Auxin Type Research Articles

A Medicago truncatula HD-ZIP gene MtHB2 is involved in modulation of root development by regulating auxin response.

HD-Zip proteins are plant-specific transcription factors known for their diverse functions in regulating plant growth, development, and responses to environmental stresses. Among the Medicago truncatula HD-Zip II genes, MtHB2 has been previously linked to abiotic stress responses. In this study, we conducted a functional characterization of MtHB2 in the regulation of root growth and development. Upon auxin stimulation, expression of MtHB2 was promptly up-regulated. Overexpression of MtHB2 in Arabidopsis thaliana led to reduced primary root growth and inhibited lateral root formation. Interestingly, the transgenic plants expressing MtHB2 exhibited differential responses to three types of auxins (IAA, NAA, and 2,4-D) in terms of root growth and development compared to the wild-type plants. Specifically, primary root growth was less affected, and lateral root formation was enhanced in the transgenic plants when exposed to auxins. This differential response suggests a potential role for MtHB2 in modulating auxin transport and accumulation, as evidenced by the reduced sensitivity of the transgenic plants to the auxin transport inhibitor NPA and lower expression levels of auxin-related reporters such as PIN-FORMED (PIN1)::PIN1-GFP, PIN3::PIN3-GFP, PIN7::PIN7-GFP, and DR5::GFP compared to wild-type plants. Additionally, microarray analysis of the root tissues revealed down-regulation of several auxin-responsive genes in transgenic seedlings compared to wild-type plants. These findings collectively indicate that MtHB2 plays a critical regulatory role in root growth and development by modulating auxin accumulation and response in the roots.

Endogenous phytohormone analysis during sequential stages of somatic embryogenesis in Musa AAA cv. Grand Naine (subgroup Cavendish)

Abstract This is the first initiative study to provide quantified levels of four endogenous phytohormones during the induction, regeneration, maturation and germination stages of somatic embryogenesis (SE) in banana, using immature male bud explants, in the popular commercial triploid cultivar Grand Naine (AAA). Phytohormones are known to play a major role in the regulation of SE and most protocols have been developed for various cultivars of banana following empirical approaches. Although, several reports are available with regard to the impact of growth regulators exogenously supplemented to the media, the vital role of endogenous growth hormones in various developmental stages of SE remain unclear in banana. Reverse Phase High Performance Liquid Chromatography (RP-HPLC) was used to analyze endogenous status of indole acetic acid (IAA), zeatin, gibberellic acid (GA) and abscisic acid (ABA). Results from this study revealed that endogenous IAA and GA along with exogenous auxin play a major role in the induction of embryogenic competence of male bud explants. The levels of endogenous IAA and zeatin were found to be higher in embryogenic calli than non-embryogenic calli, although three different types of exogenous auxins were supplemented in callogenesis medium, but not cytokinin. Higher level of ABA and GA was observed in early and late developmental stages of somatic embryo, respectively. GA also played a predominant role in germination of somatic embryos. These findings will be applied for improvement of SE protocol in recalcitrant banana cultivars by suitably altering or supplementing exogenous growth hormones.

Advances in Plant Auxin Biology: Synthesis, Metabolism, Signaling, Interaction with Other Hormones, and Roles under Abiotic Stress.

Auxin is a key hormone that regulates plant growth and development, including plant shape and sensitivity to environmental changes. Auxin is biosynthesized and metabolized via many parallel pathways, and it is sensed and transduced by both normal and atypical pathways. The production, catabolism, and signal transduction pathways of auxin primarily govern its role in plant growth and development, and in the response to stress. Recent research has discovered that auxin not only responds to intrinsic developmental signals, but also mediates various environmental signals (e.g., drought, heavy metals, and temperature stresses) and interacts with hormones such as cytokinin, abscisic acid, gibberellin, and ethylene, all of which are involved in the regulation of plant growth and development, as well as the maintenance of homeostatic equilibrium in plant cells. In this review, we discuss the latest research on auxin types, biosynthesis and metabolism, polar transport, signaling pathways, and interactions with other hormones. We also summarize the important role of auxin in plants under abiotic stresses. These discussions provide new perspectives to understand the molecular mechanisms of auxin's functions in plant development.

