Brazilian Journal of Botany最新文献

Orchid flowers possess high ornamental value owing to their delicate structure and color. The color patterns are a result of unbalanced pigment distribution among the petal segments, with bicolor being the most common and important for pollination. However, little is known about the relationship between petal bicolor patterns and metabolites and vein structure. Here, we focused on Dendrobium nobile Lindl., with pigmentation mainly at the tip of the flower petal, and D. anosmum ‘A Touch of Class’ Lindl, with pigmentation along the entire petal edge. We combined spatial and widely targeted metabolomics with venation anatomical analysis to identify metabolite and structural differences between the two flower bicolor patterns. In our study, we discovered that the concentration of energy-related substances, such as sugars, did not exhibit significant variance across different color regions of the flower. However, defensive metabolites like alkaloids, phenolic acids, and polyamines were found to be more concentrated in areas with more vibrant pigmentation. Specifically, in D. nobile, a higher accumulation of these metabolites was observed in the vein regions, as identified through spatial metabolic analysis. The study also revealed that different vein types had distinct distribution patterns, yet no significant difference was observed in the density of longitudinal and transverse veins between the two examined species. Notably, D. nobile showed a significantly higher density of open veins in the distal part (pigmented part) of the petal compared to the proximal part. In contrast, D. anosmum 'A Touch of Class' exhibited no significant difference in open vein density between these two regions. Our findings contribute to a deeper understanding of color patterning in orchid flowers and provide a theoretical foundation for the breeding of Dendrobium species.

Malvaceae is divided into nine subfamilies, one of which is Malvoideae. Wissadula Medik., a genus within the Malvoideae, is divided into two sections according to mericarp morphology and the number of ovules per locule. Species belonging to the section Wissadula have three or rarely two ovules, whereas species belonging to the section Wissada have a single ovule. In Brazil, 19 species are recorded under the two sections, including a single species (Wissadula stipulata Bovini) in section Wissada and 18 in section Wissadula. This study analyzed pollen grains from both sections of Wissadula with the aim of confirming or not the existence of these sections based on pollen morphology. All 19 taxa occurring in Brazil were analyzed. The botanical material was collected from exsiccatae deposited in national herbaria and subjected to acetolysis. Subsequently, slides were prepared, examined under light microscopy, and photomicrographed. Pollen grains are monads, isopolar, large, suboblate, and triporate. The polar area is small in most species and large in a few others. The exine is thick, with echinate ornamentation, granules, and perforations. It was possible to distinguish the analyzed species based on of pollen diameters and spine characteristics (dimensions and distance). The findings showed that the pollen grains of species belonging to the two sections of Wissadula are similar in size, shape, aperture type, aperture number, and sexine ornamentation.

Plant species tend to shift their geographical ranges in response to climate change. The extent to which they are sensitive to the change is less understood in the tropics. Here, we predicted the current and future distribution of Syzygium afromontanum, a highly prioritized plant that contributes nutritious and edible fruits but has a narrow ecological range in Ethiopia. The MaxEnt algorithm method was used to predict potential suitable habitats for the species in the long run. Twenty-two environmental variables were downloaded from the WorldClim database, and 47 spatially rarefied occurrence points were used. The current and two climate change scenarios (RCP 4.5 and RCP 8.5) for 2050 and 2070 were used. Model evaluation by AUC value ranges from 0.914–0.931 under all scenarios, placing the models in the excellent category. The jackknife evaluation of the 25 random test percentage entry for model calibration showed that solar radiation, and precipitation in the coldest, and driest quarters are significant predictors of the distribution model. Compared to the current, the potential distribution area of the species would be reduced by 3.21% and 3.32% under RCP 4.5 and RCP 8.5 of 2050 and by 2.77% and 2.86% under RCP 4.5 and RCP 8.5 of 2070, respectively. The consequence of this situation will have a long-term effect on the conservation of the species and the indigenous knowledge associated with the species. Thus, modeling plays an essential role in designing and implementing conservation policies to conserve species that have narrow ecological ranges besides being highly prioritized and socio-economically valuable plants.

Abstract

Saussurea inversa Raab-Straube is a typical alpine plant with well-developed aerenchyma, which is its most representative structural feature. Studying the formation and development of aerenchyma in S. inversa is of great theoretical significance for understanding the adaptive mechanisms of alpine plants to the environment. In this study, the aerenchyma development-related gene ShRBOH1 (GenBank accession number OP727799) was cloned from S. inversa by RT-PCR with RACE technology. Sequence analysis revealed that the cDNA of ShRBOH1 was 2158 bp long including an open reading frame of 2031 bp that encodes 676 amino acids. Subcellular localization prediction indicated that the ShRBOH1 protein is located in the cytoplasmic membrane, consistent with the localization of the NADPH protein. A comparison of the amino acid sequence homology showed that ShRBOH1 had higher similarity to CcRBOH1 of Cynara cardunculus L. The qRT-PCR analysis demonstrated that the ShRBOH1 gene was expressed in roots, stems, and leaves with significantly lower expression level in stems compared to other tissues. The expression of the ShRBOH1 gene was down-regulated under UV stress, up-regulated under cold stress, and initially up-regulated, then down-regulated, and finally up-regulated again under hypoxia stress. By comparing the changes in reactive oxygen species (ROS) content under the three types of stresses, we found that significant changes only occurred under hypoxic stress and were positively correlated with the expression of ShRBOH1. We hypothesize that ShRBOH1 positively regulates the formation of aerenchyma through ROS mediation, suggesting that the aerenchyma is primarily an important structure for adapting to hypoxia stress in alpine environments.

