Male Plants Research Articles

Coppice growth traits in sand dune willow (Salix cordata) and comparisons with two common North American shrub willows used for biomass production

Among eight native North American willow species examined for coppice growth performance, the sand dune willow, Salix cordata Michx. (COR) has proved to be one of the most productive and useful for woody biomass production. In a common garden study, clones from the eastern and southwestern regions of Ontario, Canada, outperformed those from northern populations. Geographic region, populations within regions, and clones within populations all accounted for large portions of total variation in coppice growth traits that were compared with two other willows commonly used for biomass production, S. discolor Muhl. and S. eriocephala Muhl. Each species varied significantly in coppice structure and growth. The number of coppice stems per plant (coppice stem number) showed strong positive relationships to stem dry mass in 1- and 3-year-old coppices. Female COR plants were often slightly larger than male plants in this dioecious species, but these differences were not statistically significant, and provided no evidence of a reproductive cost expressed as a differential reduction in subsequent vegetative growth in female vs. male plants. This indicated that a zero sum model in which reproductive and vegetative structures compete for assimilates was not supported by our results. In all three species, clonal selection for growth and commercial biomass production, coppice stem number (not plant sex, longest stem length or corresponding basal stem diameter) was the best criteria for selecting superior willow clones.

Evaluation of different hemp (Cannabis sativa L.) progenies resulting from crosses with focus on oil content and seed yield

One of the main breeding objectives for hemp (Cannabis sativa L.) cultivation is higher seed yield important also for the oil yields. However, there has been limited research on hemp breeding that focuses on these topical features. In this study, 17 crosses were created using 12 different hemp varieties. For each variety, five female inflorescences were selected for targeted crossing and one for self-pollination. Seeds from the crosses were sown in separate plots with a seeding density of 30 kg/ha. The number of male and female plants, plant height, internode length, steam thickness, inflorescence length, number of inflorescences per plant, and plant number per plot were measured in crossbred family plants. The absolute weight of seeds per plot, the degree of marbling and oil content were determined. The progeny of the cross between Helena and Tiborszallasi were found to have the highest 100 seed mass (1.546 g, upper half). The offspring of self-pollinated varieties Finola, Tiborszallasi, Fedora 17 and the cross between Helena and Tiborszallasi produced the highest oil content. The progeny of the cross between Futura 75 and KC Dora showed the most promising results in terms of high yield production. This study provided the first important data pertaining to hemp breeding with the goal of increasing oil content and seed yield.

Synthetic seeds for in vitro preservation of Asparagus officinalis L.

BackgroundAsparagus (Asparagus officinalis) is a perennial vegetable of economic importance for its high nutritional and medicinal value. Male plants are more desirable because of their higher spear yield. Therefore, the aim of this study was to evaluate the efficiency of the gibberellin inhibitors; paclobutrazol (PBZ) and cycocel (CCC) for in vitro preservation by encapsulation of in vitro-derived shoot tips of the superior germplasm of the first generation of asparagus male hybrid; cultivar Mary Washington 500W. MethodsAn efficient technique for synthetic seeds production was achieved, consisting of 3% (w/v) Na-alginate dissolved in water, Murashige and Skoog (MS) medium, MS medium with the growth inhibitors; PBZ and CCC at different concentrations, and 0.1 M calcium chloride (CaCl2.2H2O). Synthetic seeds were stored at 4 ℃ and then cultured after different storage durations (0, 2, 4, 8, 12, 16, 20 and 24 weeks) on MS medium supplemented with 1 mg l−1 kinetin, 0.2 mg l−1 naphthalene acetic acid and 0.5 mg l−1 gibberellic acid for shoot tip multiplication; then, recovered shoots were transferred to MS medium supplemented with 1 mg l−1 indole butyric acid and 0.5 mg l−1 PBZ for rooting.ResultsThe beads containing 1 mg l−1 PBZ considered the optimum for producing complete well-developed plantlets of Asparagus officinalis from recovered shoot tips after 24 weeks of storage that successfully acclimatized in the greenhouse.ConclusionsThis protocol is efficient for in vitro preservation by encapsulation of shoot tips and regeneration of Asparagus officinalis F1 male hybrid (Mary Washington 500w), using anti-gibberellin plant growth regulators within the beads to prolong the duration of storage and provide a continuous supply of the plant.