Plant Hormone Pathway Is Involved in Regulating the Embryo Development Mechanism of the Hydrangea macrophylla Hybrid.

The research is aimed to elucidate the role of plant hormones in regulating the development of hybrid embryos in Hydrangea macrophylla. Fruits from the intraspecific cross of H. macrophylla 'Otaksa' × 'Coerulea' were selected at the globular, heart, and torpedo stages of embryo development. Transcriptome sequencing and differential gene expression analysis were conducted. The results showed that fruit growth followed a single "S-shaped growth curve, with globular, heart, and torpedo embryos appearing at 30, 40, and 50 d post-pollination, respectively, and the embryo maintaining the torpedo shape from 60 to 90 d. A total of 12,933 genes was quantified across the three developmental stages, with 3359, 3803, and 3106 DEGs in the S1_vs_S2, S1_vs_S3, and S2_vs_S3 comparisons, respectively. Among these, 133 genes related to plant hormone biosynthesis and metabolism were differentially expressed, regulating the synthesis and metabolism of eight types of plant hormones, including cytokinin, auxin, gibberellin, abscisic acid, and jasmonic acid. The pathways with the most differentially expressed genes were cytokinin, auxin, and gibberellin, suggesting these hormones may play crucial roles in embryo development. In the cytokinin pathway, CKX (Hma1.2p1_0579F.1_g182670.gene, Hma1.2p1_1194F.1_g265700.gene, and NewGene_12164) genes were highly expressed during the globular embryo stage, promoting rapid cell division in the embryo. In the auxin pathway, YUC (Hma1.2p1_0271F.1_g109005.gene and Hma1.2p1_0271F.1_g109020.gene) genes were progressively up-regulated during embryo growth; the early response factor AUX/IAA (Hma1.2p1_0760F.1_g214260.gene) was down-regulated, while the later transcriptional activator ARF (NewGene_21460, NewGene_21461, and Hma1.2p1_0209F.1_g089090.gene) was up-regulated, sustaining auxin synthesis and possibly preventing the embryo from transitioning to maturity. In the gibberellin pathway, GA3ox (Hma1.2p1_0129F.1_g060100.gene) expression peaked during the heart embryo stage and then declined, while the negative regulator GA2ox (Hma1.2p1_0020F.1_g013915.gene) showed the opposite trend; and the gibberellin signaling repressor DELLA (Hma1.2p1_1054F.1_g252590.gene) increased over time, potentially inhibiting embryo development and maintaining the torpedo shape until fruit maturity. These findings preliminarily uncover the factors affecting the development of hybrid H. macrophylla embryos, laying a foundation for further research into the regulatory mechanisms of H. macrophylla hybrid embryo development.

The use of auxin to regenerate embryogenic callus of Indonesian local garlic varieties

Abstract Garlic is a national priority commodity with regards to reducing imports. One of the obstacles in its national production is the limitation of seed quality. This study aimed to investigate how auxin impacts the regeneration of embryogenic callus in three local garlic varieties. The experiment employed a two-factor Complete Randomized Design, involving varieties (Lumbu Putih, Geol, and Sangga Sembalun) and auxin types: A (IAA 1 ppm), B (IAA 3 ppm), C (IAA 5 ppm), D (IBA 1 ppm), E (IBA 3 ppm), and F (IBA 5 ppm). Each treatment was repeated three times so that the total treatment was 54 experimental units. Embryogenic calli, weighing about 0.2 g, were cultivated on the treatment medium. The observed variables were the diameter and texture of the callus, as well as the number of green spots on the callus. The results showed no significant interaction between variety and auxin treatment, but variety had a significant effect on callus diameter. The largest callus diameter was shown by the Sangga Sembalun variety under treatment C (2.75 mm) with a friable texture, yellowish color, and rooted structure, while the smallest callus diameter was produced by the Geol variety in treatment E (1.20 mm) with a non-friable texture and white color. The highest number of green spots was also produced from Sangga Sembalun in treatment D (7 green spots). It was concluded that auxin plays a role in the regeneration of somatic embryos in garlic, but its effectiveness depends on the genotype.

