Concentrations Of Zeatin Research Articles

Enhancement of phenolic and flavonoids compounds, antioxidant and cytotoxic effects in regenerated red cabbage by application of Zeatin

This study evaluated the roles of zeatin (2 mg/L) on direct organogenesis, phytochemical compounds, antioxidant activity, and cytotoxic activity in regenerated shoots of red cabbage. The results revealed that the extract of explant treated by 2 mg/L zeatin gives the highest content of total phenolics (5.18 mg gallic acid equivalent/g dry weight) and flavonoids (1.52 mg rutin equivalent/g dry weight). Moreover, HPLC and GC-MS analyses indicated that various bioactive compounds in red cabbage are significantly enhanced with increasing zeatin concentration. Besides that, antioxidant activity test showed that in vitro shooting culture using 2 mg/L zeatin displayed higher antioxidant activity in all assays (DPPH, FRAP and ABTS) compared to control with respective values of 68.12%, 73.28%, and 54.1%, respectively. Finally, the cytotoxic properties illustrated that the extracts of red cabbage explant treated by 2 mg/L zeatin exhibited the strongest cytotoxic effect towards cancer cells compared to control.

Effect of cytokinins on shoots proliferation and rosmarinic and salvianolic acid B production in shoot culture of Dracocephalum forrestii W. W. Smith

The current study estimates the effect of different cytokinins on shoot proliferation and biosynthesis of caffeic acid derivatives in Dracocephalum forrestii in vitro culture. The shoots were grown on Murashige and Skoog (MS) agar medium with 1 µM indole-3-acetic acid (IAA) and different content of 6-benzyloaminopurine (BAP), zeatin, kinetin (1, 2, 4, 8, 18 µM) or thidiazuron (TDZ) (0.1, 0.2, 0.5, 1, 2 µM). The highest multiplication rate (about seven shoots and/or buds per explant) was obtained after 4 weeks of culture on MS medium with 1 µM IAA and 8 or 16 µM BAP. Optimal biomass of plant material was also received on the same media. The identity of the compounds present in the hydromethanolic extracts from D. forrestii shoots grown on cytokinin-supplemented media was confirmed using UPLC–PDA–ESI–MS method. The analysis revealed the presence of nine metabolites recognized as caffeic acid derivatives. The content of the predominant phenolic acids in the extracts, i.e. rosmarinic acid (RA) and salvianolic acid B (SAB), was determined with UHPLC. The highest yield of RA was found in shoots cultivated in the medium containing 1 µM IAA and 2 µM BAP (18.7 mg/g DW). The highest level of SAB (5.3–5.9 mg/g DW) was identified in multiple shoots grown in the presence of 1 µM IAA and 0.5–1 µM TDZ or 2 µM BAP.

The effect of endogenous hormones on plant morphology and fruit quality of tomato under difference between day and night temperature

The difference between day and night temperature (DIF) was reported to influence plant morphology and fruit quality, but the mechanism was poorly known. Therefore, controlled-environment experiments were carried out to investigate the mechanism of DIF influenced plant morphology and fruit quality attributes of tomato during fruit stage. Five day/night temperature regimes 16/34, 19/31, 25/25, 31/19 and 34/16°C with respective DIFs of –18, –12, 0, +12 and +18 at a common 25°C mean daily temperature were used. The results showed that gibberellin 3, indoleacetic acid and zeatin content of stem tip were enhanced significantly by positive DIF and inhibited by negative DIF, while abscisic acid was not significantly influenced by DIF. Plant height, stem diameter, fruit diameter and leaf area were enhanced significantly by positive DIF regimes and inhibited by negative DIF regimes. The soluble sugars, vitamin C and soluble protein content increased under positive DIF while decreased under negative DIF. Both plant morphology and fruit quality of tomato were significantly related to endogenous hormones.

