Paclobutrazol

Catechin promotes the germination of Pistacia chinensis seeds via GA biosynthesis.[Pubmed:38682952]

Ann Bot. 2024 Apr 29:mcae061.

BACKGROUND AND AIMS: Chinese pistachio (Pistacia chinensis Bunge), an important horticultural plant species, holds great ornamental value with beautiful leaves and fruits. Seedling propagation of this tree species is restricted by its erratic seed germination, however, the germination mechanism is ambiguous yet. The aim of this study was to figure out the germination mechanism from the novel perspective based on the multi-omics data. METHODS: The multi-omics technique combined with hormone content measurement was first applied in seed germination of Chinese pistachio. KEY RESULTS: Due to the great accumulation during seed germination, catechin stood out from the identified metabolites by broadly targeted metabolomic analysis. Exogenous catechin of 10 mg/L significantly improved the germination of Chinese pistachio seeds. An interesting result of hormone analysis showed that the improving effect of catechin could be attributed to increase of the gibberellic acid 3 (GA3) content rather than decrease of the abscisic acid (ABA) content before germination. The Paclobutrazol (PAC, a GA biosynthesis inhibitor) and PAC + catechin treatments also showed that the promoting effect of catechin on seed germination depends on GA biosynthesis. Transcriptome analysis and qRT‒PCR further revealed that catechin induced the expression of PcGA20ox5 to activate GA biosynthesis. Several transcription factors were induced by catechin and GA treatments, such as TCP, bZIP and C3H, which may play an important regulatory role in GA biosynthesis in a catechin-mediated way. CONCLUSIONS: Catechin promotes seed germination via GA biosynthesis in Chinese pistachios. This study proposes a novel mechanism by which catechin promotes seed germination via the GA pathway, which provides new insight into a comprehensive understanding of seed dormancy and germination.

KAR(1)-induced dormancy release in Avena fatua caryopses involves reduction of caryopsis sensitivity to ABA and ABA/GA(s) ratio in coleorhiza and radicle.[Pubmed:38635035]

Planta. 2024 Apr 18;259(6):126.

The dormancy release by KAR(1) is associated with a reduction of coleorhiza and radicle sensitivity to ABA as well as with reduction the ABA/GA(s) ratio in the coleorhiza, by a decrease content of ABA, and in the radicle, by a decrease the ABA and an increase of the GA(s) contents. Both, karrikin 1 (KAR(1)) and gibberellin A(3) (GA(3)), release dormancy in Avena fatua caryopses, resulting in the emergence of coleorhiza (CE) and radicle (RE). Moreover, KAR(1) and GA(3) stimulate CE and RE in the presence of abscisic acid (ABA), the stimulation being more effective in CE. The stimulatory effects of KAR(1) and GA(3) involve also the CE and RE rates. A similar effect was observed at KAR(1) concentrations much lower than those of GA(3). KAR(1) increased the levels of bioactive GA(5) and GA(6) in embryos and the levels of GA(1), GA(5), GA(3,) GA(6) and GA(4) in radicles. The stimulatory effect of KAR(1) on germination, associated with increased levels of gibberellins (GA(s)) and reduced levels of ABA in embryos, was counteracted by Paclobutrazol (PAC), commonly regarded as a GA(s) biosynthesis inhibitor. Consequently, KAR(1) decreased the ABA/GA(s) ratio, whereas PAC, used alone or in combination with KAR(1), increased it. The ABA/GA(s) ratio was reduced by KAR(1) in both coleorhiza and radicle, the effect being stronger in the latter. We present the first evidence that KAR(1)-induced dormancy release requires a decreased ABA/GA(s) ratio in coleorhiza and radicle. It is concluded that the dormancy-releasing effect of KAR(1) in A. fatua caryopses includes (i) a reduction of the coleorhiza and radicle sensitivity to ABA, and (2) a reduction of the ABA/GA(s) ratio (i) in the coleorhiza, by decreasing the ABA content, and (ii) in the radicle, by decreasing the ABA and increasing the content GA(s), particularly GA(1). The results may suggest different mechanisms of dormancy release by KAR(1) in monocot and dicot seeds.

