IAA Content Research Articles

Auxin Transporter OsPIN1b, a Novel Regulator of Leaf Inclination in Rice (Oryza sativa L.)

Leaf inclination is one of the most important components of the ideal architecture, which effects yield gain. Leaf inclination was shown that is mainly regulated by brassinosteroid (BR) and auxin signaling. Here, we reveal a novel regulator of leaf inclination, auxin transporter OsPIN1b. Two CRISPR-Cas9 homozygous mutants, ospin1b-1 and ospin1b-2, with smaller leaf inclination compared to the wild-type, Nipponbare (WT/NIP), while overexpression lines, OE-OsPIN1b-1 and OE-OsPIN1b-2 have opposite phenotype. Further cell biological observation showed that in the adaxial region, OE-OsPIN1b-1 has significant bulge compared to WT/NIP and ospin1b-1, indicating that the increase in the adaxial cell division results in the enlarging of the leaf inclination in OE-OsPIN1b-1. The OsPIN1b was localized on the plasma membrane, and the free IAA contents in the lamina joint of ospin1b mutants were significantly increased while they were decreased in OE-OsPIN1b lines, suggesting that OsPIN1b might action an auxin transporter such as AtPIN1 to alter IAA content and leaf inclination. Furthermore, the OsPIN1b expression was induced by exogenous epibrassinolide (24-eBL) and IAA, and ospin1b mutants are insensitive to BR or IAA treatment, indicating that the effecting leaf inclination is regulated by OsPIN1b. This study contributes a new gene resource for molecular design breeding of rice architecture.

Genome-Wide Identification, Expression Analysis, and Potential Roles under Abiotic Stress of the YUCCA Gene Family in Mungbean (Vigna radiata L.).

YUCCA, belonging to the class B flavin-dependent monooxygenases, catalyzes the rate-limiting step for endogenous auxin synthesis and is implicated in plant-growth regulation and stress response. Systematic analysis of the YUCCA gene family and its stress response benefits the dissection of regulation mechanisms and breeding applications. In this study, 12 YUCCA genes were identified from the mungbean (Vigna radiata L.) genome and were named based on their similarity to AtYUCCAs. Phylogenetic analysis revealed that the 12 VrYUCCAs could be divided into 4 subfamilies. The evidence from enzymatic assays in vitro and transgenetic Arabidopsis in vivo indicated that all the isolated VrYUCCAs had biological activity in response to IAA synthesis. Expression pattern analysis showed that functional redundancy and divergence existed in the VrYUCCA gene family. Four VrYUCCAs were expressed in most tissues, and five VrYUCCAs were specifically highly expressed in the floral organs. The response toward five stresses, namely, auxin (indole-3-acetic acid, IAA), salinity, drought, high temperatures, and cold, was also investigated here. Five VrYUCCAs responded to IAA in the root, while only VrYUCCA8a was induced in the leaf. VrYUCCA2a, VrYUCCA6a, VrYUCCA8a, VrYUCCA8b, and VrYUCCA10 seemed to dominate under abiotic stresses, due to their sensitivity to the other four treatments. However, the response modes of the VrYUCCAs varied, indicating that they may regulate different stresses in distinct ways to finely adjust IAA content. The comprehensive analysis of the VrYUCCAs in this study lays a solid foundation for further investigation of VrYUCCA genes' mechanisms and applications in breeding.

Potential and Constraints on In Vitro Micropropagation of Juniperus drupacea Labill.

Juniperus drupacea Labill. (Cupressaceae) is a species with ecological and medicinal value. In Europe, it is native only in southern Greece, and is listed as endangered. Due to its uniqueness, this study attempted, for the first time, an in vitro propagation effort of Syrian juniper. Explants of the lateral shoot tips were surface-sterilized and cultured on Murashige and Skoog (MS) medium. The cultures were subcultured on MS, woody plant medium (WPM), and Driver and Kuniyaki Walnut (DKW) supplemented with different concentrations of 6-benzylaminopurine (BA), thidiazuron (TDZ), or meta-topolin [6-(3-hy-droxybenzylamino)purine] for shoot induction. Explants derived from female trees exhibited 54.17% bud proliferation on DKW medium with 4 μM meta-topolin or 4 μM TDZ and on WPM with 4 μM meta-topolin or 4 μM BA. A total of 62.50% of the male tree derived explants produced multiple shoots on DKW with 4 μM BA. The maximum average number of shoots per explant were 1.17 per explant in both cases. The length of the shoot derived from explants of female origin was 2.94 mm compared to 2.69 mm of the in vitro shoots from the explants of male trees. Overall, the best medium and plant growth regulator combination for the explants derived from both female and male trees, for the traits under study, was proven to be DKW + 4 µM TDZ. Our experiments show that Juniperus drupacea, under in vitro conditions, shows recalcitrance in rooting, as the applications of IBA, NAA, and IAA concentrations were proven to be ineffective treatments. Although the results show low values, this avant-garde study provides a foundation for further research on the in vitro regeneration of Juniperus drupacea.

