IAA-oxidase Activity Research Articles

Transcriptome Analysis of Cadmium-Treated Roots in Maize (Zea mays L.).

Cadmium (Cd) is a heavy metal and is highly toxic to all plant species. However, the underlying molecular mechanism controlling the effects of auxin on the Cd stress response in maize is largely unknown. In this study, the transcriptome produced by maize ‘Zheng 58’ root responses to Cd stress was sequenced using Illumina sequencing technology. In our study, six RNA-seq libraries yielded a total of 244 million clean short reads and 30.37 Gb of sequence data. A total of 6342 differentially expressed genes (DEGs) were grouped into 908 Gene Ontology (GO) categories and 198 Kyoto Encyclopedia of Genes and Genomes terms. GO term enrichment analysis indicated that various auxin signaling pathway-related GO terms were significantly enriched in DEGs. Comparison of the transcript abundances for auxin biosynthesis, transport, and downstream response genes revealed a universal expression response under Cd treatment. Furthermore, our data showed that free indole-3-acetic acid (IAA) levels were significantly reduced; but IAA oxidase activity was up-regulated after Cd treatment in maize roots. The analysis of Cd activity in maize roots under different Cd and auxin conditions confirmed that auxin affected Cd accumulation in maize seedlings. These results will improve our understanding of the complex molecular mechanisms underlying the response to Cd stress in maize roots.

Bio indices for 2,4-D sensitivity between two plant species: Azolla pinnata R.Br. and Vernonia cinerea L. with their cellular responses

In the present experiment a pteridophytic species Azolla and an angiospermic species Vernonia were evaluated on the basis of cellular reactivity for herbicidal action through ongoing concentrations. Initially, both the species recorded a significant activity of IAA-oxidase as mark of IAA metabolism with herbicidal sensitivity. Still, Vernonia species were more affected on 2,4-D mediated auxin catabolism. The loss of auxin concentrations on the tissues by 2,4-D reaction was also reflected on growth parameters including relative growth rate and chlorophyll biosynthesis. In a dose dependent manner Vernonia plants were more affected with loss of chlorophyll content and decline in relative growth rate. On the other hand, both those parameters were adjusted significantly with 2,4-D accumulation in Azolla. The stability of cellular metabolism was documented by significant down regulation of protein and lipid peroxidation with concomitant moderation to superoxide and hydrogen peroxide accumulation. The later two were more vulnerable to damage in the Vernonia plant with profuse accumulation of protein and lipid peroxidation products. Similarly, tissue specific reaction to superoxide and hydrogen peroxide accumulation were distinctly demarcated in two species significantly. As a whole, the cellular responses and metabolite distribution to 2,4-D sensitization are the features to describe bio-indices for aquatic fern species Azolla with comparison to angiospermic species Vernonia.

Nitric oxide is required for hydrogen gas-induced adventitious root formation in cucumber

Hydrogen gas (H2) is involved in plant development and stress responses. Cucumber explants were used to study whether nitric oxide (NO) is involved in H2-induced adventitious root development. The results revealed that 50% and 100% hydrogen-rich water (HRW) apparently promoted the development of adventitious root in cucumber. While, the responses of HRW-induced adventitious rooting were blocked by a specific NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO), NO synthase (NOS) enzyme inhibitor NG-nitro-l-arginine methylester hydrochloride (l-NAME) and nitrate reductase (NR) inhibitor NaN3. HRW also increased NO content and NOS and NR activity both in a dose- and time-dependent fashion. Moreover, molecular evidence showed that HRW up-regulated NR genes expression in explants. The results indicate the importance of NOS and NR enzymes, which might be responsible for NO production in explants during H2-induced root organogenesis. Additionally, peroxidase (POD) and indoleacetic acid oxidase (IAAO) activity was significantly decreased in the explants treated with HRW, while HRW treatment significantly increased polyphenol oxidase (PPO) activity. In addition, cPTIO, l-NAME and NaN3 inhibited the actions of HRW on the activity of these enzymes. Together, NO may be involved in H2-induced adventitious rooting, and NO may be acting downstream in plant H2 signaling cascade.

Activity of indolyl-3-acetic acid oxidase and peroxidase in roots of carrot infested with Meloidogyne hapla Chiuu.

