Inflorescence Stem Research Articles

A land plant phylogenetic framework for GLABROUS INFLORESCENCE STEMS (GIS), SUPERMAN, JAGGED and allies plus their TOPLESS co-repressor

Members of the plant specific family of C1-1i zincfinger transcriptionfactors (ZF-TFs), such as SUPERMAN, JAGGED, KNUCKLES or GIS,regulatediversedevelopmental processes including sexual reproduction. C1-1is consist of one zinc-finger and one to two EAR domains, connected by large intrinsically disordered regions (IDR). While the role of C1-i1 ZF-TFs in development processes is well known for some genes in Arabidopsis, rice or tomatoa comprehensive and broadphylogenetic background is lacking, yet knowledge of orthology is a requirement for a better understanding of C1-1i-Zf-TFs diverse roles in plants. Here, we provide a fine-grained and land plant wide classification of C1-1i sub-families and their known co-repressors TOPLESS and TOPLESS RELATED. Our work combines the identification of orthologous groups with Maximum-Likelihood phylogeny reconstructions and digital gene expression analyses mining high quality land plant genomes and transcriptomes to generate a comprehensive framework of C1-1i ZF-TF evolution. We show that C1-1i’s are low to moderate copy genesand that orthologous genesonly partiallyhaveconserved sub-family and life cycle stage dependent expression pattern across land plants while others are highly diverged. Our workprovides the phylogenetic framework for C1-1i ZF-TFs, s and strengthen C1-1 ZF-TFs as a potential model for IDR-research in plants.

Regulation of stomatal development by epidermal, subepidermal and long-distance signals.

Plant leaves consist of three layers, including epidermis, mesophyll and vascular tissues. Their development is meticulously orchestrated. Stomata are the specified structures on the epidermis for uptake of carbon dioxide (CO2) while release of water vapour and oxygen (O2), and thus play essential roles in regulation of plant photosynthesis and water use efficiency. To function efficiently, stomatal formation must coordinate with the development of other epidermal cell types, such as pavement cell and trichome, and tissues of other layers, such as mesophyll and leaf vein. This review summarizes the regulation of stomatal development in three dimensions (3D). In the epidermis, specific stomatal transcription factors determine cell fate transitions and also activate a ligand-receptor- MITOGEN-ACTIVATED PROTEIN KINASE (MAPK) signaling for ensuring proper stomatal density and patterning. This forms the core regulation network of stomatal development, which integrates various environmental cues and phytohormone signals to modulate stomatal production. Under the epidermis, mesophyll, endodermis of hypocotyl and inflorescence stem, and veins in grasses secrete mobile signals to influence stomatal formation in the epidermis. In addition, long-distance signals which may include phytohormones, RNAs, peptides and proteins originated from other plant organs modulate stomatal development, enabling plants to systematically adapt to the ever changing environment.

Коллекционные сортообразцы зернового сорго как исходный материал для селекции продуктивных сортов с высоким выходом протеина зерна

The study of samples of grain sorghum in a collection nursery during 2021-2023 made it possible to identify valuable forms according to a complex of economically useful features. A significant variation of the studied parameters was revealed – from 13.9% (weight of 1000 grains) to 38.1% (extension of the inflorescence stem). Such a wide variability of features contributed to the identification of forms with the highest values of useful indicators. The results of three years of research have shown the presence in the nursery of valuable lines with a complex of economically valuable traits that are donors of important indicators. The starting material for breeding varieties with large grains were samples k-4075, k-2058, O-k-8803 (1) and O-k-8803 (2) with a mass of 1000 seeds of 33.7-37.9 g. Donors of increased grain yield were identified – k-3267, k-1343, k-9115, k-8850, 06-2037 (5.16-5.42 t/ha) and biomass – k-10112, k-9115, k-8850, Tajik (21.12-22.35 t/ha). The variation of the protein content in the grain of the samples was found in the range from 9.58% (k-1343) to 11.44% (k-1882) at the level of the indicator for the Start standard variety of 10.13%. A high calculated protein yield in the grain yield (more than 400 kg/ha) was determined in the samples: k-99 – 414.29 kg/ha, k-3267 – 451.10 kg/ha, k-1343 – 445.47 kg/ha, Tajik – 463.07 kg/ha, k-9115 – 457.04 kg/ha, k-8850 – 509.82 kg/ha, 06-2037 – 461.81 kg/ha. The highest protein harvest was found in the grain yield of sample k-8850 – 509.82 kg/ha, exceeding the value of the indicator for the Start standard by 152.23 kg/ha or 42.6%. Keywords: GRAIN SORGHUM, COLLECTIBLE VARIETY, ELEMENTS OF SAMPLE PRODUCTIVITY, PROTEIN CONTENT AND YIELD

Global dynamics and cytokinin participation of salt gland development trajectory in recretohalophyte Limonium bicolor.

