IAA Treatment Research Articles

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.

Auxin inhibits chlorophyll accumulation through ARF7-IAA14-mediated repression of chlorophyll biosynthesis genes in Arabidopsis.

Auxin is a well-known important phytohormone in plant that plays vital roles in almost every development process throughout plant lifecycle. However, the effect of auxin on the metabolism of chlorophyll, one of the most important pigments involved in the photosynthesis, was intertwined and the underlying mechanism remained to be explored. Here, we found the auxin-defective yuc2 yuc6 double mutant displayed dark-green leaf color with higher chlorophyll content than wildtype, suggesting a negative regulatory role of auxin in chlorophyll biosynthesis. The chloroplast number and structure in mesophyll cells were altered and the photosynthetic efficiency was improved in yuc2 yuc6. In addition, the chlorophyll level was significantly improved during seedling de-etiolation in yuc2 yuc6 mutant, and decreased dramatically under IAA treatment, confirming the inhibitory role of auxin in chlorophyll biosynthesis. The analyses of gene expression in mature leaves and de-etiolation seedlings suggested that auxin suppressed the expression of many chlorophyll biosynthesis genes, especially PROTOCHLOROPHYLLIDE OXIDOREDUCTASE A (PORA) and GENOMES UNCOUPLED 5 (GUN5). Yeast-one-hybrid and luciferase assays demonstrated that the AUXIN RESPONSE FACTOR 2 (ARF2) and ARF7 bind to the promoter of PORA and GUN5 to suppress their expression with the help of INDOLE-3-ACETIC ACID14 (IAA14). Collectively, our research explicitly unraveled the direct inhibitory role of auxin in chlorophyll biosynthesis, and provided new insight into the interplay between auxin signaling and chlorophyll metabolism.

Comprehensive evolutionary analysis of growth-regulating factor gene family revealing the potential molecular basis under multiple hormonal stress in Gramineae crops.

Growth-regulating factors (GRFs) are plant-specific transcription factors that contain two highly conserved QLQ and WRC domains, which control a range of biological functions, including leaf growth, floral organ development, and phytohormone signaling. However, knowledge of the evolutionary patterns and driving forces of GRFs in Gramineae crops is limited and poorly characterized. In this study, a total of 96 GRFs were identified from eight crops of Brachypodium distachyon, Hordeum vulgare, Oryza sativa L. ssp. indica, Oryza rufipogon, Oryza sativa L. ssp. japonica, Setaria italic, Sorghum bicolor and Zea mays. Based on their protein sequences, the GRFs were classified into three groups. Evolutionary analysis indicated that the whole-genome or segmental duplication plays an essential role in the GRFs expansion, and the GRFs were negatively selected during the evolution of Gramineae crops. The GRFs protein function as transcriptional activators with distinctive structural motifs in different groups. In addition, the expression of GRFs was induced under multiple hormonal stress, including IAA, BR, GA3, 6BA, ABA, and MeJ treatments. Specifically, OjGRF11 was significantly induced by IAA at 6h after phytohormone treatment. Transgenic experiments showed that roots overexpressing OjGRF11 were more sensitive to IAA and affect root elongation. This study will broaden our insights into the origin and evolution of the GRF family in Gramineae crops and will facilitate further research on GRF function.

Downregulation of Brassica napus MYB69 (BnMYB69) increases biomass growth and disease susceptibility via remodeling phytohormone, chlorophyll, shikimate and lignin levels.

