[ROUTES OF MEDICAL CANNABIS ADMINISTRATION- IS SMOKING THE PREFERRED ROUTE?]

INTRODUCTION: The number of medical cannabis licenses in Israel is increasing persistently (over 120,000 approved licenses in October 2022), reaching about 1.5% of adult population. Medical cannabis products are available in two main forms: inflorescence (administered by smoking or evaporation) and cannabis oil (administered sub-lingually). Data from the Israel ministry of health, regarding the split between these forms, show a major preference for inflorescence products over cannabis oils. This preference is increasing over time. This article reviews the main differences between the administration of these forms and their effects on the quality of treatment. It's conclusion is that for the most common cases of cannabis treatment, sublingual oils should be preferred and that the medical community has an important role in driving this change.

Non-cell-autonomous signaling associated with barley ALOG1 specifies spikelet meristem determinacy.

Inflorescence architecture and crop productivity are often tightly coupled in our major cereal crops. However, the underlying genetic mechanisms controlling cereal inflorescence development remain poorly understood. Here, we identified recessive alleles of barley (Hordeum vulgare L.) HvALOG1 (Arabidopsis thaliana LSH1 and Oryza G1) that produce non-canonical extra spikelets and fused glumes abaxially to the central spikelet from the upper-mid portion until the tip of the inflorescence. Notably, we found that HvALOG1 exhibits a boundary-specific expression pattern that specifically excludes reproductive meristems, implying the involvement of previously proposed localized signaling centers for branch regulation. Importantly, during early spikelet formation, non-cell-autonomous signals associated with HvALOG1 expression may specify spikelet meristem determinacy, while boundary formation of floret organs appears to be coordinated in a cell-autonomous manner. Moreover, barley ALOG family members synergistically modulate inflorescence morphology, with HvALOG1 predominantly governing meristem maintenance and floral organ development. We further propose that spatiotemporal redundancies of expressed HvALOG members specifically in the basal inflorescence may be accountable for proper patterning of spikelet formation in mutant plants. Our research offers new perspectives on regulatory signaling roles of ALOG transcription factors during the development of reproductive meristems in cereal inflorescences.

A spatial transcriptome map of the developing maize ear.

A comprehensive understanding of inflorescence development is crucial for crop genetic improvement, as inflorescence meristems give rise to reproductive organs and determine grain yield. However, dissecting inflorescence development at the cellular level has been challenging owing to a lack of specific marker genes to distinguish among cell types, particularly in different types of meristems that are vital for organ formation. In this study, we used spatial enhanced resolution omics-sequencing (Stereo-seq) to construct a precise spatial transcriptome map of the developing maize ear primordium, identifying 12 cell types, including 4 newly defined cell types found mainly in the inflorescence meristem. By extracting the meristem components for detailed clustering, we identified three subtypes of meristem and validated two MADS-box genes that were specifically expressed at the apex of determinate meristems and involved in stem cell determinacy. Furthermore, by integrating single-cell RNA transcriptomes, we identified a series of spatially specific networks and hub genes that may provide new insights into the formation of different tissues. In summary, this study provides a valuable resource for research on cereal inflorescence development, offering new clues for yield improvement.

Photoperiod-1 regulates the wheat inflorescence transcriptome to influence spikelet architecture and flowering time.

Photoperiod insensitivity has been selected by breeders to help adapt crops to diverse environments and farming practices. In wheat, insensitive alleles of Photoperiod-1 (Ppd-1) relieve the requirement of long daylengths to flower by promoting expression of floral promoting genes early in the season; however, these alleles also limit yield by reducing the number and fertility of grain-producing florets through processes that are poorly understood. Here, we performed transcriptome analysis of the developing inflorescence using near-isogenic lines that contain either photoperiod-insensitive or null alleles of Ppd-1, during stages when spikelet number is determined and floret development initiates. We report that Ppd-1 influences the stage-specific expression of genes with roles in auxin signaling, meristem identity, and protein turnover, and analysis of differentially expressed transcripts identified bZIP and ALOG transcription factors, namely PDB1 and ALOG1, which regulate flowering time and spikelet architecture. These findings enhance our understanding of genes that regulate inflorescence development and introduce new targets for improving yield potential.