Salt gland is an epidermal Na+ secretory structure that enhances salt resistance in the recretohalophyte sea lavender (Limonium bicolor). To elucidate the salt gland development trajectory and related molecular mechanisms, we performed single-cell RNA sequencing of L. bicolor protoplasts from young leaves at salt gland initiation and differentiation stages. Dimensionality reduction analyses defined 19 transcriptionally distinct cell clusters, which were assigned into four broad populations-promeristem, epidermis, mesophyll, and vascular tissue-verified by in situ hybridization. Cytokinin was further proposed to participate in salt gland development by the expression patterns of related genes and cytological evidence. By comparison analyses of scRNA-seq with exogenous application of 6-benzylaminopurine, we delineated five salt gland development-associated sub-clusters and defined salt gland specific differentiation trajectories from sub-clusters 8, 4, or 6 to sub-cluster 3 and 1. Additionally, we validated the participation of TRIPTYCHON and the interacting protein Lb7G34824 in salt gland development, which regulated the expression of cytokinin metabolism and signaling related genes such as GLABROUS INFLORESCENCE STEMS 2 to maintain cytokinin homeostasis during salt gland development. Our results generated a gene expression map of young leaves at single-cell resolution for the comprehensive investigation of salt gland determinants and cytokinin participation that helps elucidate cell fate determination during epidermis formation and evolution in recretohalophytes.

Characterization of Arabidopsis eskimo1 reveals a metabolic link between xylan O-acetylation and aliphatic glucosinolate metabolism.

Glucuronoxylan is present mainly in the dicot of the secondary cell walls, often O-acetylated, which stabilizes cell structure by maintaining interaction with cellulose and other cell wall components. Some members of the Golgi localized Trichome Birefringence-Like (TBL) family function as xylan O-acetyl transferase (XOAT). The primary XOAT in the stem of Arabidopsis is ESKIMO1/TBL29, and its disruption results in decreased xylan acetylation, stunted plant growth, and collapsed xylem vessels. To elucidate the effect on metabolic reprogramming and identify the underlying cause of the stunted growth in eskimo1, we performed transcriptomic, targeted, and untargeted metabolome analysis, mainly in the inflorescence stem tissue. RNA sequencing analysis revealed that the genes involved in the biosynthesis, regulation, and transport of aliphatic glucosinolates (GSLs) were upregulated, whereas those responsible for indolic GSL metabolism were unaffected in the eskimo1 inflorescence stem. Consistently, aliphatic GSLs, such as 4-methylsulfinylbutyl (4MSOB), were increased in stem tissues and seeds. This shift in the profile of aliphatic GSLs in eskimo1 was further supported by the quantification of the soluble acetate, decrease in accumulation of GSL precursor, i.e., methionine, and increase in the level of jasmonic acid.

Symptomology, prevalence, and impact of Hop latent viroid on greenhouse-grown cannabis (Cannabis sativa L.) plants in Canada

The incidence of Hop latent viroid (HLVd) affecting cannabis plants in licenced production facilities in Canada during 2020–2023 was determined by RT-PCR analyses of 15 947 samples from nine provinces. Positive detection ranged from 5.3% to 92% of samples submitted, depending on province and year of sampling. The average country-wide HLVd infection incidence was 25.6%. Symptoms on affected plants varied with plant growth stage, and ranged from asymptomatic to mild leaf curl and mottling on stock (mother) plants and on vegetative plants, to extreme stunting and reduced inflorescence development on flowering plants. All symptomatic and some asymptomatic plants contained a 256 nucleotide RNA fragment with 100% sequence homology to HLVd from GenBank. The viroid was detected in various tissues of stock, vegetative, and flowering plants, including the uppermost leaves, at middle and lower positions in the canopy, and in the roots. The incidence of infection varied with the cannabis genotype. Flowering plants displayed yellowing or darkening of inflorescence leaves surrounding the pistillate flowers. Reductions of 12–42% in inflorescence stem lengths, fresh weights, and plant heights were observed in infected plants compared to noninfected plants, depending on the genotype. Levels of tetrahydrocannabinol (THC) and terpenes in diseased inflorescences were also significantly lower. The development of glandular trichomes which produce and store cannabinoids and terpenes was greatly reduced by HLVd infection. The affected trichomes had shorter stalk lengths and smaller glandular head sizes, and appeared shrivelled upon drying of the inflorescences. Hop latent viroid poses a significant economic threat to the cannabis industry.