Hexaploid Salix rehderiana is more suitable for remediating lead contamination than diploids, especially male plants

Willows are promising candidates for phytoremediation, but the lead (Pb) phytoremediation potential of different willow ploidy and sex has not yet been exploited. In this study, the Pb uptake, translocation and detoxification capacities of hexaploid and diploid, female and male Salix rehderiana were investigated. The results showed that Pb treatment inhibited biomass accumulation and gas exchange, caused ultrastructural and oxidative damage, and induced antioxidant, phytohormonal and transcriptional regulation in S. rehderiana. Absorbed Pb was mainly accumulated in the roots with restricted root-to-shoot transport. Despite lower biomass, greater transpiration, phytohormonal and transcriptional regulation indicated that hexaploid S. rehderiana had higher tissue Pb concentration, total accumulated Pb amount (4.39 mg, 6.19 mg, 6.60 mg and 10.83 mg in diploid and hexaploid females and males, respectively) as well as bioconcentration factors and translocation factors (0.412, 0.593, 0.921 and 1.320 for bioconcentration factors in roots, and 0.029, 0.032, 0.035 and 0.047 for translocation factors in diploid and hexaploid females and males, respectively) than diploids. Higher soil urease and acid phosphatase activities also favored hexaploids to use more available N and P than diploids in Pb-contaminated soils. Additionally, hexaploid S. rehderiana had stronger antioxidant, phytohormonal and transcriptional responses, and displayed less morphological and ultrastructural damage than diploids after Pb treatment, suggesting that hexaploids have greater Pb uptake, translocation and detoxification capacities than diploids. Moreover, S. rehderiana males had greater Pb uptake and translocation abilities, as well as stronger antioxidant, phytohormonal, and transcriptional regulation mediated Pb detoxification capacities than females. Therefore, hexaploid S. rehderiana are superior to diploids, and males are better than females in Pb phytoremediation. This study provides novel and valuable insights for selecting better willow materials to mitigate Pb contamination.

Gender-specific responses of Salix viminalis roots in morphology and physiology subjected to flooding

Flooding is one of the most common abiotic stresses that plants suffer. Roots are organs that directly sense anoxic environments, but there are few researches on the response of roots to flooding. In this research, the responses of male and female Salix viminalis plants to flooding were investigated by examining the morphological and physiological responses of roots. Our results showed that primary roots (PRs) growth was significantly inhibited and damaged to a certain extent. However, adventitious roots (ARs) formed in a short time and were essential for plants to endure flooding. To cope with flooding stress, the antioxidant enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) increased. Although Pro-contents increased, they were too low to contribute significantly to osmotic adjustment. The anaerobic respiration metabolic pathway was also activated, as proven by increased pyruvate decarboxylase (PDC), alcohol dehydrogenase (ADH), and lactate dehydrogenase (LDH) activities, and the ethanol metabolism pathway might have a key function in adapting to the hypoxic environment for S. viminalis. In addition, increased non-structural carbohydrates (NSCs) of starch and soluble sugar (SS) contents indicated that quiescence strategy might exist in S. viminalis. Overall, there were no significant differences between males and females under flooding stress, and both genders exhibited strong adaptability to the flooding environment. Therefore, two genders of S. viminalis could be applied in the riparian zone.

Reproductive challenges related to a complex sexual system in Euphorbia rosescens, a rare endemic herb

AbstractWhen the sexual system of a rare plant species is complex, characterizing floral development, plant morphology, and subpopulation structure is essential for assessing reproductive potential. Availability of pollinator rewards and positioning of sexual morphs within inflorescences relates to outcrossing potential. We studied the complex sexual system of the recently discovered Euphorbia rosescens E.L. Bridges & Orzell, a rare species occurring in a single Florida county. Euphorbia rosescens has both monomorphic subpopulations of female plants and mixed subpopulations with male and andromonoecious plants. Most data on cyathia sex, inflorescence architecture, floral visitors, and fruit set came from one female subpopulation and one mixed subpopulation. Cyathia longevity, flowering phase, nectar secretion, pollen production, and viability were measured in female, male, and hermaphrodite cyathia. Female plants had fewer inflorescence levels and cyathia and significantly smaller cyathia than male and andromonoecious plants. Andromonoecious plants were larger and produced more cyathia relative to male plants. Within mixed populations, sex switching occurred in both directions between male and andromonoecious plants. Female plants did not switch sexes. Proximal to distal inflorescence levels transitioned from hermaphrodite to male cyathia on andromonoecious plants. Nectar secretion corresponded to initiation of staminate flowering, but in female cyathia stigmas were receptive approximately a day before nectar secretion. Pollen production and viability were similar in male and hermaphrodite cyathia. Fruit maturation was minimal, primarily observed on andromonoecious plants. Nectar availability, pollen rewards, trimorphic inequalities in inflorescence display, and low fruit set suggest high geitonogamy, thus limiting outcrossing potential for this species.