Pengaruh Jenis Dan Konsentrasi Auksin Terhadap Pertumbuhan Dan Perkembangan Tanaman Anggrek Dendrobium mirbelianum Secara In Vitro

This study aims to determine the effect of auxin type and concentration on the growth and development of orchid plants. The research was conducted at the Tissue Culture Biotechnology Laboratory, Faculty of Agriculture, Sam Ratulangi University Manado, and was carried out over 2 months from July to August 2023. This study used a factorial experiment in a Completely Randomized Design (CRD) with 5 replications consisting of two factors. The first factor is the type of auxin: IAA (A1), NAA (A2), and IBA (A3), and the second factor is the concentration of each auxin: 1 ml/l (K1), 2 ml/l (K2), and 3 ml/l (K3). The data were analyzed using analysis of variance, and if the results were significant, a 5% Least Significant Difference (LSD) test was conducted. The results showed that there was an interaction between the type and concentration of auxin on variables such as the number of roots, root length, root emergence time, number of leaves, number of shoots, and shoot height. Similarly, there was an effect of auxin concentration on each type of auxin, but there was a significant effect of individual auxin types (IAA, NAA, and IBA) on the root formation of Dendrobium mirbelianum orchids, affecting variables such as the number of roots, root length, root emergence time, number of leaves, number of shoots, and shoot height.

Plant Growth Regulators and Rooting Media: A Viable Approach for Growth and Performance of Citrus

Plant growth regulators accompanied with appropriate growth medium can boost up the growth and performance of plants to a greater extent. PGRs such as auxin, gibberellin and cytokine play an exaggerative role in growth and development of the citrus. Moreover, the study reflects a clear overview of the impact of PGRs and different growth media to encourage rooting percentage, number of leaves, survival percentage, sprouting time, and root length of citrus cuttings. Citrus is a versatile fruit crop having a huge number of varieties, cultivars, and species; comes in different colours and flavours. Although, there are different methods used in the multiplication of citrus plant which includes budding, grafting, cutting, air layering, etc. However, propagation by cutting technique is the most commercial and farmer’s friendly approach. Different elements such as concentration of PGRs, age of plants and environmental factors are responsible for the successful growth of the citrus cuttings. Naphthalene acetic acid (NAA) and indole-3-butyric acid (IBA) are the two types of auxin, which are most commonly utilized in citrus propagation. Rooting medium plays a crucial role in the supply the minerals and availability of water in citrus. An absolute rooting medium must have more enough nutrients and water holding capacity with better drainage as well as sufficient air spores for excellent gaseous exchange that fruitfully influence the rooting ability and also have a profound effect on growth and development in citrus cutting. The best time for cutting of citrus stems is in between the July and August.

Şebinkarahisar’da Yetiştirilen Karadut Odun Çeliklerinin Köklenmesi Üzerine Farklı Oksin Çeşitlerinin Etkisi

