The inflorescences of Portulacaceae have traditionally been considered capitula and their morphology and architecture have not been studied in detail. The purpose of this study was to expand the knowledge on the inflorescences within this family, comparing members of distinct lineages of Portulaca occurring in Brazil, to understand some systematic and evolutionary patterns within this group. Morphological characteristics of the inflorescences were analyzed using a light stereomicroscope, and for anatomical studies, we made transversal and longitudinal sections along the entire inflorescence, including involucral bracts, analyzing them using an optical microscope. We confirmed that observed inflorescences are determinate, composed of a first-order dichasium, with second-order helicoidal branches forming a cephalioid structure. The involucral leaves differed from adjacent bracts, which did not display a constriction at the base, as commonly observed in leaves. Thus, we conclude that the congested inflorescence of Portulaca is not a capitulum, but a cephalioid with different degrees of branch reduction within the genus. The Pilosa clade displayed the most congested cephalioid compared to members of the other analyzed clades. We present a new interpretation of the congested inflorescences in Portulaca and reinforce the need to analyze solitary inflorescences to understand the importance of these data to the systematics and evolution of Portulacaceae.

Recent advances in genome editing have enormously enhanced the effort to develop biotechnology crops for more sustainable food production. CRISPR/Cas, the most versatile genome-editing tool, has shown the potential to create genome modifications that range from gene knockout and gene expression pattern modulations to allele-specific changes in order to design superior genotypes harboring multiple improved agronomic traits. However, a frequent bottleneck is the delivery of CRISPR/Cas to crops that are less amenable to transformation and regeneration. Several technologies have recently been proposed to overcome transformation recalcitrance, including HI-Edit/IMGE and ectopic/transient expression of genes encoding morphogenic regulators. These technologies allow the eroding of the barriers that make crops inaccessible for genome editing. In this review, we discuss the advances in genome editing in crops with a particular focus on the use of technologies to improve complex traits such as water use efficiency, drought stress, and yield in maize.

The recalcitrance exhibited by many maize (Zea mays) genotypes to traditional genetic transformation protocols poses a significant challenge to the large-scale application of genome editing (GE) in this major crop species. Although a few maize genotypes are widely used for genetic transformation, they prove unsuitable for agronomic tests in field trials or commercial applications. This challenge is exacerbated by the predominance of transformable maize lines adapted to temperate geographies, despite a considerable proportion of maize production occurring in the tropics. Ectopic expression of morphogenic regulators (MRs) stands out as a promising approach to overcome low efficiency and genotype dependency, aiming to achieve ’universal’ transformation and GE capabilities in maize. Here, we report the successful GE of agronomically relevant tropical maize lines using a MR-based, Agrobacterium-mediated transformation protocol previously optimized for the B104 temperate inbred line. To this end, we used a CRISPR/Cas9-based construct aiming at the knockout of the VIRESCENT YELLOW-LIKE (VYL) gene, which results in an easily recognizable phenotype. Mutations at VYL were verified in protoplasts prepared from B104 and three tropical lines, regardless of the presence of a single nucleotide polymorphism (SNP) at the seed region of the VYL target site in two of the tropical lines. Three out of five tropical lines were amenable to transformation, with efficiencies reaching up to 6.63%. Remarkably, 97% of the recovered events presented indels at the target site, which were inherited by the next generation. We observed off-target activity of the CRISPR/Cas9-based construct towards the VYL paralog VYL-MODIFIER, which could be partly due to the expression of the WUSCHEL (WUS) MR. Our results demonstrate efficient GE of relevant tropical maize lines, expanding the current availability of GE-amenable genotypes of this major crop.

Climbing plants have voluble organs, for example, tendrils and modified stems, which twine up neighboring plants to reach the canopy. These organs perform exaggerated circumnutation, during which they grow towards the shaded areas of the forest (skototropism) to find a host. In response to mechanical stimulus, they grow towards the support (thigmotropism), tailoring their development to firmly attach to it (thigmomorphogenesis). The underlying molecular pathways of these crucial mechanisms are virtually unknown. Here, we review current progress on molecular regulation of the development and growth of climber's voluble organs. Recent advances in the subject point epigenetics and sensory biology as the emerging frontiers in the study of climbing plant's growth and functioning. We briefly review new developments on the molecular basis of plants' mechanosensory system, discussing the findings in the context of the climbing habit.