IAA-oxidase and peroxidase activity was measured in storage and side roots of healthy and <i>M. hapla</i> infested carrots of two sultivars. Cultivar 'Perfekcja' is sensitive whereas cv. 'Slendero' is tolerant to the northern root-knot ne-matode. 3-, 4-, and 5-month-old plants were subjected to analyses. In <i>M. hapla</i> infested plants of both cultivars IAA-oxidase inhibitors accumulated. Kinetics of IAA oxidation <i>in vivo</i> were the same in healthy and infested plants. IAA-oxidase activity <i>in vitro</i> was inhibited in crude extracts of the infested tissues, the inhibition being prevented by PVP. Peroxidase activity increased in secondary phloem and decreased in galled side roots of both cultivars when compared with healthy controls. In galled side roots of the youngest 3-month-old plants peroxidase activity was not decreased. IAA-oxidase inhibitors accumulated in the infested roots.It is concluded that <i>M. hapla</i> has no direct effect on IAA-oxidase. Degree of tolerance to nematodes is correlated with the ratio of IAA-oxidase inhibitors to IAA-oxidase rather than with the absolute activity of IAA-oxidase.

No effect of plant growth retarding compounds and growth stimulators on indolo-3-acetic acid oxidase activity in greening cucumber cotyledons

Cotyledons dissected from 5-day-old etiolated cucumber seedlings were incubated in solutions on AMO-1618, B-Nine, CCC and Phosfon D for 48 h in light. In some tests the retardants were applied in mixed solutions with GA<sub>3</sub> or BAP. IAA oxidase was extracted and purified by means of molecular sieving through a bed of Sephadex G-25. The retardants inhibited chlorophyll synthesis by 50 % or more, and had essentially no effect on IAA oxidase activity per cotyledon basis. GA<sub>3</sub> and BAP also had no effect on enzyme activity in spite of a fact that the compounds stimulated growth of the cotyledons. The crude enzyme extract from B-Nine treated cotyledons showed lower IAA oxidase activity in comparison with the water treated control, the effect being due to a longer lag-phase preceding the initiation of IAA oxidation. KNO<sub>3</sub> strikingly stimulated expansional growth of the cotyledons, the effect being correlated with the accelerated chlorophyll accumulation. KNO<sub>3</sub> had no effect on IAA oxidase activity per cotyledon and decreased it per gram fr wt. It is concluded that [1] the growth rate of cucumber cotyledons is not correlated with IAA oxidase activity, and ;[2] the growth retarding compounds do not affect IAA oxidase system is this tissue.

Physiological and biochemical effects of morphactin IT 3233 on callus and tumour tissues of Nicotiana tabacum L. cultured in vitro. IV. IAA oxidase activity. Oat coleoptile biotest

IAA oxidase activity in callus and tumour tissue of tobacco subjected to the action of morphactin IT 3233 for shorter and longer periods was determined. Control tumour tissue shows an activity higher by about 40 per cent as compared with that of callus tissue. Morphactin applied for a short time (24-h incubation) does not change the activity of the enzyme. When application is prolonged, a considerable enhancement (up to 140%) of the enzyme activity in callus tissue is observed in dependence on the morphactin concentration. In tumour tissues the activity is stimulated by 45 per cent as compared to control. Oat coleoptile elongation growth induced by IAA is limited to 40 per cent when morphactin is added in the concentrations used for tobacco tissue cultures. The possibility of the morphactin action on tissue growth via IAA metabolism is discussed.

Activities of enzymes connected with IAA oxidation in cucumbers of various sex types

Activity of peroxidase, cqtalase, and IAA-oxidase in flower buds, stems and stem callus cultures derived from four pure genetic lines of <i>Cucumis sativus</i> L., i.e. male, monoecious, female and hermaphrodite was determined. The activities of all enzymes in flower buds and callus cultures are considerably higher in the female lines then in male ones. IAA-oxidase activity is the highest in female line, independently of the type of plant material under examination. The activities of the remaining two enzymes depend on the type of tissue or organ under examination.