Interference with sex expression, estimation of yield and bioactive compounds in bitter gourd under PGRs-induced conditions

BackgroundThe bitter gourd fruit yields are not at a desirable level due to maleness. Maleness is one of the biggest difficulties with bitter gourd, reducing fruit yields substantially. On the other hand, plant stages are the most important consideration for PGR application because of their sensitive responsiveness. Therefore, it is necessary to determine how bitter gourd plants respond to plant growth regulators, namely PGR0 (control: application of water as control treatment), PGR1 (GA3-Gibberellic acid, 100 mgL−1), PGR2 (NAA-Naphthalene acetic acid, 100 mgL−1), and PGR3 (MH- Maleic hydrazide, 100 mgL−1) at three application phases, S1: soaking of seeds; S2: four-leaf; and S3: flower bud in terms of vegetative development, male–female flower sex alteration, and fruit features including bioactive compounds.ResultsPhysiological, floral and yield characteristics of bitter gourd exposed significant changes by GA3 and MH at various stages. The number of leaves plant−1, the fresh mass of the plant, and the fresh mass of fruit and fruit dry matter content were enhanced remarkably for MH application at the seed soaking stage except for plant height and the number of branches plant−1. MH increased the number of female flowers plant−1, the number of fruits plant−1 and the yield at the 4-leaf stage of application. PGRs substantially influenced the quantity of sugar, chlorophyll, total carotenoids, protein, and water content at various phases of their application but not on ascorbic acid, TSS, or total phenol concentration.ConclusionsFor sex expression and yield attributes, 100 mgL−1 MH at the 4-leaf stage would be effective in bitter gourd. Exogenous NAA showed a considerable dual influence on plant development and antioxidant enzyme activity in bitter gourd fruits.

Genomic description of critical cannabinoid biosynthesis genes

Cannabinoid production is a key attribute of the plant Can nabis sativa and characterizing the genes involved is an essential first step to develop tools for their optimization. We used bioinformatic approaches to annotate and explore variation in the genes coding for enzymes comprising the cannabinoid pathway: olivetol synthase (OLS), olivetolic acid cyclase (OAC), cannabigerolic acid synthase (CBGAS), and the cannabinoid oxidocyclases (THCAS, CBDAS, CBCAS) in multiple C. sativa genome assemblies from diverse lineages. The former three enzymes generate the precursor molecules for the oxidocyclases to produce cannabinoids tetrahydrocannabinol (THC) and cannabidiol (CBD). We show that duplications of OLS and OAC are consistent across varieties, and that OAC has the least amount of sequence diversity based on phylogenetic comparisons. We also found that one CBGAS-like gene exhibits copy number variation among varieties. We discuss implications of these genes existing on separate chromosomes (with homologs of each found in close proximity), and the significance of CBGAS being located on the X chromosome for cannabinoid production in female plants. This study provides valuable insight on the genomic identity and variation of cannabinoid biosynthesis genes that will benefit future research on the origin and evolution of this pathway, a driver of economic, social, and medicinal value.

TPD1-like Gene as a Suitable Marker for Early Sex Determination in Date Palm (Phoenix dactylifera L.).

