole enantiomers in earthworm-soil microcosm were studied. A fast enantioseparation method of uniconazole through supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) was established. The CHIRALCEL OZ-3 column and a mixture of CO 2 and methanol (80:20, v/v) were used within 1.0 min to separate uniconazole enantiomers. The recoveries of uniconazole enantiomers in earthworm and soil samples ranged from 83.3 to 113%, and the intra-day and inter-day relative standard deviation values were lower than 11%. In earthworms, the bioaccumulation concentrations of uniconazole enantiomers increased with time and reached the maximum on the 7th day and then decreased. The elimination of uniconazole enantiomers in earthworms followed the first-order kinetics equation, and the elimination half-lives were approximately 7 days. In artificial soil, the dissipation of uniconazole enantiomers was slow, and the dissipation half-lives were both 25.7 days. No enantioselectivity occurred in the earthworm-soil microcosm. These results may reduce the uncertainty of environmental risk assessment for uniconazole.

Background Chilling injury of mung bean ( Vigna radiata (L.)) during the blooming and podding stages is a major agricultural threat in Northeast China. Uniconazole (UNZ) can alleviate water deficit stress in soybean and waterlogging stress in mung bean. However, there has been no report on the effect of UNZ application on the growth and transcriptomic profile of mung bean under chilling stress. Results UNZ application before chilling stress at the R1 stage alleviated the decline in mung bean yield. UNZ delayed the decrease in leaf chlorophyll content under chilling stress at the R1 stage and accelerated the increase in leaf chlorophyll content during the recovery period. Eighteen separate RNA-Seq libraries were generated from RNA samples collected from leaves exposed to six different treatment schemes. The numbers of DEGs specific for UNZ treatment between D1 + S vs. D1 and D4 + S vs. D4 were 708 and 810, respectively. GO annotations showed that photosynthesis genes were obviously enriched among the genes affected by chilling stress and UNZ application. KEGG pathway enrichment analysis indicated that 4 pathways (cutin, suberin and wax biosynthesis; photosynthesis; porphyrin and chlorophyll metabolism; and ribosome) were downregulated, while plant–pathogen interaction was upregulated, by chilling stress. UNZ application effectively prevented the further downregulation of the gene expression of members of these 4 KEGG pathways under chilling stress. Conclusions UNZ application effectively delayed the decrease in photosynthetic pigment content under chilling stress and accelerated the increase in photosynthetic pigment content during the recovery period, thus effectively limiting the decline in mung bean yield. UNZ application effectively prevented the further downregulation of the gene expression of members of 4 KEGG pathways under chilling stress and increased mung bean tolerance to chilling stress.

Polyphenol oxidases (PPOs) as inducible defense proteins, contribute to tea (Camellia sinensis) resistance against tea geometrid larvae (Ectropis grisescens), and this resistance has been associated with the jasmonic acid (JA) signaling by testing geometrid performance in our previous work. However, the regulation of PPO-based defense by JA and other hormone signaling underlying these defense responses is poorly understood. Here, we investigated the role of phytohormones in regulating the PPO response to tea geometrids. We profiled levels of defense hormones, PPO activity and CsPPO genes in leaves infested with tea geometrids. Then, hormone levels were manipulated by exogenous application of methyl jasmonate (MeJA), gibberellin acid (GA3), abscisic acid (ABA), JA biosynthesis inhibitors (sodium diethyldithiocarbamate trihydrate, DIECA and salicylhydroxamic acid, SHAM) and GA inhibitor (uniconazole, UNI). Upon geometrid attack, JA levels significantly increased, whereas GA levels notably decreased and ABA level was slightly decreased. And the PPO activity significantly increased in line with the transcript levels of CsPPO2 and CsPPO4 but not CsPPO1. There were an obvious antagonistic cross-talk between JA and GA signals and an association among JA signals, PPO response and herbivore resistance in tea plants. Pretreatment with MeJA increased PPO activity by activating the transcripts of CsPPO2 and CsPPO4, whereas application of JA inhibitor DIECA suppressed PPO activity. GA3 strongly enhanced PPO activity, but ABA did not alter PPO activity. These findings strongly suggest that JA is a central player in PPO-mediated tea resistance against tea geometrids in a manner that prioritizes defense over growth.

