Growth Of Lateral Buds Research Articles

Far-red light inhibits lateral bud growth mainly through enhancing apical dominance independently of strigolactone synthesis in tomato.

The ratio of red light to far-red light (R:FR) is perceived by light receptors and consequently regulates plant architecture. Regulation of shoot branching by R:FR ratio involves plant hormones. However, the roles of strigolactone (SL), the key shoot branching hormoneand the interplay of different hormones in the light regulation of shoot branching in tomato (Solanum lycopersicum) are elusive. Here, we found that defects in SL synthesis genes CAROTENOID CLEAVAGE DIOXYGENASE 7 (CCD7) and CCD8 in tomato resulted in more lateral bud growth but failed to reverse the FR inhibition of lateral bud growth, which was associated with increased auxin synthesis and decreased synthesis of cytokinin (CK) and brassinosteroid (BR). Treatment of auxin also inhibited shoot branching in ccd mutants. However, CK released the FR inhibition of lateral bud growth in ccd mutants, concomitant with the upregulation of BR synthesis genes. Furthermore, plants that overexpressed BR synthesis gene showed more lateral bud growth and the shoot branching was less sensitive to the low R:FR ratio. The results indicate that SL synthesis is dispensable for light regulation of shoot branching in tomato. Auxin mediates the response to R:FR ratio to regulate shoot branching by suppressing CK and BR synthesis.

Direct and Indirect Organogenesis in Olive (Olea europaea L.)

Olive explants included of pieces of young stems which were divided into nodal explants cultured on MS media supplemented with cytokinins and auxin. Callus induction and different forms of shooting and adventitious lateral buds regeneration were dominant results. Level of auxin IBA in all treatments was used at 0.1 mg/l. But cytokinins combination were used at different combinations. Combination of BA and ZEA led to more organogenesis and combination of BA and 2ip led to callus induction. Organogenesis was occurred with three different forms including indirect with passing callus phase, direct with growth of lateral buds and elimination of dominance apical and direct with regeneration of new lateral buds on explants.

Lateral bud induction and establishment of regeneration system of cassia mimosoides L.

To establish an efficient plant regeneration system of Cassia mimosoides, the 10-day-old seedlings were used as explants for inducing lateral buds. Results showed that the addition of BA and NAA for different ratios on the basis of 1/2 MS could effectively induce the production of lateral buds. By adding different additional elements, it was found that the growth of lateral buds was longer and stronger on the medium of 1/2 MS + 3.0 mg/l BA + 0.1 mg/l NAA + 4.0 mg/l Gln or 1/2 MS + 3.0 mg/l BA + 0.1 mg/l NAA + 1.0 mg/l AgNO3. Meanwhile, cutting with the lateral buds of tissue culture seedling, the rooting rate could reach 77.8% when 1/2 MS medium contained 0.2 mg/l NAA, although the root length was shorter. When the regenerated strong seedlings were transplanted into the soil, the survival rate was over 75%. Therefore, the best medium for lateral bud induction using 10-day-old seedlings as explants in C. mimosoides was 1/2 MS + 3.0 mg/l BA + 0.1 mg/l NAA. The growth of lateral buds can be promoted by the appropriate concentration of Gln and AgNO3, and the best rooting medium was 1/2 MS contained 0.2 mg/l NAA. Bangladesh J. Bot. 52(2): 515-521, 2023 (June) Special

Lateral bud induction and establishment of regeneration system of cassia mimosoides L.