Date palm (Phoenix dactylifera L.) is a considerably beneficial and economically profitable fruit crop. Female date palm plants produce fruit that is rich in fiber and sugar. Date palm is propagated by two means: suckers and seed. The propagation of date palm through seeds is very necessary for germplasm conservation and breeding. The late reproductive age (4-5 years) and dioecious nature of date palm make genetic improvement and breeding difficult. Early sex determination is the only way to improve breeding by selecting experimental male and female plants at the seedling stage. The primers for Tapetum Determinant 1 (TPD1-like) were designed using Amplify software. The DNA amplification of selected date palm suckers of three genotypes (Ajwa, Amber, and Medjool) was observed through PCR. Expression profiling of selected genotypes was carried out through semi-q PCR and RT-PCR by using the cDNA of suckers and unknown seedlings. Different in silico analyses were performed for the gene and protein characterization and identification of cis-acting elements in the promoter region. The promoter was identified along with the protein's properties and functionality. The expression of TPD1-like gene was found in the leaves of three selected genotypes of male sucker and in some plants of selected unknown seedlings that are considered male plants, and no expression was observed in female suckers and unknown seedlings that are considered female plants. The findings suggested that the TPD1-like gene has the potential for sex differentiation at the seedling stage, as the TPD1-like gene is essential to the specialization of tapetal cells and plays a critical role in plant reproduction.

Chromosome-scale de novo genome assembly and annotation of three representative Casuarina species: C. equisetifolia, C. glauca, and C. cunninghamiana.

Australian pine (Casuarina spp.) is extensively planted in tropical and subtropical regions for wood production, shelterbelts, environmental protection, and ecological restoration. To characterize Casuarina genomic diversity, we sequenced and constructed de novo genome assemblies of the three most widely planted species: C. equisetifolia, C. glauca, and C. cunninghamiana. We generated chromosome-scale genome sequences using both Pacific Biosciences (PacBio) Sequel sequencing and chromosome conformation capture technology (Hi-C). The total genome sizes for C. equisetifolia, C. glauca, and C. cunninghamiana are 268,942,579 bp, 296,631,783 bp, and 293,483,606 bp, respectively, of which 25.91%, 27.15%, and 27.74% were annotated as repetitive sequences. We annotated 23,162, 24,673, and 24,674 protein-coding genes in C. equisetifolia, C. glauca, and C. cunninghamiana, respectively. We then collected branchlets from male and female individuals for whole-genome bisulfite sequencing (BS-seq) to explore the epigenetic regulation of sex determination in these three species. Transcriptome sequencing (RNA-seq) revealed differential expression of phytohormone-related genes between male and female plants. In summary, this study generated three chromosome-level genome assemblies and comprehensive DNA methylation and transcriptome datasets from both male and female material for three Casuarina species, providing a basis for the comprehensive investigation of genomic diversity and functional gene discovery of Casuarina in the future.

Re-imagining Reproduction: The Queer Possibilities of Plants.

How did plant sexuality come to so hauntingly resemble human sexual formations? How did plant biology come to theorize plant sexuality with binary formulations of male/female, sex/gender, sperm/egg, active males and passive females-all of which resemble western categories of sex, gender, and sexuality? Tracing the extant language of sex and sexuality in plant reproductive biology, we examine the histories of science to explore how plant reproductive biology emerged historically from formations of colonial racial and sexual politics and how evolutionary biology was premised on the imaginations of racialized heterosexual romance. Drawing on key examples, the paper aims to (un)read plant sexuality and sexual anatomy and bodies to imagine new possibilities for plant sex, sexualities, and their relationalities. In short, plant sex and sexuality are not two different objects of inquiry but are intimately related-it is their inter-relation that is the focus of this essay. One of the key impulses from the humanities that we bring to this essay is a careful consideration of how terms and terminologies are related to each other historically and culturally. In anthropomorphizing plants, if plant sexuality were modeled on human sexual formations, might a re-imagination of plant sexuality open new vistas for the biological sciences? While our definitions of plant sexuality will always be informed by contemporary society and culture, interrogating the histories of our theories and terminologies can help us reimagine a biology that allows for new and more accurate understandings of plants, plant biology, and the evolution of reproduction.