Wplyw IAA na aktywność oksydazy kwasu indolilooctowego w siewkach pszenicy ozimej i kukurydzy w warunkach stresu osmotycznego [Influence of IAA on IAA-oxidase activity in winter wheat and maize seedlings under conditions of osmotic stress

IAA-oxidase activity was determined in etiolated 7-day-old winter wheat leaves of the variety Grana and in maize leaves of the variety KbDc-310. The results indicate that IAA applied before seeding (1.10<sup>-5</sup> M) depresses IAA-oxidase activity in the roots and shoot of the cereals tested under conditions of mannitol osmotic stress (-4.84 bar and -9.68 bar).

Changes in auxin activity in tumourous and normal tobacco calluses treated with morphactin IT 3233

The addition of morphactin IT 3233 in 1-40 mg/dm<sup>3</sup> concentrations to the medium inhibited the growth <i>in vitro</i> of normal and tumourous tobacco calluses. The auxin activity (estimated by the <i>Avena</i> coleoptile straight growth test) of the acid ether extracts from these tissues increased. The activity of zone I (R<sub>f</sub> 0.2-0.4, 0.5, solvent system: butanol:water:ammonia 10:10:1) in normal tissues increased more intensively than that of zone II (Rf 0.6-0.8, 0.9). In tumourous tissues, however, these changes were smaller and they concerned merely zone I of auxin activity (R<sub>f</sub> 0.0-0.5). It seems that the mechanism of morphactin activity in both kinds of tissue is different. It may be supposed that the excessive accumulation of auxins induces growth inhibition of tissues. A previously found increase in the activity of IAA-oxidase influenced by morphactin might be considered as an adaptation to a higher level of IAA.

Physiological and biochemical changes during organogenesis and somatic embryogenesis of HBsAg-transgenic cherry tomato mutant

Leaf explants of the HBsAg-transgenic cherry tomato (Solanum lycopersicum) mutant were cultured on Murashige and Skoog (MS) basal medium, supplemented with 1.0 mg/L 6-BA and 0.05 mg/L IAA for callus induction, to clarify the physiological and biochemical characteristics of morphogenesis development. Therefore, the physiological and biochemical changes during the development of organogenic shoots and somatic embryos in the mutant were studied. Superoxide dismutase (SOD) activities of the mutant had only one peak value on the 21st day. Peroxidase (POD) activities of the mutant declined less sharply since the explants were cultured. IAA oxidase activity of the mutant increased steadily until 42 days from culturing and then decreased sharply. Malondialdehyde (MDA) of the mutant showed a significant decreasing trend after 21 days from culturing. Growth rate of the mutant was at times lower than that of the control during its callus differentiation, and the soluble protein content of the mutant callus decreased from explant cultivation until the 28th day of culture. The mutant had greater values of chlorophyll a, carotenoid and Chlorophyll contents than the control after 14 days of culturing, and Chlorophyll b content of the mutant showed a declining trend. The electrical conductivity trend of the mutant was consistent with that in the control. It indicated that in terms of the organogenesis or somatic embryogenesis pattern, protein synthesis and catabolism were very active, and a number of antioxidant enzyme activities were consistent in the early development stages of the two regeneration systems. These findings were useful for the regeneration of the mutant.

Effect of boron on yield and physiological properties in rape (Brassica campestris)

The results of the present investigation show that the physiological properties as well as yield of rape (Brassica campestris L.) have been found to be affected by integrated applications of B and well rotten farmyard manure. The activity of indole acetic acid (IAA) oxidase was recorded a lowest value in the treatment T4 where recommended N: P2O5: K2O (80:40:40), boron at 0.5 kg/ha as calbor and well rotten farmyard manure at 5 tonnes/ha was applied. The IAA was highest in control treatment suggesting crops may suffer due to boron deficiency with an increase in IAA oxidase activity. The highest value of polyphenol oxidase (PPO) with no boron application exhibited boron deficiency while that of the same recorded a lowest value with the application of boron at 0.5 kg/ha along with 5 tonnes/ha well rotten farmyard manure did not show any boron deficiency. The highest and lowest polyphenol activity were recorded in the treatment T1 and T4 where no boron and boron at 0.5 kg/ha along with 5 tonnes/ha well rotten farmyard manure was applied respectively.