Root ABA Accumulation Delays Lateral Root Emergence in Osmotically Stressed Barley Plants by Decreasing Root Primordial IAA Accumulation

Increased auxin levels in root primordia are important in controlling root branching, while their interaction with abscisic acid (ABA) likely regulates lateral root development in water-deficient plants. The role of ABA accumulation in regulating root branching was investigated using immunolocalization to detect auxin (indoleacetic acid, IAA) and ABA (abscisic acid) in root primordia of the ABA-deficient barley mutant Az34 and its parental genotype (cv. Steptoe) barley plants. Osmotic stress strongly inhibited lateral root branching in Steptoe plants, but hardly affected Az34. Root primordial cells of Steptoe plants had increased immunostaining for ABA but diminished staining for IAA. ABA did not accumulate in root primordia of the Az34, and IAA levels and distribution were unaltered. Treating Az34 plants with exogenous ABA decreased root IAA concentration, while increasing root primordial ABA accumulation and decreasing root primordial IAA concentration. Although ABA treatment of Az34 plants increased the root primordial number, it decreased the number of visible emerged lateral roots. These effects were qualitatively similar to that of osmotic stress on the number of lateral root primordia and emerged lateral roots in Steptoe. Thus ABA accumulation (and its crosstalk with auxin) in root primordia seems important in regulating lateral root branching in response to water stress.

A male-sterile mutant with necrosis-like dark spots on anthers was generated in cotton.

Although conventional hybrid breeding has paved the way for improving cotton production and other properties, it is undoubtedly time and labor consuming, while the cultivation of male sterile line can fix the problem. Here, we induced male sterile mutants by simultaneously editing three cotton EXCESS MICROSPOROCYTES1 (GhEMS1) genes by CRISPR/Cas9. Notably, the GhEMS1 genes are homologous to AtEMS1 genes, which inhibit the production of middle layer and tapetum cells as well, leading to male sterility in cotton. Interestingly, there are necrosis-like dark spots on the surface of the anthers of GhEMS1s mutants, which is different from AtEMS1 mutant whose anther surface is clean and smooth, suggesting that the function of EMS1 gene has not been uncovered yet. Moreover, we have detected mutations in GhEMS1 genes from T0 to T3 mutant plants, which had necrosis-like dark spots as well, indicating that the mutation of the three GhEMS1 genes could be stably inherited. Dynamic transcriptomes showed plant hormone pathway and anther development genetic network were differential expression in mutant and wild-type anthers. And the lower level of IAA content in the mutant anthers than that in the wild type at four anther developmental stages may be the reason for the male sterility. This study not only facilitates the exploration of the basic research of cotton male sterile lines, but also provides germplasms for accelerating the hybrid breeding in cotton.

ПУТИ МОРФОГЕНЕЗА В КУЛЬТУРЕ IN VITRO ИЗОЛИРОВАННЫХ ПЫЛЬНИКОВ ПШЕНИЦЫ: РОЛЬ БАЛАНСА ФИТОГОРМОНОВ

The study is aimed to the study of the peculiarities of the induction of morphogenesis pathways in vitro of morphogenetically competent anther cells - microspores in the isolated anther culture of a number of spring soft wheat genotypes, recommended for cultivation in the climatic conditions of the Republic of Bashkortostan. The content of IAA in seedlings of the studied genotypes of spring sof wheat was analyzed to determine the class of the genotype – characterized by high or low auxin content. Such morphogenesis pathways in vitro as embryoidogenesis, polyembryoidogenesis and callusogenesis have been identified and studied. Morpho-histological assessment of androclinic structures is given. It was established that the induction of a certain morphogenesis pathway in vitro is determined mainly by the balance between the content of endogenous auxin IAA in anthers before inoculation on a nutrient medium and the concentration of exogenous synthetic auxin 2,4-D in the composition of the nutrient medium. The fundamental possibility of regulation of morphogenesis pathways in vitro in isolated anther culture of wheat by selecting for each genotype an adequate balance of endogenous and exogenous auxins for the induction of a specific pathway has been shown.

