Effect Of Auxin Research Articles

Study of Effect of Plant Growth Hormone Auxin on the Growth of Bacteria

Study of Effect of Plant Growth Hormone Auxin on the Growth of Bacteria

Post Flowering Management Using Plant Growth Regulators in Greengram (Vigna radiata L.)

Aim: The study was conducted to evaluate the effect of Auxin and Zeatin-based nanoformulations in post-flowering management in greengram.
 Place and Duration of Study: Nanoformulations were standardized at the Department of Nano Science and Technology, Tamil Nadu Agricultural University, Coimbatore and a field trial was carried out at Agricultural Research Station, Bhavanisagar.
 Methodology: Nanoformulations were standardized by oil in water nanoemulsion technique and effect on crop is observed by foliar spray of nanoformulations during the flowering stage of crop growth.
 Results: Increased chlorophyll content due to NAA and Zeatin and extended retention of chlorophyll in Auxin-based treatments has been recorded. Hence the crop can produce more assimilates leading to increased seed yield. Zeatin spray also recorded increased chlorophyll, mature pods, number of seeds pod-1, seed weight, pod setting percentage. Such an increase of yield attributes was mainly due to decreased flower shedding percentage.
 Conclusion: Growth regulators such as Auxin and Zeatin exhibited a significant role in increasing plant chlorophyll content and yield of greengram. Among treatments, Nanoemulsion of NAA @ 30ppm recorded a higher number of mature pods, seed yield, seed weight and lower flower shedding percentage which is concluded as the best treatment.

Effect of Auxin and Nitrogen on Seed Yield And Germination Traits of Produced Wheat Seeds

Field and laboratory experiments were conducted to assess the response of wheat to external auxin application and nitrogen. Studied factors in the field experiment were different concentrations of auxin (0, 50, and 100 ppm) and nitrogen fertilizer application (0, 75, and 150 kg/ha). In the laboratory experiment, germination traits of produced seeds from maternal plants under the field experiment treatments were assessed. Results showed that no auxin application with nitrogen application had higher stem and leaf yield than auxin application of 50 ppm with nitrogen application of 150 kg/ha. Under high nitrogen application, the negative effect of external auxin on seed yield occurred at a lower concentration. Under nitrogen application of 75 kg/ha, auxin application of 100 ppm reduced harvest index and seed weight. Nitrogen application reduced seed germination percentage but auxin broke the negative effect of nitrogen on seed germination.

Effect of culture media and auxin on growth and glucosinolate accumulation in the hairy root cultures of mustard (Brassica juncea)

Brassica juncea is a vegatable that are rich in glucosinolate (GSL) content. The hairy root (HR) cultures system is one of the most useful tools for secondary metabolites (SM) biosynthesis under various growth conditions. In the past, GSLs were mostly used as biopesticides in agriculture, anti-nutritional factors in fodder, and flavors in condiments. However, in recent days, GLSs have received much attention in human health. To investigate the growth response and variation of GSLs accumulation, HRs of mustard were grown in different growth media and auxins. The HRs growth pattern varied largely under the treatments of growth media and auxin. The full-strength SH media responded greatly for achieving the highest dry weight (DW) followed by the ½ SH media and the lowest DW was obtained in full-strength MS media. In all the auxin treatments the HRs production was higher than that of the control. It was noted that at higher NAA and IBA concentrations HR production was increased than that at the lower concentrations. In addition, different growth mediums significantly influenced the GSLs accumulation in mustard HR. The results revealed that ½ B5 media showed the highest total GSLs content followed by B5 and ½ SH. Treatment of mustard HRs with auxins such as IAA and IBA negatively influenced the accumulation of GSLs except for 4-methoxyglucobrassicin. We, therefore, suggest that HRs are a viable option for improving the GSLs content from the HR culture of mustard and that SH and ½ B5 medium provides an alternative approach for mass production of HRs and GSLs in mustard, respectively.

Auxin contributes to jasmonate-mediated regulation of abscisic acid signaling during seed germination in Arabidopsis.