Bu çalışmada Şebinkarahisar’da yetiştirilen karadut (Morus nigra L.) odun çeliklerinin köklenmesi üzerine üç farklı oksin çeşidinin etkileri araştırılmıştır. Her bir çeliğe ayrı ayrı 0, 1000, 2000, 3000, 4000 ve 5000 mg L-1 indol-3-bütirik asit (IBA), indol-3-asetik asit (IAA) ve α-naftalen asetik asit (NAA) uygulamaları yapılmıştır. Genel olarak IBA uygulamaları diğer oksin uygulamalarına göre daha yüksek köklenme yüzdelerine ulaşmıştır. En yüksek köklenme %40,30 ile 4000 mg L-1 IBA uygulamasında tespit edilmiştir. Çelik başına kök sayısı açısından en yüksek performansı 3,5 adet ile 3000 ve 5000 mg L-1 IAA uygulamaları ile 2000 ve 4000 mg L-1 NAA uygulamaları göstermiştir. Ortalama kök uzunluğu bakımından çelik başına 29,9 cm ile 5000 mg L-1 IBA en yüksek değere ulaşmıştır. Çelik başına ortalama en yüksek ikincil kök sayısına 3000 ve 5000 mg L-1 IAA uygulamaları ulaşırken (13,0 adet), 3000 mg L-1 IBA uygulaması 6,98 mm ile en yüksek ortalama kök kalınlığına sahiptir. Elde edilen tüm bu veriler, IBA uygulamalarının Şebinkarahisar’da yetiştirilen karadut odun çeliklerinin köklenmesi üzerine genel olarak daha fazla olumlu etki yaptığını göstermiştir.

Successful Grafting of Two Indonesian Clones of Piper nigrum L. with P. colubrinum Link.: Effects of IBA and NAA on Rooting and Effects of BA on Grafting

<p>This study aimed to investigate the effects of auxin types and their concentrations on rooting of the rootstock cuttings and BA on grafting. First, IBA, NAA or IBA+NAA, each at 0, 1000, 2000, and 3000 ppm were used as treatments to study rooting of <em>P</em><em>iper colubrinum</em>. In the second experiment, BA (0 and 50 ppm) was applied to <em>P. nigrum</em> scion clones of Natar-1 and Petaling-2, before being grafted to the rootstocks. Results showed, that all types of auxins (IBA, NAA or IBA+NAA) induced rooting and shoot growth, and the increase of auxin concentrations led to the increase of rooting. However, their effectiveness was different. NAA and IBA+NAA were superior to IBA, and at 2000 ppm, IBA+NAA resulted in the best plant growth, as indicated by higher values of both rooting and shoot growth parameters. Compared to control, BA treatment on scions resulted in higher grafting success (80% vs. 93%) for Natar-1, and (73% vs.100%) for Petaling-2 clones. BA treatment on scions also induced more calluses in the graft union and better shoot growth. To our knowledge, this is the first report on the use of BA to increase success of grafting between <em>P. nigrum</em> and<em> P. </em><em>colubrinum</em>.</p>

Bee honey improved the performance of indole-3-butyric acid on promoting adventitious roots formation of Cupressus macrocarpa L. var. Goldcrest: Morpho-biochemical and histoanatomical investigation

The effective role of different auxins on adventitious roots (Ars) formation of stem cuttings relies on several factors including type of auxins, concentrations and the intermixing materials. In this study, bee honey (BH) was evaluated as a cofactor for maximizing the promoting effect of indole-3-butyric acid (IBA) for better survival of propagated hard-to-root ornamental plants. To improve Ars morphogenesis of Cupressus macrocarpa L. var. Goldcrest, a greenhouse experiment was conducted to evaluate the efficacy of exogenous application of IBA intermixed with BH in comparison with talcum powder (TP) on morphological, biochemical, histoanatomical, and ultrastructural responses. Results indicated that 500 mg kg-1 IBA intermixed with BH (T5) was the superior treatment for improving rooting percentage and root growth measurements. Exogenous application of T5 led to maximize activities of polyphenol oxidase and catalase enzymes as well as total phenols content; however, it caused a sharp decline in peroxidase enzyme activity as compared with untreated cuttings. Additionally, this treatment decreased amounts of gibberellin, benzyl adenine, kinetin and abscisic acid, while the endogenous content of indole-3-acetic acid increased. Histoanatomical observations of stem cuttings treated with T5 showed four prominent phases for adventitious root formation including: induction, initiation of meristemoids, root primordial formation and Ar elongation at 0–6th, 6-12th, 12-18th and 18-30th day after planting (dap). The Ar primordia evolved via two different developmental pathways: (i) indirect genesis (i.e., callus tissues) and (ii) direct genesis (e.g., cells in the inner bark, medullary rays and surrounding tissues). The time-course histoanatomical data of this study provide insights regarding the potential utilization of IBA intermixed with BH to improve Ar formation of several hard-to-root ornamentals.