The timing of flowering and the inflorescence architecture are critical for the reproductive success of tomato (Solanum lycopersicum), but the gene regulatory networks underlying these traits have not been fully explored. Here, we show that the tomato FRUITFULL-like (FUL-like) genes FUL2 and MADS-BOX PROTEIN 20 (MBP20) promote the vegetative-to-reproductive transition and repress inflorescence branching by inducing floral meristem (FM) maturation. FUL1 fulfils a less prominent role and appears to depend on FUL2 and MBP20 for its upregulation in the inflorescence- and floral meristems. MBP10, the fourth tomato FUL-like gene, has probably lost its function. The tomato FUL-like proteins cannot homodimerize in in vitro assays, but heterodimerize with various other MADS-domain proteins, potentially forming distinct complexes in the transition meristem and FM. Transcriptome analysis of the primary shoot meristems revealed various interesting downstream targets, including four repressors of cytokinin signaling that are upregulated during the floral transition in ful1 ful2 mbp10 mbp20 mutants. FUL2 and MBP20 can also bind in vitro to the upstream regions of these genes, thereby probably directly stimulating cell division in the meristem upon the transition to flowering. The control of inflorescence branching does not occur via the cytokinin oxidase/dehydrogenases (CKXs) but may be regulated by repression of transcription factors such as TOMATO MADS-box gene 3 (TM3) and APETALA 2b (AP2b).

Over the past decades, advances in plant biotechnology have allowed the development of genetically modified maize varieties that have significantly impacted agricultural management and improved the grain yield worldwide. To date, genetically modified varieties represent 30% of the world’s maize cultivated area and incorporate traits such as herbicide, insect and disease resistance, abiotic stress tolerance, high yield, and improved nutritional quality. Maize transformation, which is a prerequisite for genetically modified maize development, is no longer a major bottleneck. Protocols using morphogenic regulators have evolved significantly towards increasing transformation frequency and genotype independence. Emerging technologies using either stable or transient expression and tissue culture-independent methods, such as direct genome editing using RNA-guided endonuclease system as an in vivo desired-target mutator, simultaneous double haploid production and editing/haploid-inducer-mediated genome editing, and pollen transformation, are expected to lead significant progress in maize biotechnology. This review summarises the significant advances in maize transformation protocols, technologies, and applications and discusses the current status, including a pipeline for trait development and regulatory issues related to current and future genetically modified and genetically edited maize varieties.

Five laccase genes are potentially involved in developmental lignification in the model C4 grass Setaria viridis and their different tissue specificities suggest subfunctionalization events. Plant laccases are copper-containing glycoproteins involved in monolignol oxidation and, therefore, their activity is essential for lignin polymerization. Although these enzymes belong to large multigene families with highly redundant members, not all of them are thought to be involved in lignin metabolism. Here, we report on the genome-wide characterization of the laccase gene family in the model C4 grass Setaria viridis and further identification of the members potentially involved in monolignol oxidation. A total of 52 genes encoding laccases (SvLAC1 to SvLAC52) were found in the genome of S. viridis, and phylogenetic analyses showed that these genes were heterogeneously distributed among the characteristic six subclades of the family and are under relaxed selective constraints. The observed expansion in the total number of genes in this species was mainly caused by tandem duplications within subclade V, which accounts for 68% of the whole family. Comparative phylogenetic analyses showed that the expansion of subclade V is specifically observed for the Paniceae tribe within the Panicoideae subfamily in grasses. Five SvLAC genes (SvLAC9, SvLAC13, SvLAC15, SvLAC50, and SvLAC52) fulfilled the criteria established to identify lignin-related candidates: (1) phylogenetic proximity to previously characterized lignin-related laccases from other species, (2) similar expression pattern to that observed for lignin biosynthetic genes in the S. viridis elongating internode, and (3) high expression in S. viridis tissues undergoing active lignification. In addition, in situ hybridization experiments not only confirmed that these selected SvLAC genes were expressed in lignifying cells, but also that their expression showed different tissue specificities, suggesting subfunctionalization events within the family. These five laccase genes are strong candidates to be involved in lignin polymerization in S. viridis and might be good targets for lignin bioengineering strategies.