Effects on gene expression during maize-Azospirillum interaction in the presence of a plant-specific inhibitor of indole-3-acetic acid production.

Amongst the sustainable alternatives to increase maize production is the use of plant growth-promoting bacteria (PGPB). Azospirillum brasilense is one of the most well-known PGPB being able to fix nitrogen and produce phytohormones, especially indole-3-acetic acid - IAA. This work investigated if there is any contribution of the bacterium to the plant's IAA levels, and how it affects the plant. To inhibit plant IAA production, yucasin, an inhibitor of the TAM/YUC pathway, was applied. Plantlets' IAA concentration was evaluated through HPLC and dual RNA-Seq was used to analyze gene expression. Statistical differences between the group treated with yucasin and the other groups showed that A. brasilense inoculation was able to prevent the phenotype caused by yucasin concerning the number of lateral roots. Genes involved in the auxin and ABA response pathways, auxin efflux transport, and the cell cycle were regulated by the presence of the bacterium, yucasin, or both. Genes involved in the response to biotic/abiotic stress, plant disease resistance, and a D-type cellulose synthase changed their expression pattern among two sets of comparisons in which A. brasilense acted as treatment. The results suggest that A. brasilense interferes with the expression of many maize genes through an IAA-independent pathway.

Integrated transcriptome and metabolome analysis unveiled the mechanisms of xenia effect and the role of different pollens on aroma formation in ‘Yali’ pear (Pyrus bretschneideri Rehd)

• ‘Hongnanguo’ pollinizer has a xenia effect on ‘Yali’ pear fruits aroma quality. • 189 DAMs and 12,032 DEGs were identified. • ‘Hongnanguo’ pollinizer increased the content of ABA, IAA, and ethylene. • Established a possible regulatory network of the mechanism of xenia effect on pear aroma formation. The flavor of ‘Yali’ pear fruits has substantially declined recently as a result of poor pollination tree selection. Xenia effect is a powerful mechanism for regulating aroma production. To study the effect of different pollens on aroma quality and the molecular basis of xenia effect in ‘Yali’ pear fruits, ‘Hongnanguo’ and ‘Xuehuali’ were used as pollinizers, and the hybrid fruits were named YH and YX, respectively. Metabolome, transcriptome, volatile compounds, and hormone were jointly analyzed in YH and YX peels with three ripening stages. After pollinating with ‘Hongnanguo’ pollen, the contents of total aroma, esters and nerolidol, the odor activity value of characteristic volatiles in YH were significantly increased, compared with the aroma character of the pollinizer cultivars, indicating ‘Hongnanguo’ pollinizer has a xenia effect on ‘Yali’ pear fruits aroma quality. Further, the content of ABA, IAA, and ethylene reveal the differences during aroma formation between YH and YX. 189 differentially accumulated metabolites (DAMs) and 12,032 differentially expressed genes (DEGs) were identified. Based on co-expression network analysis, network maps of ‘Yali’ pear aroma-related DEGs were generated. We surmise aroma biosynthesis genes ( ADH, ALDH, NES , and FPS ), ABA, IAA, ethylene signal transduction, and several transcription factors play important roles in the xenia effect.

Appropriate Condition for Cluster Buds Induction of <i>Cremastra appendiculata</i>

To screen for suitable conditions for cluster bud induction of Cremastra appendiculata . The aseptic germination protocorms of C. appendiculata  seeds were used as explant materials to explore the effects of different basic media, types of plant growth regulators, anti-browning agents and their concentrations on the induction of cluster buds of C. appendiculata . The results showed that: 1/4MS medium was the suitable basic medium for cluster buds growing; when the concentration of plant growth regulator TDZ was 2.0 mg/L and the concentration of IAA was 0.2 mg/L, the induction rates of cluster bud were higher which are 72.58% and 55.63% respectively; when the anti-browning agent was PVP and its concentration is 2 000 mg/L, the induction rate of cluster buds was higher which is 79.90%. The suitable conditions for C. appendiculata cluster buds induction are: 1/4MS + TDZ 2.0 mg/L+ IAA 0.1 mg/L+ PVP 2 000 mg/L, and the induction rate can reach 81.16%. This provided a basis for establishing a rapid propagation technology system of  C. appendiculata  and realizing its large-scale artificial cultivation.