Histone deacetylation process is controlled by histone deacetylases (HDAs), which catalyze removal of an acetyl group from the lysine residues of histone N-terminal tails. Although the HDAs are known to be involved in stress response and development in model plants, little is known about the roles of HDAs in crop species. Up to date, the HDAs in spinach (Spinacia oleracea L.) have not been identified and characterized. Here, we carried out genome-wide identification of HDA gene family in spinach, including physicochemical properties, subcellular localization prediction, phylogenetic analysis, conserved motifs, gene structure, Ka/Ks ratio, synteny analysis, functional prediction through cis-acting elements, and protein–protein interaction. Totally, six HDAs were identified from the spinach genome, and named SoSRT1, SoSRT2, SoHDA1, SoHDA2, SoHDA3, and SoHDA4. The phylogenetic tree showed that spinach HDAs were divided into four clades (Class I, Class II, RPD3-like, SIR2). RPD3/HDA1 family proteins and RPD3-like protein consisted of motif 1, Hist_deacetyl domain (PF00850), while two SIR2 class proteins included SIR2 domain (PF02146). Subcellular localization analysis indicated that the SoSRT and SoHDA proteins might localize in cytoskeleton, peroxisome, nucleus, and cytosol. SoSRT1 and SoSRT2 were located on chromosome 1, and the remaining four genes (HDA1-4) were distributed on chromosome 6. Ka/Ks ratio was lower than 1, suggesting that HDA genes might undergo purifying selection during evolution. Analysis of cis-acting elements revealed that the SoHDA genes participate in hormone regulation, light response, and abiotic stress response. New insights into the potential roles of histone deacetylases will be gained from this study in spinach, which is a cold-tolerant/heat-sensitive vegetable.

Desiccation tolerance (DT) in germinated seeds is directly related to the success of seedling survival of seasonally dry tropical forest and woodland (SDTFW) species. The objective of this study was to evaluate whether the seeds of Anadenanthera colubrina and Cenostigma pyramidale present post-germinative DT and until what stage of seedling development does tolerance persist. Seedlings of different sizes were separated into four categories of initial root length (IRL) and dried for 24 and 72 h. Seedling survival was evaluated 7 and 14 days after rehydration. DT was considered when the seedlings resumed growth after desiccation and rehydration to the original water content. Both species were tolerant to post-germination desiccation. Cenostigma pyramidale seedlings with IRL as low as 5-mm survived desiccation followed by up to 14 days of rehydration, while most larger seedlings (with IRL from 5.00 to 10.99 mm) failed to resume growth after desiccation/ rehydration. Smaller seedlings before desiccation showed greater growth and longer seedling lengths after rehydration for both species. Anadenanthera colubrina seedlings with IRL between 3.00 and 10.99 mm had their growth compromised when desiccated for a longer period. As a survival strategy, the seedlings of both species lose the primary root and produce adventitious roots after desiccation. Therefore, the survival of seedlings of both species to desiccation has a direct effect on the recruitment of SDTFW species.

The species of the genus Dracaena are the only monocotyledonous plants that have a secondary growth in the stem as well as in the roots. Our knowledge of its structure is based mainly on the study of the stem, and little is known about the structure of root secondary growth. We aimed to characterize the radial variation in the anatomy of the secondary growth of the roots of a tree-like monocot representative Dracaena draco L. and compared it with that of the stem, expecting to find some differences since root and stem grow under different environmental conditions. Based on the anatomical analysis of large-area cross sections of secondary growth we show that roots have clearly eccentric growth with more secondary tissue on the upper root side. Following bundle density across the root enables to distinguish between the concentric and eccentric phases of secondary growth. The total cross-sectional area of roots and the stem is almost identical, but they differ in the contribution of secondary growth, its distribution and the lumen area of tracheids, which is almost twice larger in roots. This study shows that the differences in root and stem secondary growth structure are quantitative, and that vascular bundle density is a promising trait to further study the eccentricity of monocot secondary growth.