ABSTRACT Background Transposable elements (TEs) are major components of plant genomes. Despite being regarded as “junk DNA” at first, TEs play important roles for the organisms they are found in. The most obvious and easily recognizable effects caused by TEs result from their mobility, which can disrupt coding sequences or promoter regions. However, with the recent advances in transcriptomics, it is becoming increasingly evident that TEs can act as an additional layer of gene expression regulation through a number of processes, which can involve production of non-coding RNAs. Here, we describe how Tnt1, a stress-responsive LTR-retrotransposon, interferes with gene expression and modulate a number of developmental aspects in tobacco. Results Through an RNAi approach, we generated tobacco (HP) lines knocked-down for Tnt1 expression. Quantitative RT-PCR experiments confirm that Tnt1 is downregulated in HP lines after ethylene exposure. A RNA-seq experiment was performed and through two independent bioinformatic approaches (with different stringencies) we found 932 and 97 differentially expressed genes in HP lines. A number of phenotypes were observed in such lines, namely lesion mimicry in leaves, underdevelopment of the root system, overproduction of root hairs and early loss of seed viability. Folding prediction of part of the Tnt1 mRNA reveals putative stem-loop secondary structures containing transcriptional regulation sequences, suggesting it could be a source of small RNAs. We also propose a model to explain the Tnt1 expression in both homeostatic and stress conditions, and how it could interact with stress-responsive genes. Conclusions Our results are consistent that interferences with Tnt1 transcript levels correlate with transcriptomic and phenotypic changes, suggesting a functional role for this element during plant development and stress response.

PREMISE The inflorescence of Passiflora species originates from a bud complex that derives from an initially undivided meristem and ultimately produces flowers and tendrils. Because the development of the inflorescence structures derived from such meristems has been variously interpreted, we investigated the ontogeny of the bud complex and the expression of APETALA1 (AP1) in Passiflora species. METHODS The anatomical development of 15 species of Passiflora was analyzed using light and scanning electron microscopy. We localized AP1 expression in tissues during inflorescence initiation in two Passiflora species using in situ hybridization. RESULTS In most species, the first primordium to differentiate from the bud complex is a bract, which develops laterally to what will become the inflorescence first-order axis, in this case, the tendril. The bract axillary meristem originates the second-order inflorescence axis meristem, which produces two bracteoles, subsequently developing into a floral meristem. AP1 is uniformly expressed in the initially undivided meristem, with expression maintained in the organ primordia derived from the bud complex. Signal is particularly strong in tendril tips. CONCLUSIONS We concluded that what is often understood as the first bract produced by a floral meristem actually is produced by the original axillary meristem. Bracteoles develop from the meristem in the bract axil; bracteoles plus floral meristem constitute the inflorescence second-order axis. Comparison of inflorescence early developmental stages in different subgenera indicates flowers are arranged in a modified cyme, with the tendril representing the inflorescence terminal portion. PasAP1 has a broad expression pattern and may have an important role during inflorescence development.

The climbing habit has evolved multiple times during the evolutionary history of angiosperms. Plants evolved various strategies for climbing, such as twining stems, tendrils and hooks. Tendrils are threadlike organs with the ability to twine around other structures through helical growth; they may be derived from a variety of structures, such as branches, leaflets and inflorescences. The genetic capacity to grow as a tendrilled climber existed in some of the earliest land plants; however, the underlying molecular basis of tendril development has been studied in only a few taxa. Here, we summarize what is known about the molecular basis of tendril development in model and candidate model species from key tendrilled families, that is, Fabaceae, Vitaceae, Cucurbitaceae, Passifloraceae and Bignoniaceae. Studies on tendril molecular genetics and development show the molecular basis of tendril formation and ontogenesis is diverse, even when tendrils have the same ontogenetic origin, for example leaflet-derived tendrils in Fabaceae and Bignoniaceae. Interestingly, all tendrils perform helical growth during contact-induced coiling, indicating that such ability is not correlated with their ontogenetic origin or phylogenetic history. Whether the same genetic networks are involved during helical growth in diverse tendrils still remains to be investigated.