荞麦、高粱根系分泌物对玉米根边缘细胞和根生长的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 荞麦、高粱根系分泌物对玉米根边缘细胞和根生长的影响 DOI: 10.5846/stxb202204090929 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 山西省重点研发计划项目(201803D221011-5) Effects of root exudates from buckwheat and sorghum on the root border cells and root growth of Maize Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:植物的根系分泌物是植物根系与周围环境之间的化学媒介,通过传递特定的信息,调节根际微环境,影响周围植物的生长。玉米(Zea mays L.)和荞麦(Fagopyrum esculentum Moench)是农作物间套作体系中典型的不能搭配的组合,其障碍因素尚不清楚。以玉米为受体植物,采用根悬空培养的方法,研究了荞麦、高粱(Sorghum bicolor (L.) Moench)根系分泌物对玉米根边缘细胞和根生长的影响。结果发现,玉米根边缘细胞离体培养条件下,用荞麦根系分泌物中的小分子物质处理4、8 h显著诱导边缘细胞凋亡、死亡,细胞活率分别比对照降低了71.6%和72.3%;荞麦根系分泌物中的小分子物质对玉米根产生氧化胁迫,诱导根SOD、POD和CAT活性分别比对照高22.6%、33.9%和107.2%,根中超氧阴离子(O-.2)和脯氨酸含量分别比对照高33.9%和49.8%;荞麦根系分泌物中小分子物质的胁迫使根细胞膜透性增大,与对照相比升高80.0%,丙二醛(MDA)含量比对照升高31.5%;荞麦根系分泌物中小分子物质诱导根内源激素(IAA)含量降低,根系活力下降,根生长受到抑制,与对照比IAA含量降低44.2%,根系活力降低14.4%,根长减少36.9%;高粱根系分泌物对玉米根边缘细胞和根生长无显著的化感胁迫影响。由此可得,荞麦根系分泌物中的小分子物质诱导玉米根边缘细胞凋亡死亡,使其失去边缘细胞的保护作用,进一步诱导根产生氧化胁迫,诱导根内吲哚乙酸(IAA)含量降低,根的生长和发育受到抑制,这可能是玉米荞麦不能间套作的原因所在。 Abstract:Plant root exudates act as the chemical mediators between root systems and the surrounding environment. Root exudates regulate the rhizosphere microenvironment and affect the growth of nearby plants by transmitting specific information. Zea mays L. (Maize) and Fagopyrum esculentum Moench (buckwheat) are the typically unsuitable combination in intercropping system of crops, however, the obstacle factors are still unclear. In this study, using maize as a recipient plant, the effects of root exudates from buckwheat or Sorghum bicolor (L.) Moench (sorghum) on the root border cells (RBCs) and root growth of maize were investigated by the method of root suspension culture. Results indicated that the viability of RBCs of maize treated with the small molecular substances in the root exudates of buckwheat for 4 and 8 hours decreased by 71.6% and 72.3%, respectively, compared with the control. The small molecular substances in buckwheat root exudates generated oxidative stress on the roots of maize, and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were 22.6%, 33.9% and 107.2% higher than those of the control, respectively. In addition, the content of the superoxide anion (O-.2) was 33.9% higher than that of the control, while the proline content in the root was 49.8% higher. Furthermore, the small molecular substances in root exudates of buckwheat increased the permeability of root cell membrane by 80.0% and the content of malondialdehyde (MDA) by 31.5% compared with those of the control. The small molecular substances in buckwheat root exudates decreased root endogenous hormone (IAA) content, root activity, and root growth. More specifically, the IAA content decreased by 44.2%, TTC reduction strength decreased by 14.4%, and root length decreased by 36.9%. Sorghum root exudates had no significant allelopathic stress effect on maize root border cells and root growth. Therefore, the small molecular substances in the root exudates of buckwheat can induce the apoptosis and death of maize root border cells, which can make them lose the protective effect of root border cells, further induce the root to produce oxidative stress, reduce the content of IAA in the root, and inhibit the growth and development of the root. We speculate that this is one of the reasons why maize and buckwheat cannot be intercropped. 参考文献 相似文献 引证文献

Production and Estimation of Plant Growth Regulators in Fungi Isolated from Western Ghats