Image Filtering to Improve Maize Tassel Detection Accuracy Using Machine Learning Algorithms.

Unmanned aerial vehicle (UAV)-based imagery has become widely used to collect time-series agronomic data, which are then incorporated into plant breeding programs to enhance crop improvements. To make efficient analysis possible, in this study, by leveraging an aerial photography dataset for a field trial of 233 different inbred lines from the maize diversity panel, we developed machine learning methods for obtaining automated tassel counts at the plot level. We employed both an object-based counting-by-detection (CBD) approach and a density-based counting-by-regression (CBR) approach. Using an image segmentation method that removes most of the pixels not associated with the plant tassels, the results showed a dramatic improvement in the accuracy of object-based (CBD) detection, with the cross-validation prediction accuracy (r2) peaking at 0.7033 on a detector trained with images with a filter threshold of 90. The CBR approach showed the greatest accuracy when using unfiltered images, with a mean absolute error (MAE) of 7.99. However, when using bootstrapping, images filtered at a threshold of 90 showed a slightly better MAE (8.65) than the unfiltered images (8.90). These methods will allow for accurate estimates of flowering-related traits and help to make breeding decisions for crop improvement.

Finding the right balance: The enduring role of florigens during cereal inflorescence development and their influence on fertility.

Flowering is a vital process in a plant's lifecycle and variation for flowering-time has helped cereals adapt to diverse environments. Much cereal research has focused on understanding how flowering signals, or florigens, regulate the floral transition and timing of ear emergence. However, flowering genes also perform an enduring role during inflorescence development, with genotypes that elicit a weaker flowering signal producing more elaborately branched inflorescences with extra floret-bearing spikelets. While this outcome indicates that variable expression of flowering genes could boost yield potential, further analysis has shown that dampened florigen levels can compromise fertility, negating the benefit of extra grain-producing sites. Here, we discuss ways that florigens contribute to early and late inflorescence development, including their influence on branch/spikelet architecture and fertility. We propose that a deeper understanding of the role for florigens during inflorescence development could be used to balance the effects of florigens throughout flowering to improve productivity.

Simultaneous analysis of cannabinoids and terpenes in Cannabis sativa inflorescence using full comprehensive two-dimensional liquid chromatography coupled to smart active modulation.

Nowadays, the higher peak capacity achievable by comprehensive two-dimensional liquid chromatography (LC×LC) for the analysis of vegetal samples is well-recognized. In addition, numerous compounds may be present in very different amounts. Cannabinoids and terpenes represent the main components of Cannabis sativa inflorescence samples, whose quantities are relevant for many application purposes. The analyses of both families are performed by different methods, at least two different separation methodologies, mainly according to their chemical characteristics and concentration levels. In this work, concentration differences and sample complexity issues were addressed using an LC×LC method that incorporates an optimized modulation strategy, namely smart active modulation, for the simultaneous analysis of cannabinoids and terpenes. The system was built by interposing an active flow splitter pump between both dimensions. This set up aimed to exploit the known advantages of LC×LC. In addition, here we proposed to use the splitter pump for online control over the splitting ratio to facilitate the selective dilution of different eluted fractions containing compounds with highly different concentrations. This work represents the first application and demonstration of smart active modulation (SAM) in LC×LC to simultaneously determine analytes with significant differences in concentration levels present in complex samples. The proposed method was tested with eight different strains, from which fingerprints were taken, and numerous cannabinoids and terpenes were identified in these samples. With this strategy, between 49 and 54 peaks were obtained in the LC×LC chromatograms corresponding to different strains. THCA-A was the main component in six strains, while CBDA was the main component in the other two strains. The main terpenes found were myrcene (in five strains), limonene (in two strains), and humulene (in one strain). Additionally, numerous other cannabinoids and terpenes were identified in these samples, providing valuable compositional information for growers, as well as medical and recreational users. The SAM strategy here proposed is simple and it can be extended to other complex matrices.