Low-temperature stress is a destructive abiotic stress that limits the production and quality of tropical and subtropical crops. In this study, we investigated the physiological responses of the soybean ( Glycine max (L.) Merr. variety ‘Kenfeng 16’ and the mungbean ( Vigna radiata (L.) R.Wilczek) variety ‘Lvfeng 2’ to exogenous uniconazole S3307 and low-temperature stress at the initial flowering (R1) stage. Uniconazole S3307 increased the photosynthetic parameters [net photosynthetic rate ( P n ), transpiration rate ( T r ), stomatal conductance ( G s ), and intercellular CO 2 concentration ( C i )], sucrose phosphate synthetase (SPS) activity, and the contents of sucrose (SUC) and starch (STA) in ‘Kenfeng 16’ and ‘Lvfeng 2’ under low-temperature stress; but it decreased the activities of acid invertase (AI), neutral invertase (NI), total invertase (IN) as well as the contents of glucose and fructose. Additionally, sucrose synthase (SS) activity was increased in ‘Kenfeng 16’ but decreased in ‘Lvfeng 2’ with uniconazole S3307 treatment. The observed changes of P n , SUC, and STA in ‘Kenfeng 16’; the AI and IN activities in ‘Lvfeng 2’; and the glucose and fructose contents in both varieties were quickly recovered after they were subjected to the 4-day recovery period. Compared with the controls, the yield and yield components of ‘Lvfeng 2’ were significantly ( P ≤ 0.05) higher on day 1 (D1), D2, and D3 of the cold-stress conditions, respectively. The yield per plant was positively correlated with the number of grains per plant, number of pods per plant, G s, SUC, and STA in ‘Lvfeng 2’ and ‘Kenfeng 16’. S3307 enhanced the G s and the accumulation of SUC and STA, but it decreased the NI activity, glucose content, and fructose content, thereby alleviating cold stress to increase the yield.

Salt stress severely inhibit plant growth and development. Uniconazole has been considered to significantly increase plant stress tolerance. However, the mechanism by which Uniconazole induces salt tolerance in rice seedlings and its impact on yield is still unclear. In this study, the effects of exogenous Uniconazole on morphogenesis, physiological metabolism, and yield of rice seedlings under salt stress were analyzed using the salt-tolerant rice variety HD961 and the salt-sensitive rice variety 9311. The results showed that salt stress significantly inhibited rice growth, disrupted the antioxidant system and pigment accumulation, and reduced photosynthesis, and yield. There were corresponding percent decreases of 13.0% and 24.1% in plant height, 31.6% and 55.8% in leaf area, 65.7% and 85.3% in root volume, respectively for HD961 and 9311. spraying However, compared to salt stress, the US treatment increased the percentage to 4.7% and 139.0% in root volume, 7.5% and 38.0% in total chlorophyll, 4.5% and 14.3% in peroxidase (POD) of leaves, 14.4% and 54.2% in POD of roots, 18.7% and 22.7% in catalase (CAT) of leaves, and 22.6% and 53.9% in CAT of roots, respectively, for HD961 and 9311. In addition, it also significantly enhanced photosynthesis at the reproductive stage, promoted the transport of carbohydrate to grains. And US treatment significantly increased the percentage to 9.0% in panicle length, 28.0% in panicle number per hole, 24.0% in filled grain number, 3.0% in 1000-grain weight, and 26.0% in yield per plant, respectively, for HD961, compared to salt stress. In summary, applying Uniconazole at the seedling stage can alleviate the damage induced by NaCl stress on rice by regulating the physiological metabolism of rice plants. This reduces the negative effects of salt stress, enhance salt tolerance, and boost rice production.

Water stress is one of the most important factors limiting sustainable crop production. Therefore, the effects of the plant growth regulators (PGRs) fulvic acid (FA), brassinolide (BR), and uniconazole (Uni) on seedling growth and physiology of two maize ( Zea mays L.) varieties were evaluated under − 0.7 MPa water stress induced by polyethylene glycol-6000. Under drought stress, the PGRs promoted seedling growth, altered the root-to-shoot ratio, and significantly increased root biomass, length, surface area, diameter, and volume. In addition, depending on the PGR, net photosynthesis rate, SPAD value (indicating chlorophyll content), and water use efficiency increased significantly, under drought stress, whereas transpiration rate decreased. The PGRs also significantly increased antioxidant enzyme activities and significantly decreased malondialdehyde accumulation in leaves and roots under drought stress. Zhengdan958 showed greater variation in physiological responses and stronger drought resistance than Xundan20. In alleviating drought stress in maize seedlings, FA had the greatest effects on shoot growth and leaf physiology; Uni exerted its effects by regulating root structure, and BR effects were intermediate. Under drought stress, the three PGRs increased maize seedling growth, which reduced drought stress-induced damage and improved plant ability to resist the adversity. Based on a comprehensive analysis of physiological indices of drought resistance, Uni is recommended as the best PGR to improve maize seedlings resistance to drought.