Introduction: The Rhizosphere is the narrow region of the soil tightly adhered to the plant root system and is under the influence of metabolites released by the associated soil microorganisms. Metabolites act as chemical messengers and attract motile microorganisms, representing a nutrient source to support their growth. These microorganisms are often called plant growthpromoting microorganisms, including bacteria, fungi, actinomycetes, and cyanobacteria. Aim/Objectives: The plant growth regulators were produced from the fungi obtained from Western Ghats. The potent PGPF was selected for HPLC and pot study analysis among the isolates obtained. Also, 18s rRNA sequencing was performed to identify the genetic similarities. Methodology: Samples were collected from the rhizosphere of the Western Ghats region. They are used for isolation and partial identification of fungi. Later, organisms were subjected to IAA and GA determination up to 15 days. The estimated IAA and GA were subjected to HPLC analysis and compared with the standards. Further, the cultured filtrate of isolated organisms was tested for IAA and GA activity by performing pot analysis with Vigna radiata. The data obtained from pot studies was statistically analyzed. The potent isolated organism was further identified using molecular sequencing and bioinformatics tools. Results: The isolated organisms were partially identified as species from Aspergillus, Rhizomucor, Fusarium, Cladosporium, and Trichoderma. Among the isolated organisms, Rhizomucor had the maximum concentration of IAA (15 days incubation), and a species of Rhizomucor and Fusarium had maximum GA (15 days incubation). The presence of IAA and GA was confirmed by comparing the standard peaks obtained from HPLC analysis. Pot study analysis showed an initial increase in shoot and root length from the 5th day onwards. Based on the statistical analysis, auxin root length showed significance at 95% interval levels. Compared with databases, the sequenced data had a 99.82% identity with Mucor irregularis. Conclusion: Auxins and gibberellins produced by the isolated organisms enhanced the root and shoot length and thus can be chosen as bioinoculants.

Fotoperyot, Bitki büyüme Düzenleyicileri ve Eksplant Büyüklüğünün Kardelende İn Vitro Soğancık Oluşumuna Etkisi

Plant tissue culture techniques have a widespread usage in rapid, easy and continuous propagation of bulbous and tuberous plants, called geophytes. The genus Galanthus (commonly called snowdrops), perennial bulbiferous geophytes belonging the Amaryllidaceae family, contain several high-value alkaloids with pharmaceutical use to treat Alzheimer’s disease. The objective of this study was to assess the effect of photoperiod, plant growth regulators and explant size on in vitro bulblet formation in snowdrop (Galanthus woronowii). Bulb twin-scale explants were cultured on MS medium containing different combinations of BAP with various concentrations of NAA, IAA and IBA under 16/8 h light/dark and 24 h dark conditions. Effect of plant growth regulators was significant on the number of bulblet, bulblet diameter, bulblet weight, and the number of bulblet bigger than 5 mm in diameter. Continuous dark application resulted in highly significant increases in bulblet formation, as compared to light treatment. The maximum number of bulblet (4.83) was recorded from 4-piece explants treated with 2 mg l-1 BAP+0.1 mg l-1 NAA hormone combination kept in 24 h dark condition. Dark treatment resulted in an increase of 57.33% in the number of bulblet bigger than 5 mm in diameter. Explant size showed no effect on any of the attributes studied. In conclusion, this study revealed that 24 h dark treatment has a very important positive effect on in vitro bulblet formation in snowdrop.

EFFECT OF DIFFERENT HORMONAL CONCENTRATIONS ONIN-VITRO REGENERAT-ION OF RICE (Oryza sativaL.)

The present study was aimed to evaluate the effect of different hormonal concentrations on the in vitro growth and multiplication of rice seeds. The experiment was performed in the tissue culture laboratory, department of biotechnology, UAJ&K Muzaffarabad, Azad Kashmir. Seeds were collected from the local market. Seeds were surface sterilized with different concentrations of Chlorox i. e. (30, 50 and 50 %) and germination percentage was calculated. The maximum (70 %) germination was recorded for seeds treated with 50% chlorox. Whereas minimum germination (37.5%) was recorded for seeds treated with 70% chlorox. The seeds were cultured on MS medium supplemented with varying concentrations of IAA (0.1, 0.2, 0.3, 0.75 and 2mg/l) and KIN at (0.5, 1, 1.5 mg/l). Maximum stem length (30.5 cm), root number (20), root length (6.6 cm), leaf number (70) and leaf length (7 cm) was recorded for MS medium supplemented with higher concentration of IAA (2mg/l) and KIN (1.5 mg/l). Minimum stem length (6.5 cm), root length (2.5 cm), root number (1) root length (2.5 cm), leaf number (1) and leaf length 1.7cm) was recorded on MS medium supplemented with IAA (0.3 mg/l) and KIN (1.5 mg/l). Results indicates that maximum germination percentage was observed in seeds treated with 50% chlorox and medium which was supplemented with high amount of IAA and KIN (2.0 mg/l, 1.5mg/l) significantly increase regeneration percentage.

