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Patchouli (Pogostemon cablin) is an aromatic plant, and its oil has diverse applications in medicine, food, and cosmetics. Patchouli alcohol is the principal bioactive constituent of its volatile oil. In China, patchouli is typically categorized into two types: patchoulol-type (PA-type) and pogostone-type (PO-type). The study evaluated physiological and biochemical indicators, phytohormone metabolites and conducted transcriptome and proteome analyses on both two chemotypes. The PA-type exhibited higher levels of chlorophyll a, b, and carotenoids than the PO-type. In total, 35 phytohormone metabolites representing cytokinin, abscisic acid, gibberellin, jasmonic acid, and their derivatives were identified using UPLC-MS/MS, 10 of which displayed significant differences, mainly belong to cytokinins and jasmonates. Transcriptome analysis identified 4,799 differentially expressed genes (DEGs), while proteome analysis identified 150 differentially expressed proteins (DEPs). Regarding the transcriptome results, the DEGs of the PO-type showed significant downregulation in the pathways of photosynthesis, photosynthesis-antenna protein, porphyrin and chlorophyll metabolism, carotenoid biosynthesis, sesquiterpene and triterpenoid biosynthesis, and starch and sucrose metabolism, but upregulation in the pathway of zeatin synthesis. A combination of transcriptome and proteome analyses revealed that the DEGs and DEPs of lipoxygenase (LOX2), β-glucosidase, and patchouli synthase (PTS) were collectively downregulated, while the DEGs and DEPs of Zeatin O-xylosyltransferase (ZOX1) and α-amylase (AMY) were jointly upregulated in the PO-type compared to the PA-type. Differential levels of phytohormones, variations in photosynthetic efficiency, and differential expression of genes in the sesquiterpene synthesis pathway may account for the morphological and major active component differences between the two chemotypes of patchouli. The findings of this study offer novel perspectives on the underlying mechanisms contributing to the formation of the two patchouli chemotypes. [ABSTRACT FROM AUTHOR]

Anthropogenic activities have drastically increased nitrogen (N) deposition, resulting in increased N availability. The continuous increase of N availability may exacerbate phosphorus (P) deficiency, which would limit forest productivity in subtropical forests. Effects of long-time N and N + P additions on SOC turnover in subtropical forests is therefore crucial for understanding the global carbon (C) cycle. The argument of whether N and N + P addition accelerates or slows SOC turnover has been under debate, particularly in P-limited subtropical forests. This study mainly aims to confirm this argument. A ten-year field experiment was conducted in a subtropical evergreen broad-leaved forest in southern Anhui, China. We measured the soil δ13CSOC contents and physicochemical properties under N (100 kg N·ha−1·a−1), N + P (100 kg N ha−1·a−1 + 50 kg P ha−1·a−1) additions, and the control (CK, no N and P additions). We also estimated the β value, which represents the soil organic carbon (SOC) turnover rate, from the slope of the regression between the log10-transformed SOC content and δ13CSOC in soil depth profiles. Our findings revealed that N addition significantly affected soil δ13CSOC compared to CK on both mid-slope and flat ridge sites. The β values responded differently to various treatments and sites. On the mid-slope, the β values did not show significant change with N and N + P additions. On the flat ridge, however, the β value decreased significantly in N and N + P additions, implying an increased SOC turnover rate. In addition, analysis of soil C–N–P stoichiometric ratios and physicochemical properties showed that N and N + P additions could affect β values by modifying soil nutrient content and composition. In general, our findings indicate that N and N + P additions could accelerate the SOC turnover in subtropical forest ecosystems, albeit with close dependence on site-specific factors. [ABSTRACT FROM AUTHOR]