To establish an efficient plant regeneration system of Cassia mimosoides, the 10-day-old seedlings were used as explants for inducing lateral buds. Results showed that the addition of BA and NAA for different ratios on the basis of 1/2 MS could effectively induce the production of lateral buds. By adding different additional elements, it was found that the growth of lateral buds was longer and stronger on the medium of 1/2 MS + 3.0 mg/l BA + 0.1 mg/l NAA + 4.0 mg/l Gln or 1/2 MS + 3.0 mg/l BA + 0.1 mg/l NAA + 1.0 mg/l AgNO3. Meanwhile, cutting with the lateral buds of tissue culture seedling, the rooting rate could reach 77.8% when 1/2 MS medium contained 0.2 mg/l NAA, although the root length was shorter. When the regenerated strong seedlings were transplanted into the soil, the survival rate was over 75%. Therefore, the best medium for lateral bud induction using 10-day-old seedlings as explants in C. mimosoides was 1/2 MS + 3.0 mg/l BA + 0.1 mg/l NAA. The growth of lateral buds can be promoted by the appropriate concentration of Gln and AgNO3, and the best rooting medium was 1/2 MS contained 0.2 mg/l NAA. Bangladesh J. Bot. 52(2): 515-521, 2023 (June) Special

Apical Dominance and Branching in Plantlets of Colt Cherry Lines Expressing Different Light and Auxin Signalling Sensitivities

The establishment of plant architecture requires coordination of distinct processes including shoot branching and apical dominance (AD). AD involves the bud apical shoot, mainly through indole-3-acetic acid (IAA) synthetized by the cells of the meristem and young leaves. The rootward flow generates an auxin gradient in the stem and buds, regulating lateral bud (LB) outgrowth. Phytochromes and AD are involved in the shade-avoidance syndrome in woody plants. However, the underlying mechanisms remain poorly understood. The aim of this study was to evaluate the sensitivity of cherry rootstocks to light, mediated by the photoreceptor phytochrome, and its effect on the role of auxin in driving branching by AD. Pharmacological treatments using transport inhibitors and a competitor of IAA were applied to transgenic lines of Colt cherry rootstock, which showed different sensitivities to light because of the ectopic expression of a rice phyA gene. Results showed different physiological behaviours among the transgenic lines and between themselves and the Colt-wt line. Exogenous IBA inhibited Colt-wt LB outgrowth, and this inhibition was less intense in transgenic lines. The IAA-inhibitors and IAA-competitor promoted branching. In in vitro phyA-transgenic plantlets, the ectopic gene induced greater branching and a higher number of buds developed in new shoots. This work confirms a positive action of phytochrome on lateral branching in cherry rootstock, playing a role in the regulation of AD. Moreover, we suggest that the confined in vitro system might now be used as a phenotyping screening to test the plasticity of the response, highlighting the behaviour of modified genotypes due to an ectopic insertion event by simple and rapid procedures.

The transcription factor SPL13 mediates strigolactone suppression of shoot branching by inhibiting cytokinin synthesis in Solanum lycopersicum.

Plant architecture imposes a large impact on crop yield. IDEAL PLANT ARCHITECTURE 1 (IPA1), which encodes a SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factor, is a target of molecular design for improving grain yield. However, the roles of SPL transcription factors in regulating tomato (Solanum lycopersicum) plant architecture are unclear. Here, we show that the expression of SPL13 is down-regulated in the lateral buds of strigolactone (SL)-deficient ccd mutants and is induced by GR24 (a synthetic analog of SL). Knockout of SPL13 by CRISPR/Cas9 resulted in higher levels of cytokinins (CKs) and transcripts of the CK synthesis gene ISOPENTENYL TRANSFERASES 1 (IPT1) in the stem nodes, and more growth of lateral buds. GR24 suppresses CK synthesis and lateral bud growth in ccd mutants, but is not effective in spl13 mutants. On the other hand, silencing of the IPT1 gene inhibited bud growth of spl13 mutants. Interestingly, SL levels in root extracts and exudates are significantly increased in spl13 mutants. Molecular studies indicated that SPL13 directly represses the transcription of IPT1 and the SL synthesis genes CAROTENOID CLEAVAGE DIOXYGENASE 7 (CCD7) and MORE AXILLARY GROWTH 1 (MAX1). The results demonstrate that SPL13 acts downstream of SL to suppress lateral bud growth by inhibiting CK synthesis in tomato. Tuning the expression of SPL13 is a potential approach for decreasing the number of lateral shoots in tomato.