An efficient in vitro callogenesis from various explants of Passiflora vitifolia kunth: An important medicinal and ornamental plant

An efficient In vitro protocol was established for callogenesis from various plant parts (Leaf, stem, flower bud and tendril) of Passiflora vitifolia Kunth. On Murashige and Skoog (MS) basal medium supplemented with various concentration of auxins (NAA, IAA, 2,4-D) and cytokinins (BAP and Kn ). Different concentrations of auxins (0.5 to 4 mg/L), IAA (0.5 to 2mg/L), NAA (0.5 to 2 mg/l) and cytokinin BAP (0.5 to 2 mg/L), Kn (0.5 to 2 mg/L) were assessed for callus induction. Growth regulators when supplemented individually on MS medium produced hard white callus in stem and tendril explant, soft friable callus in leaf and flower bud explants. The callogenic response was more in leaf, stem and flower explant on MS media supplemented with NAA (1.5mg/L) and the callogenic response was more in tendril explants on MS media supplemented with 2,4-D (1mg/L).

Auxin homeostasis in maize (Zea mays) is regulated via 1-O-indole-3-acetyl-myo-inositol synthesis at early stages of seedling development and under abiotic stress

Main conclusionIndole-3-acetyl-myo-inositol biosynthesis is regulated during maize seedling development and in response to drought and cold stress. The main purpose of this pathway is maintenance of auxin homeostasis.Indole-3-acetic acid (IAA) conjugation to myo-inositol is a part of a mechanism controlling free auxin level in maize. In this work, we investigated changes in the indole-3-acetyl-myo-inositol (IAInos) biosynthesis pathway in 3-d- and 6-d-old maize seedlings and germinating seeds as well as in seedlings subjected to drought and cold stress to evaluate a role of this pathway in maize development and stress response. In germinating seeds, activity of the enzymes involved in IAInos biosynthesis remains unchanged between 3-d- and 6-d-old material but increases in coleoptiles and radicles of the seedlings. Under cold stress, in germinating seeds and in coleoptiles, activity of the enzymes decreases and increases, respectively; however, it does not entail changes in auxin level. In drought-exposed germinating maize seeds, totally diminished activities of IAInos synthesis pathway enzymes resulted in almost twofold increase of free IAA content. Similar increase of auxin level was observed in radicles of drought-subjected seedlings together with lack of catalytic activity of the first enzyme of the pathway. Exogenous IAInos has no effect on the level of non-enzymatic antioxidant, ascorbate. It has also either no effect on the protein carbonylation and lipid peroxidation, or it affects it in a similar way as exogenously applied IAA and myo-inositol, which are products of IAInos hydrolysis. Thus, IAInos biosynthesis pathway acts in maize development and stress responses by regulation of free IAA concentration, as IAInos itself does not appear to have a distinct role in these processes.

Transcriptomic dissection underlying physiological and anatomical characteristics of poplar wood in response to changes in light intensity and nitrogen availability

To dissect the transcriptomic reprograming underlying the physiological and anatomical characteristics in the wood of Populus species in response to changes in light and nitrogen (N) availability, the saplings of P. alba × P. glandulosa were exposed to either control or high light intensity in combination with one of low, normal and high N levels. High light caused greater CO2 assimilation rate, higher concentrations of soluble sugars and starch, decreased enzymatic activities of NR and GS and increased activities of GOGAT and GDH, higher IAA and lower ABA, JA and SA contents, narrower fibers, and thinner thickness of fiber wall in the wood of poplars under normal N condition. Low N supply led to greater levels of sucrose and starch, lower contents of most amino acids, IAA, ABA and JA, and narrower vessels and fibers, and high N caused the opposite effects in poplar wood exposed to control light. Transcriptomic reprograming occurred underlying the physiological and anatomical changes of P. alba × P. glandulose in acclimation to high light in combination with one of low, normal and high N levels. High light- and low/high N-induced differential expression of the key genes including neutral invertases, ASN1, JAZ1, and TIP1;3, involved in the metabolism of carbohydrate, amino acids and phytohormones, and water transport, corresponded well to changes in physiological and anatomical characteristics in poplar wood in response to high light and altered N availability. These results suggest that physiological and anatomical characteristics are altered in the wood and the underlying transcriptomic reprograming is critical for the wood in acclimation to high light in combination with changing N availability.