2, 3-Butanediol activated disease-resistance of creeping bentgrass by inducing phytohormone and antioxidant responses

Brown patch, caused by Rhizoctonia solani, is a serious disease in Agrostis stolonifera. 2, 3-butanediol (2, 3-BD) is the major component of volatile organic compounds and was found to initiate induced systemic resistance (ISR). To investigate the induced resistance mechanism of 2, 3-BD, we examined the effects of resistance by area affected, along with changes in the content of phytohormones (Zeatin (ZT), Abscisic Acid (ABA) and Indole-3-Acetic Acid (IAA)), the activities of three phenylpropanoid metabolic enzymes (Phenylalaninammo-Nialyase (PAL), Chalcone Isomerase (CHI) and 4-Coumarate:Coenzyme A Ligase (4CL)) and the level of secondary metabolites (total phenols, flavonoid and lignin). The result showed that 2, 3-BD treatment at 250 μmoL/L had the best induction effect with the area affected decreased from 95% of the control to 55%. Compared to the controls, treatment with 250 μmoL/L 2, 3-BD induced higher levels of PAL, CHI and 4CL activity and increased total phenols, flavonoid and lignin levels. While 2, 3-BD treatment decreased the content of ZT and ABA but increased the content of IAA compared to controls. This study provides a basis for elucidating the mechanism of 2, 3-BD as a new plant disease control agent.

Expression of grape ACS1 in tomato decreases ethylene and alters the balance between auxin and ethylene during shoot and root formation

Ethylene plays an important role in the grape rachis, where its production can be 10 times higher than in the berry. VvACS1 is the only rachis-specific ACC synthase (ACS) gene, and its expression is coincident with ethylene production in the rachis of Vitis vinifera ‘Thompson seedless’. VvACS1 was cloned and ectopically expressed in tomato (Solanum lycopersicum ‘Moneymaker’). Lateral buds were increased in two- or four-week-old 35s∷VvACS1 transgenic tomato plants after transplanting. Compared with wild-type (WT) plants, the transgenic tomato plants showed higher expression of the VvACS1 gene in the flowers, leaves, rachis, and fruits. There was no obvious difference of ACS activity in the fruit of tomato, and only increased ACS activity in the rachis of tomato. Ethylene production was decreased in flowers, leaves, and fruits (seven weeks after full bloom), while the relative expression of endogenous tomato ACS1 and ACS6 genes was not down-regulated by the ectopic expression of VvACS1. These results imply that post-transcriptional or post-translational regulation of ACS may occur, resulting in lower ethylene production in the transgenic tomato plants. Moreover, expression of VvACS1 in tomato resulted in decreased auxin and increased zeatin contents in the lateral buds, as well as reduced or delayed formation of adventitious roots in lateral bud cuttings. RNA-Seq and qRT-PCR analyses of rooted lateral bud cuttings indicated that the relative expression levels of the genes for zeatin O-glucosyltransferase-like, auxin repressed/dormancy-associated protein, and ERF transcription factors were higher in transgenic tomatoes than in WT, suggesting that ethylene may regulate auxin transport and distribution in shoots and that adventitious root formation employs coordination between auxin and ethylene.

Shoot Induction from Axillary Shoot Tip Explants of Fig (Ficus carica) cv. Japanese BTM 6.

Fig, or Ficus carica, is a fruit tree from the Moraceae family and is widely grown in tropical and subtropical regions of the world. Fig plants are mainly propagated through grafting, air layering, and hardwood cutting whereby these methods were found to be less efficient. Plant tissue culture is efficient method to propagate plants, particularly to produce true-to-type platelets for mass multiplication. The aim of this study is to induce multiple shoot formation on Ficus carica cv. Japanese BTM 6 through identifying and optimising the concentrations of 6-Benzylaminopurine (BAP) and Zeatin suited for shoot formation. The axillary shoot tip explants were cultured in MS media supplemented with different concentrations of BAP and Zeatin (0, 0.5, 1.0, 1.5 and 2.0 mg/L) to determine the optimal concentration for the formation of multiple shoots. Number of shoots per explants and the differences in shoot height of explants were calculated after 8 and 12 weeks of culture respectively. Of all the treatments of BAP, MS media containing with 2 mg/L BAP marked the highest number of shoots per explant with the average value of 1.67 ± 0.33 while 1.5 and 2 mg/L of BAP produced the highest differences in shoot height with 0.51 ± 0.08 cm and 0.51 ± 0.07 cm after 12 weeks respectively. Murashige and Skoog (MS) media supplemented with 2 mg/L Zeatin showed the highest production of multiple shoots and differences in shoot height with the average of 0.83 ± 0.219 and 0.32 ± 0.04 cm respectively among all the different treatments of Zeatin. In this study, BAP performed better in shoot induction and elongation as compared to Zeatin for the cultivar Japanese BTM 6.