Arid and semi-arid ecosystems are widely distributed around the world, covering about 60% of the earth’s land area. This type of ecosystem has low resilience and high fragmentation caused by human activities related to land use changes to agricultural uses. It has been seen that one of the mechanisms that can help recover the structure and functioning of this type of ecosystem is facilitative interaction. It has been documented that in these environments, the greatest recruitment and establishment of seedlings occur under the cover of a nurse plant. This has led us to investigate whether the life forms of the benefited plants have any relationship with this type of interaction, since the presence and distribution of beneficiaries of particular life forms may result from the evolution of the facilitating interaction. In total, we registered 16 nurse species in the sampling sites, and underneath the canopies of these species, we recorded approximately 250 individuals benefiting from these plants. The majority (51%) were succulent plants, followed by shrubs comprising 27.5%. The functional attributes of the nurse plants that were most strongly associated with the succulent life form were height (H) and canopy density (CD) (Axis 1 of the PCA), as well as leaf area (LA) and specific leaf area (SLA) (Axis 2). These relationships may be due to the fact that succulents seek out nurse plants that have ample canopy cover for the best protection. These findings may help in the selection of effective nurse species for restoring functional diversity in degraded drylands.

Vateria indica L. is an endangered tree species indigenous to South Western-Ghats regions of India, which is of immense economic importance. The natural regeneration process of this species is hindered by many factors including seed recalcitrance, which is a major problem hindering its natural regeneration, thus posing a great challenge in its seed storage and conservation. Recalcitrant seeds show marked differences from orthodox seeds in development. The onset of different stages is marked by a definite peaking and lowering of phytohormones and this hormonal pattern varies in orthodox and recalcitrant seeds. Phytohormonal dynamics in recalcitrant seeds, is a poorly investigated area and the present investigation was undertaken with a view to understand the hormonal changes during embryogeny and germination in this recalcitrant species. We have tested fifteen plant growth regulators simultaneously to get a better understanding about their role in embryogeny and germination. During April–July 2020, seeds were collected from their native habitats in the South Western-Ghats. From the randomly selected seeds, the embryonic tissues were chopped and frozen for LC–MS/MS hormonal profiling. The triplet hormonal interplay (between auxin, cytokinin and gibberellins) was found to be very crucial for the development of the embryo in Vateria indica L. In the present study, we can see a clear antagonism of cis Jasmonate with Brassinosteroid, cis Jasmonate declining during seed shed (14.44 ± 0.39 ng g-1fw) and germination phases, while Brassinosteroid increasing during these phases (32.24 ± 1.69 ng g-1fw). A clear hormonal interplay can also be seen between Auxin (Indole-3 Butyric acid—45.44 ± 0.3 ng g-1fw) and Brassinosteroid (24epi-Brassinolide—32.24 ± 1.69 ng g-1fw) at the time of seed germination. Phytohormone interplay and crosstalk provides an emerging knowledge about connections between phytohormones which are pivotal for growth and development and even stress responses in plants.

Graphical abstract

Chromatogram of Phytohormones.

Chromatogram of Phytohormones -X axis represents time and Y axis represents absorbance A, B and C—In Negative mode (ES-): Salicylic acid, IAA, IBA, JA, Benzene Adenine, ABA, GA-7, GA-4, GA-3, Epibrassinolide. D, E and F—In Positive mode (ES +): ACC, Cis-Jasmonate, Zeatin, Methyl Jasmonate and Trans Zeatin Riboside.

Chromatogram of Phytohormones. X axis represents time and Y axis represents absorbance D and E—In Negative mode (ES-): Salicylic acid, IAA, IBA, JA, Benzene Adenine, ABA, GA-7, GA-4, GA-3, Epibrassinolide. I and J—In Positive mode (ES +): ACC, Cis-Jasmonate, Zeatin, Methyl Jasmonate and Trans Zeatin Riboside.

Abstract

Canscora alata (Roth) Wall. (Gentianaceae) commonly known as Shankhapushpi, is an annual herbaceous threatened medicinal plant distributed mainly in the understory of wild Sal (Shorea robusta Gaertn.) forest and demands immediate conservation measures, for which understanding of its reproductive ecology is important. We studied aspects of floral biology, reproductive phenology and the breeding systems of the plant species. While undertaking the experiments, it was found that the species is self-compatible with a greater capability of autonomous self-pollination and doesn’t depend largely on pollinators for seed sets. However, geitonogamous and xenogamous modes of reproduction were observed. In natural habitat, visitors' frequency was extremely low, and most of the time they were absent. Outcrossing is rare, but it is occasionally facilitated by the fly, Paragus (Paragus) Latreille. We observed an "open-close-reopen" flowering rhythm during the anthesis of a flower. The mode of floral development clearly indicates that autonomous self-pollination is favored by the movement of stamens, styles, and stigmas during its “open-close-reopen” pattern of flowering. The plant also exhibits a larger anisomorphic stamen, orange in color. Even though the “fail safe” mechanism is an adaptive trait seen in outcrossing plant species, we have observed it here as well. The larger anisomorphic stamen helped to pollinate in order to ensure reproductive assurance through a delayed selfing mechanism; this is a rare occurrence in autogamous species. Despite self-compatibility, the ability to produce fruits and seeds through hand cross-pollination treatments implies that the plant species follow a selfing-outcrossing strategy to assure successful reproduction in its natural habitat. We hope these findings will be useful in strategic planning for the conservation of this plant species.