Zinc Oxide Nanoparticles and Fe-Modified Activated Carbon Affecting the In Vitro Growth of Date Palm Plantlets cv. Medjool

The survival and growth of in vitro plantlets are still problematic for the date palm; thus, the application of nanotechnology may provide date palm plantlets that develop faster with enhanced growth and biochemical parameters. Moreover, the usage of Fe-modified activated carbon (Fe-AC) prepared from date palm pits instead of activated charcoal (AC) in tissue culture media during the current investigation can be considered an innovative approach. Furthermore, the effect of zinc oxide nanoparticles (ZnO-NPs) and bulk particles (ZnO-BPs) on the rooting and growth of date palm plantlets and on some physiological indices was also investigated. X-ray diffraction, dynamic light scattering, scanning electron microscopy, and transmission electron microscopy were used to characterize Fe-AC and ZnO-NPs. As detected from the characterization, the particle size was 720 nm for Fe-AC and 60 nm for ZnO-NPs. The obtained results indicated that AC significantly enhanced plantlet growth, plantlet height, number of leaves/plantlet, root length, number of roots/plantlet, and the concentrations of IAA, chlorophyll a and chlorophyll b compared with Fe-AC. On the other hand, sugars and phenols concentrations, and POD and PAL activities were highly increased with Fe-AC. There was no significant difference in terms of plant fresh weight (FW), leaf length, leaf width, protein, amino acids, and carotenoids. ZnO nanoparticles significantly improved plant height, leaf length, leaf width, root length, and the concentrations of IAA, chlorophylls a and b, and carotenoids; in contrast, the bulk form increased roots/plantlet, amino acids, and total sugars. Supplying the MS medium with combinations of ZnO-NPs or ZnO-BPs and AC or Fe-AC significantly increased all growth and physiological parameters. Plant height, leaf length, leaf width, root length, and the concentrations of IAA, protein, and chlorophylls a and b significantly increased when ZnO-NPs were combined with AC. Amino acids, total sugars, carotenoids, and phenols concentrations and the activities of POD and PAL increased when ZnO-BPs and Fe-AC were added together.

Coated diammonium phosphate combined with Paecilomyces variotii extracts improves root architecture, enhances spring low temperature tolerance, and increases wheat yield

The growth, development, and grain yield of winter wheat (Triticum aestivum L.) was seriously limited by the low use efficiency of phosphorus (P) fertilizers and the spring low-temperature events. Diammonium phosphate is one of the most important sources of P fertilizers worldwide. Controlled release diammonium phosphate (CRDAP) synchronizes fertilizers P release and crop growth demand is positive to improve P use efficiency (PUE) and reduce P loss, whereas biostimulants such as Paecilomyces variotii extracts (ZNC) have ultrahigh activity in promoting crop growth and abiotic stress resistance. However, little information is available on synergistic effects of CRDAP and ZNC on winter wheat growth. A three-year field experiment from October 2017 to June 2020 was conducted with five treatments: DAP (application of conventional diammonium phosphate); CDAP (CRDAP application); DAPZ (application of diammonium phosphate–ZNC composite); CDAPZ (application of CRDAP–ZNC composite); Control (no P fertilizer or ZNC). Plant growth (root, shoot, and photosynthesis), hormone (auxin content from roots and leaves, and ABA content from leaves), ROS scavenging system (H2O2, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and glutathione reductase (GR)), and soil available P were measured along with yield and PUE. The results showed that the yield and PUE of CDAPZ were significantly more (by 6.0% and 9.3 percentage points, respectively) than for CDAP. The interactive effects between CRDAP and ZNC were evidenced by the CDAPZ enhanced soil available-P supply and increased average available-P content (22.0% more than CDAP in the 0–40 cm soil layer) and improved root growth with 29.9% increase in total root length by CDAPZ than CDAP at the jointing stage. Moreover, the IAA content of roots from CDAPZ was higher than any other treatments, and the effect of ZNC on IAA content was verified by a laboratory incubation experiment. Similarly, the highest photosynthetic rate was found in CDAPZ, which was 11.0–17.0% higher than that in CDAP. The application of CRDAP combined with ZNC decreased H2O2 content by 8.6%, and increased the activities of SOD, POD, CAT, and GR, thereby enhancing the cold tolerance of wheat. Hence, CRDAP–ZNC composite may serve as an emerging green fertilizer technology and play a crucial role in improving crops response to climate change, and increasing crop yield and PUE.