Jujube witches' broom phytoplasmas inhibit ZjBRC1-mediated abscisic acid metabolism to induce shoot proliferation.

Jujube witches' broom (JWB) phytoplasmas parasitize the sieve tubes of diseased phloem and cause an excessive proliferation of axillary shoots from dormant lateral buds to favour their transmission. In previous research, two JWB effectors, SJP1 and SJP2, were identified to induce lateral bud outgrowth by disrupting ZjBRC1-mediated auxin flux. However, the pathogenesis of JWB disease remains largely unknown. Here, tissue-specific transcriptional reprogramming was examined to gain insight into the genetic mechanisms acting inside jujube lateral buds under JWB phytoplasma infection. JWB phytoplasmas modulated a series of plant signalling networks involved in lateral bud development and defence, including auxin, abscisic acid (ABA), ethylene, jasmonic acid, and salicylic acid. JWB-induced bud outgrowth was accompanied by downregulation of ABA synthesis within lateral buds. ABA application rescued the bushy appearances of transgenic Arabidopsis overexpressing SJP1 and SJP2 in Col-0 and ZjBRC1 in the brc1-2 mutant. Furthermore, the expression of ZjBRC1 and ABA-related genes ZjHB40 and ZjNCED3 was negatively correlated with lateral main bud outgrowth in decapitated healthy jujube. Molecular evidence showed that ZjBRC1 interacted with ZjBRC2 via its N-terminus to activate ZjHB40 and ZjNCED3 expression and ABA accumulation in transgenic jujube calli. In addition, ZjBRC1 widely regulated differentially expressed genes related to ABA homeostasis and ABA signalling, especially by binding to and suppressing ABA receptors. Therefore, these results suggest that JWB phytoplasmas hijack the ZjBRC1-mediated ABA pathways to stimulate lateral bud outgrowth and expansion, providing a strategy to engineer plants resistant to JWB phytoplasma disease and regulate woody plant architecture to promote crop yield and quality.

Effects of exogenous strigolactone on growth, dry matter accumulation, and yield of tissue-cultured ginger

ABSTRACT Ginger tissue culture seedlings can reduce the incidence of soil-borne diseases. However, they have several branches, small ginger bulbs, and slow seed recovery. Strigolactone can inhibit the growth of lateral buds, adjust plant types, and increase crop yield. This study used exogenous strigolactone to treat tissue-cultured ginger and assess its effects on growth, dry matter accumulation, and yield. The results showed that the number of branches and ginger bulbs per plant decreased significantly with the application of exogenous GR24 (Synthetic analog of strigolactone, rac-GR24), and higher concentrations led to a greater decrease. Plant height, stem diameter, root, rhizome, stem sheath, leaf and plant dry matter accumulation, average ginger bulb weight, and yield increased significantly, increasing initially and then decreasing with increasing concentration. Depending on the concentrations, exogenous strigolactone can inhibit the branching of tissue-cultured ginger, reduce the number of branches, increase plant height and stem diameter, optimize the aboveground plant type, increase dry matter accumulation and root-shoot ratio, decrease the number of ginger bulbs per plant, increase the average ginger ball weight, and increase yield. When the GR24 concentration was further increased, the number of branches, the plant height, stem diameter, dry matter accumulation, root shoot ratio, ginger bulbs per plant, average weight of ginger bulbs, and ginger yield decreased. Treatment with 7.5 um L−1 of exogenous GR24 could optimize the plant type of tissue-cultured ginger and increase yield.