Water strategy improves the inflorescence primordia formation of 'Arra 15' grapevine in the Brazilian semiarid region.

Failure in irrigation management of grapevines grown in the Brazilian semiarid region can affect bud fertility. Adequate irrigation, considering both the development of bunches in the current cycle and the formation of fertile buds for subsequent cycles, can bring significant advances to viticulture. Therefore, the objective of this research was to investigate the effect of different irrigation levels during flowering on the formation of buds and potential bunches of 'Arra 15' grapevine and its relationship with metabolic processes. A field experiment was carried out in a commercial vineyard in Petrolina, Pernambuco, Brazil, during the 2021 and 2022 seasons. The experiment was designed in randomized blocks with four replications and five irrigation levels (70; 85; 100; 115 and 130% of crop evapotranspiration - ETc) during three production cycles. The variables fertile bud, vegetative bud, dead bud, potential fertility of the basal, median, and apical regions of the branches, number of potential bunches, reducing sugar, total soluble sugar, net photosynthesis, stomatal conductance, transpiration, and relative chlorophyll index were evaluated. The 115% ETc irrigation level improved the number of fertile buds and number of potential bunches. Irrigation level above 115% ETc increased gas exchange and relative chlorophyll index, while 70% ETc increased leaf sugar content. The most appropriate irrigation strategy is the application of 115% ETc during the flowering stage, for the increase of fertile buds and potential bunches of the next cycle, without influencing the vine metabolism. Total soluble sugars are a promising indicator of water deficit during flowering and as an indicator of vegetative bud formation for the next cycle.

Hemp cultivation opportunities for marginal lands development.

Agricultural diversification and high-quality products deriving from sustainable crops such as hemp can represent a solution to revitalize marginal areas and reverse land abandonment. This study aimed at comparing four different hemp cultivars (Carmagnola Selezionata, "CS"; Futura 75, "FUT"; Felina 32, "FEL"; Secuieni Jubileu, "JUB") to provide information to select the best suited cultivar for cultivation in mountain marginal areas and for specific end-use applications. Hemp cultivars were cultivated in a single experimental field to compare their ecological and agronomic behavior (duration of life cycle phases, plant size and biomass allocation, and plant resource-use strategies). Through metabolomic analysis of both vegetative and reproductive parts of the plants we tested the presence of substances of nutraceutical interest and traced seed nutritional profile. The four cultivars had different ecological and agronomic behavior, and nutritional profile. We found several compounds with potential pharmaceutical and nutraceutical values in all parts of the plant (leaves, inflorescences, and stems). JUB resulted the most suitable for seed production while CS showed the highest content of bioactive compounds in flowers and leaves. FUT, showed the best suitability for multi-purpose cultivation, while FEL seemed to be not appropriate for the cultivation in mountain area. The multi-disciplinary approach we adopted was effective in distinguish across hemp cultivars and provided information to farmers for the selection of the best hemp cultivar to select. Hemp had a high potential for cultivation in marginal lands, demonstrating to be an economic resource due to its multi-purpose use and to the possibility to generate high-added values products. Our results could serve as a stimulus for the reintroduction of this culture in the study area and in other similar environments.

Green biosourced composite for efficient reactive dye decontamination: immobilized Gibberella fujikuroi on maize tassel biomatrix.