Aims: Increasing global nitrogen (N) and phosphorus (P) deposition may affect the response mechanism of litter decomposition. We aimed to explore the responses of nutrient release and enzyme activities to exogenous N and P inputs. Methods: We conducted a two‑year field litterbag experiment in larch (Larix principis-rupprechtii) plantation at the Saihanba Forest Farm in Hebei Province, China. Four treatments, i.e., N addition (+ N), P addition (+ P), N and P addition (N + P), and control (CK) were designed and examined the overall effect of the fertilization treatments on the remaining mass, nutrients, and enzymatic activity. Results: In contrast to CK, the + N, + P, and N + P treatments significantly reduced the remaining leaf litter mass by 36.33%, 35.21%, and 38.50% at the end of the experiment, respectively. During the decomposition of leaf litter, + N had a significant effect on carbon (C) release and no significant effect on N and P release. + P promoted C release and significantly reduced the N remaining but increased the P remaining. Invertase activity decreased sharply in the early stage of decomposition. However, the activities of catalase, urease, and acid phosphatase declined in the middle stage in each treatment. The effect of + N on enzyme activities was not significant, while + P significantly increased urease activity. Conclusion: The results reveal that continuous N and P deposition could promote the litter decomposition rate, while altered the nutrient release pattern in larch plantation. [ABSTRACT FROM AUTHOR]

Background: Cypripedium subtropicum is a unique, endangered lady's slipper orchid with evergreen leaves on non-dormant shoots that is native to southwestern China. This study documents the major developmental events in C. subtropicum seed development from fertilization to seed maturity, determines the optimum period for seed collection, and examines the cytokinin requirements for asymbiotic germination and protocorm survival. Results: Structural studies revealed that embryo development proceeded after successful fertilization at 60 days after pollination (DAP). At 105 DAP, a globular embryo with the shrinking inner seed coat was observed, and seeds collected at this time point exhibited optimal germination. After 120 DAP, most seeds had a mature embryo within the capsule, and within the cells of the embryo proper, numerous proteins/lipid bodies were present as the main storage products. In addition, the inner seed coat had compressed into a thin layer that tightly enclosed the embryo, while the outer seed coat had progressively elongated, resulting in a hair-like appearance of the mature seed. Histochemical staining using Nile red and toluidine blue O (TBO) indicated that the lignified inner and outer seed coats may lead to coat-imposed dormancy. Seeds collected at this stage germinated poorly. Analyses of cytokinin preferences and optimal concentrations for germination and protocorm survival showed that both 6-(γ,γ-dimethylallylamino) purine (2iP) and 6-benzylaminopurine (BA) enhanced germination compared with the control, although higher concentrations of BA (4 and 8 μM) suppressed germination. The protocorm survival rate improved with increasing 2iP concentration. Conclusions: This study provides a reproducible procedure for culturing immature seeds of C. subtropicum based on a defined time schedule of seed development. In addition, the cytokinin 2iP was shown to improve germination and protocorm survival. This study provides a scientific basis for seedling establishment through asymbiotic seed culture for further reintroduction efforts. [ABSTRACT FROM AUTHOR]

Winter rapeseed is the largest source of edible oil in China and is especially sensitive to low temperature, which causes tremendous agricultural yield reduction and economic losses. It is still unclear how DNA methylation regulates the formation of freezing tolerance in winter rapeseed under freezing stress. Therefore, in this study, the whole-genome DNA methylation map and transcriptome expression profiles of freezing-resistant cultivar NTS57 (NS) under freezing stress were obtained. The genome-wide methylation assay exhibited lower levels of methylation in gene-rich regions. DNA methylation was identified in three genomic sequence contexts including CG, CHG and CHH, of which CG contexts exhibited the highest methylation levels (66.8%), followed by CHG (28.6%) and CHH (9.5%). Higher levels of the methylation were found in upstream 2 k and downstream 2 k of gene regions, whereas lowest levels were in the gene body regions. In addition, 331, 437, and 1720 unique differentially methylated genes (DMGs) were identified in three genomic sequence contexts in 17NS under freezing stress compared to the control. Function enrichment analysis suggested that most of enriched DMGs were involved in plant hormones signal transduction, phenylpropanoid biosynthesis and protein processing pathways. Changes of genes expression in signal transduction pathways for cytokinin (CK) and jasmonic acid (JA) implied their involvement in freezing stress responses. Collectively, these results suggested a critical role of DNA methylation in their transcriptional regulation in winter rapeseed under freezing stress. [ABSTRACT FROM AUTHOR]

