Development Of Vascular Bundles Research Articles

Physiological Mechanisms of BvCPD Regulation in Sugar Beet Growth

Sugar beet is an important sugar crop, and its roots are mainly used for processing raw materials to produce products such as sugar, molasses, and saccharin, as well as being used as fodder for livestock. BvCPD, a key enzyme gene for brassinosteroid (BR) synthesis, regulates the development of parenchyma cells and vascular bundles by promoting BR synthesis, which promotes the expansion of the sugar beet taproot and influences the growth, development, and yield of sugar beets. This study investigated the impact of BvCPD on the physiological metabolism of sugar beet utilizing BvCPD overexpression, silent, and wild-type (WT) lines. BvCPD increased the chlorophyll content and maximum photochemical efficiency and improved the photosynthetic characteristics of sugar beet leaves. Simultaneously, BvCPD increased the rate of sugar beet taproot respiration and ATP content by enhancing the activities of phosphoglycerate kinase, alcohol dehydrogenase, sucrose synthase, and sucrose synthase catabolism. Moreover, BvCPD induced changes in the sugar fraction content, which increased the sugar yield of a single plant. In addition, BvCPD promoted water absorption, nitrogen accumulation, and lignin/cellulose synthesis activities, facilitated by increased activities of phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, cellulose synthase, and protein serine/threonine phosphatases, providing the requisite energy and materials for sugar beet growth. These findings not only provide a new perspective for understanding the physiological mechanisms regulating the growth of sugar beets but also provide a theoretical basis for the future improvement of sugar beet varieties through molecular breeding techniques.

Effects of GA3 Treatments on Fruit Vascular Structure and Water Transport of Grape

ABSTRACT Exogenous gibberellic acid was applied to regulate fruit growth of grapes to acquire high quality seedless berries. The vascular bundles provide the pathway of water and nutrient transport into the fruit and play an important role in berry growth and sugar accumulation. Therefore, changes in berry size and quality are closely related to the structure and function of the vascular tissue. In this study, 10-year-old “Shine Muscat” grape vines were treated with GA3 in grapevine production. Based on previous research and experimental environmental conditions, four treatments were applied: elongating cluster（5 mg L−1 GA3 on Apr. 28）+ seedless（25 mg L−1 GA3 on May. 24）+ expanding（50 mg L−1 GA3 on Jun. 7） (T1), seedless（25 mg L−1 GA3 on May. 24）+ expanding（50 mg L−1 GA3 on Jun. 7） (T2), expanding（50 mg L−1 GA3 on Jun. 7） (T3) and water (CK). Compared to CK, all fruits treated with GA3 had greater berry size. In addition, GA3 treated grapes had greater vascular bundle areas, including the areas of both phloem and xylem, as well as a greater number of vessels compared to control fruit. During the first rapid growth stage, water transport into the grape was rapid and did not differ among treatments. During veraison, the water transport rate among the four treatments differed, and the rank of speed was T2>T3>CK>T1. Therefore, we found that GA3 treatment can significantly promote the differentiation of vascular tissues and improve water transport capacity and phloem sugar unloading; T2 promoted the development of vascular bundles, enhanced water transport speed and phloem sugar unloading of fruit after veraison, and increased berry size.

Bulked Segregant RNA-Seq Reveals Different Gene Expression Patterns and Mutant Genes Associated with the Zigzag Pattern of Tea Plants (Camellia sinensis).

The unique zigzag-patterned tea plant is a rare germplasm resource. However, the molecular mechanism behind the formation of zigzag stems remains unclear. To address this, a BC1 genetic population of tea plants with zigzag stems was studied using histological observation and bulked segregant RNA-seq. The analysis revealed 1494 differentially expressed genes (DEGs) between the upright and zigzag stem groups. These DEGs may regulate the transduction and biosynthesis of plant hormones, and the effects on the phenylpropane biosynthesis pathways may cause the accumulation of lignin. Tissue sections further supported this finding, showing differences in cell wall thickness between upright and curved stems, potentially due to lignin accumulation. Additionally, 262 single-nucleotide polymorphisms (SNPs) across 38 genes were identified as key SNPs, and 5 genes related to zigzag stems were identified through homologous gene function annotation. Mutations in these genes may impact auxin distribution and content, resulting in the asymmetric development of vascular bundles in curved stems. In summary, we identified the key genes associated with the tortuous phenotype by using BSR-seq on a BC1 population to minimize genetic background noise.