Expression profiling and function analysis highlight the positive involvement of sweet cherry PavTCP17 in regulating flower bud dormancy

The TCP transcription factors function diversely in plant growth, development and stress response. The flower bud dormancy was particularly important for the yield formation of fruit trees. However, there has been no in-depth study on the involvement of TCP genes in regulating flower bud dormancy in sweet cherry so far. In the present study, a total of 18 TCP genes were obtained based on the whole genome, which were divided into two subfamilies and three subclasses (PCF, CIN, CYC/TB1) by multiple sequence alignment and evolutionary analysis. Four TCP genes targeted by miR319 were identified in the degradome results. Tissue-specific expression of TCP gene was verified based on transcriptome data and qRT-PCR. The expression patterns of PavTCPs under cold treatment in dormant buds of two cold-requiring sweet cherry cultivars were analyzed, among which PavTCP17 was significantly positively correlated with the gene expressions of gibberellin (GA) degradation and abscisic acid (ABA) synthesis. The abundance of PavTCP17 gene expression was significantly reduced after low cold-requiring cultivars met its chilling demand. The qRT-PCR quantification also showed a decreasing trend of PavTCP17 expression level during blooming process. To further unravel the role of PavTCP17 gene in positively regulating floral bud dormancy, transgenic Arabidopsis overexpressed PavTCP17 was obtained by genetic transformation. Compared with the WT, the number of main branches and rosette leaves was significantly reduced in PavTCP17-overexpressing lines. Moreover, the outgrowth of lateral buds of the PavTCP17-overexpressing lines were remarkably inhibited, mirroring the formation of bud dormancy. Furthermore, PavTCP17 might directly bind to PavNCED3 promoter of sweet cherry, suggesting the implication of PavTCP17 in promoting ABA synthesis, which was essential for bud dormancy. Our study bettered the understanding of TCP gene functions and revealed the mechanism by which PavTCP17 positively regulates flower bud dormancy in sweet cherry.

Brassinosteroid Biosynthetic Gene CmDWF4 Regulates Bud Outgrowth in Chrysanthemum morifolium

Brassinosteroids (BRs), a class of steroid phytohormones, play a critical role in plant growth and development. The <i>DWF4</i> gene encodes a cytochrome P450 enzyme (CYP90B1), which is considered a rate-limiting enzyme in BR biosynthesis. Here, we identified a homologous gene of <i>DWF4</i> in chrysanthemum, <i>CmDWF4</i>. This gene was predicted to encode 491 amino acid residues with a molecular weight of 56.2 kDa and an isoelectric point (pI) of 9.10. Overexpression of <i>CmDWF4</i> in chrysanthemum was found to significantly increase growth rate, number, and length of lateral buds. Transcriptome analysis showed that multiple xyloglucan endotransglycosylase/hydrolase (XTH) family encoding genes associated with cell wall modification were up-regulated in <i>CmDWF4</i>-overexpressing lines. qRT-PCR assay confirmed the up-regulation of <i>CmXTH6</i>, <i>CmXTH23</i>, and <i>CmXTH28</i> in <i>CmDWF4</i>-overexpression line. Overall, this work establishes a mechanism by which BR biosynthetic gene <i>CmDWF4</i> promotes lateral bud outgrowth in chrysanthemum, possibly through regulating cell elongation and expansion.

TCP Transcription Factors Involved in Shoot Development of Ma Bamboo (Dendrocalamus latiflorus Munro).