MYB transcription factors are major actors regulating plant development and adaptability. Brassica napus is a staple oil crop and is hampered by lodging and diseases. Here, four B. napus MYB69 (BnMYB69s) genes were cloned and functionally characterized. They were dominantly expressed in stems during lignification. BnMYB69 RNA interference (BnMYB69i) plants showed considerable changes in morphology, anatomy, metabolism and gene expression. Stem diameter, leaves, roots and total biomass were distinctly larger, but plant height was significantly reduced. Contents of lignin, cellulose and protopectin in stems were significantly reduced, accompanied with decrease in bending resistance and Sclerotinia sclerotiorum resistance. Anatomical detection observed perturbation in vascular and fiber differentiation in stems, but promotion in parenchyma growth, accompanied with changes in cell size and cell number. In shoots, contents of IAA, shikimates and proanthocyanidin were reduced, while contents of ABA, BL and leaf chlorophyll were increased. qRT-PCR revealed changes in multiple pathways of primary and secondary metabolisms. IAA treatment could recover many phenotypes and metabolisms of BnMYB69i plants. However, roots showed trends opposite to shoots in most cases, and BnMYB69i phenotypes were light-sensitive. Conclusively, BnMYB69s might be light-regulated positive regulators of shikimates-related metabolisms, and exert profound influences on various internal and external plant traits.

Hormones regulate the flowering process in saffron differently depending on the developmental stage.

Flowering in saffron is a highly complex process regulated by the synchronized action of environmental cues and endogenous signals. Hormonal regulation of flowering is a very important process controlling flowering in several plants, but it has not been studied in saffron. Flowering in saffron is a continual process completed in months with distinct developmental phases, mainly divided into flowering induction and flower organogenesis/formation. In the present study, we investigated how phytohormones affect the flowering process at different developmental stages. The results suggest that different hormones differentially affect flower induction and formation in saffron. The exogenous treatment of flowering competent corms with abscisic acid (ABA) suppressed both floral induction and flower formation, whereas some other hormones, like auxins (indole acetic acid, IAA) and gibberellic acid (GA), behaved contrarily at different developmental stages. IAA promoted flower induction, while GA suppressed it; however, GA promoted flower formation, whereas IAA suppressed it. Cytokinin (kinetin) treatment suggested its positive involvement in flower induction and flower formation. The expression analysis of floral integrator and homeotic genes suggests that ABA might suppress floral induction by suppressing the expression of the floral promoter (LFY, FT3) and promoting the expression of the floral repressor (SVP) gene. Additionally, ABA treatment also suppressed the expression of the floral homeotic genes responsible for flower formation. GA reduces the expression of flowering induction gene LFY, while IAA treatment upregulated its expression. In addition to these genes, a flowering repressor gene, TFL1-2, was also found to be downregulated in IAA treatment. Cytokinin promotes flowering induction by increasing the expression levels of the LFY gene and decreasing the TFL1-2 gene expression. Moreover, it improved flower organogenesis by increasing the expression of floral homeotic genes. Overall, the results suggest that hormones differently regulate flowering in saffron via regulating floral integrator and homeotic gene expression.

Global analysis of basic leucine zipper transcription factors in trifoliate orange and the function identification of PtbZIP49 in salt tolerance

As one of the most widely distributed and highly conserved transcription factors in eukaryotes, basic leucine zipper proteins (bZIPs) are involved in a variety of biological processes in plants, but they are largely unknown in citrus. In this study, 56 bZIP family members were identified genome-wide from an important citrus rootstock, namely trifoliate orange (Poncirus trifoliata L. Raf.), and these putative bZIPs were named PtbZIP1–PtbZIP56. All PtbZIPs were classified into 13 subgroups by phylogenetic comparison with Arabidopsis thaliana bZIPs (AtbZIPs), and they were randomly distributed on nine known (50 genes) chromosomes and one unknown (6 genes) chromosome. Sequence analysis revealed the detailed characteristics of PtPZIPs, including their amino acid length, isoelectric point (pI), molecular weight (MW), predicted subcellular localization, gene structure, and conserved motifs. Prediction of promoter elements suggested the presence of drought, low-temperature, wound, and defense and stress responsive elements, as well as multiple hormone-responsive cis-acting elements. Spatiotemporal expression analysis showed the transcriptional patterns of PtbZIPs in different tissues and under dehydration, high salt, ABA, and IAA treatments. In addition, 21 PtbZIPs were predicted to have direct or indirect protein–protein interactions. Among these, PtbZIP49 was experimentally proven to interact with PtbZIP1 or PtbZIP11 by using a yeast two-hybrid assay and bimolecular fluorescence complementation (BiFC). Subcellular localization analysis further revealed that PtbZIP1, PtbZIP11, and PtbZIP49 were localized in the nucleus. Moreover, PtbZIP49 was functionally identified as having an important role in salt stress via ectopic expression in A. thaliana and silenced in trifoliate orange using virus-induced gene silencing (VIGS). This study provided comprehensive information on PtbZIP transcription factors in citrus and highlights their potential functions in abiotic stress.