Feasible strategies for efficient propagation system of Paeonia lactiflora ‘Hang Baishao’: In vitro culture of embryos

Herbaceous peony (Paeonia lactiflora Pall.) is a renowned traditional Chinese flower, which has been cherished by people since ancient times. It holds significant value as both an agricultural cash crop and an ornamental and medicinal plant. However, the lack of in vitro propagation system has been long hindered the commercial production of this species and the development of new cultivars. In this study, the low chilling requirement cultivar Paeonia lactiflora ‘Hang Baishao’ that originated from low latitudes of China, was used to study the in vitro culture of embryos. The results of our experiment showed that the optimal medium for in vitro culture of embryos was a 1/2 Murashige and Skoog (MS) medium supplemented with 1.0 mg/L 6-benzyladenine (6-BA), 1.0 mg/L gibberellic acid (GA3) and 2.0 g/L polyvinyl pyrrolidone (PVP). Additionally, histological observations revealed the crucial role of vascular bundle development in the survival of transplants. Plants with well-developed vascular tissue exhibited better transplanting success. This study presents, for the first time, a protocol for embryos propagation and transplanting of ‘Hang Baishao’, a cultivar with low chilling requirement (CR) during winter. This study provides an efficient method for in vitro culture of ‘Hang Baishao’, and makes it possible for large-scale production, utilization, and germplasm preservation of this species.

BvCPD promotes parenchyma cell and vascular bundle development in sugar beet (Beta vulgaris L.) taproot.

Constitutive photomorpogenic dwarf (CPD) is a pivotal enzyme gene for brassinolide (BR) synthesis and plays an important role in plant growth, including increasing plant biomass and plant height, elongating cells, and promoting xylem differentiation. However, little is known about the function of the CPD gene in sugar beet. In the current study, we isolated CPD from Beta vulgaris L. (BvCPD), which encodes protein localized in the nucleus, cell membrane, and cell wall. BvCPD was strongly expressed in parenchyma cells and vascular bundles. The transgenic sugar beet overexpressing BvCPD exhibited larger diameter than that of the wild type (WT), which mainly owing to the increased number and size of parenchyma cells, the enlarged lumen and area of vessel in the xylem. Additionally, overexpression of BvCPD increased the synthesis of endogenous BR, causing changes in the content of endogenous auxin (IAA) and gibberellin (GA) and accumulation of cellulose and lignin in cambium 1-4 rings of the taproot. These results suggest that BvCPD can promote the biosynthesis of endogenous BR, improve cell wall components, promote the development of parenchyma cells and vascular bundle, thereby playing an important role in promoting the growth and development of sugar beet taproot.

Introduction pages, NBHA-CN 51(2), 2023

The papers published in Notulae Botanicae Horti Agrobotanici Cluj-Napoca, Issue 2, Volume 51, 2023 represent new exciting research in different topics of life science, respectively in plant science, horticulture, agronomy, crop science, and forestry. Among the interesting articles we invite you to find news about: Cloning and analysis of DlERF23 gene in flower induction; Transcriptomic analysis reveals transcription factors involved in vascular bundle development and tissue maturation in ginger rhizomes (Zingiber officinale Roscoe); In vitro direct organogenesis of the medicinal single-mountain local prioritized vulnerable Greek endemic Achillea occulta under different medium variants; Methodological contribution on seed germination and seedling initial growth tests in wild plants; Deciphering the myth of cold tolerance in soybean: An overview of molecular breeding applications; The gall midge Obolodiplosis robiniae Haldemann (Diptera Cecidomyiidae) new invasive alien species in Europa; Effect of silvicultural treatment of individual selection on the horizontal structure of a pine-oak forest in northern Mexico.