Unifacial leaves are described in different angiosperm groups, especially in monocotyledons, which show anatomical and molecular evidence of an abaxialization process. Among the structural characters, the anatomy of epidermis and growth tissues has been reported. Special focus has been given to vascularization patterns, such as the presence and organization of peripheral vascular bundles. In the Aizoaceae, peripheral vascular bundles exhibit two patterns: exoscopic and endoscopic bundles; however, studies including an ontogenetic approach with evidence for a unifacial condition in the group are lacking. We investigated eleven Ruschioideae species, including members of two tribes (Ruschieae and Dorotheantheae), which present flat and terete leaves. Our results show that all leaves present a bifacial leaf base, with xylem cells oriented toward the adaxial face present in collateral vascular bundles. However, the occurrence of peripheral endoscopic vascular bundles in the leaf blade in all terete leaves demonstrates a unifacial condition which is present only at the leaf blades. Based on ontogenetics studies, we demonstrate that the peripheral endoscopic bundles begin their differentiation in the abaxial side of the leaf primordia, suggesting the occurrence of an abaxialization process during leaf blade development.

Climbers are abundant in tropical forests, where they constitute a major functional plant type. The acquisition of the climbing habit in angiosperms constitutes a key innovation. Successful speciation in climbers is correlated with the development of specialized climbing strategies such as tendrils, i.e., filiform organs with the ability to twine around other structures through helical growth. Tendrils are derived from a variety of morphological structures, e.g., stems, leaves, and inflorescences, and are found in various plant families. In fact, tendrils are distributed throughout the angiosperm phylogeny, from magnoliids to asterids II, making these structures a great model to study convergent evolution. In this study, we performed a thorough survey of tendrils within angiosperms, focusing on their origin and development. We identified 17 tendril types and analyzed their distribution through the angiosperm phylogeny. Some interesting patterns emerged. For instance, tendrils derived from reproductive structures are exclusively found in the Core Eudicots, except from one monocot species. Fabales and Asterales are the orders with the highest numbers of tendrilling strategies. Tendrils derived from modified leaflets are particularly common among asterids, occurring in Polemoniaceae, Bignoniaceae, and Asteraceae. Although angiosperms have a large number of tendrilled representatives, little is known about their origin and development. This work points out research gaps that should help guide future research on the biology of tendrilled species. Additional research on climbers is particularly important given their increasing abundance resulting from environmental disturbance in the tropics.

Background: Passiflora (passionflowers) makes an excellent model for studying plant evolutionary development. They are mostly perennial climbers that display axillary tendrils, which are believed to be modifications of the inflorescence. Passionflowers are also recognized by their unique flower features, such as the extra whorls of floral organs composed of corona filaments and membranes enclosing the nectary. Although some work on Passiflora organ ontogeny has been done, the developmental identity of both Passiflora tendrils and the corona is still controversial. Here, we combined ultrastructural analysis and expression patterns of the flower meristem and floral organ identity genes of the MADS-box AP1/FUL clade to reveal a possible role for these genes in the generation of evolutionary novelties in Passiflora.Results: We followed the development of structures arising from the axillary meristem from juvenile to adult phase in P.edulis. We further assessed the expression pattern of P.edulis AP1/FUL homologues (PeAP1 and PeFUL), by RT-qPCR and in situ hybridization in several tissues, correlating it with the developmental stages of P.edulis. PeAP1 is expressed only in the reproductive stage, and it is highly expressed in tendrils and in flower meristems from the onset of their development. PeAP1 is also expressed in sepals, petals and in corona filaments, suggesting a novel role for PeAP1 in floral organ diversification. PeFUL presented a broad expression pattern in both vegetative and reproductive tissues, and it is also expressed in fruits.Conclusions: Our results provide new molecular insights into the morphological diversity in the genus Passiflora. Here, we bring new evidence that tendrils are part of the Passiflora inflorescence. This points to the convergence of similar developmental processes involving the recruitment of genes related to flower identity in the origin of tendrils in different plant families. The data obtained also support the hypothesis that the corona filaments are likely sui generis floral organs. Additionally, we provide an indication that PeFUL acts as a coordinator of passionfruit development.