Effects of Exogenous Auxin on Mesocotyl Elongation of Sorghum.

The length of sorghum mesocotyl plays a vital role in seed emergence from the soil, which is the foundation of healthy growth. In this study, we aimed to understand how exogenous auxin (IAA) promoted mesocotyl elongation of sorghum and its physiology mechanism. The results presented that exogenous IAA significantly promoted mesocotyl elongation in MS24B (short mesocotyl inbred line) by increasing the cell length, while with extra exogenous NPA (IAA inhibitor) application, the mesocotyl length presented a significant short phenotype. In Z210 (long mesocotyl inbred line), exogenous IAA had a slight effect on mesocotyl length elongation, while the NPA treatment decreased the mesocotyl length considerably. In MS24B, IAA treatment increased the activity of amylase to degrade starch to soluble sugar, and the activity of hexokinase was improved to consume the increased soluble sugar to offer more energy. The energy will help to increase the activity of PM H+-ATPase and the expression of expansin-related genes, which ultimately will promote the acidification of the plasma membrane in MS24B for cell elongation. Overall, the exogenous IAA functioned on the activation of energy metabolism, which in turn, inducted the acidification of the plasma membrane for mesocotyl elongation.

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.

Characterization and pretreatment of breaking seed dormancy Livistona speciosa Kurz, collection of Bogor Botanical Gardens

The palm plant, Livistona speciosa Kurz, belongs to the Arecaceae family. The slow germination of the seeds is just one of the issues this plant faces throughout its growth. This research aims to identify seeds’ morphological traits and the breakdown of seed dormancy. Observations made were testing viability, moisture content, characteristics of fruit and seeds, the effect of pretreatment on seed germination. The dry heat treatment at 50°C, the hot water soak at 50°C, the soak with GA and IAA solution for 1 hour, and the seed scarification treatment are the methods used to treat seeds that are breaking their dormancy. The results revealed the fruit was rounded, average length: 26,755 ± 1,253 mm; Diameter: 21.33 ± 1,356 mm and weight: 7,786 ± 0.906 grams. Ovoid-shaped seeds; average length: 20,772 ± 1.182 mm; diameter: 16.561 ± 1,160 mm and weight: 3.756 ± 0.648 gr. The highest germination capacity (pre-treatment of oven-dry 50°C and immersion with GA and IAA treatments) and the highest germination coefficient and simultaneously (hot water treatment at 50°C).

SlGATA17, A tomato GATA protein, interacts with SlHY5 to modulate salinity tolerance and germination

The GATA transcription factor family participates in plant biological processes and abiotic stress across various crop species, but their function in response to salinity stress remains unexplored, particularly in tomato. Here, a tomato (Solanum lycopersicum) GATA gene, SlGATA17, was characterized in the tolerance to salinity stress. SlGATA17 had transcription activity in yeast, and the transcriptional activation domain was location on 32–60 amino acids of the N-terminal. SlGATA17 expression was induced by heat, cold, ABA, ACC and IAA treatments, but inhibited by NaCl and PEG treatments. In this study, the Slgata17 mutant plants showed slight injury symptoms compared to wild-type plants under salinity stress, and higher expression levels of stress-related marker genes (SlDREB2A, SlAREB1, SlRD29A and SlP5CS1). Heterologous expression of SlGATA17 in Arabidopsis promoted seed germination under NaCl, ABA and mannitol conditions, and inhibited ABA content and the expression levels of ABA related genes (AtNCED3, AtNCED5, AtNCED9, AtABI3, AtEM1 and AtEM6). However, SlGATA17 transgenic Arabidopsis were hypersensitive to NaCl at the post-germination stage. Yeast two assay and BiFC assay showed that tomato transcription factor ELONGATED HYPOCOTYL (SlHY5) interacts with SlGATA17. Yeast one assay and Dual-Luc assay showed that SlHY5 negatively regulated SlGATA17 expression via binding to the GATA-box of SlGATA17 promoter. SlHY5-SlGATA17 might function as a regulatory module in response to abiotic stress.