Ácido 2,3,5-tri-iodobenzoico (TIBA) na micropropagação de abacaxizeiro 'IAC Gomo-de-Mel'

O abacaxi 'IAC Gomo-de-Mel' é uma espécie economicamente importante devido a diversas características sensoriais. Uma das técnicas para obter maior número de plantas é a micropropagação. Assim, o objetivo deste trabalho foi avaliar a ação do TIBA (ácido 2,3,5-tri-iodobenzoico) na formação de brotos e raízes do abacaxizeiro 'IAC Gomo-de-Mel', assim como possíveis alterações na morfologia de tecidos foliares. Foram utilizados segmentos das gemas da coroa de abacaxi, com aproximadamente 1 cm, oriundos de cultivo em meio líquido, suplementadas com 1,0 mg L-1 BAP+ 0,5 mg L-1 NAA , sendo posteriormente inoculados em meio MS líquido contendo diversas concentrações de TIBA, em condição de luz e temperatura controladas, implantando 3 diferentes experimentos para as análises biométrica, bioquímica e anatômica. Os experimentos foram implantados em delineamento experimental inteiramente ao acaso, com 8 tratamentos, com 4 repetições para as análises biométricas e 5 repetições para a bioquímica e anatômica. Ao final de 60 dias, foram avaliados o número e o comprimento das brotações, o comprimento da planta-mãe e o número de raízes. A análise da atividade de AIA-oxidase foi realizada no dia da instalação do experimento e aos 15; 30; 45 e 60 dias de cultivo. Conclui-se que o TIBA isoladamente não induz brotações. A redução na atividade da AIA-oxidase foi relacionada com a emissão de novas raízes, e o aumento na espessura dos tecidos foliares ocorreu após aplicação exógena de TIBA, em abacaxizeiro in vitro.

Perturbation of Auxin Homeostasis Caused by Mitochondrial FtSH4 Gene-Mediated Peroxidase Accumulation Regulates Arabidopsis Architecture

Reactive oxygen species and auxin play important roles in the networks that regulate plant development and morphogenetic changes. However, the molecular mechanisms underlying the interactions between them are poorly understood. This study isolated a mas (More Axillary Shoots) mutant, which was identified as an allele of the mitochondrial AAA-protease AtFtSH4, and characterized the function of the FtSH4 gene in regulating plant development by mediating the peroxidase-dependent interplay between hydrogen peroxide (H2O2) and auxin homeostasis. The phenotypes of dwarfism and increased axillary branches observed in the mas (renamed as ftsh4-4) mutant result from a decrease in the IAA concentration. The expression levels of several auxin signaling genes, including IAA1, IAA2, and IAA3, as well as several auxin binding and transport genes, decreased significantly in ftsh4-4 plants. However, the H2O2 and peroxidases levels, which also have IAA oxidase activity, were significantly elevated in ftsh4-4 plants. The ftsh4-4 phenotypes could be reversed by expressing the iaaM gene or by knocking down the peroxidase genes PRX34 and PRX33. Both approaches can increase auxin levels in the ftsh4-4 mutant. Taken together, these results provided direct molecular and genetic evidence for the interaction between mitochondrial ATP-dependent protease, H2O2, and auxin homeostasis to regulate plant growth and development.

Effect of Naphthalene Acetic Acid on Adventitious Root Development and Associated Physiological Changes in Stem Cutting of Hemarthria compressa

In order to find a way to induce rooting on cuttings of Hemarthria compressa cv. Ya’an under controlled conditions, a project was carried out to study the effect of naphthalene acetic acid (NAA) on rooting in stem cuttings and related physiological changes during the rooting process of Hemarthria compressa. The cuttings were treated with five concentrations of NAA (0, 100, 200 300, 400 mg/l) at three soaking durations (10, 20, 30 minutes), and cuttings without treatment were considered as control. Samples were planted immediately into pots after treatment. IAA-oxidase (IAAO) activity, peroxidase (POD) activity and polyphenol oxidase (PPO) activity were determined after planting. Results showed that NAA had positive effect on rooting at the concentration of 200 mg/l compared to other concentrations at 30 days after planting (DAP). Among the three soaking durations, 20 minutes (min) of 200 mg/l NAA resulted in higher percentages of rooting, larger numbers of adventitious roots and heavier root dry weight per cutting. The lowest IAAO activity was obtained when soaked at 200 mg/l NAA for 20 min soaking duration. This was consistent with the best rooting ability, indicating that the lower IAAO activity, the higher POD activity and PPO activity could be used as an indicator of better rooting ability for whip grass cuttings and might serve as a good marker for rooting ability in cuttings.