Acetic acid priming may mitigate salt stress to plants by modulating lipid metabolism. Carex rigescens is a stress-tolerant turfgrass species with a widespread distribution in north China. The objective of this study was to figure out whether modification of lipid profiles, including the contents, compositions and saturation levels of leaf lipids, may contribute to acetic acid modulated salt tolerance in C. rigescens. Plants of C. rigescens were primed with or without acetic acid (30 mM) and subsequently exposed to salt stress (300 mM NaCl) for 15 days. Salt stress affected the physiological performance of C. rigescens , while acetic acid-primed plants showed significantly lower malondialdehyde content, proline content, and electrolyte leakage than non-primed plants under salt stress. Acetic acid priming enhanced the contents of phospholipids and glycolipids involved in membrane stabilization and stress signaling (phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, digalactosyl diacylglycerol, monogalactosyl diacylglycerol, and sulfoquinovosyldiacylglycerol), reduced the content of toxic lipid intermediates (free fatty acids) during subsequent exposure to salt stress. Furthermore, expression levels of genes involved in lipid metabolism such as CK and PLDα changed due to acetic acid priming. These results demonstrated that acetic acid priming could enhance salt tolerance of C. rigescens by regulating lipid metabolism. The lipids could be used as biomarkers to select for salt-tolerant grass germplasm. • Acetic acid priming induced salt tolerance of Carex rigescens. • Salt tolerance due to acetic acid priming was associated with lipid metabolism. • Improved structural lipids contents contributed to the acquired salt tolerance. • Acetic acid priming reduced the lipid intermediates induced lipotoxicity. [ABSTRACT FROM AUTHOR]

Background: Dwarf rootstocks have important practical significance for high-density planting in pear orchards. The shoots of 'Cuiguan' grafted onto the dwarf rootstock were shorter than those grafted onto the vigorous rootstock. However, the mechanism of shorter shoot formation is not clear., Results: In this study, the current-year shoot transcriptomes and phytohormone contents of 'CG‒QA' ('Cuiguan' was grafted onto 'Quince A', and 'Hardy' was used as interstock) and 'CG‒DL' ('Cuiguan' was grafted onto 'Duli', and 'Hardy' was used as interstock) were compared. The transcriptome results showed that a total of 452 differentially expressed genes (DEGs) were identified, including 248 downregulated genes and 204 upregulated genes; the plant hormone signal transduction and zeatin biosynthesis pathways were significantly enriched in the top 20 KEGG enrichment terms. Abscisic acid (ABA) was the most abundant hormone in 'CG‒QA' and 'CG‒DL'; auxin and cytokinin (CTK) were the most diverse hormones; additionally, the contents of ABA, auxin, and CTK in 'CG‒DL' were higher than those in 'CG‒QA', while the fresh shoot of 'CG‒QA' accumulated more gibberellin (GA) and salicylic acid (SA). Metabolome and transcriptome co-analysis identified three key hormone-related DEGs, of which two (Aldehyde dehydrogenase gene ALDH3F1 and YUCCA2) were upregulated and one (Cytokinin oxidase/dehydrogenase gene CKX3) was downregulated., Conclusions: Based on the results of transcriptomic and metabolomic analysis, we found that auxin and CTK mainly regulated the shoot differences of 'CG-QA' and 'CG-DL', and other hormones such as ABA, GA, and SA synergistically regulated this process. Three hormone-related genes ALDH3F1, YUCCA2, and CKX3 were the key genes contributing to the difference in shoot growth between 'CG-QA' and 'CG-DL' pear. This research provides new insight into the molecular mechanism underlying shoot shortening after grafted onto dwarf rootstocks., (© 2024. The Author(s).)