Abscisic acid (ABA) represses seed germination and postgerminative growth in Arabidopsis thaliana. Auxin and jasmonic acid (JA) stimulate ABA function; however, the possible synergistic effects of auxin and JA on ABA signaling and the underlying molecular mechanisms remain elusive. Here, we show that exogenous auxin works synergistically with JA to enhance the ABA-induced delay of seed germination. Auxin biosynthesis, perception, and signaling are crucial for JA-promoted ABA responses. The auxin-dependent transcription factors AUXIN RESPONSE FACTOR10 (ARF10) and ARF16 interact with JASMONATE ZIM-DOMAIN (JAZ) repressors of JA signaling. ARF10 and ARF16 positively mediate JA-increased ABA responses, and overaccumulation of ARF16 partially restores the hyposensitive phenotype of JAZ-accumulating plants defective in JA signaling in response to combined ABA and JA treatment. Furthermore, ARF10 and ARF16 physically associate with ABSCISIC ACID INSENSITIVE5 (ABI5), a critical regulator of ABA signaling, and the ability of ARF16 to stimulate JA-mediated ABA responses is mainly dependent on ABI5. ARF10 and ARF16 activate the transcriptional function of ABI5, whereas JAZ repressors antagonize their effects. Collectively, our results demonstrate that auxin contributes to the synergetic modulation of JA on ABA signaling, and explain the mechanism by which ARF10/16 coordinate with JAZ and ABI5 to integrate the auxin, JA, and ABA signaling pathways.

Plant growth regulators induce differential responses on primary and specialized metabolism of Annona emarginata (Annonaceae)

Plants belonging to the Annonaceae family are known to produce several specialized metabolites, including alkaloids and volatiles of pharmacological interest. However, there are no reports on how specialized metabolism (SM) can respond to the exogenous application of plant regulators and how this possible modulation is associated with primary metabolism (PM). Thus, the aim of this work was to evaluate SM and PM responses of Annona emarginata as a function of the application of plant growth regulators. For this, young plants were treated with auxin, methyl jasmonate , salicylic acid and abscisic acid at various concentrations. To know the particular effect of auxin, a second experiment was carried out using auxin and its inhibitor, observing responses at various times after application. SM responses were the quantification of total alkaloids, oxoaporphine liriodenine, number of alkaloids in roots and leaf volatile profile. For PM, gas exchange and chlorophyll a fluorescence variables were determined. Some plant regulators promoted changes over photosynthesis variables in Annona emarginata at specific concentrations and evaluation times; the most pronounced effects were caused by auxin, mainly reduction in net carbon assimilation and less photochemical dissipation at 10 -6 M. The application of 10 -6 M auxin and 10 -3 M salicylic acid in A. emarginata caused increase in total alkaloids and liriodenine. All regulators altered the composition of leaf volatiles, that were reflected in the classes of volatiles or in individual molecules, for example, with auxin, methyl jasmonate and salicylic acid decreasing the relative proportion of monoterpenes, and abscisic acid causing alterations in sesquiterpenes. Thus, it was possible to demonstrate that A. emarginata alters the energy flow between primary and specialized metabolism as a function of the applied plant regulator and that the number and proportion of specialized metabolites are modulated according to the applied plant regulator. • Auxin and salicylic acid caused an increase in alkaloids in A. emarginata. • Auxin, methyl jasmonate, and salicylic acid reduced the monoterpenes hydrocarbons. • Salicylic acid caused an increase in α-humulene sesquiterpene. • A. emarginata modifies the production of alkaloids and VOCs by phytoregulators. • A. emarginata modulates primary and/or secondary metabolism due to phytoregulators.

Chemical genetic screening identifies nalacin as an inhibitor of GH3 amido synthetase for auxin conjugation

Auxin inactivation is critical for plant growth and development. To develop plant growth regulators functioning in auxin inactivation pathway, we performed a phenotype-based chemical screen in Arabidopsis and identified a chemical, nalacin, that partially mimicked the effects of auxin. Genetic, pharmacological, and biochemical approaches demonstrated that nalacin exerts its auxin-like activities by inhibiting indole-3-acetic acid (IAA) conjugation that is mediated by Gretchen Hagen 3 (GH3) acyl acid amido synthetases. The crystal structure of Arabidopsis GH3.6 in complex with D4 (a derivative of nalacin) together with docking simulation analysis revealed the molecular basis of the inhibition of group II GH3 by nalacin. Sequence alignment analysis indicated broad bioactivities of nalacin and D4 as inhibitors of GH3s in vascular plants, which were confirmed, at least, in tomato and rice. In summary, our work identifies nalacin as a potent inhibitor of IAA conjugation mediated by group II GH3 that plays versatile roles in hormone-regulated plant development and has potential applications in both basic research and agriculture.