An essential role for mannan degradation in both cell growth and secondary cell wall formation.

Coordination of secondary cell wall deposition and cell expansion during plant growth is required for cell development, particularly in vascular tissues. Yet the fundamental coordination process has received little attention. We observed that the Arabidopsis endo-1,4-mannanase gene, AtMAN6, is involved in the formation of cell walls in vascular tissues. In the inflorescence stem, the man6 mutant had smaller vessel cells with thicker secondary cell walls and shorter fiber cells. Elongation growth was reduced in the root, and secondary cell wall deposition in vessel cells occurred early. Overexpression of AtMAN6 resulted in the inverse phenotypes of the man6 mutant. AtMAN6 was discovered on the plasma membrane and was specifically expressed in vessel cells during its early development. The AtMAN6 protein degraded galactoglucomannan to produce oligosaccharides, which caused secondary cell wall deposition in vessel and fiber cells to be suppressed. Transcriptome analysis revealed that the expression of genes involved in the regulation of secondary cell wall synthesis was changed in both man6 mutant and AtMAN6 overexpression plants. AtMAN6's C-terminal cysteine repeat motif (CCRM) was found to facilitate homodimerization and is required for its activity. According to the findings, the oligosaccharides produced by AtMAN6 hydrolysis may act as a signal to mediate this coordination between cell growth and secondary cell wall deposition.

UBC6, a ubiquitin-conjugating enzyme, participates in secondary cell wall thickening in the inflorescence stem of Arabidopsis

Secondary cell wall (SCW) thickening in plant inflorescence stems is a complicated cellular process that is essential for stem strength and biomass. Although Arabidopsis NAC transcription factor (TF) 1 (NST1) regulates the SCW thickening in anther walls, the single T-DNA-insertion mutant (nst1) does not show disrupted SCW thickening in anther endothecium, interfascicular fibers or xylem. To better understand the regulatory mechanism of this process, we generated an ethyl methanesulfonate (EMS)-mutagenized Arabidopsis population with the nst1 background. scd5 (SCW-defective mutant 5) was isolated in a forward genetic screen from the EMS mutant library, which displayed not only less lignin deposition in the interfascicular fiber and xylem than the wild type but also a pendent inflorescence stem. The EMS-induced mutation associated with the scd5 phenotype was found in the 5th exon of At2G46030 that encodes a ubiquitin-conjugating enzyme (UBC6), we thereby renamed the allele nst1 ubc6. Overexpressing UBC6 in nst1 ubc6 rescued the defective SCW, whereas disrupting UBC6 in nst1 by the CRISPR/Cas9 system caused a phenotype similar to that observed in nst1 ubc6. UBC6 was localized to the nucleus and plasma membrane, and possessed E2 ubiquitin-conjugating activity in vitro. MYB7 and MYB32 are considered as transcription repressors in the phenylpropanoid pathway and are involved in NAC TF-related transcriptional regulation in SCW thickening. UBC6 can interact with MYB7 and MYB32 and positively mediate the degradation of MYB7 and MYB32 by the 26S proteasome. Overall, these results indicated the contribution of UBC6 to SCW thickening in Arabidopsis inflorescence stems.