English

A field experiment was conducted at State Horticultural Farm, Kanyakumari District undertaken by the Horticultural College and Research Institute, Tamil Nadu Agricultural University, Periyakulam during the year 2010 to 2012. In general, mango flowering is considered as a complex phenomenon. Besides, favorable climate conditions that favours off-season flowering, genetic potential of the varieties, physiological and biochemical variations and better management interventions could also play the vital role in promoting off season flowering. The environmental variables play a key and vital role in induction of mango flowering. The result was revealed by the Horticultural College and Research Institute, Tamil Nadu Agricultural University, Periyakulam during the year 2010 to 2012. The number of inflorescence m-2 (32.10 and 26.40), hermaphrodite flower per cent (37.95 and 33.25), male flower per cent (47.97 and 52.60) and fruit set per cent (0.67 and 0.63) were higher in cv. Neelum during main season and off–season respectively. With regard to physiological parameters, the highest soluble protein (12.55 and 11.94 mg100 g-1) and total phenols (3.510 and 3.250 mg100 g-1) and the lowest of IAA oxidase activity (169.85 and 178.20 µg g-1) and Gibberellic acid content (1.05 and 1.06 µg g-1) were recorded in cv. Neelum during main season and off–season respectively.   Key words: Flowering, physiological parameters, mango cultivars, season.

Dynamics of indole-3-acetic acid oxidase activity in suspension culture of sunflower crown-gall

IAA oxidase activity was determined in several growth phases of a suspension culture of sunflower crown-gall. During the short phase of intensive growth (zero passage - PO) a negative correlation was noted between enzymatic activity and the rate of growth. IAA oxidase activity increased to a certain level is not a factor limiting cell division. For protraction of the phase of intensive growth (first passage - P1), however, a decrease in the activity of this enzyme seems indispensable. IAA oxidase activity in the tested culture is under the control of inhibitors present in the cells and medium. High enzyme inhibition was observed in PO cells during the phase, of intensive growth and in P1 at the beginning and in the middle part of this phase. These results suggest' that the -auxin level determined in earlier studies in sunflower crown-gall culture is controlled by the IAA oxidase set. During the long phase of intensive growth (P1) this control is of negative feedback type.

28-Homobrassinolide-Induced Exaggerated Growth, Biochemical Molecular Aspects of Brassica Juncea L. RLM-619 Seedlings under High Temperature Stress

The present study was pertaining to study the mechanism and signaling of BRs under high temperature stress in Brassica juncea L. plants. Results advised that high temperature stress reduced the shoot length, root length, fresh weight of the plants but 28-homobrassinosteroids (28-homoBL) treatment reduced the toxic effect of high temperature stress by improving the same of B. juncea L. plants. To ascertain these free radical scavenging enzymes (superoxide dismutase (SOD), Catalase (CAT), Peroxidase (POD), Ascorbate peroxidase (APOX), Polyphenol oxidase (PPO) and Indole acetic acid oxidase (IAAO) and lipid oxidation (MDA) were assayed along with photosynthetic pigments, total carbohydrates, reducing sugars and non-reducing sugars. All studied scavenging enzymes activities were ameliorated by the homoBL treatments. The pigments decreased under temperature stress were also protected by homoBL treatments. Proteins profiling by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDSPAGE) were also studied to know the behavior of proteins under temperature stress as well as with the treatment of homoBL. Protein bands disappeared in temperature stress while in the presence of homoBL treatment existing proteins displayed more accumulation leading to the appearance of new bands. Native-PAGE of SOD, CAT and POD suggested the presence of in isoenzymic forms in cells. Application of different concentration of homoBL increased intensities of these isoenzymes under temperature and normal condition as compared to control untreated seedlings. The gene expression of SOD and CAT also suggested that synthesis these enzymes were decreased under high temperature stress but ameliorated with the treatment of homoBL. Present study demonstrated that 28-homoBL have stress-ameliorative properties in B. juncea seedlings exposed to high temperature stress by improving seedling growth and enhancing protein content as well as activities of SOD, CAT, APOX, PPO and IAA Oxidase. Further, it was suggested by decreasing the MDA content after the treatments of 28-homoBL. This study demonstrate the culmination of BR’s as an anti-stressor for protection of plant exposed to high temperature stress but extensive studies are still needed to know the various aspects related to stress and role of brassinosteroids in regulating them at molecular and signaling level.