Difference in calcium accumulation in the fruit of two apple varieties and its relationship with vascular bundle development in the pedicel

Calcium (Ca) is an essential mineral element for plant growth and development that plays a key role in fruit growth and quality formation. To study the absorption and transport of Ca in ‘Tonami’ (susceptible to bitter pit (BP)) and ‘Fuji’ (resistant to BP), fruiting branches of ‘Tonami’ and ‘Fuji’ were injected with 0.05% 44Ca at the fruitlet stage (37 days after full bloom (DAFB)) and fruit expansion stage (72 DAFB). At the fruitlet and fruit expansion stages, the 44Ca content of fruiting branches increased from high to low in leaves, shoots, and fruit. In fruit, the 44Ca content was highest in the peel and lowest in the flesh. In both ‘Tonami’ and ‘Fuji’, Ca uptake was more efficient at the fruitlet stage than at the fruit expansion stage. ‘Tonami’ had a shorter growth and development time and earlier loss of fruit pedicel xylem structure and functionality than ‘Fuji’, resulting in less Ca accumulation in the fruit. The low Ca uptake efficiency of ‘Tonami’ fruit, the short Ca accumulation time, and the high Ca dilution resulted in low 44Ca content in the fruit, which may explain the susceptibility of ‘Tonami’ fruit to BP disease.

Transcriptomic analysis reveals transcription factors involved in vascular bundle development and tissue maturation in ginger rhizomes (Zingiber officinale Roscoe)

Ginger (Zingiber officinale Roscoe) is an important vegetable with medicinal value. Rhizome development determines ginger yield and quality. However, little information is available about the molecular features underlying rhizome expansion and maturation. In this study, we investigated anatomy characteristics, lignin accumulation and transcriptome profiles during rhizome development. In young rhizomes, the vascular bundle (VB) was generated with only vessels in it, whereas in matured rhizomes, three to five layers of fibre bundle in the xylem were formed, resulting in VB enlargement. It indicates VB development favouring rhizome swelling. With rhizome matured, the lignin content was remarkably elevated, thus facilitating tissue lignification. To explore the regulators for rhizome development, nine libraries including ginger young rhizomes (GYR), growing rhizomes (GGR), and matured rhizomes (GMR) were established for RNA-Seq, a total of 1264 transcription factors (TFs) were identified. Among them, 35, 116, and 14 differentially expressed TFs were obtained between GYR and GGR, GYR and GMR, and GGR and GMR, respectively. These TFs were further divided into three categories. Among them, three ZobHLHs (homologs of Arabidopsis LHW and AtbHLH096) as well as one DIVARICATA homolog in ginger might play crucial roles in controlling VB development. Four ZoWRKYs and two ZoNACs might be potential regulators associated with rhizome maturation. Three ZoAP2/ERFs and one ZoARF might participate in rhizome development via hormone signalling. This result provides a molecular basis for rhizome expansion and maturation in ginger.

BEAR1, a bHLH transcription factor, controls seedling growth by regulating gibberellins biosynthesis in rice

The genetic pathways of rice seedling growth have a major impact on seedling emergence from soil and development. In this study, we identified a new bHLH transcription factor, BEAR1, from rice RNAi mutant library. Both the BEAR1-RNAi and bear1 CRISPR mutants had accelerated seedling growth. Histological section of leaves showed accelerated development of lacuna and vascular bundles in bear1 mutant. GUS staining revealed that BEAR1 was highly expressed in coleoptiles and leaves at seedling stage. Expression analysis of gibberellin (GA) biosynthesis and metabolic genes and content determination of active GAs indicated that the expression of GA biosynthesis genes, especially OsKS4 and OsCPS2, were upregulated and the GAs content were significantly increased in bear1, which correlated with the seedling phenotype of bear1 mutant. Molecular and biochemical assays revealed that BEAR1 directly binds to the promoter of OsKS4, thereby repressing its expression. Haplotypes analysis showed clear differentiation in indica and japonica rice varieties, and a strong correlation with seedling height. These findings provide novel insights into the regulation of seedling growth in rice.