IAA Plays an Important Role in Alkaline Stress Tolerance by Modulating Root Development and ROS Detoxifying Systems in Rice Plants

Auxin regulates plant growth and development, as well as helps plants to survive abiotic stresses, but the effects of auxin on the growth of alkaline-stressed rice and the underlying molecular and physiological mechanisms remain unknown. Through exogenous application of IAA/TIBA, this study explored the physiological and molecular mechanisms of alkaline stress tolerance enhancement using two rice genotypes. Alkaline stress was observed to damage the plant growth, while exogenous application of IAA mitigates the alkaline-stress-induce inhibition of plant growth. After application of exogenous IAA to alkaline-stressed rice, dry shoot biomass, foliar chlorophyll content, photosynthetic rate in the two rice genotypes increased by 12.6-15.6%, 11.7-40.3%, 51.4-106.6%, respectively. The adventitious root number, root surface area, total root length and dry root biomass in the two rice genotypes increased by 29.3-33.3%, 26.4-27.2%, 42.5-35.5% and 12.8-33.1%, respectively. The accumulation of H2O2, MAD were significantly decreased with the application of IAA. The activities of CAT, POD, and SOD in rice plants were significantly increased by exogenous application of IAA. The expression levels of genes controlling IAA biosynthesis and transport were significantly increased, while there were no significant effects on the gene expression that controlled IAA catabolism. These results showed that exogenous application of IAA could mitigate the alkaline-stress-induced inhibition of plant growth by regulating the reactive oxygen species scavenging system, root development and expression of gene involved in IAA biosynthesis, transport and catabolism. These results provide a new direction and empirical basis for improving crop alkaline tolerance with exogenous application of IAA.

Exogenous IAA improves the seedling growth of Syringa villosa via regulating the endogenous hormones and enhancing the photosynthesis

Auxin is a core regulator of plant growth and an effective promoter of cell division and cell expansion. Effects of auxin on improving plant growth of Syringa plants remain poorly elucidated. The present study was carried out to investigate the effects of exogenous indole-3-acetic acid (IAA) on morphogenesis, endogenous hormone content, photosynthesis capacity and find the basis of IAA-induced physiological effects of Syringa villosa by transcriptome sequencing technology. The results indicated that exogenous IAA significantly contributed to the plant height, stem diameter, leaf area and leaf number, which improved the accumulation of whole plant quality. Contents of endogenous IAA and gibberellic acid (GA3) were markedly higher than control after IAA treatment, while abscisic acid (ABA) content was significantly declined. For photosynthetic parameters, photosynthesis capacity was promoted by the application of IAA, as evidenced by a significant increase in net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) and a lower intercellular CO2 concentration (Ci). In addition, the transcriptome of S. villosa was first sequenced which revealed that genes related to the synthesis and signal transduction of growth-promoting hormones such as IAA, GA3, cytokinin (CTK), and brassinolide (BR) were significantly up-regulated within 2 h of IAA treatment. The expression levels of genes related to photosynthesis, antenna proteins, and carbon fixation of photosynthetic organisms were also enhanced by exogenous IAA. Additionally, the application of exogenous IAA had a positive effect on growth and development by rapidly inducing genes related to cell division and cell expansion. By profiling the transcriptome of IAA response, potential target genes were identified based on the hormone levels and photosynthesis. These results provide insights for further functional genomic studies on the regulatory mechanisms of IAA underlying Syringa plants architecture.

Widely targeted metabolomics analysis reveals the effect of exogenous auxin on postharvest resistance to Botrytis cinerea in kiwifruit (Actinidia chinensis L.)