Litsea Males Are Better Adapted to Pb Stress Than Females by Modulating Photosynthesis and Pb Subcellular Distribution

Litsea cubeba Pers., a dioecious species, is an important tree species for the bioenergy industry with great potential for lead (Pb)-polluted soil phytoremediation. However, the sex-specific morphological and physiological characteristics of L. cubeba under Pb stress remain largely unknown. In this study, L. cubeba was used as a study model to identify sex differences in leaf traits, chlorophyll, photosynthetic gas parameters, chlorophyll fluorescence, Pb subcellular distribution, and photosynthesis-related nutrient contents in chloroplasts and cell nuclei under three different Pb concentrations [0 (CK), 1 (P1), 2 (P2), and 3 (P3) mmol/kg]. The results indicate that Pb stress significantly decreases photosynthetic leaf pigments in both sexes, mainly caused by changes in Ca, Mg, and Mn contents. Furthermore, L. cubeba male plants exhibited greater adaptability to Pb stress by enlarging their leaf area, enhancing photosynthesis and excess light energy in the form of heat dissipation when compared to female plants. Notably, we observed that more Pb reached the organelle fraction and damaged chloroplasts and mitochondria in female leaves under high-level Pb treatments compared to those of the opposite sex. Transcriptome analysis demonstrated that Pb stress could significantly up-regulate more genes involved in photosynthetic antenna proteins and photosynthesis pathways in male leaves than in female leaves. Taken together, L. cubeba male plants are clearly more resistant to Pb toxicity than female plants—at least under the described Pb treatments—which is most likely due to differences in Pb allocation. This research offers a theoretical foundation for the utilization of male and female L. cubeba as suitable plants for the remediation of Pb-polluted soil.

Flower development and sexual dimorphism in Vernicia montana

The mu oil tree (Vernicia montana Lour.) is a dioecious species, but the genetic mechanisms underlying its phenotypic sexual dimorphism are unclear. In this study, we determined two pivotal phases of sex differentiation of mu oil tree via morphological and histological analyses of unisexual flowers: (I) differentiation of male or female primordia to produce staminate flowers (SFs) or transient hermaphrodite flowers (HFs), and (II) complete abortion of stamens in transient HFs to generate pistillate flowers (PFs). A total of 1621 sex-biased genes were identified by comparative transcriptome analysis which exhibited elevated rates of protein evolution than unbiased genes. The female-biased genes were enriched in the production of defense compounds while male-biased genes were focused on the production of viable pollens. Transcriptome-based analysis revealed that the differentially expressed genes (DEGs) between PFs and SFs in phase I involved in abscisic acid (ABA), auxin (AUX), cytokinin (CK), ethylene (ET), and gibberellin (GA) biosynthesis and signaling showed higher expression levels in males than in females in general, whereas the DEGs involved in jasmonic acid (JA) and salicylic acid (SA) pathways displayed opposite expression patterns. Moreover, differentially expressed endogenous ABA, AUX, GAs, JA, and SA exhibited consistent biased expression patterns with the DEGs by UPLC-MS-based analysis. Exogenous application of an anti-ethylene plant growth regulator could promote the development of stamens in PFs and generated HFs. Comparative transcriptomic and hormonal analyses of PFs and SFs in phase II indicated an increase in ET concentration when abortion of stamens in PFs occurred. This study suggested that phytohormones play key roles in sex dimorphism and ET may determine the development of stamens in PFs of mu oil tree, which provides an insight into plant sex differentiation mechanisms.

Effect of the sowing ratios on the yield and quality of seed from maize genotypes

Objective: To identify optimal sowing ratios, validation of production technology and seed quality in maize hybrids. Design/methodology/approach: Sowing ratios of 4:2 and 6:2 were studied to observe their effect on the genotypes, as well as their quality and response in seed production; this was done by evaluating the following variables: days to male and female flowering, plant and ear height, percentage of ear and seed in cobs, commercial seed yield, thousand seed weight, number of seeds per kilogram, standard germination and hectoliter weight of the seed. An analysis of variance was carried out using a completely randomized design with factorial arrangement and four replications, the experimental unit being furrows of 20 linear meters. Results: Significant differences were detected in the hybrids with respect to the variables and sowing ratios, which specifically influences the weight, size and number of seeds; the hybrid H-386A had the best response to the environment and ratios, exceeding the rest of the hybrids evaluated by 72.92 %. Limitations on study/implications: The interaction of genotype and environment are factors that limit seed production; however, performing evaluations in different environments allows finding stable hybrids with high yields. Findings/conclusions: The generation of knowledge allows us to make decisions regarding crop establishment and quality in seed production lots, being a recommended environment in CIRPAC’s area of influence

Pollen Mitosis is a Good Choice for Gametophytic Chromosome Study in Higher Plants—Investigation with <i>Allium cepa</i> L. and <i>Aloe vera</i> L.