OsAAP15, an amino acid transporter in response to nitrogen concentration, mediates panicle branching and grain yield in rice

N is essential for plant architecture, particularly tillering. However, whether and how N mediates panicle branching and influences rice grain yield remains unclear. In order to identify genes and pathways associated with N-regulated panicle branching, we treated rice with different concentrations of N to determine the key genes by transcriptomic analysis and function verification. We measured panicle growth in response to N, and found that panicle branching benefits from 2 mM exogenous N, and 2–5 mM N is essential for vascular bundle, phloem, and xylem development in these branches. Interestingly, total N concentrations increased continuously with N 0–2 mM and decreased continuously with N 5–15 mM, whereas the concentrations of amino acids Tyr and Val increased continuously with N 0–15 mM in the panicle. Furthermore, N metabolism, phytohormone signal transduction, stress response, and photosynthesis pathways play important roles in response to nitrogen of regulating panicle branching. Altered expression of key N-response amino acid transporter gene OsAAP15 positively regulated panicle branching at low N concentrations, however, OsAAP15 negatively influenced it at high N concentrations. Overexpression of OsAAP15 in the field significantly increased primary and secondary branches, filled grain number, and grain yield by regulating the concentrations of amino acids Tyr and Val in the panicle. Taken together, OsAAP15, an amino acid transporter in response to nitrogen concentration, could mediate panicle branching and grain yield, and it may have applications in rice breeding to improve grain yield under extreme N concentrations.

Effects of semi-deep water irrigation on hybrid indica rice lodging resistance.

Recently, rice-aquatic animal integrated farming (RAAIF) has grown rapidly in China due to its favorable benefits and the lower application of pesticides and fertilizers. However, rice lodging occurs frequently under RAAIF, which restricts rice yield. We assumed that semi-deep water irrigation may cause weaker rice-lodging resistance since it is the most significant environmental factor for RAAIF that distinguishes it from rice monoculture. To investigate the response of rice stem lodging resistance to semi-deep water irrigation and its mechanism, three irrigation management modes, namely the typical high-yield irrigation model that is mainly based on swallow and wetting (CK), semi-deep water irrigation from the late tillering stage to the jointing stage (SDI1), and semi-deep water irrigation from the jointing stage to the middle grain-filling stage (SDI2), were conducted using three hybrid indica rice varieties: Shenliangyou136 (SLY136), Huiliangyousimiao (HLYSM), and Wanxiangyou982 (WXY982). Mechanics analysis indicated that the bending moment by the whole plant (WP) and the breaking strength (M) were both decreased by semi-deep water irrigation when compared with CK, while M presented a larger decreasing amplitude than WP, which induced the increased lodging index (LI) of rice, for all the tested varieties. SLY136 and HLYSM were affected more strongly by SDI1, whereas WXY982 was affected more strongly by SDI2. Significant weaker breaking force under two semi-deep water irrigation modes contributed to the decreased M relative to CK. Morphology results showed that semi-deep water irrigation reduced the thickness of mechanical tissues, sclerenchyma cells, and parenchyma cells; reduced the number of vascular bundles; and caused a looser arrangement, inducing the lower fullness of the rice basal internode. Decreased accumulation of lignin and cellulose was also linked to the weaker breaking force of the basal internode under semi-deep water irrigation, which was verified by correlation analysis. WXY982 had obvious lower structural carbohydrates content under semi-deep water irrigation than the other two varieties and thus showed worse breaking force and LI. In conclusion, the worse mechanical strength of the rice basal internode under semi-deep water irrigation was closely associated with weaker vascular bundle development and suppressed structural carbohydrate accumulation, and the decreasing degree of lodging resistance varied between rice varieties and semi-deep water irrigation periods.