A preliminary analysis of the effects of bisphenol A on the plant root growth via changes in endogenous plant hormones

Bisphenol A (BPA) is ubiquitous in the environment worldwide, affecting plant growth and development. Endogenous plant hormones serve as switches that regulate plant growth and development. However, plants have different physiological requirements and environmental adaptive capacities during the different growth stages. Here, we investigated the effects of BPA on soybean (Glycine max L.) root growth at the three growth stages and analyzed the mechanisms underlying the effects of BPA on the root growth by assessing changes in endogenous hormone. The results showed that low concentration of BPA (1.5mgL−1) improved root growth (except at the seed-filling stage), increased indole-3-acetic acid (IAA) content at the first two growth stages, and increased zeatin (ZT) content and decreased gibberellic acid (GA3) content at the seedling stage. But low concentration of BPA caused decreased ethylene (ETH) contents and constant abscisic acid (ABA) content at all three stages. However, BPA at moderate and high concentrations (6.0 and 12.0mgL−1) inhibited root growth, causing the decreased IAA, GA3 and ETH contents and increased ABA content at all three growth stages. The change degrees of above indices were weakened with prolonging the growth stages. After BPA withdrawal, both the root growth and the hormone contents recovered (with the exception of ZT and ETH), and the recovery degrees had negative correlation with the BPA exposure concentration and had positive correlation with the growth stage. Changes in residual BPA content in the roots were also observed at different BPA concentrations and different growth stages. Our results demonstrated the effects of BPA on root growth were related to BPA-induced changes in hormone, which performed differently at various growth stages.

Mother plant luminescence and zeatin concentration in the in vitro establishment of an olive plant

This study aimed to evaluate the effect of the presence and absence of light provided to the mother plant and zeatin concentrations in vitro establishment, to reduce oxidation and promote the establishment of olive explants. The trials were carried out at the Fruit Tree Propagation Lab, Federal University of Pelotas, Brazil. In the first experiment, plants of olive 'Arbequina' were subjected to the absence and presence of light and established on WPM with 0 and 2mg.L-1 zeatin. In the second experiment, plants of olive 'Leccino', 'Arbequina' and 'Frantoio' 'were submitted to the absence of light, and established in vitro on WPM with 0,4 and 8 mg.L-1 Zeatin. Mother plants of olive tree 'Arbequina' in conditions of absence of light are the most suitable in vitro establishment. The concentration of 2 mg.L-1 of zeatin promotes survival of explants of olive 'Arbequina'. The concentrations 0,4 and 8 mg.L-1 of zeatin) results no difference between Leccino and Arbequina cultivars for the variable fungal contamination.

Proteomic Analysis of Differences in Fiber Development between Wild and Cultivated Gossypium hirsutum L.

Upland cotton (Gossypium hirsutum L.) is one of the world's most important fiber crops, accounting for more than 90% of all cotton production. While their wild progenitors have relatively short and coarse, often tan-colored fibers, modern cotton cultivars possess longer, finer, stronger, and whiter fiber. In this study, the wild and cultivated cottons (YU-3 and TM-1) selected show significant differences on fibers at 10 days postanthesis (DPA), 20 DPA, and mature stages at the morphological level. To explore the effects of domestication, reveal molecular mechanisms underlying these phenotypic differences, and better inform our efforts to further enhance cotton fiber quality, isobaric tags for relative and absolute protein quantification-facilitated proteomic methods were performed on developing fibers. There were 6990 proteins identified; among them, 336 were defined as differentially expressed proteins between fibers of wild versus domesticated cotton. The down- or up-regulated proteins in wild cotton were involved in phenylpropanoid biosynthesis, zeatin biosynthesis, fatty acid elongation, and other processes. Association analysis between transcriptome and proteome showed positive correlations between transcripts and proteins at both 10 DPA and 20 DPA. Differences in proteomics have been verified at the mRNA level by quantitative real-time polymerase chain reaction and have been validated at the physiological and biochemical levels by POD (peroxidase) activity assays and ZA (zeatin) content estimates. This work corroborates the major pathways involved in cotton fiber development and demonstrates that POD activity and zeatin content have a great potential related to fiber elongation and thickening.