Ma bamboo (Dendrocalamus latiflorus Munro) is the most widely cultivated clumping bamboo in Southern China and is valuable for both consumption and wood production. The development of bamboo shoots involving the occurrence of lateral buds is unique, and it affects both shoot yield and the resulting timber. Plant-specific TCP transcription factors are involved in plant growth and development, particularly in lateral bud outgrowth and morphogenesis. However, the comprehensive information of the TCP genes in Ma bamboo remains poorly understood. In this study, 66 TCP transcription factors were identified in Ma bamboo at the genome-wide level. Members of the same subfamily had conservative gene structures and conserved motifs. The collinear analysis demonstrated that segmental duplication occurred widely in the TCP transcription factors of Ma bamboo, which mainly led to the expansion of a gene family. Cis-acting elements related to growth and development and stress response were found in the promoter regions of DlTCPs. Expression patterns revealed that DlTCPs have tissue expression specificity, which is usually highly expressed in shoots and leaves. Subcellular localization and transcriptional self-activation experiments demonstrated that the five candidate TCP proteins were typical self-activating nuclear-localized transcription factors. Additionally, the transcriptome analysis of the bamboo shoot buds at different developmental stages helped to clarify the underlying functions of the TCP members during the growth of bamboo shoots. DlTCP12-C, significantly downregulated as the bamboo shoots developed, was selected to further verify its molecular function in Arabidopsis. The DlTCP12-C overexpressing lines exhibited a marked reduction in the number of rosettes and branches compared with the wild type in Arabidopsis, suggesting that DlTCP12-C conservatively inhibits lateral bud outgrowth and branching in plants. This study provides useful insights into the evolutionary patterns and molecular functions of the TCP transcription factors in Ma bamboo and provides a valuable reference for further research on the regulatory mechanism of bamboo shoot development and lateral bud growth.

Cyclanilide Induces Lateral Bud Outgrowth by Modulating Cytokinin Biosynthesis and Signalling Pathways in Apple Identified via Transcriptome Analysis.

Cyclanilide (CYC), a plant growth regulator, is a potent shoot branching agent in apple. However, its mechanism remains unclear. The current study revealed that CYC treatment resulted in massive reprogramming of the axillary bud transcriptome, implicating several hormones in the response. We observed a marked increase (approximately 2-fold) in the level of zeatin riboside and a significant decrease (approximately 2-fold) in the level of abscisic acid (ABA). Zeatin metabolism gene cytokinin (CTK) oxidase 1 (CKX 1) was down-regulated at 168 h after CYC treatment compared with the control. Weighted gene co-expression network analysis of differentially expressed genes demonstrated the turquoise module clusters exhibited the highest positive correlation with zeatin riboside (r = 0.92) and the highest negative correlation with ABA (r = −0.8). A total of 37 genes were significantly enriched in the plant hormone signal transduction pathway in the turquoise module. Among them, the expressions of CTK receptor genes WOODEN LEG and the CTK type-A response regulators genes ARR3 and ARR9 were up-regulated. ABA signal response genes protein phosphatase 2C genes ABI2 and ABI5 were down-regulated in lateral buds after CYC treatment at 168 h. In addition, exogenous application of 6-benzylaminopurine (6-BA, a synthetic type of CTK) and CYC enhanced the inducing effect of CYC, whereas exogenous application of lovastatin (a synthetic type of inhibitor of CTK biosynthesis) or ABA and CYC weakened the promoting effect of CYC. These results collectively revealed that the stimulation of bud growth by CYC might involve CTK biosynthesis and signalling, including genes CKX1 and ARR3/9, which provided a direction for further study of the branching promoting mechanism of CYC.

Proteomic Analysis of Chrysanthemum Lateral Buds after Removing Apical Dominance Based on Label-Free Technology

Studying the genetic basis and regulatory mechanism of chrysanthemum lateral bud outgrowth is of great significance for reduction the production cost of cut chrysanthemum. To clarify the molecular basis of lateral bud elongation after removal of apical dominance in chrysanthemum, label-free quantification analysis was used to analyze the proteome changes after apical bud removal. Quantitative real-time PCR (qPCR) was used to analyze the changes in the expression of three plant hormone-related genes. A total of 440 differentially expressed proteins were successfully identified at three time points during the lateral bud elongation. The number of differentially expressed proteins in the three stages (24 h/0 h, 48 h/0 h, 48 h/24 h) were 219, 332, and 97, respectively. The difference in expressed proteins in the three comparison stages mainly involves RNA processing and modification; translation, ribosomal structure and biogenesis; Posttranslational modification, protein turnover, and chaperones. Path analysis showed that there was various physiological activities in the process of lateral bud dormancy breaking and elongation, which involved energy metabolism, biosynthesis, signal transduction and stress response in the growth process of lateral buds. qPCR indicated that the expression of cytokinin synthesis related gene was significantly increased after the removal of apical dominance, while the expression of strigolactones synthesis related gene experiences a dramatic fall to promote the development of the lateral buds. However, there was a drop before a slight increase in the expression of the auxin synthesis related gene, which was mainly due to the removal of apical dominance that led to the loss of indoleacetic acid in the main stem. However, with formation of the new apical source, indoleacetic acid can be released again.