[Effects of Pesticides Use on Pesticides Residues and Its Environmental Risk Assessment in Xingkai Lake（China）].[Pubmed:38629531]

Huan Jing Ke Xue. 2024 May 8;45(5):2678-2685.

Xingkai Lake, located in Heilongjiang Province, is an important fishery and agricultural base and is seriously polluted by agricultural non-point sources. To clarify the residual status of many pesticides in the surface water of Xingkai Lake, 27 types of pesticides, herbicides, and their degradation products were analyzed in rice paddy, drainage, and surface water around Xingkai Lake (China) during the rice heading and maturity periods. The results showed that all 27 types of pesticides, herbicides, and their degradation products were detected during the rice heading period, and the total concentration ranged from 247.97 to 6 094.49 ng.L(-1). Additionally, 25 species were detected during the rice maturity period, and the total concentration ranged from 485.36 to 796.23 ng.L(-1). In comparison, more pesticides, herbicides, and derived degradation products were detected during the heading period, and their total concentration was higher as well. During the rice heading period, atrazine, simetryn, and Paclobutrazol were the main detected pesticides, atrazine and isoprothiolane were the main pesticides detected during the maturity period. The distribution characteristics of pesticides and herbicides in the surface water around Xingkai Lake (China) was similar to that in drainage, so they were probably imported from the drainage and rice paddy. The average risk quotient (RQ) values of atrazine, simetryn, prometryn, butachlor, isoprothiolane, and oxadiazon were higher than 0.1 in drainage and Xingkai Lake (China), which showed a potential risk to aquatic organisms.

Core Soil Microorganisms and Abiotic Properties as Key Mechanisms of Complementary Nanoscale Zerovalent Iron and Nitrification Inhibitors in Decreasing Paclobutrazol Residues and Nitrous Oxide Emissions.[Pubmed:38530782]

J Agric Food Chem. 2024 Apr 10;72(14):7672-7683.

Agrochemical residues and nitrous oxide (N(2)O) emissions have caused considerable threats to agricultural soil ecology. Nanoscale zerovalent iron (nZVI) and nitrification inhibitors might be complementary to each other to diminish soil agrochemical residues and N(2)O emissions and enhance soil bacterial community diversities. Compared to the control, the nZVI application declined soil Paclobutrazol residues by 5.9% but also decreased the bacterial community co-occurrence network node. Combined nZVI and Dicyandiamide applications significantly decreased soil N(2)O emission rates and Paclobutrazol residues but promoted Shannon diversity of the bacterial community. The increased soil pH, ammonium nitrogen, and Actinobacteriota could promote soil Paclobutrazol dissipation. The nZVI generated double-edged sword effects of positively decreasing Paclobutrazol residues and N(2)O emissions but negatively influencing soil multifunctionalities. The nZVI and Dicyandiamide could be complementary to each other in diminishing soil agrochemical residues and N(2)O emission rates but promoting soil bacterial community diversities simultaneously.

Stereoselectivity of paclobutrazol enantiomers to oxidative stress in wheat.[Pubmed:38384151]

Chirality. 2024 Feb;36(2):e23638.

Chiral pesticides have the special chiral structures, so enantioselective biological effects are usually observed in living organisms. Current study used Paclobutrazol as a case study and explored the enantioselective degradation and oxidative stress effect on wheat. The results demonstrated that the degradation of R-Paclobutrazol was faster than S-Paclobutrazol significantly and improved the content of MDA and O(2) (-) in wheat plants, which proved that the R-Paclobutrazol induced oxidative damage in wheat, showing selective biological effects, and S-Paclobutrazol was friendly to wheat. This study provided a theoretical basis for the selective activity of chiral pesticides and the development of chiral pesticide monomers.

Gibberellins involved in fruit ripening and softening by mediating multiple hormonal signals in tomato.[Pubmed:38344652]

Hortic Res. 2023 Dec 18;11(2):uhad275.