P-body dynamics revealed by DDX6 protein knockdown via the auxin-inducible degron system.

The transcriptome dynamically changes via several transcriptional and post-transcriptional mechanisms. RNA-binding proteins contribute to such mechanisms to regulate the cellular status. DDX6 is one such protein and a core component of processing bodies (P-bodies), membrane-less cytosolic substructures where RNA and proteins localize and are functionally regulated. Despite the importance of DDX6, owing to the lack of tightly controlled methods for protein knockdown, it was difficult to assess in high time resolution how its depletion exactly affects the P-body assembly structure. Therefore, we adopted an advanced protein degradation method, the auxin-induced degron (AID) system, to degrade DDX6 acutely in ES cells. By introducing AID-tagged DDX6 and the E3 ligase subunit of OsTIR1 into ES cells, we successfully degraded DDX6 following auxin analog (indole-3-acetic acid, IAA) treatment. The degradation rate of DDX6 was slower than that of the cytosolic reporter protein EGFP but was enhanced by increasing the OsTIR1 dosage. Lastly, we confirmed that a substantial portion of P-bodies disappears around the time of 1hr after IAA addition consistent with DDX6 depletion detected by western blot. In accordance with this, we detected transcriptome changes by 6hr after IAA treatment. Therefore, we demonstrated the applicability of the AID method to gain insight into the function of P-bodies and their protein components.

Genome-wide identification of RUB activating enzyme and conjugating enzyme gene families and their expression analysis under abiotic stresses in Capsicum annuum.

NEDD8/RUB, as a ubiquitin-like protein, participates in the post-translational modification of protein and requires unique E1, E2, and E3 enzymes to bind to its substrate. The RUB E1 activating enzyme and E2 conjugating enzyme play a significant role in the neddylation. However, it is unknown whether RUB E1 and E2 exist in pepper and what its function is. In this study, a total of three putative RUB E1 and five RUB E2 genes have been identified in the pepper genome. Subsequently, their physical and chemical properties, gene structure, conserved domains and motifs, phylogenetic relationship, and cis-acting elements were analyzed. The structure and conserved domain of RUB E1 and E2 are similar to that of Arabidopsis and tomato. The RUB E1 and E2 genes were randomly distributed on seven chromosomes, and there were two pairs of collinearity between pepper and Arabidopsis and eight pairs of collinearity between pepper and tomato. Phylogenetic analysis reveals that RUB E1 and E2 genes of pepper have a closer relationship with that of tomato, potato, and Nicotiana attenuate. The cis-elements of RUB E1 and E2 genes contained hormone response and stress response. RUB E1 and E2 genes were expressed in at least one tissue and CaRCE1.3 and CaRCE2.1 were exclusively expressed in flowers and anthers. Moreover, the expression of RUB E1 genes (CaECR1, CaAXR1.1, and CaAXR1.2) and RUB E2 genes (CaRCE1.1, CaRCE1.2, and CaRCE2.1) was increased to varying degrees under low-temperature, drought, salt, ABA, and IAA treatments, while CaRCE1.3 and CaRCE2.2 were down-regulated under low-temperature treatment. In addition, these genes were hardly expressed under MeJA treatment. In summary, this study provides a theoretical foundation to explore the role of RUB E1 and E2 in the response of plants to stress.