Biosorptive treatment with microbial biomass is regarded as an environmentally friendly and effective way to reduce dye contamination in contaminated aquatic environments. Immobilizing microbial cells for use in this process can significantly improve their effectiveness as biosorbents in the water treatment process. The current investigation searches for a sustainable and environmentally friendly approach to decolorization by employing a green biocomposite material sorbent system (ZM@GFC) created by immobilizing fungal cells (Gibberella fujikuroi) on maize tassel tissues to efficiently remove Reactive Yellow 2 (RY2) from contaminated water sources. Batch and dynamic flow tests were performed to evaluate the biodecolorization properties of the newly created immobilized biomaterial as well as the effects of several essential operating conditions factors on the sorption behavior. Biosorption yields of 95.7% and 90.0% in batch and dynamic modes were achieved for experimental dye decolorization. The biosorption of RY2 by ZM@GFC occurred fast and achieved equilibrium within 60 min. The pseudo-second-order kinetic model elucidated the dye biosorption onto ZM@GFC. The Langmuir model provided a more accurate representation of the results than the Freundlich model. At the same time, Redlich-Peterson isotherm demonstrated the best level of agreement with the experimental data. These findings indicate that the biosorption mechanism predominantly involved the formation of a monolayer covering and that the energy properties of the ZM@GFC surface were uniform. The breakthrough capacity at the exhaustion time was 537.32 mg g-1. The predicted cost of generating ZM@GFC was anticipated to be 61.03 USD/kg. The investigations on safe disposal demonstrated that the biosorption process did not generate any secondary pollution. In conclusion, using maize tassel tissue as an immobilized decolorization agent offers a possible method for removing reactive azo dye pollutants from the aquatic medium that is both economical and environmentally benign.

Development and evolution of the Asteraceae capitulum.

Asteraceae represent one of the largest and most diverse families of plants. The evolutionary success of this family has largely been contributed to their unique inflorescences, capitula that mimic solitary flowers but are typically aggregates of multiple florets. Here, we summarize the recent molecular and genetic level studies that have promoted our understanding of the development and evolution of capitula. We focus on new results on patterning of the enlarged meristem resulting in the iconic phyllotactic arrangement of florets in Fibonacci numbers of spirals. We also summarize the current understanding of the genetic networks regulating the characteristic reproductive traits in the family such as floral dimorphism and differentiation of highly specialized floral organs. So far, developmental studies in Asteraceae are still limited to a very narrow selection of model species. Along with the recent advancements in genomics and phylogenomics, Asteraceae and its relatives provide an outstanding model clade for extended evo-devo studies to exploit the morphological diversity and the underlying molecular networks and to translate this knowledge to the breeding of the key crops in the family.

Genetic control of thermomorphogenesis in tomato inflorescences.

Understanding how plants alter their development and architecture in response to ambient temperature is crucial for breeding resilient crops. Here, we identify the quantitative trait locus qMULTIPLE INFLORESCENCE BRANCH 2 (qMIB2), which modulates inflorescence branching in response to high ambient temperature in tomato (Solanum lycopersicum). The non-functional mib2 allele may have been selected in large-fruited varieties to ensure larger and more uniform fruits under varying temperatures. MIB2 gene encodes a homolog of the Arabidopsis thaliana transcription factor SPATULA; its expression is induced in meristems at high temperature. MIB2 directly binds to the promoter of its downstream gene CONSTANS-Like1 (SlCOL1) by recognizing the conserved G-box motif to activate SlCOL1 expression in reproductive meristems. Overexpressing SlCOL1 rescue the reduced inflorescence branching of mib2, suggesting how the MIB2-SlCOL1 module helps tomato inflorescences adapt to high temperature. Our findings reveal the molecular mechanism underlying inflorescence thermomorphogenesis and provide a target for breeding climate-resilient crops.

Molecular mechanisms of macrophage immunomodulation mediated by Areca inflorescence polysaccharides based on RNA-seq analysis.

The elucidation of the immunomodulatory molecular mechanisms of polysaccharides has contributed to their further development and application. In this study, the effect of Areca inflorescence polysaccharide (AFP2a) on macrophage activation was confirmed and the detailed mechanisms were investigated based on a comprehensive transcriptional study and specific inhibitors. The results showed that AFP2a induced macrophage activation (M1 polarization), promoting macrophage proliferation, reactive oxygen species production, nitric oxide and cytokine release, and costimulatory molecule expression. RNA-seq analysis identified 5919 differentially expressed genes (DEGs). For DEGs, GO, KEGG, and Reactome enrichment analyses and PPI networks were conducted, elucidating that AFP2a activated macrophages mainly by triggering the Toll-like receptor cascade and corresponding adapter proteins (TIRAP and TRIF), thereby resulting in downstream NF-κB, TNF, and JAK-STAT signaling pathway expression. The inhibition assay revealed that TLR4 and TLR2 were essential for the recognition of AFP2a. This work provides an in-depth understanding of the immunoregulatory mechanism of AFP2a while offering a molecular basis for AFP2a to serve as a potential natural immunomodulator.