Cytotoxic Effects of Indonesian Betel Quid Components on Oral Keratinocytes and Fibroblasts

A betel quid (BQ) chewing habit has been strongly associated with the development of several oral mucosal diseases. In order to investigate whether individual components of BQ mixtures have distinct physio-pathological effects on oral mucosal cells, we examined the impact of areca nut (AN), Piper betle leaf (Leaf), Piper betle stem inflorescence (SI), areca husk (Husk) and the complete BQ mixture on the growth of oral keratinocytes (OKF-6) and primary oral fibroblasts (MMF-1). Based on their known chemical properties, we selected BQ samples from Banda Aceh (BA) and West Papua (WP) regions for our in vitro study. We used a fluorescein diacetate assay (FDA) to assess the cell viability of BQ components on OKF-6 and MMF-1 cells. The cytotoxic effect of WP-AN on the OKF-6 cell line was observed at a concentration of 100 μg/mL, resulting in a 50% reduction in cell viability (IC50) after a 2-day incubation. Similarly, BA-AN exhibited cytotoxic effect, although at a higher concentration (500 μg/mL). WP-SI also displayed cytotoxic effects at a concentration of 500 μg/mL following 2 days of incubation. In contrast, Leaf, BQ mixture and husk extracts did not show any cytotoxic effects even after 3 days of incubation. No cytotoxic effects were observed at any concentration of BQ components when exposed to MMF-1 cells. Regarding cell proliferation, MMF-1 cells exposed to BA-AN and WP-AN showed increased growth on day 1, followed by decreased growth on day 2, in a dose- and time-dependent manner. Overall, our study indicates that BQ components induce distinctive cytotoxic effects on stromal and epithelial cells from the oral cavity.

Aplicação de melatonina e sacarose no prolongamento da vida de vaso de flores de corte de amarilis (Hippeastrum hybridum Herb)

Abstract The effects of melatonin application by itself and mixed with sucrose solution on vase life and physicochemical changes in amaryllis cut flowers were investigated. Amaryllis stems with flower buds at harvest points were placed into vases containing different maintenance solutions: Melatonin (Mt; 0.01 mM), Sucrose (Suc; 4%), Melatonin + Sucrose (Mt + Suc; 0.01 mM + 4%) and distilled water (Control). Each treatment consisted of five repetitions, with one inflorescence stem per vase. The vases remained at 22 ± 3 °C and constant lighting of 13 µmol m-2 s-1 for 14 days. Immersion of stems in Suc or Mt + Suc delayed the initial senescence processes of the amaryllis cut flower. Vase life was prolonged for additional 2 days compared to stems immersed in water (control), increasing from 10 to 12 days of conservation. Floral stem mass was kept more stable; the degradation of anthocyanin and flavonoid pigments was delayed; and the stability of phenolic compounds and total carbohydrates was maintained for 14 days. These findings confirm the role of melatonin as a preservative in cut flowers. However, its preservative effect was potentialized by the addition of sucrose to the water of the amaryllis cut flowers. More work needs to be carried out to investigate the physiological mechanisms promoted by the interaction of melatonin and sucrose in the regulation of senescence in amaryllis cut flowers, including the analysis of gene expression and activity of the antioxidant system.

Anatomical observation and transcriptome analysis of branch-twisted mutations in Chinese jujube

BackgroundPlant organs grow in a certain direction and organ twisted growth, a rare and distinctive trait, is associated with internal structure changes and special genes. The twisted branch mutant of Chinese jujube jujube, an important fruit tree native to China and introduced to nearly 50 countries, provides new typical materials for exploration of plant twisted growth.ResultsIn this study, the cytological characteristics and related genes of twisted branches in Chinese jujube were revealed by microscopy observation and transcriptome analysis. The unique coexistence of primary and secondary structures appeared in the twisted parts of branches, and special structures such as collateral bundle, cortical bundles, and internal phloem were formed. Ninety differentially expressed genes of ‘Dongzao’ and its twisted mutant were observed, in which ZjTBL43, ZjFLA11, ZjFLA12 and ZjIQD1 were selected as candidate genes. ZjTBL43 was homologous to AtTBL43 in Arabidopsis, which was involved in the synthesis and deposition of cellular secondary wall cellulose. The attbl43 mutant showed significant inflorescence stem bending growth. The transgenic lines of attbl43 with overexpression of ZjTBL43 were phenotypically normal.The branch twisted growth may be caused by mutations in ZjTBL43 in Chinese jujube. AtIQD10, AtFLA11 and AtFLA12 were homologous to ZjIQD1, ZjFLA11 and ZjFLA12, respectively. However, the phenotype of their function defect mutants was normal.ConclusionIn summary, these findings will provide new insights into the plant organ twisted growth and a reference for investigation of controlling mechanisms of plant growth direction.