In higher groups of plants, the somatic cells are conventionally used for karyomorphological studies, which contain a diploid (2n) set of chromosomes. Similar to diploid sporophytic cells, a chromosomal study in haploid (n) gametophytic cells is also necessary as it unfolds the karyomorphological status of germ cells. The mature male gametophytic plant body (i.e., pollen grain) is only two- or three-celled structures. This study focused on the first mitotic division in a microspore, popularly known as ‘pollen mitosis-I.’ Allium cepa L. and Aloe vera L. are two model species for karyomorphological study. Microspores of these species have been stained with 2.0% acetocarmine. The present finding reveals that the cell division in microspores of these two species is completely normal without any significant irregularities. As expected, the chromosome number of the microspores of Allium cepa is n=8 and Aloe vera is n=7, exactly half the number of their sporophytic plants. The haploid karyotype of Allium cepa is the symmetric type with karyotype formula ‘6m+2sm,’ whereas that of Aloe vera is between symmetric and asymmetric types with karyotype formula ‘3sm+4st.’ This study not only enriches the chromosomal database of gametophytes of Allium cepa and Aloe vera, but also will encourage further research on this extremely neglected topic—chromosome study in the gametophytic generation of flowering plants. As Allium cepa and Aloe vera are easily available and model species for karyomorphological study, and with two contrast karyotypes (i.e., symmetric and asymmetric), this article also helps numerous school/college teachers to teach their students about the structure and behavior of gametophytic chromosomes.

Genetic characterization of downy mildew resistance from the hop (Humulus lupulus L.) line USDA 64035M

AbstractDowny mildew (caused by Pseudoperonospora humuli) resistance (DMR) will facilitate the success of hop (Humulus lupulus L.) production in humid, temperate climates. However, DMR in hop has a narrow genetic base, and its genetic architecture is poorly understood. In this study, we characterized the genetic control of DMR using a biparental mapping population derived from a cross between a female, the susceptible cultivar ‘Comet,’ and a male plant, the resistant line USDA 64035M. Resistance was evaluated after inoculation with the downy mildew pathogen as disease severity and percent leaf area with sporulating lesions under greenhouse conditions. Significant (p value < 0.01) genotypic differences were observed for the traits. Broad‐sense heritability was 0.33 for disease severity and 0.72 for percent leaf area with sporulating lesions. Genome–phenome association between 4090 markers and 274 individuals identified three significant markers for disease severity and five for percent leaf area with sporulating lesions. Our study demonstrated that DMR was under polygenic control with small effect loci in this population. In addition, a pleiotropic locus on chromosome two was found to be associated with both disease severity and percent leaf area with sporulating lesions. Identifying the gene(s) underlying such a pleiotropic locus can help improve our understanding of hop response to pathogen infection.

Knockout of DDM1 in Physcomitrium patens disrupts DNA methylation with a minute effect on transposon regulation and development.

The Snf2 chromatin remodeler, DECREASE IN DNA METHYLATION 1 (DDM1) facilitates DNA methylation. In flowering plants, DDM1 mediates methylation in heterochromatin, which is targeted primarily by MET1 and CMT methylases and is necessary for silencing transposons and for proper development. DNA methylation mechanisms evolved throughout plant evolution, whereas the role of DDM1 in early terrestrial plants remains elusive. Here, we studied the function of DDM1 in the moss, Physcomitrium (Physcomitrella) patens, which has robust DNA methylation that suppresses transposons and is mediated by a MET1, a CMT, and a DNMT3 methylases. To elucidate the role of DDM1 in P. patens, we have generated a knockout mutant and found DNA methylation to be strongly disrupted at any of its sequence contexts. Symmetric CG and CHG sequences were affected stronger than asymmetric CHH sites. Furthermore, despite their separate targeting mechanisms, CG (MET) and CHG (CMT) methylation were similarly depleted by about 75%. CHH (DNMT3) methylation was overall reduced by about 25%, with an evident hyper-methylation activity within lowly-methylated euchromatic transposon sequences. Despite the strong hypomethylation effect, only a minute number of transposons were transcriptionally activated in Ppddm1. Finally, Ppddm1 was found to develop normally throughout the plant life cycle. These results demonstrate that DNA methylation is strongly dependent on DDM1 in a non-flowering plant; that DDM1 is required for plant-DNMT3 (CHH) methylases, though to a lower extent than for MET1 and CMT enzymes; and that distinct and separate methylation pathways (e.g. MET1-CG and CMT-CHG), can be equally regulated by the chromatin and that DDM1 plays a role in it. Finally, our data suggest that the biological significance of DDM1 in terms of transposon regulation and plant development, is species dependent.