Enhancing hairy root proliferation: Optimization of auxin, carbon sources, and dark-light regimes in safed musli (Chlorophytum borivilianum)

Safеd musli, also known as Chlorophytum borivilianum, is gaining recognition in thе hеrbal industry due to its rich phytochеmical contеnt, extracted from the rhizome. In an attempt to produce these phytochemicals via an alternative method, optimization of proliferation of safed musli hairy roots were conducted. The primary objective was to identify and optimize the conditions that promote the growth of hairy roots in Safеd musli such as the type and concentrations of auxin, carbon sourcеs, and dark-light regimes. Thе hairy roots wеrе cultured in mеdia with varying concеntrations of IBA and NAA (ranging from 0 to 0.8 mg/L), both individually and in combinations. Thе combination of 0.8 mg/L IBA and 0.6 mg/L NAA proved to be most еffеctivе resulting in 100 % branching within 12 days. This combination yiеldеd 25.2 branchеs with an avеragе root length of 16.23 cm, whereas in control no branching occurred. Following this, carbon sources (sucrose and fructose) under light and dark conditions were studied. Significant enhancement on proliferation of hairy roots was obtained in treatment with 3 % sucrose giving a fresh weight of 3.68 g, root length of 242.4 cm, root diameter of 0.82 mm, and higher surface area (49.7 cm2) under light (16 h, 35 μmol m−2 s−1). This study on optimization of auxin, carbon sources and light-dark regimes has demonstrated the potential for enhancing hairy root proliferation, offering a robust and efficient method to produce bioactive compounds which can be upscaled for industrial bioreactor production.

Clonal micropropagation of apple trees

The purpose of the review is to analyze the state of knowledge of the issue of apple tree reproduction in Russia and abroad. Of all the methods of tissue culture, clonal micropropagation is the most studied, which has a number of advantages in comparison with traditional vegetative multiplication: obtaining healthy material, rapid reproduction, obtaining genetically homogeneous material, the possibility of releasing material throughout the year. Micropropagation has played an important role in the production of healthy, disease-free plants and in the rapid multiplication of apple varieties and rootstocks. This review shows that over the past decades, foreign and domestic researchers, including scientists of our institute, have developed a large number of methods for cultivating of varieties and rootstocks of apple trees. Due to the heterozygosity of the genus Malus, protocols for specific gene types are often developed. The conducted research analysis showed that the successful reproduction of apple trees is influenced by external and internal factors (genotype, physiological state, components of nutrient media, conditions of adaptation of micro-plants). The review reflects various approaches to solving such problems as obtaining an aseptic culture at the initiation stage, reducing the negative effect of phenol oxidation products, increasing the proliferative activity of explants using various nutrient media, as well as natural and synthetic growth hormones - cytokinins, problems of stimulating root formation as a result of the use of various types of auxins and methods of exposure, the development of conditions for the adaptation of microplants of varieties and rootstocks of apple trees in vivo. The emergence of new varieties will require the development of new cultivation conditions.