Expression Analysis of DgD14, DgBRC1 and DgLsL in the Process of Chrysanthemum Lateral Bud Formation

The growth of lateral bud can greatly affect the development of apical bud and reduce the quality of single-flower cut chrysanthemum. However, the wide use of artificial bud removal in production leads to the increase on production cost. Therefore, it is important to study the lateral bud development mechanism in chrysanthemum for plant type regulation and genetic improvement. Auxin (IAA), cytokinins (CKs) and strigolactones (SLs) have direct or indirect effects on the formation of lateral buds. D14, BRC1 and LsL are key factors regulating the signal pathways of hormones, but their regulation mechanisms on the development of lateral buds in chrysanthemum are still unclear. In this study, single-flower cut chrysanthemum ‘Jinba’ and spray cut chrysanthemum ‘Fenyan’ were used as experimental materials. Quantitative real-time PCR was used to observe the effects of apical bud removal and exogenous hormones on the growth of lateral buds and the expression levels of DgD14, DgBRC1 and DgLsL, so as to clarify the expression characteristics of three genes in the process of lateral bud formation. The results showed that GA was effective in promoting the growth of lateral buds, whereas IAA and ABA had little effects on lateral bud growth or even inhibited. Removing apical dominance can significantly affect the expression levels of three genes, which regulated the formation and elongation of lateral buds. Additionally, the three genes showed different responses to different hormone treatments. DgD14 had a significant response to GA, but a gentle response to ABA. The expression levels of DgBRC1 varied in different trends, and it responded to IAA in a more dramatic way. The levels of DgLsL reached the peaks quickly before decreased in most experimental groups, and its response to GA was extraordinary severe.

The leaf senescence-promoting transcription factor AtNAP activates its direct target gene\xa0CYTOKININ OXIDASE\xa03 to facilitate senescence processes by degrading cytokinins

Cytokinins (CKs) are a class of adenine-derived plant hormones that plays pervasive roles in plant growth and development including cell division, morphogenesis, lateral bud outgrowth, leaf expansion and senescence. CKs as a “fountain of youth” prolongs leaf longevity by inhibiting leaf senescence, and therefore must be catabolized for senescence to occur. AtNAP, a senescence-specific transcription factor has a key role in promoting leaf senescence. The role of AtNAP in regulating CK catabolism is unknown. Here we report the identification and characterization of AtNAP-AtCKX3 (cytokinin oxidase 3) module by which CKs are catabolized during leaf senescence in Arabidopsis. Like AtNAP, AtCKX3 is highly upregulated during leaf senescence. When AtNAP is chemically induced AtCKX3 is co-induced; and when AtNAP is knocked out, the expression of AtCKX3 is abolished. AtNAP physically binds to the cis element of the AtCKX3 promoter to direct its expression as revealed by yeast one-hybrid assays and in planta experiments. Leaves of the atckx3 knockout lines have higher CK concentrations and a delayed senescence phenotype compared with those of WT. In contrast, leaves with inducible expression of AtCKX3 have lower CK concentrations and exhibit a precocious senescence phenotype compared with WT. This research reveals that AtNAP transcription factor˗AtCKX3 module regulates leaf senescence by connecting two antagonist plant hormones abscisic acid and CKs.