Anatomical insights into the vascular layout of the barley rachis: implications for transport and spikelet connection.

BACKGROUND AND AIMS: Vascular patterning is intimately related to plant form and function. Here, using barley (Hordeum vulgare) as a model, we studied the vascular anatomy of the spike-type inflorescence. The main aim of the present work was to clarify the relationship between rachis (spike axis) vasculature and spike size, to define vascular dynamics and to discuss the implications for transport capacity and its interaction with the spikelets. METHODS: We used serial transverse internode sections to determine the internode area, vascular area and number of veins along the rachis of several barley lines. KEY RESULTS: Internode area and total vascular area show a clear positive correlation with spike size, whereas the number of veins is only weakly correlated. The lateral periphery of the rachis contains large mature veins of constant size, whereas the central part is occupied by small immature veins. Spikelet-derived veins entering the rachis often merge with the immature rachis veins but never merge with the mature veins. An increase in floret fertility through the conversion of a two-rowed barley into an isogenic six-rowed line, in addition to a decrease in floret fertility owing to enhanced pre-anthesis tip degeneration caused by the mutation tip sterile 2.b (tst2.b), significantly affected vein size but had limited to no effects on the number of veins or internode area. CONCLUSIONS: The rachis vasculature is the result of a two-step process involving an initial layout followed by size adjustment according to floret fertility/spike size. The restriction of large mature vessels to the periphery and that of small immature vessels to the centre of the rachis suggests that long-distance transport and local supply to spikelets are spatially separated processes. The identification of spikelet-derived veins entering the rachis without fusing with its vasculature indicates that a vascular continuity between rachis and spikelets might be non-essential.

Genome-Wide Association Study and Prediction of Tassel Weight of Tropical Maize Germplasm in Multi-Parent Population.

Tassel weight (TW) is a crucial agronomic trait that significantly affects pollen supply and grain yield development in maize breeding. To improve maize yield and develop new varieties, a comprehensive understanding of the genetic mechanisms underlying tassel weight is essential. In this study, tropical maize inbred lines, namely CML312, CML373, CML444, and YML46, were selected as female parents and crossed with the elite maize inbred line Ye107, which served as the common male parent, to develop a multi-parent population comprising four F8 recombinant inbred line (RIL) subpopulations. Using 6616 high-quality single nucleotide polymorphism (SNP) markers, we conducted genome-wide association analysis (GWAS) and genomic selection (GS) on 642 F8 RILs in four subpopulations across three different environments. Through GWAS, we identified 16 SNPs that were significantly associated with TW, encompassing two stable loci expressed across multiple environments. Furthermore, within the candidate regions of these SNPs, we discovered four novel candidate genes related to TW, namely Zm00001d044362, Zm00001d011048, Zm00001d011049, and Zm00001d031173 distributed on chromosomes 1, 3, and 8, which have not been previously reported. These genes are involved in processes such as signal transduction, growth and development, protein splicing, and pollen development, all of which play crucial roles in inflorescence meristem development, directly affecting TW. The co-localized SNP, S8_137379725, on chromosome 8 was situated within a 16.569 kb long terminal repeat retrotransposon (LTR-RT), located 22.819 kb upstream and 26.428 kb downstream of the candidate genes (Zm00001d011048 and Zm00001d011049). When comparing three distinct GS models, the BayesB model demonstrated the highest accuracy in predicting TW. This study establishes the theoretical foundation for future research into the genetic mechanisms underlying maize TW and the efficient breeding of high-yielding varieties with desired tassel weight through GS.

The ALOG domain defines a family of plant-specific transcription factors acting during Arabidopsis flower development.