The phytohormone ethylene is well known for its important role in the ripening of climacteric fruit, such as tomato (Solanum lycopersicum). However, the role and mode of action of other plant hormones in climacteric fruit ripening regulation are not fully understood. Here, we showed that exogenous GA treatment or increasing endogenous gibberellin content by overexpressing the gibberellin synthesis gene SlGA3ox2 specifically in fruit tissues delayed tomato fruit ripening, whereas treatment with the GA biosynthesis inhibitor Paclobutrazol (PAC) accelerated fruit ripening. Moreover, exogenous ethylene treatment cannot completely reverse the delayed fruit ripening phenotype. Furthermore, exogenous GA treatment of ethylene signalling mutant Never ripe (Nr) or SlEBF3-overexpressing lines still delayed fruit ripening, suggesting that GA involved in fruit ripening partially depends on ethylene. Transcriptome profiling showed that gibberellin affect the ripening of fruits by modulating the metabolism and signal transduction of multiple plant hormones, such as auxin and abscisic acid, in addition to ethylene. Overall, the results of this study provide new insight into the regulation of gibberellin in fruit ripening through mediating multiple hormone signals.

TLC-Bioautography-Guided Isolation and Assessment of Antibacterial Compounds from Manuka (Leptospermum scoparium) Leaf and Branch Extracts.[Pubmed:38338460]

Molecules. 2024 Feb 4;29(3):717.

A rapid procedure for the targeted isolation of antibacterial compounds from Manuka (Leptospermum scoparium) leaf and branch extracts was described in this paper. Antibacterial compounds from three different Manuka samples collected from New Zealand and China were compared. The active compounds were targeted by TLC-bioautography against S. aureus and were identified by HR-ESI-MS, and -MS/MS analysis in conjunction with Compound Discoverer 3.3. The major antibacterial component, grandiflorone, was identified, along with 20 beta-triketones, flavonoids, and phloroglucinol derivatives. To verify the software identification, grandiflorone underwent purification via column chromatography, and its structure was elucidated through NMR analysis, ultimately confirming its identity as grandiflorone. This study successfully demonstrated that the leaves and branches remaining after Manuka essential oil distillation serve as excellent source for extracting grandiflorone. Additionally, we proposed an improved TLC-bioautography protocol for evaluating the antibacterial efficacy on solid surfaces, which is suitable for both S. aureus and E. coli. The minimum effective dose (MED) of grandiflorone was observed to be 0.29-0.59 mug/cm(2) against S. aureus and 2.34-4.68 mug/cm(2) against E. coli, respectively. Furthermore, the synthetic plant growth retardant, Paclobutrazol, was isolated from the samples obtained in China. It is hypothesized that this compound may disrupt the synthesis pathway of triketones, consequently diminishing the antibacterial efficacy of Chinese Manuka extract in comparison to that of New Zealand.

NADPH oxidase-dependent H(2)O(2) production mediates salicylic acid-induced salt tolerance in mangrove plant Kandelia obovata by regulating Na(+)/K(+) and redox homeostasis.[Pubmed:38308390]

Plant J. 2024 May;118(4):1119-1135.

Salicylic acid (SA) is known to enhance salt tolerance in plants. However, the mechanism of SA-mediated response to high salinity in halophyte remains unclear. Using electrophysiological and molecular biological methods, we investigated the role of SA in response to high salinity in mangrove species, Kandelia obovata, a typical halophyte. Exposure of K. obovata roots to high salinity resulted in a rapid increase in endogenous SA produced by phenylalanine ammonia lyase pathway. The application of exogenous SA improved the salt tolerance of K. obovata, which depended on the NADPH oxidase-mediated H(2)O(2). Exogenous SA and H(2)O(2) increased Na(+) efflux and reduced K(+) loss by regulating the transcription levels of Na(+) and K(+) transport-related genes, thus reducing the Na(+)/K(+) ratio in the salt-treated K. obovata roots. In addition, exogenous SA-enhanced antioxidant enzyme activity and its transcripts, and the expressions of four genes related to AsA-GSH cycle as well, then alleviated oxidative damages in the salt-treated K. obovata roots. However, the above effects of SA could be reversed by diphenyleneiodonium chloride (the NADPH oxidase inhibitor) and Paclobutrazol (a SA biosynthesis inhibitor). Collectively, our results demonstrated that SA-induced salt tolerance of K. obovata depends on NADPH oxidase-generated H(2)O(2) that affects Na(+)/K(+) and redox homeostasis in response to high salinity.