Kiwifruit has high economic value but is susceptible to fungal infection after harvest. Botrytis cinerea (B. cinerea) is one of these fungal pathogens that cause huge economic losses and potential food safety problems. Auxin is a vital plant growth regulator that has been reported to play a role in plant defense. In this study, postharvest kiwifruit was treated with different concentrations of indole-3-acetic acid (IAA), after which the average incidence rate and lesion area were analyzed to determine the appropriate concentration of IAA for disease resistance. Defense enzymes, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were detected. Ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS)-based widely targeted metabolomic analysis was used to investigate the mechanism of kiwifruit active compounds during IAA treatment and B. cinerea infection. Exogenous IAA treatment (especially at 50 μg/ mL) enhanced the resistance of kiwifruit to B. cinerea, resulting in reduced disease incidence and lesion area, and showed higher pathogen resistance-related defense enzyme activity in response to B. cinerea infection. Further metabolomic analysis revealed 776 metabolites in kiwifruit after IAA treatment, among which 51 metabolites in IAA_24h (24 h after IAA treatment) vs. CK (sterilized ddH2O treatment) fruit, 55 metabolites in IAA_72h (72 h after IAA treatment) vs. CK, and 67 metabolites in IAA_24h vs. IAA_72h were found to be significantly different. KEGG analysis showed that the resistance induced in kiwifruit by IAA treatment was closely related to the activation of phenylpropanoids, including flavonoids and phenols, terpenoids, carbohydrate metabolism, and hormone signaling pathways. These results might reveal the mechanism of IAA-induced resistance in kiwifruit and provide a new theoretical basis for the safe and efficient control of postharvest diseases in kiwifruit.

Integrative analysis based on transcriptome revealed the relation of auxin to turnip hypocotyl-tuber formation

Turnip (Brassica campestris L. ssp. rapifera Matag syn. B. rapa L.) is characterized by bulbous hypocotyl-tuber, which is an important agronomic trait of the Brassica plants, but the molecular mechanism underlying the development of turnip hypocotyl-tuber has rarely been explored. Contrary to turnip, pak-choi (B. campestris L. ssp. chinensis Makino syn. B. rapa ssp. chinensis) is characterized by small and long hypocotyl. Based on the difference in morphological and anatomical characteristics of hypocotyl between turnip and pak-choi at different developmental stages, integrative analysis was performed in this study. Comparative transcriptomic analysis demonstrated that the changes of expression patterns of genes related to plant hormones especially auxin in hypocotyl were closely related to turnip hypocotyl enlargement at the early stages (8 and 32 days after sowing). The immunolocalization of auxin during early hypocotyl development stages also showed auxin signal differences in secondary xylem of hypocotyl between the two subspecies, and further 1-Naphthaleneacetic acid (NAA) treatments confirmed the effect of auxin in turnip hypocotyl-tuber formation. Our study provided valuable information for further exploration of the role of auxin underlying turnip hypocotyl enlargement, enabling a more comprehensive understanding of plant storage organ development.

Effects of α-Naphthylacetic Acid on Cadmium Stress and Related Factors of Tomato by Regulation of Gene Expression

Cadmium (Cd) is absorbed and accumulated by crops, and it adversely affects plant growth and development. To explore the effect of exogenous auxin on Cd stress, we applied different concentrations of α-naphthaleneacetic acid (NAA) and the auxin transport inhibitor 2,3,5-triiodobenzoic acid (TIBA) to tomato plants exposed to Cd stress in a hydroponic system. NAA and TIBA at different concentrations were used under Cd stress. Plant growth, root morphology, and auxin distribution were observed. Lipid peroxidation and antioxidant enzyme activities in leaves, cadmiumcontent, and migration coefficient of plants were determined. Transcriptome sequencing and qRT-PCR were used to analyze the differentially expressed genes. Results showed that auxin was concentrated in the leaf veins, stem base, and roots in P5::GUS “Chico III” transgenic tomato, indicating NAA polar transport to the roots and promotion of root growth under Cd stress. Cd was absorbed by the roots and transported to the shoots. It then inhibited plant growth and promoted antioxidant enzyme activities, O2− production, H2O2 accumulation, and membrane lipid peroxidation. Treatment with 0.5 μM NAA improved antioxidant enzyme activities, reduced reactive oxygen, maintained membrane permeability, and decreased malondialdehyde and proline contents. Transcriptome analysis revealed that NAA activated a large number of genes in the roots: 1998 genes were differentially expressed in response to Cd or NAA treatment, and 1736 genes were specifically expressed in response to NAA treatment under Cd stress. Among the differentially expressed genes, tomato metallocarboxypeptidase inhibitor TCMP-2 (2A11) and Solanum lycopersicum heavy metal-associated isoprenylated plant protein (HIPP) 7-like (LOC101264884), which are closely related to plant response to heavy metal stress, may be the key sites of NAA. In conclusion, the NAA-mediated response to Cd stress was closely associated with “defense response” genes in shoots and “oxidoreductase activity, oxidizing metal ions” and “response to auxin” genes in roots.