Effect of non-structural carbohydrate accumulation in the stem pre-anthesis on grain filling of wheat inferior grain

To promote the grain weight of wheat, the key is to improve the grain filling of inferior grain. The remobilization of non-structural carbohydrate (NSC) stored in reserve in the stem (sheath+culm) pre-anthesis is important for the grain filling of cereal. However, the mechanism that regulates the NSC reserve in the stem pre-anthesis on grain filling of inferior grains of wheat remains unclear. In the present study, six wheat cultivars with different grain weight were used. Additionally, different rates of nitrogen (N) fertilizer were examined. The objective of the present study was to investigate the relation between the NSC reserve in the stem pre-anthesis and grain filling of inferior grain of wheat and determine the mechanism of that relation. The results showed that the grain weight of inferior grain was significantly lower than that of superior grain, and the inferior grain was more affected by environmental factors than the superior grain. The superior grain had higher content of zeatin (Z)+zeatin riboside (ZR) and activities of synthase (SS) and ADP-glucose pyrophosphorylase (AGPP) and lower rate of ethylene (ETH) evolution than those of inferior grain. Because of these differences, the superior grain had higher sink strength and grain-filling rate and therefore had higher grain weight than that of inferior grain. With a high NSC reserve stored in the stem pre-anthesis, the Z+ZR content increased and the ETH evolution rate decreased in inferior grain significantly, which promoted the sink strength and grain-filling rate of inferior grain of wheat. Suitable nitrogen (N) fertilizer application notably increased the NSC reserve stored in the stem pre-anthesis, which promoted the sink strength and grain-filling rate of inferior grain. However, excess N fertilizer significantly decreased the NSC accumulation in the stem pre-anthesis and inhibited the sink strength and grain-filling rate of inferior grain of wheat.

Zeatin and Thidiazuron Induced Embryogenic Calli From In Vitro Leaf and Stem of Jojoba (Simmondsia chinensis).

Jojoba is a promising industrial plant, which recommended with pharmaceutical benefits. The present study was conducted to stimulate embryogenic calli formation from jojoba using zeatin and thidiazuron (TDZ), as well as determination of the antioxidant activity of proliferated calli. For callus induction, leaf and stem explants derived from in vitro grown shootlets, were cultured on Murashige and Skoog (MS) medium with different combinations of 0.5 mg L-1 benzyl adenine (BA) or kinetin with 2,4-Dichlorophenoxyacetic acid (2,4-D), Naphthalene acetic acid (NAA) and picloram at 0.5 or 1mg L-1. To stimulate embryogenic calli, friable callus were transferred to woody plant medium (WPM) supplemented with different concentrations of zeatin or TDZ. Antioxidant activity of different treatments was determined using hexane or petroleum ether extraction. Data was analyzed as mean±standard deviation (SD). The MS medium supplemented with 0.5 mg L-1 BA+0.5 or 1 mg L-1 picloram was the best treatment to obtain friable calli from both explants types. WPM medium supplemented with 2 mg L-1 zeatin gave the highest percentage of embryogenic calli derived from leaf explants. While the highest percentage of embryogenic calli derived from stem explants was registered using 1 or 4 mg L-1 TDZ containing medium. Embryogenic calli originated from leaves explants on 1.5 mg L-1 zeatin showed promising activity of antioxidant with hexane extraction. However, embryogenic calli originated from stem explants on 1 mg L-1 TDZ showed the highest antioxidant activity with petroleum ether extraction. TDZ has promising effect on embryogenic callus induction from stem explants. While, zeatin has promising effect on embryogenic callus induction from leaf explants.

Impact of Zeatin and Thidiazuron on Phenols and Flavonoids Accumulation in Callus Cultures of Gardenia (Gardenia jasminoides).