Changes in cytokinins and auxins levels in the rind of ‘Nules Clementine’ mandarin as related to the fruit position on the tree and the susceptibility to non-chilling rind breakdown disorder

• Phytohormonal changes in relation to citrus rind disorder was examined postharvest. • Fruit were harvested from inside and outside canopy position of the tree. • Endogenous levels of cytokinins (CK), auxins, isomers and conjugates were analysed. • Cis -zeatin-type CK concentrations were higher in outside canopy fruit postharvest. The role of phytohormones in mitigating or enhancing the incidence of non-chilling rind physiological disorder of citrus fruit is largely unknown. Therefore, this study attempted to elucidate cytokinins (CK) and auxin changes in ‘Nules Clementine’ mandarin fruit rind from different canopy positions during postharvest non-chilling cold storage regarding rind breakdown disorder (RBD). Fruit from the inside canopy (IC) and outside canopy (OC) positions of citrus trees were harvested at commercial maturity from Eastern Cape (EC) and Western Cape (WC) provinces of South Africa, respectively. Endogenous levels of CK, auxins, their isomers, and conjugates were analysed using ultra-performance liquid chromatography coupled with a triple quadrupole mass spectrometer (MS/MS) equipped with an electrospray interface. Cis -zeatin-type cytokinins were significantly higher in the OC fruit than in the IC fruit from both provinces during cold storage. Whereas dihydrozeatin concentration (the most abundant CK) was significantly higher in fruit from IC (326.10 and 29.38 nmol kg −1 ) than in OC (65.75 and 17.72 nmol kg −1 ) fruit before cold storage, respectively. Fruit without rind disorder had lower CK - conjugates than fruit with the disorder. The IAA concentration was higher in the IC fruit (344.15 nmol kg −1 ) than in the OC fruit (194.20 nmol kg −1 ) from EC at week 0 while the IAA concentration of OC fruit from WC was below the limit of detection and IC fruit had 53.20 nmol kg −1 at week 0. Fruit without the disorder had more IAA concentration than fruit with RBD while indole-3-acetylaspartic acid (IAAsp) was higher in fruit with RBD than fruit without the disorder, indicating the preventive role of IAA in the incidence of the disorder. This study is the first to record the negative effect of IAAsp in RBD and revealed the crucial role and synergistic role of CK, IAA and their isomers in RBD of ‘Nules Clementine’ fruit.

Transcriptome analysis provides insights into the role of phytohormones in regulating axillary bud development of flower stalk in Phalaenopsis

• Exogenous application of diethyl aminoethyl hexanoate (DA-6) promotes ABFS development in Phalaenopsis. • The content of IAA, zeatin and GA3 was significantly affected during the development of the ABFS. • Differentially expressed genes related to hormone metabolism and signal transduction were identified through transcriptome analysis. • The hormonal signaling network plays an important role in regulating the outgrowth of axillary buds during DA-6 induced ABFS development. The inflorescence architecture of Phalaenopsis is determined by the development of the axillary buds of flower stalk (ABFS) in Phalaenopsis . Numerous studies have shown that plant hormones are the primary factors involved in the regulation of axillary bud development. However, the molecular mechanisms controlling how phytohormones regulate the development of ABFS in Phalaenopsis remain unknown. Here, we report that diethyl aminoethyl hexanoate (DA-6), a plant growth regulator, promotes ABFS development in Phalaenopsis 'Yen Shuai Red Grape'. The phytohormone contents were measured at five stages (bud length 0 cm (before axillary bud emergence), 0.5 cm, 1.0 cm, 1.5 cm, and 2.0 cm). We found that the GA 3 concentration increased gradually during DA-6-induced-ABFS development, whereas the IAA and ZA/ZT concentrations decreased from 0 cm to 1.0 cm. Then, we performed a comprehensive transcriptome study at five stages and the results showed that differentially expressed genes (DEGs) involved in plant hormone metabolism and signal transduction were significantly enriched at the early stage of ABFS development. Furthermore, we used weighted gene coexpression network analysis (WGCNA) to dissect the phytohormone regulatory network during DA-6-induced ABFS development. The turquoise module, which was positively correlated with GA 3 concentration and negatively related to zeatin concentration was identified and the genes involved in GA, CK, and SL metabolism and signal transduction were clustered in the turquoise module. In addition, the PhTB1 genes which encode integrators of diverse hormonal signaling networks were also found in the turquoise module. Collectively, our results provide novel insight into the mechanisms of DA-6-induced-ABFS development through the regulation of hormone metabolism/signal transduction and phytohormone regulatory networks.