THE INFLUENCE OF THE USUAL HOLDING SOLUTIONS ON Hyacinthus orientalis CUT FLOWER VASE LIFE

In this study, four holding solutions very often used by florists and the final consumer were tested to analyse their impact on the development of the inflorescence, as well as the elongation, weight and degree of bending of the hyacinth flowers. The use of these solutions has a general character, and the flower species react differently due to both their genetics and the conditions in which they were cultivated, handled and stored. To verify the effectiveness of the preservative solutions on Hyacinthus orientalis vase life, four solutions were prepared with 2% sucrose and none or one of the follow-ing antimicrobial substances: sodium hypochlorite, acetic acid and ascorbic acid. During the study, measurements were made on the weight, elongation of the floral stems, chlorophyll content of the leaves and vase life days. The vase life of the hyacinths in this experiment was 5 days, except for the flowers from the 2% sucrose holding solution, which started to wilt on day 5. On day 6, the flowers showed signs of senescence. The increase in the length of the inflorescence stem showed significant differences for the sucrose + ascorbic acid holding solution, with a maximum of 0.8 cm on day 4. However, the interest was not to maximise the elongation of the floral stem but to slow down this process since elongation leads to the bending of the stem, causing it to require additional support.

Correlation relationships of economically valuable characteristics of sugar sorghum samples in arid conditions of the Lower Volga region

Relevance. Sugar sorghum is one of the leading forage crops in the regions of arid agriculture. Comprehensive in-depth study and improvement of breeding-valuable indicators, determination of correlations between traits to identify the strongest dependencies in order to accelerate the breeding process is relevant.Methods. The field assessment of 11 morphometric indicators and productivity elements of the studied samples (43 in total) was carried out according to the methodology of the state variety testing of agricultural cultures. The assessment of the conjugacy of features was carried out according to the correlation analysis using the «Agros 2.09» program.Results. The different degree of conjugacy of the signs is revealed. On average, in 2020–2022, the yield of sugar sorghum biomass depended on seed productivity (r = 0.70), seed size (r = 0.41), the area of the largest leaf (r = 0.39). At the same time, the seed yield correlated with the mass of 1000 grains and the area of the largest leaf (r = 0.45–0.46). There was a significant positive correlation between the height of plants at maturity and the extension of the inflorescence stem (r = 0.58). It was found that in sugar sorghum, the seed size correlated with the area of the largest leaf (r = 0.49). At the same time, the length and width of the inflorescence have a conjugacy equal to 0.46. In addition, in years differing in meteorological conditions, there was a different degree of manifestation of the interrelationships between the considered signs, which must be taken into account when conducting the selection process. Knowledge of the features of correlations provides acceleration of the creation of new varieties with the specified parameters.

Variability of the main breeding traits of sorgo CMS lines depending on the weather conditions of the Saratov region

Determining the nature of the interaction between the genotype and the environment is one of the critical stages of breeding practice for selecting effective parental forms of hybrids of the first generation of sorghum and their stable seed reproduction in the arid conditions of the Saratov region. The contribution of regulated and unregulated factors to the overall variability of a trait can be determined using a two-factor analysis of variance used in this work. The research objects were 11 sterile lines of grain sorghum grown on the experimental field of the Federal State Budgetary Research Institution RosRISM (Russian Research Institute of Sorghum and Maize) “Rossorgo” during 2009–2018. The meteorological conditions of plant cultivation varied significantly: in 2013 and 2017, they were characterised as sufficiently humid (Hydrothermal coefficient - HTC = 0.98–1.01), 2011 – acutely dry (HTC = 0.26), other years – dry (HTC = 0.45–0.68). As a result of the tests, it was found that the CMS lines differed in economically valuable traits. The sterile line A1 Efremovskoe 2 should be classified as tall (131.2 cm) and more productive (4.41 t/ha of seeds) with a well-developed leaf apparatus (the area of the giant leaf is 238.0 cm2). Low-growing CMS lines M35 and 9E Pishchevoe 614 (94.9–98.5 cm) were distinguished by the protrusion of the inflorescence stem - 21.6 cm, and A3, A4 and 9E Zheltozernoe 10 (109.8–110.2 cm) - with a long leaf (50.7–51.5 cm). Medium-sized lines A2 Vostorga and A4 KP 70 had a long inflorescence (23.0–24.5 cm), while A3 Feterita 14 had a short inflorescence (13.7 cm). It was found that the genotype (41.4–61.6%) had a more substantial effect on the overall variability of plant height, length and protrusion of the stem of the inflorescence, and leaf length, while the environmental factor had a more substantial effect on seed yield (55.3%).