Genome- and transcriptome-wide identification and analysis of B3 superfamily members and their association with salt stress response in the common bean (Phaseolus vulgaris L)

The plant-specific transcription factor B3 superfamily members mediate plant growth, development, and stress response. Although the B3 gene has been studied in various plants, its role in the common bean (Phaseolus vulgaris L) is unknown. In this study, 110 PvB3 genes were identified from the common bean genome and analyzed based on the phylogeny, gene structure, motifs, cis-regulatory elements, collinearity, and Ka/Ks. PvB3s were divided into four subgroups based on motifs and gene structure. The cis-element composition of the most PvB3 were involved in hormone production, abiotic stress response, and germination. Most PvB3 were highly expressed in the vigorously growth tissue of common bean, such as nodules, young pods, and young trifoliate. Moreover, RNA-seq results showed that PvB3-001/010/027/032/047/048/059/090 were enriched in tryptophan metabolism pathway (involves in AUX/IAA, GH3, and SAUR) of common bean under salt stress. Notably, exogenous IAA treatment could increase endogenous IAA content and the number of lateral roots, while altering the expression level of PvB3s in salt-sensitive common bean variety under salt stress. Taken together, the result indicated that PvB3 transcription factors may be involved in common bean salt stress response by participating in the synthesis and metabolic regulation of IAA. This study provides a theoretical basis for further study on the role of PvB3s in common bean abiotic stresses response.

Ectopic expression of NAC transcription factor HaNAC3 from Haloxylon ammodendron increased abiotic stress resistance in tobacco.

HaNAC3 is a transcriptional activator located in the nucleus that may be involved in the response to high temperature, high salt and drought stresses as well as phytohormone IAA and ABA treatments. Our study demonstrated that HaNAC3 increased the tolerance of transgenic tobacco to abiotic stress and was involved in the regulation of a range of downstream genes and metabolic pathways. This also indicates the potential application of HaNAC3 as a plant tolerance gene. NAC transcription factors play a key role in plant growth and development and plant responses to biotic and abiotic stresses. However, the biological functions of NAC transcription factors in the desert plant Haloxylon ammodendron are still poorly understood. In this study, the NAC transcription factor HaNAC3 was isolated and cloned from a typical desert plant H. ammodendron, and its possible biological functions were investigated. Bioinformatics analysis showed that HaNAC3 has the unique N-terminal NAC structural domain of NAC transcription factor. Quantitative real-time fluorescence analysis showed that HaNAC3 was able to participate in the response to simulated drought, high temperature, high salt, and phytohormone IAA and ABA treatments, and was very sensitive to simulated high temperature and phytohormone ABA treatments. Subcellular localization analysis showed that the GFP-HaNAC3 fusion protein was localized in the nucleus of tobacco epidermal cells. The transcriptional self-activation assay showed that HaNAC3 had transcriptional self-activation activity, and the truncation assay confirmed that the transcriptional activation activity was located at the C-terminus. HaNAC3 gene was expressed exogenously in wild-type Nicotiana benthamiana, and the physiological function of HaNAC3 was verified by simulating drought and other abiotic stresses. The results indicated that transgenic tobacco had better resistance to abiotic stresses than wild-type B. fuminata. Further transcriptome analysis showed that HaNAC3 was involved in the regulation of a range of downstream resistance genes, wax biosynthesis and other metabolic pathways. These results suggest that HaNAC3 may have a stress resistance role in H. ammodendron and has potential applications in plant molecular breeding.

The Interconnected Relationship between Auxin Concentration Gradient Changes in Chinese Fir Radial Stems and Dynamic Cambial Activity