Aegilops tauschii Coss, a notorious wheat field weed, poses a serious threat to wheat in China. Tillers are an important agronomic tool for yield. In this study, a total of 12 Ae. tauschii populations were collected from China to investigate the effect of plant density on tiller occurrence and its phytohormonal regulation. We assayed the growth parameters of Ae. tauschii and the levels of endogenous hormones at different plant densities. The results showed that plant density had a significant effect on the quantity and quality of Ae. tauschii seeds produced per plant. In particular, the tiller and spike numbers per plant were negatively affected by plant density (P < 0.0001). The contents of 13 endogenous hormones in the tiller nodes changed in response to plant density. Among them, indole-3-acetic acid (IAA) and gibberellin (GA) positively responded to plant density. However, the reverse result was found for cytokinin (CTK). Interestingly, phylogenetic tree analysis of auxin (AeYUCCA), CK (AeIPT) and GA (AeCPS) biosynthesis related genes found that phylogenies in the Gramineae for the three different genes were various, hinting at horizontal gene transfer. Moreover, the dynamics of the expression of AeYUCCA , AeIPT and AeCPS were roughly consistent with their phytohormone contents during tillering stage. When externally sprayed on plants of Ae. tauschii , 2,4-D isooctyl ester and GA 3 markedly reduced its tillering while 6-BA had no significant effect. Image 1 • Plant density affected the tiller and spike productions of Aegilops tauschii Coss. • Cytokinin had a stimulatory role in Ae. tauschii tiller response to plant density. • Auxin and gibberellin inhibited Ae. tauschii tillering response to plant density. • Phylogenies in the Gramineae for AeYUCCA, AeIPT and AeCPS genes were various. • 2,4-D isooctyl ester and GA 3 application inhibited the tillering of Ae. tauschii. [ABSTRACT FROM AUTHOR]

• It was established that transformed shoots can spontaneously regenerate on hairy root of D. forrestii. • It was proven that used type purine- cytokinin influence on proliferation of transformed shoots and content of metabolites. • In hydromethanolic extract from plant material indicated eight phenolic compounds. • It was determined that the main metabolite was rosmarinic acid. • The flavonoids glucosides were identified for the first time in the D. forrestii. Dracocephalum forrestii is a perennial, endemic to China plant with a number of pharmaceutical properties. Transformed shoots of the species spontaneously regenerated from hairy roots induced by Agrobacterium rhizogenes. The transgenic nature of the shoots was confirmed by polymerase chain reaction (PCR). The shoot culture was multiplied on Murashige and Skoog (MS) medium with 0.2 mg/l IAA and 0.2, 0.5, 1.0, 2.0 or 5.0 mg/l purine-type cytokinins (m T, BAR, BPA or BAP). The highest multiplication rate (about thirteen shoot or buds per explant) was obtained on MS medium with 0.2 mg/l m T after four weeks of culture. The phenolic compounds present in the hydromethanolic extracts from the D. forrestii transgenic shoots were characterized using UPLC–PDA–ESI–MS. The shoots were found to biosynthesize three phenolic acids and five flavonoid glycosides. UHPLC analysis of the hydromethanolic extracts found the predominant phenolic acid to be rosmarinic acid, with its highest content observed in shoots cultivated with 5.0 mg/l BPA. In contrast, the greatest production of flavonoid derivatives (especially acacetin derivatives) was observed in the medium supplemented with 2 mg/l BPA. [ABSTRACT FROM AUTHOR]