Biomolecular Strategies for Vascular Bundle Development to Improve Crop Yield.

The need to produce crops with higher yields is critical due to a growing global population, depletion of agricultural land, and severe climate change. Compared with the "source" and "sink" transport systems that have been studied a lot, the development and utilization of vascular bundles (conducting vessels in plants) are increasingly important. Due to the complexity of the vascular system, its structure, and its delicate and deep position in the plant body, the current research on model plants remains basic knowledge and has not been repeated for crops and applied to field production. In this review, we aim to summarize the current knowledge regarding biomolecular strategies of vascular bundles in transport systems (source-flow-sink), allocation, helping crop architecture establishment, and influence of the external environment. It is expected to help understand how to use sophisticated and advancing genetic engineering technology to improve the vascular system of crops to increase yield.

Characterization of the Transcriptome and Proteome of Brassica napus Reveals the Close Relation between DW871 Dwarfing Phenotype and Stalk Tissue.

Rapeseed is a significant oil-bearing cash crop. As a hybrid crop, Brassica napus L. produces a high yield, but it also has drawbacks such as a tall stalk, easy lodging, and is not suitable for mechanized production. To address these concerns, we created the DW871 rapeseed dwarf variety, which has a high yield, high oil content, and is suitable for mechanized production. To fully comprehend the dwarfing mechanism of DW871 and provide a theoretical foundation for future applications of the variety, we used transcriptome and proteome sequencing to identify genes and proteins associated with the dwarfing phenotype, using homologous high-stalk material HW871 as a control. By RNA-seq and iTRAQ, we discovered 8665 DEGs and 50 DAPs. Comprehensive transcription and translation level analysis revealed 25 correlations, 23 of which have the same expression trend, involving monolignin synthesis, pectin-lignin assembly, lignification, glucose modification, cell wall composition and architecture, cell morphology, vascular bundle development, and stalk tissue composition and architecture. As a result of these results, we can formulate a hypothesis about the DW871 dwarfing phenotype: plant hormone signal transduction, such as IAA and BRs, is linked to the formation of dwarf phenotypes, and metabolic pathways related to lignin synthesis, such as phenylpropane biosynthesis, also play a role. Our works will contribute to a better understanding of the genes and proteins involved in the rapeseed dwarf phenotype, and we will propose new insights into the dwarfing mechanism of Brassica napus L.

Overexpression of PvWOX3a in switchgrass promotes stem development and increases plant height

Switchgrass (Panicum virgatum L.) is an important perennial, noninvasive, tall ornamental grass that adds color and texture to gardens and landscapes. Moreover, switchgrass has been considered a forage and bioenergy crop because of its vigorous growth, low-input requirements, and broad geography. Here, we identified PvWOX3a from switchgrass, which encodes a WUSCHEL-related homeobox transcription factor. Transgenic overexpression of PvWOX3a in switchgrass increased stem length, internode diameter, and leaf blade length and width, all of which contributed to a 95% average increase in dry weight biomass compared with control plants. Yeast one-hybrid and transient dual-luciferase assays showed that PvWOX3a can repress the expression of gibberellin 2-oxidase and cytokinin oxidase/dehydrogenase through apparently direct interaction with their promoter sequences. These results suggested that overexpression of PvWOX3a could increase gibberellin and cytokinin levels in transgenic switchgrass plants, which promotes cell division, elongation, and vascular bundle development. We also overexpressed PvWOX3a in a transgenic miR156-overexpressing switchgrass line that characteristically exhibited more tillers, thinner internodes, and narrower leaf blades. Double transgenic switchgrass plants displayed significant increases in internode length and diameter, leaf blade width, and plant height but retained a tiller number comparable to that of plants expressing miR156 alone. Ultimately, the double transgenic switchgrass plants produced 174% more dry-weight biomass and 162% more solubilized sugars on average than control plants. These findings indicated that PvWOX3a is a viable potential genetic target for engineering improved shoot architecture and biomass yield of horticulture, fodder, and biofuel crops.