Auxin has been shown to exhibit a striking concentration gradient distribution in radial sections of angiosperm and gymnosperm species, in which peak auxin levels are concentrated in dividing cambial cells, while the absolute auxin concentration sharply declines toward developing secondary phloem and xylem regions. The coincidence of auxin concentration gradient across shoot tissues and xylem cell developmental gradient has prompted that auxin could act as “a plant morphogen” to provide a positional signal for cambial cell development. However, the specific location of vascular cambium and the lack of mutants altering auxin distribution in shoots of woody species made further verification experiments difficult to explore. To address this issue, different concentrations of exogenous IAA were applied to decapitated Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) trunks in this study to induce the change in the auxin concentration gradient in radial stems, and its effects on cambial activities were examined on the physiological, cellular and molecular levels. Our findings manifested that exogenous IAA treatments resulted in vast changes in endogenous hormone concentrations (including IAA, ZR, GA3 and ABA), cambial cell developmental behaviors and transcriptional activities of genes related to polar auxin transport (PAT), auxin signaling, the biosynthesis and signal transduction of other plant hormones and the genetic control of cambial activity. Based on above findings, we postulated a model of auxin concentration gradient involved in the control of cambial activity and secondary growth in tree trunks. In this model, the contrasting expression of AUX1/LAX and PIN family carriers in distinct Chinese fir wood-forming tissues dynamically modulates PAT into the cambial zone adjacent to the secondary phloem side and secondary xylem tissues, resulting in a sharp and wide auxin spatial gradient distribution across shoots in different stages of secondary growth, respectively. This change in auxin concentration gradient distribution in radial sections in turn acts on cambial developmental behaviors by modulating the expression of auxin signaling genes and key transcription factors and the production of other plant hormones in distinct woody tissues. Findings in this study provide important insights for understanding the biological significance of auxin concentration gradient existing in the radial stems of woody species.

Pengaruh Pemberian IAA pada Pembibitan Setek Vanili (Vanila planifolia) yang diperkaya Bakteri Pelarut Fosfat dan Bakteri Pelarut Kalium

Propagation of vanilla plants is generally using vegetative methods like cuttings. The use of external growth regulators can support the growth of nurseries. Phosphate solubilising bacteria and potassium solubilising bacteria as plant growth promoting rhizobacteria are producing microbial IAA. This study used auxin in synthetic IAA combined with IAA microbes from phosphate solubilising bacteria and potassium solubilising bacteria. This study aimed to determine the effectiveness of each microbe at each dose of synthetic IAA that was applied. The study was conducted from November 2021-April 2022 in the Biological Soil Laboratory and Greenhouse University of Jember. The research uses a randomised block design with three replications with the factorial arrangement. The first factor was organic matter which was enriched with bacterial isolate (B0 = control, B1 = BPF isolate, and B2 = BPK isolate). The second factor was concentration of IAA (A0 = 0 mg.l-1, A1 = 100 mg.l-1, and A2 = 200 mg.l-1). The data were analysed by ANOVA and further tested with Duncan Multiple Range Test (DMRT) with a 95% confidence level. The results showed that treatment of synthetic IAA affects the parameters of length and volume of adventitious roots, which are effective in helping to supply nutrients with the best treatment at a concentration of 200 ppm. Meanwhile, enrichment of media with isolates of phosphate solubilising bacteria and potassium solubilising bacteria gave a better effect than control on the observation of tendril length, number of leaves, number of adventitious roots and taproots, length of adventitious roots and taproots, the volume of adventitious roots and taproot, and fresh weight of vanilla seedlings.

Cloning, Subcellular Location and Expression Analysis of Grape Myb Gene

MYB gene plays an important role in plant growth, development and response to abiotic stress. In the present study, ‘Yatomi Rosa’ grape (Vitis vinifera L.) was used as the test material. Two MYB, VvMYBB1 and VvMYBA3 gene were obtained by homologous cloning, and their subcellular location, different organs, and expression patterns under stress treatment and hormone induction were obtained. VvMYBB1 and VvMYBA3 proteins were located in the nucleus and belonged to nuclear proteins. They were highly expressed in roots and flowers. These genes might have a negative effect on the formation of peel color. VvMYB1 gene and VvMYBA3 gene might play an important role in drought resistance and salt stress resistance. Under the induction of exogenous hormones, relative expression of VvMYBB1 gene was higher than that of VvMYBA3 gene under IAA, ETH, SA and MeJA treatment. Relative expression of VvMYBB1 gene was lower than that of VvMYBA3 gene under 6-BA, GA3 and ABA treatment. It showed that MYB gene played an important role in the development of different organs of grapes, fruit color, and response to abiotic stress and exogenous hormones induction in grape. Bangladesh J. Bot. 51(3): 499-506, 2022 (September)