Quality variation of maidong (Ophiopogon japonicus and Liriope spicata) - A HPTLC-based approach.[Pubmed:38280236]

J Pharm Biomed Anal. 2024 Apr 15;241:115990.

The tuberous roots of Ophiopogon japonicus and Liriope spicata are used for the same therapeutic purpose in traditional Chinese medicine and are collectively referred to as maidong medicine. Interestingly, it was observed that the price of tuberous roots varies depending on their location on the plant, and fibrous roots are usually discarded post-harvest. Mislabeling might be of concern due to similarities in morphological features between the two species. Moreover, Paclobutrazol has been observed to be heavily applied during the production, and therefore might be of health concern. Overall, maidong might suffer from quality inconsistencies while its metabolomic complexity is influenced by growing region and cultivation practices, botanical species, and plant parts. To address these challenges, this study employed High-Performance Thin Layer Chromatography (HPTLC) approach, in which sample preparation and derivatization procedure were optimized to enable to capture more detailed and comprehensive metabolomic fingerprints. By integrating with rTLC algorithm and Multivariate Data Analysis (MVDA), an improved quality assessment was achieved. Samples were collected from four production regions and supplemented with commercial products from markets. The optimized HPTLC analysis recognized species- and region-specific metabolomic patterns of maidong, uncovering a 4% of mislabelled cases. Moreover, findings highlight the underexplored therapeutic potential of fibrous roots, and comparable therapeutic efficacy between different root types. Additionally, complemented by Liquid Chromatography-Mass Spectrometry (LC-MS) for Paclobutrazol residue evaluation, 24.66% of the commercial maidong samples surpassed maximum residue limits of Paclobutrazol, raising safety concerns. This research represents a significant analytical advancement, offering a robust, cost-effective, and comprehensive method for maidong quality control, and paving the way for more strict residue regulation and updates to herbal pharmacopoeias and monographs.

Effects of paclobutrazol seed priming on seedling quality, photosynthesis, and physiological characteristics of fragrant rice.[Pubmed:38229011]

BMC Plant Biol. 2024 Jan 17;24(1):53.

BACKGROUND: Paclobutrazol is widely used in the agricultural field. This study investigated the effects of seed priming with different concentrations of Paclobutrazol on seedling quality, 2-acetyl-1-pyrroline (2-AP, a key aroma component of fragrant rice) biosynthesis, and related physiological and biochemical indicators in fragrant rice seedlings. RESULTS: The experiment is being conducted at the College of Agriculture, South China Agricultural University. In the experiment, three concentrations of Paclobutrazol (Pac 1: 20 mg.L(-1); Pac 2: 40 mg.L(-1); Pac 3: 80 mg.L(-1)) were used to initiate the treatment of fragrant rice seeds, while water treatment was used as a control (CK). The results showed that compared with CK, Paclobutrazol treatment reduced plant height, increased stem diameter, and increased fresh and dry weight of aromatic rice seedlings. Moreover, Paclobutrazol treatment also increased the seedlings' photosynthetic pigment content and net photosynthetic rate. CONCLUSIONS: This study demonstrates that Paclobutrazol primarily increases the content of proline by reducing the content of glutamate and down-regulating the expression of P5CS2, thereby promoting the conversion of proline to the aromatic substance 2-AP. Under the appropriate concentration of Paclobutrazol (40 mg.L(-1)~80 mg.L(-1)), the seedling quality, stress resistance, and aroma of fragrant rice can be improved.

GRAS gene family in rye (Secale cereale L.): genome-wide identification, phylogeny, evolutionary expansion and expression analyses.[Pubmed:38216860]

BMC Plant Biol. 2024 Jan 13;24(1):46.