Rambutan genome revealed gene networks for spine formation and aril development

Rambutan is a popular tropical fruit known for its exotic appearance, has long flexible spines on shells, extraordinary aril growth, desirable nutrition, and a favorable taste. The genome of an elite rambutan cultivar Baoyan 7 was assembled into 328 Mb in 16 pseudo-chromosomes. Comparative genomics analysis between rambutan and lychee revealed that rambutan chromosomes 8 and 12 are collinear with lychee chromosome 1, which resulted in a chromosome fission event in rambutan (n = 16) or a fusion event in lychee (n = 15) after their divergence from a common ancestor 15.7 million years ago. Root development genes played a crucial role in spine development, such as endoplasmic reticulum pathway genes, jasmonic acid response genes, vascular bundle development genes, and K+ transport genes. Aril development was regulated by D-class genes (STK and SHP1), plant hormone and phenylpropanoid biosynthesis genes, and sugar metabolism genes. The lower rate of male sterility of hermaphroditic flowers appears to be regulated by MYB24. Population genomic analyses revealed genes in selective sweeps during domestication that are related to fruit morphology and environment stress response. These findings enhance our understanding of spine and aril development and provide genomic resources for rambutan improvement.

A positive response of ginger root zone and rhizome development to suitable sowing depth.

Sowing depth significantly affects ginger (Zingiber officinale Roscoe) yields, and sowing depth can affect rhizosphere community structure through root exudates. However, the relationship between the reaction process in root zone and ginger rhizome development is unclear. In this study, we investigated the rhizome and root development and rhizosphere environment at different sowing depths (2cm (SD2), 5cm (SD5), and 10cm (SD10)). It was found that SD10 significantly increased ginger yield, which is related to the development of vascular bundles and the expression of aquaporin. PLS-PM analysis found that root length, root absorption capacity, and soil enzymes have the strongest correlation with yield, while root diameter is negatively correlated with yield. Under SD10, the increase of auxin and ethylene content together with the expression of ARF7, LBD16, and PIN1 promoted the development of lateral roots. In addition, SD10 increased the secretion of root organic acids, amino acids, and carbohydrates, which in turn promoted the development of rhizosphere bacteria. The promotion of SD10 on nitrogen cycle and nitrogen fixation ability in turn promoted the development of ginger.

Knockout of Auxin Response Factor SlARF4 Improves Tomato Resistance to Water Deficit.

Auxin response factors (ARFs) play important roles in various plant physiological processes; however, knowledge of the exact role of ARFs in plant responses to water deficit is limited. In this study, SlARF4, a member of the ARF family, was functionally characterized under water deficit. Real-time fluorescence quantitative polymerase chain reaction (PCR) and β-glucuronidase (GUS) staining showed that water deficit and abscisic acid (ABA) treatment reduced the expression of SlARF4. SlARF4 was expressed in the vascular bundles and guard cells of tomato stomata. Loss of function of SlARF4 (arf4) by using Clustered Regularly Interspaced Short Palindromic Repeats/Cas 9 (CRISPR/Cas 9) technology enhanced plant resistance to water stress and rehydration ability. The arf4 mutant plants exhibited curly leaves and a thick stem. Malondialdehyde content was significantly lower in arf4 mutants than in wildtype plants under water stress; furthermore, arf4 mutants showed higher content of antioxidant substances, superoxide dismutase, actual photochemical efficiency of photosystem II (PSII), and catalase activities. Stomatal and vascular bundle morphology was changed in arf4 mutants. We identified 628 differentially expressed genes specifically expressed under water deficit in arf4 mutants; six of these genes, including ABA signaling pathway-related genes, were differentially expressed between the wildtype and arf4 mutants under water deficit and unlimited water supply. Auxin responsive element (AuxRE) elements were found in these genes’ promoters indicating that SlARF4 participates in ABA signaling pathways by regulating the expression of SlABI5/ABF and SCL3, thereby influencing stomatal morphology and vascular bundle development and ultimately improving plant resistance to water deficit.