Species of the suborder Portulacineae (Caryophyllales) often possess succulent leaves with wide morphological diversity, including flat and terete leaves. Terete leaves are described as not developing a marginal meristem during their growth, but in Portulacineae little is known about anatomical development in this particular leaf type. To better understand the mechanisms underlying the development of different leaf morphologies within this group, we examined leaf histogenesis in species of four families with succulent leaves-Basellaceae, Didiereaceae, Portulacaceae, and Talinaceae-through optical microscopy. We observed two morphological patterns (terete and flat leaves) and three developmental patterns regarding blastozone positioning. While species with flat leaves always show the expected pattern of marginal blastozone activity, terete leaves of Didiereaceae present marginal blastozones for only a very brief period. On the other hand, terete leaves of Portulacaceae show a persistent peripheral blastozone enveloping the entire leaf during its development. We also demonstrate anatomical evidence suggesting that the terete leaves of Portulacaceae are adaxialized, i.e., their entire surface is homologous to the adaxial side, while terete leaves of Didiereaceae seem to result from a less severe modification.

By their wide morphological diversity, succulent leaves have aroused the interest of many researchers. Nonetheless, comparative anatomical studies of unifacial, bifacial, and subunifacial leaves are scarce. To address this gap, our study examines the growth and differentiation of vascular tissues in succulent leaves of 12 families of angiosperms. Altogether, we identified six arrangements arising as variations of three basic vascularization patterns. In addition, cases of convergent evolution were identified in (1) terete leaves showing both endoscopic peripheral bundles and a central bundle in some Crassulaceae (Saxifragales, eudicots) and Aizoaceae (Caryophyllales, eudicots) and (2) terete leaves showing exclusively endoscopic peripheral bundles in some Asteraceae (eudicots) and Orchidaceae (monocots). Both endoscopic and exoscopic bundles originate from a peripheral region, and in all species with endoscopic peripheral bundles, the differentiation of the vascular bundles begins from abaxial domains, whereas in leaf blades with exoscopic bundles, differentiation begins from adaxial domains. These observations suggest that the molecular mechanism(s) involved in the abaxialization/adaxialization process of the leaf blade could be related to activity of the peripheral region. Therefore, further investigation is being carried out to elucidate peripheral meristematic activity responsible for the differentiation of vascular bundles and the fundamental system.

vegetativa para reprodutiva em diversas angiospermas.

The objective is to analyze and discuss the factors and conditions necessary to the emergence of business networks. The main guide is the theoretical assertive that all companies are in a networks, whether they use or not their connections. The primary proposition is that it is necessary the presence of social and resource dependence variables as determinants for the emergence and development of networks. Previous reflections indicate that the most relevant social variables would be trust and cooperation, and the most relevant resource dependence variables would be access to markets, access to technology and economy resources. The research instrument used was interviews, observation and documentation research. The analytic technique was the contend analysis. The results sustained the proposition, since there are cases of emergence of networks that occur only when the variables was presents. The work present a theoretical contribution regards the emergence of business networks and methodological contribution with the presentation of a test specifically developed to the task, which did not exist in the Brazilian academy.

O interesse gerado no aumento da produtividade de etanol, tem despertado o interesse para estudo, visando uma melhoria na produção do etanol. As leveduras tem sido foco destas pesquisas uma vez que estes micro-organismos é o responsável na produção de etanol. Estudos que mostrem a importância do desempenho fermentativo de linhagens de leveduras no processo de fermentação alcoólica são importantes, uma vez que estas leveduras são o componente essencial nos processos fermentativos para a produção de etanol. Este estudo visa avaliar linhagens de leveduras cultivas em mosto a base de caldo de cana em relação a capacidade fermentativa: biomassa e viabilidade celular. Estudos para entender os diferentes mecanismos fisiológicos de linhagens de leveduras para a produção de etanol, sobre diferentes concentrações osmóticas as leveduras analisadas apresentaram capacidade fermentativa nas concentrações analisadas, os dados mostram que a concentração de 15º Brix apresentou a melhor produção de biomassa e etanol, estudos da capacidade fermentativa pode ser uma importante ferramenta para alavancar e assegurar o desenvolvimento do setor sucroenergético no Brasil.

O presente projeto visa avaliar os isolados de leveduras selvagens de aspecto rugoso, e sua capacidade fermentativa buscando aquela mais adaptada ao processo, produzindo um melhor rendimento alcoólico, para que o setor sucroenergético possa atingir seu potencial máximo. Avaliar a produção de biomassa e a viabilidade celular visando comparar a sua capacidade fermentativa, buscando formar um banco de dados de leveduras regional.