Morphological, phenological, and transcriptional analyses provide insight into the diverse flowering traits of a mutant of the relic woody plant Liriodendron chinense

Flowering is crucial to plant reproduction and controlled by multiple factors. However, the mechanisms underlying the regulation of flowering in perennial plants are still largely unknown. Here, we first report a super long blooming 1 (slb1) mutant of the relict tree Liriodendron chinense possessing a prolonged blooming period of more than 5 months, in contrast to the 1 month blooming period in the wild type (WT). Phenotypic characterization showed that earlier maturation of lateral shoots was caused by accelerated axillary bud fate, leading to the phenotype of continuous flowering in slb1 mutants. The transcriptional activity of genes related to hormone signaling (auxin, cytokinin, and strigolactone), nutrient availability, and oxidative stress relief further indicated active outgrowth of lateral buds in slb1 mutants. Interestingly, we discovered a unique FT splicing variant with intron retention specific to slb1 mutants, representing a potential causal mutation in the slb1 mutants. Surprisingly, most slb1 inbred offspring flowered precociously with shorter juvenility (~4 months) than that (usually 8–10 years) required in WT plants, indicating heritable variation underlying continuous flowering in slb1 mutants. This study reports an example of a perennial tree mutant that flowers continuously, providing a rare resource for both breeding and genetic research.

Jujube witches' broom phytoplasma effectors SJP1 and SJP2 induce lateral bud outgrowth by repressing the ZjBRC1-controlled auxin efflux channel.

Comprehensively controlling phytoplasma-associated jujube witches' broom (JWB) disease is extremely challenging for the jujube industry. Although the pathogenesis of phytoplasma disease has been highlighted in many plant species, the release of lateral buds from dormancy under JWB phytoplasma infection has not been characterized in woody perennial jujube. Here, two 16SrV-B group phytoplasma effectors, SJP1 and SJP2, were experimentally determined to induce witches' broom with increased lateral branches. In vivo interaction and subcellular localization analyses showed that both SJP1 and SJP2 were translocated from the cytoplasm to the nucleus to target the CYC/TB1-TCP transcription factor ZjBRC1. The N- and C-terminal coiled-coil domains of SJP1 and SJP2 were required for the TCP-binding ability. ZjBRC1 bound directly to the auxin efflux carrier ZjPIN1c/3 promoters and down-regulated their expression to promote the accumulation of endogenous auxin indole-3-acetic acid in jujube calli. Furthermore, JWB phytoplasma infection suppressed ZjBRC1 accumulation and induced ZjPIN1c/3 expression to stimulate lateral bud outgrowth. Therefore, SJP1 and SJP2 stimulate lateral bud outgrowth, at least partly, by repressing the ZjBRC1-controlled auxin efflux channel in jujube, representing a potential strategy for comprehensive phytoplasma-associated disease control and a resource for gene editing breeding to create new cultivars with varying degrees of shoot branching.

Regulation of shoot branching in arabidopsis by trehalose 6-phosphate.

Trehalose 6-phosphate (Tre6P) is a sucrose signalling metabolite that has been implicated in regulation of shoot branching, but its precise role is not understood. We expressed tagged forms of TREHALOSE-6-PHOSPHATE SYNTHASE1 (TPS1) to determine where Tre6P is synthesized in arabidopsis (Arabidopsis thaliana), and investigated the impact of localized changes in Tre6P levels, in axillary buds or vascular tissues, on shoot branching in wild-type and branching mutant backgrounds. TPS1 is expressed in axillary buds and the subtending vasculature, as well as in the leaf and stem vasculature. Expression of a heterologous Tre6P phosphatase (TPP) to lower Tre6P in axillary buds strongly delayed bud outgrowth in long days and inhibited branching in short days. TPP expression in the vasculature also delayed lateral bud outgrowth and decreased branching. Increased Tre6P in the vasculature enhanced branching and was accompanied by higher expression of FLOWERING LOCUS T (FT) and upregulation of sucrose transporters. Increased vascular Tre6P levels enhanced branching in branched1 but not in ft mutant backgrounds. These results provide direct genetic evidence of a local role for Tre6P in regulation of axillary bud outgrowth within the buds themselves, and also connect Tre6P with systemic regulation of shoot branching via FT.