Metabolome and transcriptome analyses identify the underground rhizome growth through the regulation of rhizome apices in Panax ginseng

Panax ginseng C. A. Mey. is a well-known oriental medicine as a stimulant and dietary supplement. The ginseng rhizome, as one of the principal medicinal organs, plays an important role in aboveground organ growth and root development, although no studies on ginseng rhizome growth have been recorded. In this study, we identified that shoot apical meristem (SAM) was included in the rhizome bud, which could regulate the underground rhizome growth of ginseng. In microscopic examination, ginseng SAM included the central zone, peripheral zone, rib zone, and organizing center; secondary root structures were observed in ginseng main roots and lateral roots; primary root structures were observed in ginseng fibrous roots; rhizome had a stem structure with pith and discontinuous cambium. The metabolites in different underground ginseng organs were identified using ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS), with oleanane (OA)-type ginsenosides accumulating primarily in the rhizome buds. In addition, ginseng rhizome buds contained a low level of 3-indoleacetonitrile (IAN, one type of auxin), a high amount of abscisic acid (ABA), and a high level of jasmonoyl-isoleucine (JA-Ile, active form of jasmonic acid). ABA and JA-Ile could drastically limit the shooting rate of ginseng embryonic calli, however IAN boosted the rooting rate. Furthermore, the expression of genes involved in ginsenoside biosynthesis, phytohormone production, and shoot stem cell regulatory pathways were studied. This is the first study of SAM in medicinal herbs, and we believe that the results may offer new information about the development of ginseng underground rhizomes.

Efecto de diferentes tipos de sustratos y auxinas en el establecimiento ex vitro de segmentos nodales de arándano Var. Biloxi

Micropropagation of Vaccinium spp. using Murashige Skoog (MS) and benzylaminopurine (BAP) has been successfully developed. This work aimed to determine the effect of different types of substrates and auxins (naftalen acetic acid NAA, indol acetic acid IAA y, indol butyric acid IBA) on ex vitro establishment and rooting of nodal segments of V. corymbosum Var. Biloxi to create a donor bank of blueberry plants. The influence of five different substrates and three types of auxins using five concentrations was assessed for a better nodal segment ex vitro establishment. The 40 % coconut fiber substrate, 20 % pomine + 40 % peat improved ex vitro establishment of V. corymbosum Var. Biloxi nodal segments. Otherwise, using 100 ppm of NAA the ex vitro establishment of V. corymbosum Var. Biloxi nodal segments increased. These results will facilitate the conformation of a donor bank of youth plants of V. corymbosum, increasing possibilities of in vitro establishment for massive micropropagation. Keywords: acclimatization, eriaceae, hormones, Vaccinum.

In Vitro Regeneration Protocol for Securidaca longepedunculata Fresen., a Threatened Medicinal Plant within the Region of Lubumbashi (Democratic Republic of the Congo)

Securidaca longepedunculata Fresen. is an overexploited forest species in the Lubumbashi region (south-eastern DR Congo), as its roots are highly valued in traditional medicine. Conventional propagation of this species is affected by seed dormancy and a high mortality rate during early seedling development. To improve on existing methods, we developed an in vitro seed germination protocol. After observing the germination rates, the effects of different doses (0.5, 1, 1.5, and 2 mg/L) of cytokinins (6-benzylaminopurine, kinetin, and meta-topolin) on S. longepedunculata seedling development were compared. Our results showed that soaking for 10 min in NaOCl (10%) followed by 5 min in ethanol (70%) effectively reduced the death rate of seeds while increasing the germination rate to almost 77%. The addition of cytokinins improved plantlet growth: a 12.2× increase in the number of plantlets was obtained with 1.5 mg/L meta-topolin, while only a single stem was obtained from the control. The effects of different auxin types on rhizogenesis did not differ significantly. The best recovery and rooting were noted with microcuttings from the basal parts of S. longepedunculata plantlets. Finally, the seedlings produced survived during the acclimatisation phase regardless of the type of substrate used. The established protocol provides a means for large-scale production of S. longepedunculata plantlets for the restoration of degraded landscapes and agroforestry.

The Effect Of ZPT Types and Concentration on The Growth Of Kebiul Plant Cuttings (Caesalpinia bonduc L.)