Shoot gravitropism and organ straightening cooperate to arrive at a mechanically favorable shape in Arabidopsis

Gravitropism is the plant organ bending in response to gravity, while a straightening mechanism prevents bending beyond the gravitropic set-point angle. The promotion and prevention of bending occur simultaneously around the inflorescence stem tip. How these two opposing forces work together and what part of the stem they affect are unknown. To understand the mechanical forces involved, we rotated wild type and organ-straightening-deficient mutant (myosin xif xik) Arabidopsis plants to a horizontal position to initiate bending. The mutant stems started to bend before the wild-type stems, which led us to hypothesize that the force preventing bending was weaker in mutant. We modeled the wild-type and mutant stems as elastic rods, and evaluated two parameters: an organ-angle-dependent gravitropic-responsive parameter (β) and an organ-curvature-dependent proprioceptive-responsive parameter (γ). Our model showed that these two parameters were lower in mutant than in wild type, implying that, unexpectedly, both promotion and prevention of bending are weak in mutant. Subsequently, finite element method simulations revealed that the compressive stress in the middle of the stem was significantly lower in wild type than in mutant. The results of this study show that myosin-XIk-and-XIf-dependent organ straightening adjusts the stress distribution to achieve a mechanically favorable shape.

A BrLINE1-RUP insertion in BrCER2 alters cuticular wax biosynthesis in Chinese cabbage (Brassica rapa L. ssp. pekinensis).

Glossiness is an important quality-related trait of Chinese cabbage, which is a leafy vegetable crop in the family Brassicaceae. The glossy trait is caused by abnormal cuticular wax accumulation. In this study, on the basis of a bulked segregant analysis coupled with next-generation sequencing (BSA-seq) and fine-mapping, the most likely candidate gene responsible for the glossy phenotype of Chinese cabbage was identified. It was subsequently named Brcer2 because it is homologous to AtCER2 (At4g24510). A bioinformatics analysis indicated a long interspersed nuclear element 1 (LINE-1) transposable element (named BrLINE1-RUP) was inserted into the first exon of Brcer2 in HN19-G via an insertion-mediated deletion mechanism, which introduced a premature termination codon. Gene expression analysis showed that the InDel mutation of BrCER2 reduced the transcriptional expression levels of Brcer2 in HN19-G. An analysis of cuticular waxes suggested that a loss-of-function mutation to BrCER2 in Chinese cabbage leads to a severe decrease in the abundance of very-long-chain-fatty-acids (> C28), resulting in the production of a cauline leaf, inflorescence stem, flower, and pistil with a glossy phenotype. These findings imply the insertion of the LINE-1 transposable element BrLINE1-RUP into BrCER2 can modulate the waxy traits of Chinese cabbage plants.

Ectopic Expression of BcCUC2 Involved in Sculpting the Leaf Margin Serration in Arabidopsis thaliana.

Leaf margin serration is a morphological characteristic in plants. The CUC2 (CUP-SHAPED COTYLEDON 2) gene plays an important role in the outgrowth of leaf teeth and enhances leaf serration via suppression of growth in the sinus. In this study, we isolated the BcCUC2 gene from Pak-choi (Brassica rapa ssp. chinensis), which contains a 1104 bp coding sequence, encoding 367 amino acid residues. Multiple sequence alignment exhibited that the BcCUC2 gene has a typical conserved NAC domain, and phylogenetic relationship analysis showed that the BcCUC2 protein has high identity with Cruciferae plants (Brassica oleracea, Arabidopsis thaliana, and Cardamine hirsuta). The tissue-specific expression analysis displayed that the BcCUC2 gene has relatively high transcript abundance in floral organs. Meanwhile, the expression profile of BcCUC2 was relatively higher in the '082' lines with serrate leaf margins than the '001' lines with smooth leaf margins in young leaves, roots, and hypocotyls. In addition, the transcript level of BcCUC2 was up-regulated by IAA and GA3 treatment, especially at 1-3 h. The subcellular localization assay demonstrated that BcCUC2 was a nuclear-target protein. Furthermore, leaf serration occurred, and the number of the inflorescence stem was increased in the transgenic Arabidopsis thaliana plants' overexpressed BcCUC2 gene. These data illustrated that BcCUC2 is involved in the development of leaf margin serration, lateral branches, and floral organs, contributing to further uncovering and perfecting the regulation mechanism of leaf serration in Pak-choi.