6‐Benzyladenine (6‐BA, a synthetic cytokinin) could improve the ability to resist adversity. However, very little attention has been given to its role in alleviating waterlogging damages on grain growth. A field experiment was performed to investigate effects of exogenous 6‐BA after waterlogging for 6 days at the third leaf stage (V3‐WL + 6‐BA) or the sixth leaf stage (V6‐WL + 6‐BA) on grain filling, and endogenous hormone of summer maize hybrids DengHai605 (DH605) and ZhengDan958 (ZD958), which were planted popularly in China. Exogenous 6‐BA alleviated waterlogging damages on grain filling by improving grain weight and volume, which was beneficial to yield increase. Grain yield of DH605 under V3‐WL + 6‐BA and V6‐WL + 6‐BA increased by 16% and 12%, respectively, compared with that of V3‐WL (waterlogging at the third leaf stage) and V6‐WL (waterlogging at the sixth leaf stage), while the corresponding values for ZD958 increased by 20% and 15%, respectively. Moreover, exogenous 6‐BA alleviated waterlogging damages on grain endogenous hormone content by increasing levels of endogenous indole‐3‐acetic acid, zeatin riboside, and gibberellic acid, and decreasing level of abscisic acid in grain of waterlogged summer maize during grain‐filling periods. Clearly, exogenous 6‐BA improved grain‐filling characteristics, and endogenous hormone, resulting in a significant yield increase of waterlogged summer maize. [ABSTRACT FROM AUTHOR]

High yields of mechanized intensive rice-based cropping systems, e.g. double-season cropping using early- and late-season rice, are important to ensure national food security in China. However, few studies addressing the relationship between grain weight and grain yield of early-season rice under machine-transplanted conditions. A field experiment was conducted to determine the critical grain-filling characteristics and related physiological aspects that contribute to high grain weight in machine-transplanted early-season rice. The results showed that grain yield was significantly positively correlated with grain weight but not with panicles per m2, spikelets per panicle, and spikelet-filling percentage. Furthermore, this study demonstrated that there was a significant positive correlation between grain weight and mean grain-filling rate, which was significantly positively correlated with harvest index and grain cytokinin content. These results indicate that high grain-filling rate driven by good transport of assimilates to grains and strong grain sink strength is responsible for high grain weight in machine-transplanted early-season rice. [ABSTRACT FROM AUTHOR]

• Autotetraploidization enhanced the salt tolerance of Ziziphus jujuba Mill. var. spinosa. • Salinity stress induced differential expression of many value genes and pathways between the diploid and autotetraploid. • More diverse transcription factors and complex protein-protein interaction networks may enhance salt tolerance of the autotetraploid. • More up-regulated genes and greater fold change related to osmotic adjustment exhibited in the autotetraploid than that in diploid. Chinese jujube (Ziziphus jujuba Mill.), native to China, is an important deciduous fruit tree. This species is mainly propagated by grafting, with Z. jujuba var. spinosa widely used as the rootstock because of its resistance to adverse conditions such as saline environments. In a previous study, we found that autotetraploid jujube is phenotypically superior to the corresponding diploid, furthermore, the differences in salt tolerance between the two plant materials and the underlying molecular mechanism were still unclear. To clarify this issue, we investigated the leaf and shoot morphology and physiology of diploid and autotetraploid plants treated with NaCl for 0, 2, 6, 10, and 14 days. We also carried out transcriptome profiling after 0, 1, and 2 days of salinity treatment. Comparisons of diploid and autotetraploid plants under salinity conditions in morphology and eight physiological traits indicating that the autotetraploid has superior salt tolerance. Many differentially expressed genes related to salt stress response in diploid and autotetraploid Z. jujuba were assigned to functional categories such as detoxification, stimulus response, catalytic enzyme activity, antioxidant enzyme activity, glutathione metabolism, phenylpropanoid biosynthesis, flavonoid biosynthesis, peroxisome, plant hormone signaling, and ABC transport. These genes constituted a complex regulatory network for maintaining osmosis and intracellular ion homeostasis and resisting oxidative stress. In addition, several genes encoding MYB, AP2/ERF-ERF, WRKY, GRAS, and C2H2 as well as hub proteins, including aquaporins, heat stress transcription factors, chaperone, cytochrome P450, and kinases, were differentially expressed under salt stress. The number, function, and fold changes of these genes differentially expressed under salinity treatment differed between the diploid and its autotetraploid, with more active, diverse strategies taking place in the autotetraploid to adapt to long-term salt stress. Finally, we found that there were more up-regulated DEGs and greater fold change related to osmotic adjustment in autotetraploid than in diploid which could further explain the enhanced salt stress tolerance in the autotetraploid. Our findings contribute to an understanding of the genetic basis of salt tolerance in autotetraploid jujube, which can guide future tolerance breeding of jujube cultivars and their rootstocks. [ABSTRACT FROM AUTHOR]