The purpose of this study is to find out the effect of ZPT types and concentrations on the growth of cuttings of Kebiul plants (Caesalpinia bonduc L). The design used is a factorial complete randomized design (CRD) with 2 factors, namely the first factor is the type of Growth Regulatory Substance Giberelin, Auxin and Cytokinins, while the second is concentration control, 15 mg/l, 30 mg/l, and 45mg/l. Based on the tested levels of the two factors, 12 treatment combinations were obtained. Each treatment combination was repeated 3 times and 36 experimental units. The results of this study indicate that the interaction has no significant effect between the types of synthetic ZPT treatments and concentrations on all parameters and observations. The results of the study were analyzed using Analysis of Variety and if they had a significant effect, further tests were carried out using Duncan's Multiple Range Test (DMRT) at 5% level. Treatment of synthetic ZPT types significantly affected the length of shoots 9.12 WAP and the number of shoots 9 WAP, very significantly affected the number of shoots 3.12 MST, the number of leaves 9.12 WAP, root length and number of roots. Treatment Concentration had a significant effect on the number of shoots 9 MST, and the percentage of living cuttings, however it had a very significant effect on shoot length 3, 6, 9 MST, number of shoots 6, 12 MST, number of leaves 3, 6, 9 12 MST, root length and number of roots on Kebiul plant cuttings.

Growth Responses of Clove Seedlings (Sizigium aromaticum L) to Natural Auxin and Household Waste Media

Indonesia is the number 1 clove producing country in the world, in amount of 140,812 tons (The Ministry of Indonesian Agriculture, 2022). Cloves are commonly used as a flavor enhancer for food and drinks. Its warm and spicy sensation is quite popular among people, especially those who live in cold areas. In addition, cloves are also useful for aromatic mixture of cigarettes. In addition, cloves are also good for the health of the body because they are known contain phosphorus, iron, magnesium, calcium, potassium, zinc, sodium and vitamins. This study aims were to determine the optimum concentration of organic auxin and the effect of using household waste media on the growth of clove plant seedlings. This study used a factorial experimental method which was arranged in a Completely Randomized Design (CRD) consisting of two factors. The first factor was the dose of household waste consisting of L0 = no household waste (control/ only with 2.5 g NPK fertilizer); L1 = household waste 10%; L2 = household waste 20% and L3 = household waste 30%. The second factor was the type of organic auxins, which consist of A0 = without organic auxin; A1 = red onion organic auxin; A2 = tomato organic auxin; A3 = auxin organic mung bean sprouts. Each treatment was repeated 4 times, resulting in 64 experimental units. The results showed that there was no interaction between the dose of household waste and natural auxins on the growth of clove seedling. Household waste can replace NPK fertilizer starting from a dose of 10 g/plant. Kinds of natural auxin did not affect the growth of clove seedlings. The seedling cultivation is enough profitable.

Application of Auxins in Haploid Embryo Induction in Hexaploidy Wheat

Doubled haploid (DH) plant production plays a crucial role in modern plant breeding programs, offering an efficient means to generate homozygous lines from heterozygous parents within a single generation. Different types of auxins have been utilized in wheat cross with maize DH production, with 2,4-D being the most widely used and effective hormone, followed by dicamba. Other auxins, including picloram, Indole-3-acetic acid (IAA), phenylacetic acid (PAA), silver nitrate, 1-naphthaleneacetic acid (NAA), kinetin, 6-benzyladenine (BA), and zearalenone, have also been tested for their potential role in haploid embryo induction. Various methods have been explored for the application of 2,4-D, such as spray, tiller injection, dipping, and spikelet culture methods. 2,4-D found to be most effective auxin treatment both alone and with combination with other phytohormones.

Transcriptome analysis reveals that auxin promotes strigolactone-induced adventitious root growth in the hypocotyl of melon seedlings.