Effect of Auxin on Weedy Rice Mesocotyl Cell Wall Oxidase

The seedling was developed on the dark condition by artificial climate chamber to determine the content of Auxin (IAA), activity of indoleacetic acid oxidase (IAO) and cell wall peroxidase (POD), mesocotyl length change and cell wall oxidase activity variation applied IAA. The study proves that endogenous hormone IAA content of long mesocotyl in weedy rice were much higher than that of short mesocotyl in Akimitsu. With the growth of mesocotyl elongation, endogenous IAA content showed cumulative effects. And then accumulation of IAA content reached up to maximum, when the Mesocotyl elongation stoped to grow. IAA might play a decisive role in the process of hypocotyl elongation. Reduction in the activity of IAO and POD accelerated the transformation from bound IAA to free IAA and promoted cell elongation and mesocotyl elongation.

Effects of calcium on the activities of cytosolic antioxidative enzymes and IAA oxidase during in vitro adventitious rooting of mung bean seedlings

The effects of Ca2+ on antioxidative enzymes and indole-3-acetic acid (IAA) oxidase during adventitious rooting were investigated in mung bean (Vigna radiata). CaCl2 significantly promoted the formation and growth of adventitious roots. EGTA (a Ca2+ chelator) or ruthenium red (a Ca2+-channel blocker) significantly inhibited root formation and growth, but these inhibitory effects could be partially reversed by CaCl2. Furthermore, inclusion of 5 mM CaCl2 significantly increased superoxide dismutase (SOD) activity by 10% at 3 h and catalase (CAT) activity by an average of 29.6% at each time point. CaCl2 decreased peroxidase (POD) activity by 9.4% and 21% at 12 and 24 h, respectively, and ascorbate peroxidase (APX) activity by an average of 13.9% at each time point. These CaCl2-induced changes in enzymatic activities were similar to changes caused by indole-3-butyric acid (IBA). Treatment with EGTA or ruthenium red decreased SOD activity by an average of 18.4% and 15.2%, respectively; POD activity by 27.4% and 57.6%, respectively; APX activity by 10.3% and 15.6%, respectively; and CAT activity by 19.3% and 5.2%, respectively, when compared with CaCl2. In addition, CaCl2 increased IAA oxidase activity by an average of 5.5% beginning at 6 h, whereas EGTA significantly decreased IAA oxidase activity by 29.2%, 22.9%, and 13.5% at 6, 9, and 12 h, respectively. The inhibitory effects of EGTA could be partially suppressed by addition of CaCl2. These results imply that the stimulative effect of Ca2+ on adventitious rooting is partially related to Ca2+-induced changes in the activities of antioxidative enzymes and IAA oxidase.

Effect of γ‐Ray Irradiation on Food Qualities and Sprouting Inhibition of Sweet Potato Roots (Ipomea batatas Lam.)

AbstractWe examined the effect of γ‐ray irradiation on food quality and sprouting inhibition of sweet potato roots. The weight loss of sweet potato roots with γ‐ray irradiation was slightly higher than that of control, but hardness, sugar content, and β‐carotene and vitamin contents were not significantly different from those of control (P > 0.05). Also, the amount of hydroxyl radical (●OH) reached is similar to that of the control from 2 weeks after storage. All sweet potato roots with γ‐ray irradiation did not sprout at all storage temperature, but the control sprouted at storage temperatures of 12 and 25C from 6 and 4 weeks after storage; the sprouting rate reached 10.8 ± 2.3 and 70.4 ± 3.4% 8 weeks after storage. Furthermore, peroxidase and indole acetic acid oxidase activity of all sweet potato roots with γ‐ray irradiation were higher than those of the control.Practical ApplicationsRecently, the consumption of sweet potatoes as a functional food has greatly increased. Because the sprouting and the deterioration of sweet potato roots in import and export occur and present a problem for the plant quarantine system, we suggest that the γ‐ray irradiation technique is an efficient method for inhibiting the sprouting of sweet potato roots without negative effect.