Peptide signaling through leucine-rich repeat receptor kinases: insight into land plant evolution.

Multicellular organisms need mechanisms for communication between cells so that they can fulfill their purpose in the organism as a whole. Over the last two decades, several small post-translationally modified peptides (PTMPs) have been identified as components of cell-to-cell signaling modules in flowering plants. Such peptides most often influence growth and development of organs not universally conserved among land plants. PTMPs have been matched to subfamily XI leucine-rich repeat receptor-like kinases with > 20 repeats. Phylogenetic analyses, facilitated by recently published genomic sequences of non-flowering plants, have identified seven clades of such receptors with a history back to the common ancestor of bryophytes and vascular plants. This raises a number of questions: When did peptide signaling arise during land plant evolution? Have orthologous peptide-receptor pairs preserved their biological functions? Has peptide signaling contributed to major innovations, such as stomata, vasculature, roots, seeds, and flowers? Using genomic, genetic, biochemical, and structural data and non-angiosperm model species, it is now possible to address these questions. The vast number of peptides that have not yet found their partners suggests furthermore that we have far more to learn about peptide signaling in the coming decades.

Identifying Genes Associated with Female Flower Development of Phellodendron amurense Rupr. Using a Transcriptomics Approach.

Phellodendron amurense Rupr., a species of Rutaceae, is a nationally protected and valuable medicinal plant. It is generally considered to be dioecious. With the discovery of monoecious P. amurense, the phenomenon that its sex development is regulated by epigenetics has been revealed, but the way epigenetics affects the sex differentiation of P. amurense is still unclear. In this study, we investigated the effect of DNA methylation on the sexual development of P. amurense. The young inflorescences of male plants were treated with the demethylation agent 5-azaC, and the induced female flowers were obtained. The induced female flowers' morphological functions and transcriptome levels were close to those of normally developed plants. Genes associated with the development of female flowers were studied by comparing the differences in transcriptome levels between the male and female flowers. Referring to sex-related genes reported in other plants, 188 candidate genes related to the development of female flowers were obtained, including sex-regulating genes, genes related to the formation and development of sexual organs, genes related to biochemical pathways, and hormone-related genes. RPP0W, PAL3, MCM2, MCM6, SUP, PIN1, AINTEGUMENTA, AINTEGUMENTA-LIKE6, AGL11, SEUSS, SHI-RELATED SEQUENCE 5, and ESR2 were preliminarily considered the key genes for female flower development. This study has demonstrated that epigenetics was involved in the sex regulation of P. amurense, with DNA methylation as one of its regulatory modes. Moreover, some candidate genes related to the sexual differentiation of P. amurense were obtained with analysis. These results are of great significance for further exploring the mechanism of sex differentiation of P. amurense and studying of sex differentiation of plants.

Recurrent neo-sex chromosome evolution in kiwifruit.

Sex chromosome evolution is thought to be tightly associated with the acquisition and maintenance of sexual dimorphisms. Plant sex chromosomes have evolved independently in many lineages1,2 and can provide a powerful comparative framework to study this. We assembled and annotated genome sequences of three kiwifruit species (genus Actinidia) and uncovered recurrent sex chromosome turnovers in multiple lineages. Specifically, we observed structural evolution of the neo-Y chromosomes, which was driven via rapid bursts of transposable element insertions. Surprisingly, sexual dimorphisms were conserved in the different species studied, despite the fact that the partially sex-linked genes differ between them. Using gene editing in kiwifruit, we demonstrated that one of the two Y-chromosome-encoded sex-determining genes, Shy Girl, shows pleiotropic effects that can explain the conserved sexual dimorphisms. These plant sex chromosomes therefore maintain sexual dimorphisms through the conservation of a single gene, without a process involving interactions between separate sex-determining genes and genes for sexually dimorphic traits.