Plants are often repeatedly exposed to stresses during their lives and have a mechanism called stress imprinting that provides "memories" of stresses they experience and increases their ability to cope with later stresses. To test hypotheses that primed bryophytes can preserve their stress imprinting after 6 days of recovery and induce higher levels of osmolytes and ROS‐scavenging activities upon later stress exposure, and there exist population‐level differentiation in their desiccation defenses, we transplanted samples of two populations of each of two moss species, Hypnum plumaeforme and Pogonatum cirratum, in a nature reserve in southern China. After 16 months of acclimation, sets of each population were subjected to control, one‐time desiccation stress, duplicated desiccation stress and cross‐stress (low temperature stress followed by desiccation stress) treatments. Levels of oxidant enzymes, osmolytes, and phytohormones in the samples were then determined. The desiccation stress generally led to increases in activities or contents of superoxide dismutase, guaiacol peroxidase, catalase, proline, soluble sugars, soluble proteins, and stress hormones including abscisic acid (ABA), jasmonates (JA), and salicylic acid (SA), with differences between both species and populations. After a 6‐day recovery period, contents of phytohormones (including ABA, JA, SA, and cytokinins) in stressed H. plumaeforme had substantially fallen toward control levels. The duplicated and cross‐stress treatments generally led to further accumulation of proline, soluble sugars, and soluble proteins, with further increases in activities of antioxidant enzymes in some cases. Furthermore, significant differences between allochthonous and native populations were found in contents of malondialdehyde and osmolytes, as well as antioxidant enzyme activities. Our results confirm the hypotheses and highlight the importance of osmolytes in mosses' stress responses. [ABSTRACT FROM AUTHOR]

Both cytokinin and NAC transcription factors were reported to involve in leaf senescence. However, the mechanism of NAC transcription factors how to regulate cytokinin-delayed leaf senescence is still unknown. In this study, application of N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU), a cytokinin analogue, significantly delayed leaf senescence and maintained cytokinin content of Chinese flowering cabbage during storage. Meanwhile, the expression of an NAC transcriptional activator (BrNAC029) was increased but suppressed by CPPU treatment. Furthermore, BrNAC029 activated the expressions of chlorophyll catabolic genes BrPAO and BrSGR2, cytokinin oxidase gene BrCKX1 and senescence maker gene BrSAG113 by binding to their promoters. Additionally, overexpressions of BrNAC029 in tobacco and Arabidopsis accelerated leaf senescence and up-expressed the related genes. Taken together, it was suggested that BrNAC029 may serve as a transcriptional activator to activate the transcriptions of these related genes to eventually accelerate leaf senescence of Chinese flowering cabbage by promoting chlorophyll degradation and reducing endogenous cytokinin level., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Field trials were carried out in three provinces of China to study the dissipation and residue of forchlorfenuron in citrus fruits. The results had shown that the degradation rate of forchlorfenuron in citrus fruits followed the first-order kinetics equation C = A·e. The half-lives of forchlorfenuron were 15.8-23.0 days, the final residues of forchlorfenuron in pulp were all ≤0.002 mg/kg, and most of the residues were concentrated in the peel. The risk assessment revealed that no significant potential health risk would be induced by forchlorfenuron in citrus fruits. Therefore, it could be safe to apply forchlorfenuron in citrus fruits, and the results of this study could also be regarded as a reference to the setting of maximum residue limit for forchlorfenuron in citrus fruits in China. [ABSTRACT FROM AUTHOR]