Gardenia (Gardenia jasminoides) has many pharmacological actions such as anti-inflammatory, antioxidant and fibrolytic activities and cytotoxic effects, etc. This study was conducted to recognize the effect of zeatin and thidiazuron (TDZ) on callus proliferation, total phenolic content, total flavonoids and DPPH scavenging activity of gardenia callus cultures. Calli were cultured on Murashige and Skoog (MS) medium supplement with different concentrations (2, 4 or 6 mg L-1) of zeatin or TDZ individually as well as combination of 2 mg L-1 zeatin+4 mg L-1 TDZ. Cultures contained 4 mg L-1 TDZ gave the highest callus fresh weight followed by those contained 2 mg L-1 zeatin then that cultured on 4 mg L-1 zeatin. Data reported as Mean±Standard Deviation (SD). Data were subjected to one-way analysis of variance (p< 0.05). Results were processed by Excel (2010) and SPSS Version 17.0. It was found that callus growing on medium supplemented with 4 mg L-1 zeatin gave the maximum value (14.93%) of yield extract. Callus cultured on 4 mg L-1 zeatin recorded the maximum total phenol (268.33 mg GAE/100 g FW of callus) and total flavonoids (2703.33 μg QE/100 g FW of callus) accumulation. The antioxidant activity of each extract was determined through DPPH radical scavenging activity. Callus cultured on 4 mg L-1 TDZ showed the highest antioxidant activity then those cultured on 4 mg L-1 zeatin. The HPLC analysis for phenolic acids showed that chlorogenic acid, rosmarinic acid and cinnamic reached their highest contents with callus cultured on 4 mg L-1 TDZ (123.24, 322.14 and 278.22 μg g-1, respectively). Regarding flavonoids and using HPLC analysis, rutin, apigenin-7-glucoside and kaempferol were detected. Callus cultured with 4 mg L-1 TDZ gave the highest rutin and kaempferol contents (287.76 and 10.38 μg g-1, respectively). However, apigenin-7-glucoside was detected with high content (129.86 μg g-1) in callus culture with 4 mg L-1 Zeatin. The HPLC analysis recommended that TDZ is more effective in accumulation of individual phenolic and flavonoid than Zeatin. The present study provided a useful system for further study on in vitro culture of G. jasminoides as alternative and new source for important secondary products.

Different exogenous sugars affect the hormone signal pathway and sugar metabolism in "Red Globe" (Vitis vinifera L.) plantlets grown in vitro as shown by transcriptomic analysis.

Exogenously applied 2% fructose is the most appropriate carbon source that enhances photosynthesis and growth of grape plantlets compared with the same concentrations of sucrose and glucose. The role of the sugars was regulated by the expression of key candidate genes related to hormones, key metabolic enzymes, and sugar metabolism of grape plantlets ( Vitis vinifera L.) grown in vitro. The addition of sugars including sucrose, glucose, and fructose is known to be very helpful for the development of grape (V. vinifera L.) plantlets in vitro. However, the mechanisms by which these sugars regulate plant development and sugar metabolism are poorly understood. In grape plantlets, sugar metabolism and hormone synthesis undergo special regulation. In the present study, transcriptomic analyses were performed on grape (V. vinifera L., cv. Red Globe) plantlets in an in vitro system, in which the plantlets were grown in 2% each of sucrose (S20), glucose (G20), and fructose (F20). The sugar metabolism and hormone synthesis of the plantlets were analyzed. In addition, 95.72-97.29% high-quality 125bp reads were further analyzed out of which 52.65-60.80% were mapped to exonic regions, 13.13-28.38% to intronic regions, and 11.59-28.99% to intergenic regions. The F20, G20, and S20 displayed elevated sucrose synthase (SS) activities; relative chlorophyll contents; Rubisco activity; and IAA and zeatin (ZT) contents. We found F20 improved the growth and development of the plantlets better than G20 and S20. Sugar metabolism was a complex process, which depended on the balanced expression of key potential candidate genes related to hormones (TCP15, LOG3, IPT3, ETR1, HK2, HK3, CKX7, SPY, GH3s, MYBH, AGB1, MKK2, PP2C, PYL, ABF, SnRK, etc.), key metabolic enzymes (SUS, SPS, A/V-INV, and G6PDH), and sugar metabolism (BETAFRUCT4 and AMY). Moreover, sugar and starch metabolism controls the generation of plant hormone transduction pathway signaling molecules. Our dataset advances our knowledge of the genes involved in sugar metabolism and improves the understanding of complex regulatory networks involved in signal transduction in grape plantlets.

Pre-drought priming sustains grain development under post-anthesis drought stress by regulating the growth hormones in winter wheat (Triticum aestivum L.).