ABP1-TMK auxin perception for global phosphorylation and auxin canalization.

The phytohormone auxin triggers transcriptional reprogramming through a well-characterized perception machinery in the nucleus. By contrast, mechanisms that underlie fast effects of auxin, such as the regulation of ion fluxes, rapid phosphorylation of proteins or auxin feedback on its transport, remain unclear1-3. Whether auxin-binding protein 1 (ABP1) is an auxin receptor has been a source of debate for decades1,4. Here we show that a fraction of Arabidopsis thaliana ABP1 is secreted and binds auxin specifically at an acidic pH that is typical of the apoplast. ABP1 and its plasma-membrane-localized partner, transmembrane kinase 1 (TMK1), are required for the auxin-induced ultrafast global phospho-response and for downstream processes that include the activation of H+-ATPase and accelerated cytoplasmic streaming. abp1 and tmk mutants cannot establish auxin-transporting channels and show defective auxin-induced vasculature formation and regeneration. An ABP1(M2X) variant that lacks the capacity to bind auxin is unable to complement these defects in abp1 mutants. These data indicate that ABP1 is the auxin receptor for TMK1-based cell-surface signalling, which mediates the global phospho-response and auxin canalization.

Functional Characterization and Phenotyping of Protoplasts on a Microfluidics-Based Flow Cytometry.

A better understanding of the phenotypic heterogeneity of protoplasts requires a comprehensive analysis of the morphological and metabolic characteristics of many individual cells. In this study, we developed a microfluidic flow cytometry with fluorescence sensor for functional characterization and phenotyping of protoplasts to allow an unbiased assessment of the influence of environmental factors at the single cell level. First, based on the measurement of intracellular homeostasis of reactive oxygen species (ROS) with a DCFH-DA dye, the effects of various external stress factors such as H2O2, temperature, ultraviolet (UV) light, and cadmium ions on intracellular ROS accumulation in Arabidopsis mesophyll protoplasts were quantitatively investigated. Second, a faster and stronger oxidative burst was observed in Petunia protoplasts isolated from white petals than in those isolated from purple petals, demonstrating the photoprotective role of anthocyanins. Third, using mutants with different endogenous auxin, we demonstrated the beneficial effect of auxin during the process of primary cell wall regeneration. Moreover, UV-B irradiation has a similar accelerating effect by increasing the intracellular auxin level, as shown by double fluorescence channels. In summary, our work has revealed previously underappreciated phenotypic variability within a protoplast population and demonstrated the advantages of a microfluidic flow cytometry for assessing the in vivo dynamics of plant metabolic and physiological indices at the single-cell level.

Auxin and abscisic acid antagonistically regulate ascorbic acid production via the SlMAPK8-SlARF4-SlMYB11 module in tomato.