The occurrence and development of riparian forests, which were mainly dominated by mesophytes species related closely with surface water. Since there was no water discharged to the lower reaches of Tarim River in the past three decade years, the riparian forests degrade severely. The groundwater table, the saline content of the groundwater, as well as the content of free proline, soluble sugars, plant endogenous hormones (abscisic acid (ABA), and cytokinins (CTK)) of the leaves and relative rates of sap flow of the Populus euphratica Oliv. (arbor species), Tamarix ramosissima Ldb. (bush species), and Apocynum venetum L. (herb species) were monitored and analyzed at the lower reaches of the Tarim River in the study area where five positions on a transect were fixed at 100 m intervals along a sampling direction from riverbank to the sand dunes before and after water release. The physiological responses and acclimation strategies of three species to variations in water and salinity stress were discussed. It was found that A. venetum population recovered to groundwater table ranging from –1.73 to –3.56 m, and when exposed to saline content of the groundwater ranging from 36.59 to 93.48 m mol/L; P. euphratica appeared to be more sensitive to the elevation of groundwater table than the A. venetum and T. ramosissima at groundwater table ranging from –5.08 to –5.80 m, and when exposed to saline content of the groundwater ranging from 42.17 to 49.55 m mol/L. T. ramosissima tended to be the best candidate species for reclamation in this hyper-arid area because it responded to groundwater table ranging from –1.73 to –7.05 m, and when exposed to saline content of the groundwater ranging from 36.59 to 93.48 m mol/L. These results explained the distribution patterns of desert vegetation in the lower reaches of the Tarim River. Understanding the relationships among ecological factors variables, physiological response and acclimation strategies of plant individuals could provide guidance to sustainable management, reclamation and development of this and similar regions. [ABSTRACT FROM AUTHOR]

Callusing was induced from three kinds of explants of Chinese medical plantScutellaria baicalensiswith thidiazuron (TDZ) as an exogenous growth regulator. Multiple shoots were formed from these calli on hormone-free media. Calli induced by 0.3 mg/l TDZ produced shoots directly on the induction medium after culturing for 30-40 days without any interval, while at a higher concentrations of TDZ (1.0, 2.0, and 5.0 mg/l), regeneration occurred only after transfer to hormone-free medium. Endogenous hormones were detected by reverse-phase HPLC-MS and ELISA. The higher TDZ concentrations decreased endogenous benzyladenine (BA) and IAA levels, while iPA and ZR levels and their ratios to IAA were not correlated with TDZ concentrations, growth of calli, or plant regeneration. BA was the dominant cytokinin during calli growth and bud formation, 10 000-fold more abundant than iPA and ZR. Moreover, low IAA/BA ratio, rather than low IAA or high cytokinin levels alone, is the most important factor for shoot formation by calli. TDZ might act indirectly by changing endogenous hormonal levels, most likely the IAA/BA ratio which controls the calli growth and bud formation. [ABSTRACT FROM AUTHOR]