The ALOG (Arabidopsis LIGHT-DEPENDENT SHORT HYPOCOTYLS 1 (LSH1) and Oryza G1) proteins are conserved plant-specific Transcription Factors (TFs). They play critical roles in the development of various plant organs (meristems, inflorescences, floral organs, and nodules) from bryophytes to higher flowering plants. Despite the fact that the first members of this family were originally discovered in Arabidopsis, their role in this model plant has remained poorly characterized. Moreover, how these transcriptional regulators work at the molecular level is unknown. Here, we study the redundant function of the ALOG proteins LSH1,3,4 from Arabidopsis. We uncover their role in the repression of bract development and position them within a gene regulatory network controlling this process and involving the floral regulators LEAFY, BLADE-ON-PETIOLE, and PUCHI. Next, using in vitro genome-wide studies, we identified the conserved DNA motif bound by ALOG proteins from evolutionarily distant species (the liverwort Marchantia polymorpha and the flowering plants Arabidopsis, tomato, and rice). Resolution of the crystallographic structure of the ALOG DNA-binding domain in complex with DNA revealed the domain is a four-helix bundle with a disordered NLS and a zinc ribbon insertion between helices 2 and 3. The majority of DNA interactions are mediated by specific contacts made by the third alpha helix and the NLS. Taken together, this work provides the biochemical and structural basis for DNA-binding specificity of an evolutionarily conserved TF family and reveals its role as a key player in Arabidopsis flower development.

Gene expression and metabolite levels converge in the thermogenic spadix of skunk cabbage.

The inflorescence (spadix) of skunk cabbage (Symplocarpus renifolius) is strongly thermogenic and can regulate its temperature at around 23 °C even when the ambient temperature drops below freezing. To elucidate the mechanisms underlying developmentally controlled thermogenesis and thermoregulation in skunk cabbage, we conducted a comprehensive transcriptome and metabolome analysis across 3 developmental stages of spadix development. Our RNA-seq analysis revealed distinct groups of expressed genes, with selenium-binding protein 1/methanethiol oxidase (SBP1/MTO) exhibiting the highest levels in thermogenic florets. Notably, the expression of alternative oxidase (AOX) was consistently high from the prethermogenic stage through the thermogenic stage in the florets. Metabolome analysis showed that alterations in nucleotide levels correspond with the developmentally controlled and tissue-specific thermogenesis of skunk cabbage, evident by a substantial increase in AMP levels in thermogenic florets. Our study also reveals that hydrogen sulfide, a product of SBP1/MTO, inhibits cytochrome c oxidase (COX)-mediated mitochondrial respiration, while AOX-mediated respiration remains relatively unaffected. Specifically, at lower temperatures, the inhibitory effect of hydrogen sulfide on COX-mediated respiration increases, promoting a shift toward the dominance of AOX-mediated respiration. Finally, despite the differential regulation of genes and metabolites throughout spadix development, we observed a convergence of gene expression and metabolite accumulation patterns during thermogenesis. This synchrony may play a key role in developmentally regulated thermogenesis. Moreover, such convergence during the thermogenic stage in the spadix may provide a solid molecular basis for thermoregulation in skunk cabbage.

Darwin's inflorescence syndrome is indeed associated with bee pollination.

KEY MESSAGE: A relationship between vertical acropetal inflorescences with protandrous flowers and bee pollination was hypothesized by Darwin back in 1877. Here we provide empirical evidence supporting this association across the angiosperms. Plant reproduction is not only determined by flower traits but also by the arrangement of flowers within inflorescences. Based on his observations of the orchid Spiranthes autumnalis, Darwin proposed in 1877 that bee-pollinated plants presenting protandrous flowers on vertical acropetal inflorescences, where proximal flowers open first, can exploit the stereotypical foraging behavior of their pollinators (i.e., upward movement through the inflorescence) to promote pollen exportation and reduce self-pollination. In these inflorescences, male-phase flowers lie spatially above female-phase flowers. To examine this untested hypothesis, we compiled literature information from 718 angiosperms species and evaluated the association between vertical acropetal inflorescences with protandrous flowers and bee pollination within a phylogenetic comparative framework. Results reveal that this type of inflorescence is indeed more common in species pollinated by bees. Moreover, this association does not seem to be weakened by the presence of alternative self-pollination avoidance mechanisms, like self-incompatibility, suggesting that this inflorescence type benefits mainly male rather than female fitness. Other inflorescence types placing male-phase flowers above female-phase flowers, e.g., vertical basipetal inflorescences with protogynous flowers, do not provide strong evidence of a differential association with pollination by bees. Female-biased nectar production in vertical acropetal inflorescences with protandrous flowers may reinforce the behavior of bees to fly upwards, rendering Darwin's configuration more adaptive than other inflorescence configurations.