Drought stress during grain filling is the most yield-damaging to wheat. Pre-drought priming facilitated the wheat plants to sustain grain development against the post-anthesis drought stress by modulating the levels of growth hormones. Post-anthesis drought stress substantially reduces grain yield in wheat (Triticum aestivum L.) due to impaired grain development associated with imbalanced levels of growth hormones. To investigate whether pre-drought priming could sustain grain development in wheat by regulating favorable levels of growth hormones under post-anthesis drought conditions, the plants of a drought-sensitive (Yangmai-16) and drought-tolerant (Luhan-7) wheat cultivar were exposed to a moderate drought stress during tillering (Feekes 2 stage) for priming, and then, a subsequent severe drought stress was applied from 7 to 14days after anthesis. The results showed that drought-stressed plants of both cultivars showed a decline in flag leaf water potential, chlorophyll contents, photosynthetic rate, grain size initiation, and grain filling as compared to well-watered plants; however, decline in these traits was less in pre-drought primed (PD) plants than in nonprimed (ND) plants. Under drought stress, the PD plants regulated higher concentrations of zeatin and zeatin riboside, indole-3-acetic acid, gibberellins, and lower abscisic acid content in grains, resulting in higher endosperm cell division and expansion, grain size initiation, grain-filling rate and duration, and finally higher grain dry weights as compared to ND plants. The PD plants of both cultivars showed higher potential to tolerate the post-anthesis drought stress, but more effect was displayed by drought-tolerant cultivar. From the achieved results, it was concluded that pre-drought priming facilitated the wheat plants to sustain higher grain development and yield against the most yield-damaging post-anthesis drought stress by modulating the levels of growth hormones.

INDUKSI PERTUMBUHAN TUNAS DARI EKSPLAN ANGGREK Dendrobium Heterocarpum Lindl. DENGAN PEMBERIAN HORMON ZEATIN DAN NAA

Dendrobium heterocarpum Lindl. is a native orchid in Indonesia. Its population continue to decline due to unsustainable exploitation. One solution to increase its population is via in vitro technique propagation. This research aimed to determine effect of hormone addition (Zeatin and NAA) to induce shoot multiplication of D. heterocarpum Lindl. grown in Murashige and Skoog (MS) basic medium. The research was conducted in Tissue Culture Laboratory, Department of Biology, Faculty of Mathematics and Science, Udayana University from November 2015 until March 2016. The experiment employed Completely Randomized Design (CRD) with 20 combinations of treatments, with three replicates each treatment. The treatment werer addition of Zeatin and NAA, with five concentrations of Zeatin (0, 0.1, 0,5, sweet corn and hybrids corn as the natural Zeatin); four NAA concentrations (0, 0.05, 0.1 and 0.5). Variable recorded include such as the number of shoots, roots and explant’s vigor. The quantitative data which include number of leaves and shoots after 12 weeks, were analyzed using Analysis of Variance (ANOVA); and if significantly different, tested further using Duncan Multiple Range Test (DMRT) at 5% level. Z5N3 medium revealed significantly different on amount of leaves and shoot height and also the best medium on amount of roots. Best hormone combination that can induce multiplication of new shoots are medium Z4N3 and Z5N1.

Study on the in vitro growth of Lily Sorbonne bulblet

In this study, the effects of light and dark condition, sucrose concentration, and plant growth regulators on the in vitro growth of bulblet from Lily Sorbonne shoot were studied. Morphological, physiological and biochemical changes in the bulblet growth were analyzed. Shoots in the light condition developed into plant while shoots in continuous darkness formed bulblet. Sucrose (90 g/L) increased the size of scale and starch accumulation of bulb. 6-Benzylaminopurine (BA 1,5 mg/L) stimulated the divison of parenchyma cell. The combination of 90 g/L sucrose and 1,5 mg/L BA in dark condition stimulated the division and size of the parenchyma cells, which increase the number and size of scales and size and weight of the bulblet. Respiratory rate, zeatin content and starch accumulation were increased in the bulblet growth. The correlation of light condition, sucrose concentration, plant hormone, respiration rate, starch accumulation, and bulblet growth were discussed. The combination of 90 g/L sucrose, 1.5 mg/L BA and 0.5 zeatin mg/L in dark strongly induced the growth of in vitro Lily bulblet, especially the number of scale.

Response of photosystem II performance and antioxidant enzyme activities in stay-green wheat to cytokinin

WN6 (a stay-green wheat cultivar) and JM20 (control) were used to evaluate the effects of exogenous cytokinin on photosynthetic capacity and antioxidant enzymes activities in flag leaves. Results showed that WN6 reached the higher grain mass, which was mainly due to the higher photosynthetic rate resulting from the higher maximal quantum yield of PSII photochemistry (ΦPSII) and probability that a trapped exaction transfers an electron into the electron transport chain beyond QA (Ψo), and lower relative variable fluorescence intensity at the J-step (Vj). Exogenous 6-benzylaminopurine (6-BA) enhanced antioxidant enzymes activities and decreased malondialdehyde (MDA) content. Enhanced Ψo and electron transport rate (ETR), and decreased Vj contributed to improved photosynthetic rate in the 6-BA treatment. In addition, exogenous 6-BA significantly increased endogenous zeatin (Zt) content, which was significantly and positively correlated with the antioxidant enzyme activity and ΦPSII, implying that higher Zt content was responsible for the improved antioxidant status and photosynthetic performance.