Functional analysis of the cotton CLE polypeptide signaling gene family in plant growth and development

The CLAVATA3 (CLV3)/EMBRYO SURROUNDING REGION (ESR)–RELATED (CLE) gene family encodes a large number of polypeptide signaling molecules involved in the regulation of shoot apical meristem division and root and vascular bundle development in a variety of plants. CLE family genes encode important short peptide hormones; however, the functions of these signaling polypeptides in cotton remain largely unknown. In the current work, we studied the effects of the CLE family genes on growth and development in cotton. Based on the presence of a conserved CLE motif of 13 amino acids, 93 genes were characterized as GhCLE gene family members, and these were subcategorized into 7 groups. A preliminary analysis of the cotton CLE gene family indicated that the activity of its members tends to be conserved in terms of both the 13-residue conserved domain at the C-terminus and their subcellular localization pattern. Among the 14 tested genes, the ectopic overexpression of GhCLE5::GFP partially mimicked the phenotype of the clv3 mutant in Arabidopsis. GhCLE5 could affect the endogenous CLV3 in binding to the receptor complex, comprised of CLV1, CLV2, and CRN, in the yeast two-hybrid assay and split-luciferase assay. Silencing GhCLE5 in cotton caused a short seedling phenotype. Therefore, we concluded that the cotton GhCLE gene family is functionally conserved in apical shoot development regulation. These results indicate that CLE also plays roles in cotton development as a short peptide hormone.

Sufficient assimilate provision to fruits in different positions within an inflorescence: a critical factor determining the morphogenesis and development of Yatu in ‘Yali’ pear (Pyrus bretschneideri Rehd.)

ABSTRACT In ‘Yali’ pears (Pyrus bretschneideri Rehd.) there is extra tissue formed on one side of the fruit, near the pedicel, causing a shape like a duck head termed Yatu, which is based on the Chinese phonetic alphabets of the raised duck head. The cell number of Yatu tissue has been known to be a direct factor influencing Yatu formation. The Yatu formation status among the fruits within an inflorescence is different, although the reason is not yet clear. Here, the per cent of first-order fruits with Yatu was 1.36 times higher than that of sixth-order fruits. The fruits with typical Yatu in first-order fruits were 3.52 times higher than in sixth-order fruits. The shorter peduncles of first-order fruits developed with a 1.25 times greater diameter compared to sixth-order fruits. The longitudinal diameter of the cross-section of vascular bundles was significantly higher in first-order fruits than in sixth-order fruits. The relatively higher GA3 and ZR levels, lower ABA content at second day before bloom (DBB) promoted the vascular bundle development. These results suggest that the well-developed vascular bundles, relatively higher GA3 content, and lower ABA content promoted Yatu development. The first-order fruits have a higher ability to form Yatu than sixth-order fruits.

Transcription-mediated tissue-specific lignification of vascular bundle causes trade-offs between growth and defence capacity during invasion of Solidago canadensis.

Allocation of more resources to growth but less to defense causing growth vigor of invasive alien plant populations contributes to successful invasion. However, few studies has addressed to relationship between vascular development variation and this mechanism. In this study, a common garden experimentwas established to compare the growth and vascular bundle development between native and introduced populations of Solidago canadensis, which is a wide-distributed invasive species in China. Our results suggested that the rapid growth of introduced populations could be explained by the well-developed and highly lignified xylem; while native populations present more developed and highly lignified phloem, which contributed more resistance to the infection of Sclerotiun rofsii compared with introduced populations. This difference was resulted from tissue-specific tradeoff distribution of lignification related gene expression between xylem and phloem, which is regulated by upstream MYB transcription factors. Our study gives a novel insight of mechanism that explain invasion success: lignin-related gene transcription-mediated tissue-specific lignification of vascular bundle contributes tradeoffs in resource allocation between growth and defence capacity during successful invasion of S. canadensis.