Long non-coding RNAs (lncRNAs) play important roles in plant growth and stress responses. As a dominant abiotic stress factor in soil, boron (B) deficiency stress has impacted the growth and development of citrus in the red soil region of southern China. In the present work, we performed a genome-wide identification and characterization of lncRNAs in response to B deficiency stress in the leaves of trifoliate orange (Poncirus trifoliata), an important rootstock of citrus. A total of 2101 unique lncRNAs and 24,534 mRNAs were predicted. Quantitative real-time polymerase chain reaction (qRT-PCR) experiments were performed for a total of 16 random mRNAs and lncRNAs to validate their existence and expression patterns. Expression profiling of the leaves of trifoliate orange under B deficiency stress identified 729 up-regulated and 721 down-regulated lncRNAs, and 8419 up-regulated and 8395 down-regulated mRNAs. Further analysis showed that a total of 84 differentially expressed lncRNAs (DELs) were up-regulated and 31 were down-regulated, where the number of up-regulated DELs was 2.71-fold that of down-regulated. A similar trend was also observed in differentially expressed mRNAs (DEMs, 4.21-fold). Functional annotation of these DEMs was performed using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, and the results demonstrated an enrichment of the categories of the biosynthesis of secondary metabolites (including phenylpropanoid biosynthesis/lignin biosynthesis), plant hormone signal transduction and the calcium signaling pathway. LncRNA target gene enrichment identified several target genes that were involved in plant hormones, and the expression of lncRNAs and their target genes was significantly influenced. Therefore, our results suggest that lncRNAs can regulate the metabolism and signal transduction of plant hormones, which play an important role in the responses of citrus plants to B deficiency stress. Co-expression network analysis indicated that 468 significantly differentially expressed genes may be potential targets of 90 lncRNAs, and a total of 838 matched lncRNA-mRNA pairs were identified. In summary, our data provides a rich resource of candidate lncRNAs and mRNAs, as well as their related pathways, thereby improving our understanding of the role of lncRNAs in response to B deficiency stress, and in symptom formation caused by B deficiency in the leaves of trifoliate orange. [ABSTRACT FROM AUTHOR]

Wheat yield is largely determined by the grains per spike, which in turn is related to the fertile floret development prior to anthesis. The aim of this study was to assess the physiological mechanism of exogenous 6-benzylaminopurine (6-BA) on fertile floret development and grain setting characteristics by foliar application in winter wheat. Field experiments were conducted during the 2016–2017 and 2017–2018 growing seasons in China. Two foliar spraying applications with water (S0) and 6-BA (S1) were applied to a large-spike variety (V1) and a multiple-spike variety (V2) 25 days after jointing. At anthesis, spike dry weight and soluble sugar, sucrose, auxin, and cytokinin were all positively correlated with the number of fertile florets and grains per spike. During the abortion stage of fertile florets, 6-BA application compared to the control reduced the auxin content, increased the cytokinin content and spike dry matter and transported more soluble sugar and sucrose from the non-spike organs to the spike. Exogenous 6-BA application increased the number of fertile florets (~1.84 to ~2.50) and number of grains (~2.83 to ~3.51) by primarily suppressing the number of degenerated and aborted florets. The results provide important evidence that 6-BA application has a positive effect on floret fertility and grain setting, which lead to a further increase in grain yield. [ABSTRACT FROM AUTHOR]

Soil properties affect the bioavailability of cadmium (Cd). In general, soils in southern China are rich in iron (Fe) and contain manganese (Mn), which form ferromanganese nodules through biological or chemical reactions. In this study, it is hypothesized that the formation of Fe/Mn oxides can reduce the bioavailability of Cd and play an important role in reducing the uptake of Cd by rice. In this study, the effects of Fe and Mn on the contents of Fe (II)-oxidizing bacteria (FeOB) communities, Fe oxides, and Cd speciation in Cd-contaminated paddy soils were studied in a pot experiment. Results showed that, compared with the CK treatment, the addition of Mn (II) increased the abundance of FeOB (Thiobacillus sp.) in the soil, thereby increasing the content of amorphous Fe oxides in the rhizosphere. Amorphous Fe oxides effectively immobilized Cd in the soil, that is, with an increasing content of Cd bound to amorphous Fe/Mn oxides in the rhizosphere and non-rhizosphere soils, the mobility and bioavailability of Cd were reduced. After the addition of Mn (II) and Fe (II), the Fe content in the root Fe plaque of rice increased significantly, while the Cd content decreased significantly. The increase of Fe in the root Fe plaque inhibited rice uptake of soil Cd; thus, the Cd content in rice shoots was significantly lower than the Cd content in the CK treatment. Compared with the addition of Fe (II), the addition of Mn (II) effectively reduced the Cd content in rice shoots. These findings suggested that the addition of Mn (II) can promote the formation of Fe oxides in soils and reduce the Cd content in rice. These research results provide support for using Mn-based soil remediation materials to remedy Cd-contaminated soils. [ABSTRACT FROM AUTHOR]