BACKGROUND: The GRAS transcription factor family plays a crucial role in various biological processes in different plants, such as tissue development, fruit maturation, and environmental stress. However, the GRAS family in rye has not been systematically analyzed yet. RESULTS: In this study, 67 GRAS genes in S. cereale were identified and named based on the chromosomal location. The gene structures, conserved motifs, cis-acting elements, gene replications, and expression patterns were further analyzed. These 67 ScGRAS members are divided into 13 subfamilies. All members include the LHR I, VHIID, LHR II, PFYRE, and SAW domains, and some nonpolar hydrophobic amino acid residues may undergo cross-substitution in the VHIID region. Interested, tandem duplications may have a more important contribution, which distinguishes them from other monocotyledonous plants. To further investigate the evolutionary relationship of the GRAS family, we constructed six comparative genomic maps of homologous genes between rye and different representative monocotyledonous and dicotyledonous plants. The response characteristics of 19 ScGRAS members from different subfamilies to different tissues, grains at filling stages, and different abiotic stresses of rye were systematically analyzed. Paclobutrazol, a triazole-based plant growth regulator, controls plant tissue and grain development by inhibiting gibberellic acid (GA) biosynthesis through the regulation of DELLA proteins. Exogenous spraying of Paclobutrazol significantly reduced the plant height but was beneficial for increasing the weight of 1000 grains of rye. Treatment with Paclobutrazol, significantly reduced gibberellin levels in grain in the filling period, caused significant alteration in the expression of the DELLA subfamily gene members. Furthermore, our findings with respect to genes, ScGRAS46 and ScGRAS60, suggest that these two family members could be further used for functional characterization studies in basic research and in breeding programmes for crop improvement. CONCLUSIONS: We identified 67 ScGRAS genes in rye and further analysed the evolution and expression patterns of the encoded proteins. This study will be helpful for further analysing the functional characteristics of ScGRAS genes.

Genome-Wide Identification and Expression Analysis Reveals the B3 Superfamily Involved in Embryogenesis and Hormone Responses in Dimocarpus longan Lour.[Pubmed:38203301]

Int J Mol Sci. 2023 Dec 21;25(1):127.

B3 family transcription factors play an essential regulatory role in plant growth and development processes. This study performed a comprehensive analysis of the B3 family transcription factor in longan (Dimocarpus longan Lour.), and a total of 75 DlB3 genes were identified. DlB3 genes were unevenly distributed on the 15 chromosomes of longan. Based on the protein domain similarities and functional diversities, the DlB3 family was further clustered into four subgroups (ARF, RAV, LAV, and REM). Bioinformatics and comparative analyses of B3 superfamily expression were conducted in different light and with different temperatures and tissues, and early somatic embryogenesis (SE) revealed its specific expression profile and potential biological functions during longan early SE. The qRT-PCR results indicated that DlB3 family members played a crucial role in longan SE and zygotic embryo development. Exogenous treatments of 2,4-D (2,4-dichlorophenoxyacetic acid), NPA (N-1-naphthylphthalamic acid), and PP(333) (Paclobutrazol) could significantly inhibit the expression of the DlB3 family. Supplementary ABA (abscisic acid), IAA (indole-3-acetic acid), and GA(3) (gibberellin) suppressed the expressions of DlLEC2, DlARF16, DlTEM1, DlVAL2, and DlREM40, but DlFUS3, DlARF5, and DlREM9 showed an opposite trend. Furthermore, subcellular localization indicated that DlLEC2 and DlFUS3 were located in the nucleus, suggesting that they played a role in the nucleus. Therefore, DlB3s might be involved in complex plant hormone signal transduction pathways during longan SE and zygotic embryo development.

A study of the pesticide residues in rapeseeds in China: Levels, distribution and health risk assessment.[Pubmed:38184066]

Environ Res. 2024 Apr 1;246:118110.