TCP Transcription Factors in Plant Reproductive Development: Juggling Multiple Roles.

TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) transcription factors (TFs) are plant-specific transcriptional regulators exerting multiple functions in plant growth and development. Ever since one of the founding members of the family was described, encoded by the CYCLOIDEA (CYC) gene from Antirrhinum majus and involved in the regulation of floral symmetry, the role of these TFs in reproductive development was established. Subsequent studies indicated that members of the CYC clade of TCP TFs were important for the evolutionary diversification of flower form in a multitude of species. In addition, more detailed studies of the function of TCPs from other clades revealed roles in different processes related to plant reproductive development, such as the regulation of flowering time, the growth of the inflorescence stem, and the correct growth and development of flower organs. In this review, we summarize the different roles of members of the TCP family during plant reproductive development as well as the molecular networks involved in their action.

Identification of DELLA gene family in head cabbage and analysis of mRNA transport in the heterograft.

DELLA gene family is involved in the regulation of signal transduction of plant hormones. mRNAs of GA insensitive (GAI), the member of DELLA gene family, are also signaling molecules of long-distance transport in plants. Genome-wide identification and mRNA transport analysis of the members of DELLA gene family in head cabbage (Brassica oleracea var. capitata) can provide basic data for their application in head cabbage. In this study, five members of DELLA gene family (BoRGA1, BoRGA2, BoRGL1, BoRGL2, and BoRGL3) were identified in head cabbage using genome and transcriptome data. However, head cabbage lacked a GAI gene in its genome. The scion (head cabbage, inbred line G27) and the rootstock Chinese flowering cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) (sijiucaixin) were cleft-grafted together to produce the heterograft. Inflorescence stem of the rootstock and the corresponding inflorescence stem in Chinese flowering cabbage seedlings (as controls) were purified and analyzed with transcriptome sequencing. The total of 8, 9, 3, 5, and 1 exogenous read(s), derived respectively from BoRGA1, BoRGA2, BoRGL1, BoRGL2, and BoRGL3, were identified in the transcriptomes of the rootstocks. Nevertheless, mRNA transport of DELLA family genes from scion to rootstock did not increase the transcriptional level of the members of DELLA gene family in the rootstocks. Correlation analysis suggested that mRNA transport efficiency of the DELLA family genes was correlated with the sequence and the transcriptional level of the respective DELLA gene in the scion (head cabbage). This study lays the foundation for further investigation on the molecular mechanism of mRNA transport of the members of DELLA gene family in head cabbage.

Contribution of vasculature to stem integrity in Arabidopsis thaliana.

In plants, coordinated growth is important for organ mechanical integrity because cells remain contiguous through their walls. So far, defects in inflorescence stem integrity in Arabidopsis thaliana have mainly been related to epidermal defects. Although these observations suggest a growth-limiting function at the stem cortex, deeper layers of the stem could also contribute to stem integrity. The nac secondary cell wall thickening promoting factor1 (nst1) nst3 double-mutant background is characterized by weaker vascular bundles without cracks. By screening for the cracking phenotype in this background, we identified a regulator of stem cracking, the transcription factor INDETERMINATE DOMAIN9 (IDD9). Stem cracking was not caused by vascular bundle breakage in plants that expressed a dominant repressor version of IDD9. Instead, cracking emerged from increased cell expansion in non-lignified interfascicular fiber cells that stretched the epidermis. This phenotype could be enhanced through CLAVATA3-dependent cell proliferation. Collectively, our results demonstrate that stem integrity relies on three additive mechanical components: the epidermis, which resists inner cell growth; cell proliferation in inner tissues; and growth heterogeneity associated with vascular bundle distribution in deep tissues.