Ascorbic acid (AsA) is a multifunctional phytonutrient that is essential for the human diet as well as plant development. While much is known about AsA biosynthesis in plants, how this process is regulated in tomato (Solanum lycopersicum) fruits remains unclear. Here, we found that auxin treatment inhibited AsA accumulation in the leaves and pericarps of tomato. The auxin response factor gene SlARF4 is induced by auxin to mediate auxin-induced inhibition of AsA accumulation. Specifically, SlARF4 transcriptionally inhibits the transcription factor gene SlMYB11, thereby modulating AsA accumulation by regulating the transcription of the AsA biosynthesis genes l-galactose-1-phosphate phosphatase, l-galactono-1,4-lactone dehydrogenase, and dehydroascorbate. By contrast, abscisic acid (ABA) treatment increased AsA accumulation in tomato under drought stress. ABA induced the expression of the mitogen-activated protein kinase gene SlMAPK8. We demonstrate that SlMAPK8 phosphorylates SlARF4 and inhibits its transcriptional activity, whereas SlMAPK8 phosphorylates SlMYB11 and activates its transcriptional activity. SlMAPK8 functions in ABA-induced AsA accumulation and drought stress tolerance. Moreover, ABA antagonizes the effects of auxin on AsA biosynthesis. Therefore, auxin- and ABA-induced regulation of AsA accumulation is mediated by the SlMAPK8-SlARF4-SlMYB11 module in tomato during fruit development and drought stress responses, shedding light on the roles of phytohormones in regulating AsA accumulation to mediate stress tolerance.

Auxin-Cytokinin Cross Talk in Somatic Embryogenesis of Coffea canephora.

Cytokinins (CK) are plant growth regulators involved in multiple physiological processes in plants. One less studied aspect is CK homeostasis (HM). The primary genes related to HM are involved in biosynthesis (IPT), degradation (CKX), and signaling (ARR). This paper demonstrates the effect of auxin (Aux) and CK and their cross talk in a Coffea canephora embryogenic system. The transcriptome and RT-qPCR suggest that Aux in pre-treatment represses biosynthesis, degradation, and signal CK genes. However, in the induction, there is an increase of genes implicated in the CK perception/signal, indicating perhaps, as in other species, Aux is repressing CK, and CK are inducing per se genes involved in its HM. This is reflected in the endogenous concentration of CK; pharmacology experiments helped study the effect of each plant growth regulator in our SE system. We conclude that the Aux–CK balance is crucial to directing somatic embryogenesis in C. canephora.

Determination of genotoxic damages of picloram and dicamba with comet assay in Allium cepa rooted in tissue culture and distilled water.

Many genotoxicity tests allow us to understand the mechanism of damages on genetic material occurring in living organisms against various physical and chemical agents. One of them is the Comet test. The current study aimed to evaluate genotoxic caused by picloram and dicamba to root meristems of Allium cepa utilizing comet assay. Two different protocols were used for rooting and auxin/pesticide application. (i) A. cepa bulbs were rooted in MS medium and then treated with Murashige and Skoog (MS) medium (control) and 0.67, 1.34, 2.01, 2.68, 3.35, 4.02, and 8.04mg/L of picloram and dicamba using aseptic tissue culture techniques. (ii) A. cepa bulbs were then rooted in bidistilled water and treated with 0 (control), 0.67, 1.34, 2.01, 2.68, 3.35, 4.02, and 8.04mg/L of picloram and dicamba in distilled water. The A. cepa root tip cells in both treatment groups were examined using comet test to find the possible DNA damaging effects of picloram and dicamba. The results obtained at all the concentrations were statistically compared with their control groups. Almost at all the concentrations of Picloram and dicamba increased comet tail intensity (%) and tail moment in roots treated in MS medium. Two highest concentrations revealed toxic effect. On the other hand, DNA damaging effect of both auxins was only noted on the highest (> 4.02mg/L) in roots treated in distilled water. This study approve and confirm genotoxic effects of how growth regulators on plants. These findings give an evidence of DNA damage in A. cepa. Therefore, both picloram and dicamba should only be used in appropriate and recommended concentrations in agriculture to conserve ecosystem and to pose minimum threat to life.

Morphological and Proteomic Analyses of Soybean Seedling Interaction Mechanism Affected by Fiber Crosslinked with Zinc-Oxide Nanoparticles.