Relationship between inorganic elements in rhizosphere soil and rhizome radial striations in Ligusticum chuanxiong

The study is aimed to reveal the fluctuation of the inorganic elements in the rhizosphere soil of Ligusticum chuanxiong during their whole growth period, and explore the relationship between that fluctuation and the formation of radial striations character in the rhizomes. During the cultivation period of L. chuanxiong, the rhizosphere soil samples were taken regularly, and the content of 26 inorganic elements were determined by X-ray fluorescence spectrometry(XRF). Then the difference between the radial striations and un-radial striations rhizomes were analyzed for their fluctuation of the inorganic elements. The results showed that there were different &quot;key period&quot; and &quot;key elements&quot; in the rhizosphere elements content of L. chuanxiong rhizome with radial and un-radial striations, and different element coordination and antagonistic relationship. The key fluctuation period of rhizosphere elements in un-radial striations group were in 0-60 and 60-150 days, of which 22 elements such as Na, Mg, Al were the key elements in 0-60 days, and 5 elements such as Sr, Hf, Pb, Co, Ce were the key elements in 60-150 days. The key fluctuation period of rhizosphere elements in radial striations group were in 0-60 and 210-270 days, of which four elements such as Na, Co, Ce, As are the key change elements in 0-60 days, and 18 elements such as Mg, Al, Si are the key change elements in 210-270 days. At the same time, the study showed that the fluctuation of inorganic elements in rhizosphere soil coincided with the growth and development process of L. chuanxiong and the key period of the formation of &quot;radial striations rhizome&quot;. The key stage which the rapid growth of lateral buds of rhizome affected the formation of radial striations is 60-150 days after planting, while the increase of Sr and Co elements is likely to be an important reason for the expansion of lateral buds of rhizome and the failure to form typical &quot;radial striations rhizome&quot; in un-radial striations group.

Peculiarities of regeneration of representatives of the genus Amelanchier medik. in vitro

The article presents the results of a study of the organogenesis of representatives of the genus Amelanchier Medik. at the stage of micropropagation. Serviceberry is a promising culture for Russia, characterized by resistance to various abiotic factors and possessing valuable fruit qualities. The purpose of this work was to identify the peculiarirties of regeneration and optimization the stage of micropropagation of varieties of serviceberry. Varieties belonging to different species of the genus Amelanchier Medik were used as objects of study: Krasnoyarskaya, Mandan (Amelanchier alnifolia (Nutt.) Nutt. Ex M. Roem.); Prince William (Amelanchier canadensis (L.) Medik.); Ballerina (Amelanchier×grandiflora Rehder); ×Amelasorbus Rehder. The influence of the genotype, the source of cytokinin and its concentration on the height of microshoots, count of microshoots and the multiplication rate of varieties of serviceberry has been established. 6-benzylaminopurn induced the formation of adventive explants microshoots, and 2-isopentyl-adenine had a weak stimulating effect on the growth of lateral buds. The use of 6-benzylaminopurine at a concentration of 1.0 mg/l leads to a significant increase in count of microshoots in all studied genotypes. In varieties of Prince William (A. canadensis) and Ballerina (A.×grandiflora), the maximum height of microshoots was achieved in a nutrient medium with 1.0 mg/l of 6-BAP and 18.8 and 19.1 mm. The highest microshoots height in varieties A. alnifolia (Krasnoyarskaya, Mandan) and × Amelasorbus was obtained on a medium with 0.2 mg/l 6-BAP (19.0 and 16.4 mm). The maximum count of microshoots was characterized by the Krasnoyarskaya variety (4.8), the minimum by Prince William variety (1.9).