In vitro propagation as a tool to enhance the use of native ornamentals in archaeological sites of Greece

This work, as a part of a research programme on the integrated management of vegetation at archaeological sites of Greece, aims at study the micropropagation protocols for small shrubby species belonging to the Greek macchia vegetation. The following species were selected: Anthyllis barba-jovis (A. splendens), A. hermanniae, Atriplex halimus, Ballota acetabulosa, Calamintha cretica, C. nepeta, Lomelosia cretica, L. hymettia, Limoniastrum monopetalum, Teucrium capitatum, Thymelaea hirsute and T. tartonraira. A satisfactory in vitro initiation (80-100%) was obtained using node explants excised from young seedlings grown in vitro. Higher percentage of species (80%) was successfully established on hormone-free (HF) MS medium, but most species showed higher multiplication rate on media supplemented with benzyladenine (BA), kinetin (KIN) and zeatin (ZEA). Shoots grown on multiplication medium supplemented with BA, show the best performance at low BA concentrations (0.25-0.5 mg L-1); this was not the case for shoots grown on ZEA-media which had satisfactory multiplication at ZEA concentration 1.0-4.0 mg L-1. When KIN was added to the medium, the best performance was scored for the concentration 2 mg L-1. The rooting process was genotype-dependent: almost half of the species rooted successfully at 80-100%, while A. halimus showed poor rooting, and T. hirsuta and T. tartonraira failed to root. Although 50% of the species rooted efficiently on HF-half strength MS medium, 3-indolebutyric acid (IBA) increased the rate of rooted species. The highest rate of rooted species (80%) was observed with 1.0 mg L-1 IBA. Ex vitro acclimatization on a peat:perlite (1:1, v/v) mixture was highly successful (90-100%) for all rooted species.

Study on the flower growth and opening to extend the vase life of the cut lotus flower (Nelumbo nucifera Gaertn.)

Morphological and physiological changes were investigated during flower growth and opening to extend the vase life of cut lotus flowers. When holding the flowers in distilled water, the edge of petals and the top edge of petals became black, and the stems were bent after 17 hours. Flowers fully opened and senesced after 25 hours. At full opening flower stage, there were decreases in fresh weight, and content of starch, auxin and zeatin, and increases in dry weight, and content of total sugar, anthocyanins and flavonols, ABA and gibberellin. Petal extract showed the presence two absorption peaks at 354 nm ( due to flavonols) and 535 nm (due to anthocyanins). Among the treatments, the combination of wilted flower (5 % fresh weight) and spraying of 2 mg/L NAA and 10 % coconut water (with 0,1 % Tween 20) gave a 2 days (43,22 hours) longer for cut lotus flowers than the control.

Identification and comparative analysis of microRNAs in Pinus massoniana infected by Bursaphelenchus xylophilus

Pine wilt disease seriously endangers pine tree growth and can lead to wilting and death. In this study, Masson pine (Pinus massoniana) was used as the donor plant to study miRNA expression by high-throughput sequencing in needle leaves of trees during the first 3 days after infection by Bursaphelenchus xylophilus. The results showed that the number of differentially expressed miRNAs first increased and then decreased in samples within 3 days of infection, with the highest expression in samples collected on day 2. Analysis of miRNA target genes in needles on different days after infection revealed enrichment in two pathways: plant hormone signal transduction and RNA transport. Further comparison of the samples indicated differential expression of 10 miRNAs on different days after infection, and the corresponding target genes, such as those participating in plant hormone signal transduction, were also significantly enriched. In addition, the concentrations of zeatin and indole acetic acid in needle tissues were significantly lower after infection than in the control sample. The above results indicated that B. xylophilus infection influenced the expression of miRNAs related to plant hormone signal transduction in P. massoniana, decreasing plant hormone synthesis and ultimately affecting the growth of Masson pine.