Strigolactone (SL) and auxin are two important phytohormones involved in plant root development, but whether they show synergistic or mutual promotion effects during adventitious root (AR) formation has not been adequately explored. In this study, we investigated the mechanisms of GR24 (synthetic SL) and indole-3-acetic acid (IAA; a type of auxin) in the formation of ARs using melon as the study material. Morphological measurements showed that the AR number, length, superficial area, and volume under the GR24 treatment were 1.60-3.27, 1.58-3.99, 2.06-3.42, and 3.00-6.11 times greater than those of the control group, respectively, at 6-10 days; the GR24+IAA treatment further promoted AR formation in melon seedlings, and the AR number, length, superficial area, and volume under the GR24+IAA treatment were 1.44-1.51, 1.28-1.73, 1.19-1.83, and 1.31-1.87 times greater than those obtained with the GR24 treatment, respectively. Transcriptome analysis revealed 2,742, 3,352, and 2,321 differentially expressed genes (DEGs) identified from the GR24 vs. control, GR24+IAA vs. control, and GR24+IAA vs. GR24 comparisons, respectively. The GR24 treatment and GR24+IAA treatment affected auxin and SL synthesis as well as components of the phytohormone signal transduction pathway, such as auxin, brassinosteroid (BR), ethylene (ETH), cytokinin (CK), gibberellin (GA), and abscisic acid (ABA). The concentrations of auxin, GA, zeatin (ZT), and ABA were evaluated using high-performance liquid chromatography (HPLC). From 6 to 10 days, the auxin, GA, and ZT contents in the GR24 treatment group were increased by 11.48%-15.34%, 11.83%-19.50%, and 22.52%-66.17%, respectively, compared to the control group, and these features were increased by 22.00%-31.20%, 21.29%-25.75%, 51.76%-98.96%, respectively, in the GR24+IAA treatment group compared with the control group. Compared to that in the control, the ABA content decreased by 10.30%-11.83% in the GR24 treatment group and decreased by 18.78%-24.00% in the GR24+IAA treatment group at 6-10 days. Our study revealed an interaction between strigolactone and auxin in the induction of AR formation in melon seedlings by affecting the expression of genes related to plant hormone pathways and contents.

In vitro direct organogenesis of the medicinal single-mountain local prioritized vulnerable Greek endemic Achillea occulta under different medium variants

Achillea species are of high medicinal value based on their use in traditional medicine and their content in secondary metabolites with potential application in dermatology and cosmetic industry. Achillea occulta is a single-mountain local prioritized vulnerable Greek endemic encountering propagation problems through seeds and root division. In vitro propagation can be used for the rapid and mass production of clonal plants complying with phytochemical and sanitary quality criteria. In this study, several culture medium variants were tested including the effect of different indole-3-butyric acid (IBA) concentrations with 6-benzyladenine (BA), different cytokinin types, agar concentrations, and zeatin (ZT) sterilization methods on in vitro shoot proliferation, as well as the effect of different auxin types and concentrations on in vitro rooting and ex vitro survival rate of shoot-tip explants. The results showed BA was the most preferable cytokinin type as evidenced by all proliferation attributes and autoclaved ZT provided longer shoots. Therefore, the two more promising and cost-effective treatments for proliferation were 2.2 μM BA + 0.25 μM IBA or 4.4 μM BA + 0.5 μM IBA after 21 days of culture on modified Murashige-Skoog (MS) medium (x2 Fe) enriched with 20 g L-1 sucrose and 6-7 g L-1 Agar (90-93.8% shoot formation, 2.7-2.9 shoots 0.4-0.6 cm long, 2.5-2.6 proliferation rates). Explants rooted better after 21 days of culture on plain MS medium with 2 μM IBA or 1 μM α-naphthalene acetic acid (NAA) (13.3-20% rooting, 1-1.5 roots 1.8-2 cm long). NAA gave more roots, IBA longer roots, while both auxins exhibited highest rooting (13.33-20%) and ex vitro survival rates (50-66.7%).