Comparative floral development in Mimosa (Fabaceae: Caesalpinioideae) brings new insights into merism lability in the mimosoid clade.

The genus Mimosa L. (Leguminosae; Caesalpinioideae; mimosoid clade), comprising more than 500 species, is an intriguing genus because, like other members of the mimosoid clade, it presents an enormous variation in floral characteristics and high merism lability. Thus, this study aimed to elucidate the floral development and identify which ontogenetic pathways give rise to merism variation and andromonoecy in Mimosa caesalpiniifolia, M. pudica, M. bimucronata, and M. candollei. Floral buds at various stages of development and flowers were collected, fixed, and processed for surface analysis (SEM). The development of the buds is synchronous in the inflorescences. Sepals appear simultaneously as individualized primordia in M. caesalpiniifolia and in reversed unidirectional order in M. bimucronata, with union and formation of an early ring-like calyx. Petal primordia appear in unidirectional order, with a noticeably elliptical shape in M. caesalpiniifolia. The wide merism variation in Mimosa results from the absence of organs from inception in the perianth and androecium whorls: in dimerous, trimerous, or tetramerous flowers, the additional organs primordia to compose the expected pentamerous flowers are not initiated. The haplostemonous androecium of M. pudica results from the absence of antepetalous stamens from inception. In the case of intraspecific variations (instabilities), there is no initiation and subsequent abortion of organs in the events of reduction in merosity. In addition, extra primordia are initiated in supernumerary cases. On the other hand, staminate flowers originate from the abortion of the carpel. Mimosa proved to be an excellent model for studying merism variation. The lability is associated with actinomorphic and rather congested flowers in the inflorescences. Our data, in association with others of previous studies, suggest that the high lability in merism appeared in clades that diverged later in the mimosoid clade. Thus, phylogenetic reconstruction studies are needed for more robust evolutionary inferences. The present investigation of ontogenetic processes was relevant to expand our understanding of floral evolution in the genus Mimosa and shed light on the unstable merism in the mimosoid clade.

GLABROUS INFLORESCENCE STEMS3 binds to and activates RHD2 and RHD4 genes to promote root hair elongation in Arabidopsis.

Root hairs are crucial in the uptake of essential nutrients and water in plants. This study showed that a zinc finger protein, GIS3 is involved in root hair growth in Arabidopsis. The loss-of-function gis3 and GIS3 RNAi transgenic line exhibited a significant reduction in root hairs compared to the wild type. The application of 1-aminocyclopropane-1-carboxylic acid (ACC), an exogenous ethylene precursor, and 6-benzyl amino purine (BA), a synthetic cytokinin, significantly restored the percentage of hair cells in the epidermis in gis3 and induced GIS3 expression in the wild type. More importantly, molecular and genetic studies revealed that GIS3 acts upstream of ROOT HAIR DEFECTIVE 2 (RHD2) and RHD4 by binding to their promoters. Furthermore, exogenous ACC and BA application significantly induced the expression of RHD2 and RHD4, while root hair phenotype of rhd2-1, rhd4-1, and rhd4-3 was insensitive to ACC and BA treatment. We can therefore conclude that GIS3 modulates root hair development by directly regulating RHD2 and RHD4 expression through ethylene and cytokinin signals in Arabidopsis.