Nanoparticles (NPs) enhance soybean growth; however, their precise mechanism is not clearly understood. To develop a more effective method using NPs for the enhancement of soybean growth, fiber crosslinked with zinc oxide (ZnO) NPs was prepared. The solution of ZnO NPs with 200 nm promoted soybean growth at the concentration of 10 ppm, while fibers crosslinked with ZnO NPs promoted growth at a 1 ppm concentration. Soybeans grown on fiber cross-linked with ZnO NPs had higher Zn content in their roots than those grown in ZnO NPs solution. To study the positive mechanism of fiber crosslinked with ZnO NPs on soybean growth, a proteomic technique was used. Proteins categorized in photosynthesis and secondary metabolism accumulated more in soybeans grown on fiber crosslinked with ZnO NPs than in those grown in ZnO NPs solution. Furthermore, significantly accumulated proteins, which were NADPH oxidoreductase and tubulins, were confirmed using immunoblot analysis. The abundance of NADPH oxidoreductase increased in soybean by ZnO NPs application. These results suggest that fiber crosslinked with ZnO NPs enhances soybean growth through the increase of photosynthesis and secondary metabolism. Additionally, the accumulation of NADPH oxidoreductase might relate to the effect of auxin with fiber crosslinked with ZnO NPs on soybean growth.

STUDY ON in vitro INDUCTION OF ROOTING AND CHANGES IN ENDOGENOUS HORMONE CONTENT OF Lagerstroemia indica ‘ZIJINGLING’

Different media had different effects on the induction of rooting of Lagerstroemia indica ‘Zijingling’. The aims of this study were to identify the best rooting medium, determine the changes in endogenous hormone content in aseptic seedlings of ‘Zijingling’, and then analyze its role in the rooting process, to improve the rooting rate. Using a test tube seedling of ‘Zijingling’ as the experimental material, the tissue cells were observed via paraffin sectioning, and the changes in endogenous hormone content during the rooting process were determined using high-performance liquid chromatography. The results showed that 1/2 MS Medium had the most significant effect on rooting in the basic medium. The promoting effects of different auxins on rooting decreased in magnitude in the order 3-Indolebutyric acid (IBA) > Naphthalene acetic acid (NAA)> Indole-3-aceticacid (IAA). The optimal rooting medium was 1/2 MS + 0.6 mg L-1 IBA+ 15 g L-1 sucrose + 5 g L-1 agar + 200 mg L-1 activated carbon , and the highest induction rate of adventitious roots was 92.5%. The rooting of ‘Zijingling’ is classified as a primordial type of induced rooting. Exogenous IBA content promoted an increase in endogenous IAA and Gibberellic acid (GA3) contents. High contents of IAA, GA3, and Abscisic acid (ABA) and low content of Zeatin riboside (ZR) promoted the growth of adventitious roots, whereas high contents of IAA and ZR, and low contents of GA3 and ABA were required for the induction of root primordia. High levels of IAA/ZR and low levels of IAA/ABA promoted the differentiation of root primordia. However, low levels of IAA/ZR and high levels of IAA/ABA promoted adventitious root elongation.

Growth regulators in the induction of calli in anthers of the Goldex hybrid yellow melon

The melon is of socio-economic importance, especially in the north-east of Brazil. Obtaining homozygous lines has been an obstacle in breeding programs. In vitro androgenesis is one alternative, requiring the development of protocols for anther culture. The aim of this work was to study the effect of auxins and cytokinins on callus induction in anthers of the Goldex hybrid yellow melon. Two experiments were conducted in a completely randomised design, with 25 replications. In the first experiment, in a 3 x 3 factorial scheme, the treatments comprised concentrations of 6-furfurylaminopurine - KIN (0.0, 3.0 and 6.0 mg L-1) and indolylacetic acid - IAA (0.0, 3.0 and 6.0 mg L-1), added to Murashige and Skoog (MS) medium. In the second experiment, six treatments were tested: MS with no growth regulator; MS + 0.20 mg L-1 6-benzylaminopurine (BAP); MS + 0.20 mg L-1 naphthaleneacetic acid (NAA); MS + 0.45 mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D); MS + 0.20 mg L-1 BAP + 0.20 mg L-1 NAA; and MS + 0.20 mg L-1 BAP + 0.45 mg L-1 2,4-D. The following were evaluated 60 days after anther inoculation: induction percentage, oxidation intensity, colour, texture, and the area and fresh weight of the callus. The auxins (IAA, NAA and 2,4-D) and cytokinins (KIN and BAP) induce callogenesis in anthers, but only in combination, the most suitable being 0.20 mg L-1 BAP + 0.45 mg L-1 2,4-D. The calli have a beige colour, friable texture and medium oxidation, with a strong association between the fresh weight and the area.