Selection of Optimum Internal Control Genes for RT-qPCR Analysis of Schisandra chinensis under Four Hormone Treatments

qRT-PCR technology is now one of the commonly used methods to study gene expression levels. The selection of accurate reference gene detection is an essential work before gene expressing analysis. In the current study, 8 candidate internal control genes (ACTIN, TUBA, GAPDH, UBC, MUB, TIP41, APX, and CAPA) were selected, and four statistical algorithms were used to evaluate their stability under different hormone treatments. The results confirmed that when using one internal control genes, TUBA emerged as the first ranking internal control gene in all experimental groups. When using two internal control genes, TUBA and MUB, were the most acceptable internal control genes for the GA3 treatment group; TUBA and GAPDH were identified as internal control genes in the IAA treatment group; TUBA and ACTIN were the most reliable combination in the ZT and ABA experimental groups; TUBA and TIP41 were recommended most suitable control genes in control group. Furthermore, the reliability of the internal control genes was further verified by the expression of GAG, a gene related to the development of Schisandra chinensis. The conclusion of this work will be helpful for the subsequent research on gene expression analysis of Schisandra chinensis.

Overexpression of TaLBD16-4D alters plant architecture and heading date in transgenic wheat.

Lateral organ boundaries domain (LBD) proteins, a class of plant-specific transcription factors with a special domain of lateral organ boundaries (LOB), play essential roles in plant growth and development. However, there is little known about the functions of these genes in wheat to date. Our previous study demonstrated that TaLBD16-4D is conducive to increasing lateral root number in wheat. In the present work, we further examined important agronomical traits of the aerial part of transgenic wheat overexpressing TaLBD16-4D. Interestingly, it was revealed that overexpressing TaLBD16-4D could lead to early heading and multiple alterations of plant architecture, including decreased plant height, increased flag leaf size and stem diameter, reduced spike length and tillering number, improved spike density and grain width, and decreased grain length. Moreover, auxin-responsive experiments demonstrated that the expression of TaLBD16-4D in wild-type (WT) wheat plants showed a significant upregulation through 2,4-D treatment. TaLBD16-4D-overexpression lines displayed a hyposensitivity to 2,4-D treatment and reduced shoot gravitropic response. The expressions of a set of auxin-responsive genes were markedly different between WT and transgenic plants. In addition, overexpressing TaLBD16-4D affected the transcript levels of flowering-related genes (TaGI, TaCO1, TaHd1, TaVRN1, TaVRN2, and TaFT1). Notably, the expression of TaGI, TaCO1, TaHd1, TaVRN1, and TaFT1 displayed significant upregulation under IAA treatment. Collectively, our observations indicated that overexpressing TaLBD16-4D could affect aerial architecture and heading time possibly though participating in the auxin pathway.

Genome-Wide Identification and Characterization of Members of the ACS Gene Family in Cucurbita maxima and Their Transcriptional Responses to the Specific Treatments.

Ethylene biosynthesis and signal transduction play critical roles in plant sex differentiation. ACS (1-aminocyclopropane-1-carboxylic acid synthase) is a rate-limiting enzyme in ethylene biosynthesis. However, the understanding of the ACS gene family in Cucurbita maxima is limited. Here, we identified and characterized 13 ACS genes in the C. maxima genome. All ACS genes could be divided into three groups according to a conserved serine residue at the C-terminus. Thirteen CmaACS genes were found to be randomly distributed on 10 of the 20 chromosomes of C. maxima. The ACS gene exhibits different tissue-specific expression patterns in pumpkin, and four ACS genes (CmaACS1, CmaACS4, CmaACS7, and CmaACS9) were expressed specifically in both the female and male flowers of C. maxima. In addition, the expression levels of CmaACS4 and CmaACS7 were upregulated after ethephon and IAA treatments, which ultimately increased the number of female flowers, decreased the position of the first female flower and decreased the number of bisexual flowers per plant. These results provide relevant information for determining the function of the ACS genes in C. maxima, especially for regulating the function of ethylene in sex determination.