The aim of this survey was to evaluate the residue levels, distribution and exposure risk of the 38 most commonly used pesticides in rapeseed samples collected from the main production areas in China over a two-year period. The sampling area covered 12 provinces, including Guizhou, Shaanxi, Yunnan, Hunan, Jiangxi, Sichuan, Chongqing, Anhui, Henan, Hubei, Zhejiang, and Jiangsu provinces. The pesticide residues were determined using a QuEChERS (Quick Easy Cheap Effective Rugged and Safe) method coupled with gas chromatography-tandem mass spectrometry and liquid chromatography-tandem mass spectrometry. 8.4% of the rapeseed samples contained pesticides with a residue level ranging from 0.001 to 0.634 mg/kg. The detected analytes were imidacloprid, quizalofop-P-ethyl, thiamethoxam, Paclobutrazol, prochloraz, tebuconazole, difenoconazole, s-metolachlor, carbofuran, and carbendazim. The concentrations of four analytes, including thiamethoxam, difenoconazole, carbendazim and prochloraz, exceeded the maximum residue level set by the Chinese government for rapeseed, with exceedance rates of 0.1%, 0.1%, 0.1%, and 1.1%, respectively. Based on the index of quality for residues (IqR) values, 91.6% of the total rapeseed samples had an IqR category of Excellent (IqR = 0). Only 1.5% of the tested samples were of inadequate quality. Furthermore, the assessment of chronic and acute exposure, as well as health risks associated with pesticide residues in rapeseed, was conducted for different age groups within the Chinese population, including adults (6-14 years), children (15-49 years), and the elderly (50-74 years). The results of this assessment indicated that pesticide residues in rapeseed cultivated in China are not expected to be of short- or long-term risks to the Chinese customers.

Gibberellin-mediated far-red light-induced leaf expansion in cucumber seedlings.[Pubmed:38170395]

Protoplasma. 2024 May;261(3):571-579.

Our experiments explored the effects of far-red (FR) light on cucumber (Cucumis sativus L. 'Zhongnong No. 26') seedling growth. Our results indicated that FR light significantly promoted the growth of cucumber seedlings. Specifically, it promoted the accumulation of shoot biomass and the elongation of internodes and leaves (except the first leaf at the bottom). Further analysis showed that FR light had no effect on the accumulation contents of abscisic acid (ABA) and auxin (IAA) in seedling leaves. Still, it significantly caused the increase of the gibberellin (GA3, GA4, and GA7) contents and the decrease of GA1 content, which suggested that the leaf expansion progress under FR light may be primarily related to GA. Therefore, the cucumber seedling leaf expansion response to GA was evaluated under different light sources. The exogenous spraying of different GA4/7 contents significantly promoted the leaf expansion of cucumber seedlings under white light, while the GA biosynthesis inhibitor Paclobutrazol (PAC) significantly promoted the expression of GA hydrolytic genes (GA2ox2 and GA2ox4) and decreased the content of endogenous active GA, which inhibited the leaf expansion induced by FR light. As expected, the combination of exogenous GA4/7 and PAC restored the growth promotion effect of FR light on cucumber seedling leaves. It increased the contents of endogenous active GA (GA1, GA3, GA4, and GA7), and the expression trend in GA synthetic/hydrolytic-related genes was the opposite of that of PAC was applied alone. All of the above results indicated that FR light regulates leaf expansion progress in cucumber seedlings through GA.

Dispersive solid phase extraction based on cross-linked hydroxypropyl beta-cyclodextrin polymers for simultaneous enantiomeric determination of three chiral triazole fungicides in water.[Pubmed:38087124]

Mikrochim Acta. 2023 Dec 13;191(1):18.

An efficient method is presented for simultaneous enantioselective determination of three chiral triazole fungicides (namely Paclobutrazol, hexaconazole, and diniconazole) in water samples by DSPE-HPLC-UV. The perfect chiral separation of the enantiomers was achieved on a Chiralpak IH column within 15 min. In order to adsorb and enrich the analytes from water matrices, a cross-linked hydroxypropyl beta-cyclodextrin polymer was synthesized. The prepared material exhibited good adsorption capacity, which was assessed by adsorption kinetic and adsorption thermodynamic experiments. One-variable-at-a-time and the response surface methodology were used to optimize the extraction parameters. Under the optimum sample preparation conditions, good linearity (2.0 ~ 800 microg L(-1), R(2) >/= 0.9978), detection limits (0.6 to 1.0 microg L(-1)), quantitation limits (2.0 to 3.2 microg L(-1)), recoveries (86.7 ~ 105.8%), and the relative standard deviation (intra-day RSD