Brazilian Journal of Botany最新文献

Floral mimicry is a captivating phenomenon wherein flowers imitate traits of other plants to attract specific pollinators. The Caesalpinioideae legumes in general have relatively unspecialized flowers, which has allowed the development of disparate morphologies adapted to different groups of pollinators. This study describes the pollination of Moldenhawera nutans L.P. Queiroz, G.P. Lewis & Allkin, and explores its potential floral mimicry toward Malpighiaceae flowers. Our investigation revealed that M. nutans is pollinated by bees of the genera Centris and Xylocopa. It also presents compelling evidence supporting the hypothesis of floral mimicry, including striking similarities in floral display, shared oil-collecting pollinators, oil collection behavior in M. nutans despite the absence of oil production, and the reliance on exogenous pollen for reproduction. These findings suggest that species of Centris visit M. nutans flowers under the mistaken impression of oil availability, subsequently transitioning to pollen collection. We explored other potential cases of floral mimicry with Malpighiaceae in the Caesalpinioideae legumes by optimizing the Malpighiaceae-like floral display on a dated phylogeny of this subfamily. However, current information does not allow us to determine whether the similarities in floral morphology represent cases of floral mimicry, phylogenetic inertia, or simple convergence. Hypothesis tests are suggested that can guide the study of these fascinating evolutionary processes in the group.

Cyclic nucleotide-gated ion channels (CNGCs) genes play an important role to tolerate the abiotic stress tolerance in crop plants. The present study was designed to compare the molecular aspects of CNCG genes in Arabidopsis thaliana L. and Helianthus annuus L. using various computational tools. Through protein blast analysis, we identified nine CNGCs in H. annuus and subcellular locations indicated that these genes were unevenly distributed in various cellular components. The phylogenetic analysis of CNGCs genes was conducted among of A. thaliana, H. annuus, Gossypium hirsutum L., Brassica oleracea L. and Brassica rapa L. It was noted that in phylogenetic tree CNCG proteins of these crops were divided into four clads. Expression profiling of RNA-seq-data indicated that HanCNGC16 and HanCNGC15 play putative role under drought stress. The cis-regulatory analysis also identified several stress-responsive elements in HanCNGCs. The comparative genomics provided insights into the evolutionary history, duplication, divergence, gene gain and loss, species relationship, and structural diversity of CNGC in five species. These findings will not only provide widespread implications of CNGCs for their roles under drought stress in various crop species but also provided a reference study for the CNGC gene family in H. annuus.

The structural diversity of pollinia is one of the most relevant characters for the species classification in Orchidaceae. In this study, we analyzed the development of the pollinia and caudicle in Epidendrum species belonging to the subgenus Amphyglottium, one of the groups with the most variable morphology of the genus. These species have different pollination strategies (e.g., presence vs. absence of nectar) and grow in different types of habitat. Floral buds and flowers at anthesis were collected, and the usual methodology for performing anatomical studies, scanning microscopy, and confocal microscopy following established protocols. Our investigations revealed that the studied species have bithecal anthers and each theca has two pollinia and two caudicles. No interspecific variation was observed regarding the formation of the male gametophyte, indicating that is a stable character for the genus: the archesporial cells undergo a meiotic process that originates microspores, which remain united in tetrad and pass through asymmetric mitosis to form viable pollen grains. The caudicle is of the appendicular type and shows the male gametophyte formation.

The purpose of this research was to examine the impacts of varying levels of Ca concentrations (0, 5, and 10 mM) on mint plants (Mentha longifolia L.) cultivated hydroponically, specifically under conditions of zinc (Zn) toxicity (300, and 600 μM). Various aspects, including chlorophyll and proline metabolisms, defense mechanisms (antioxidant and glyoxalase systems), ion balance, and sulfur assimilation process, were examined to assess the effects. Zn treatment resulted in the initiation of oxidative stress, hindered nutrient absorption, and led to an increase in Zn leaf concentration. These effects together contributed to the impairment of the photosynthesis apparatus and a subsequent decrease in the growth of mint seedlings. However, adding Ca by modulating proline and chlorophyll metabolisms raised proline and chlorophyll levels. Ca treatment (especially 10 mM) reduced methylglyoxal (31.1 and 38%), malondialdehyde (44.9 and 42.1%), and hydrogen peroxide (31.2 and 48.5%) levels and electrolyte leakage (22 and 30.6%) in Zn-stressed plants by strengthening the antioxidant machinery. The application of Ca by attenuating Zn amount and facilitating the uptake of mineral nutrients maintained the ionic balance under Zn toxicity. Ca addition resulted in the upregulation of enzymes associated with the sulfur metabolism, leading to elevated amounts of cysteine, glutathione, and phytochelatins. Therefore, our findings point out that Ca increased the adaptation of mint seedlings during Zn phytotoxicity by modulating proline and chlorophyll metabolism, reinforcing the antioxidant capacity, maintaining ionic homeostasis, and inducing the sulfur assimilation mechanism.

Strigolactones (SLs) are carotenoid-derived terpenoid lactones. Natural SLs are grouped into two types, namely, strigol-type and orobanchol-type, and 20 SLs have been identified from different plant kingdoms or species. The more stable SLs, called GR24, derived synthetically, were utilized for the investigation of SL responses. SLs are crucial endogenous plant hormones that play a multifactorial role in plant and rhizosphere interactions by controlling mycorrhization and lateral shoot branching. SLs participate in the organization of plant architecture by reducing bud outgrowth in addition to various morphological and developmental processes, collectively with other plant growth hormones such as auxins, cytokinins, gibberellins, and abscisic acid. Strigolactones regulate root growth and structure by inhibiting lateral root production and enhancing root hair elongation. Targeted genetic engineering of SL biosynthetic genes leads to potential alterations in rooting and vegetative systems and assists in generating plants that are more appropriate to different adverse environmental conditions, such as drought, salt stress, cold, and water deficit. The present review provides a clear outline of the structure, type, biosynthesis, and signaling mechanisms of SLs. In addition, their potential functions in plant growth, development, and response to stress conditions are also discussed.

In order to clarify the characteristics of the chloroplast (cp) genome of Vaccinium ashei Reade cv. ‘brightwell’ and understand its phylogenetic status, the whole cp genome of this sepcies was sequenced and assembled, and its genome structure, gene composition, and signs of adaptation were analyzed. The cp genome has a quadripartite structure with a size of 176,115 bp and a total GC content of 36.81%. The length of large single copy (LSC) region, small single copy (SSC) region and two inverted repeat (IR) regions was 106,029 bp, 3004 bp, and 33,541 bp, respectively. It has a total of 103 genes, containing 74 protein-coding genes, 25 tRNA genes and 4 rRNA genes. A total of 187 SSR sites were observed, with the largest number of mononucleotides in the repeat type, accounting for 72% of the total. By comparing with related Vaccinium genotypes, 25 single nucleotide polymorphisms (SNPs) and 35 insertion/deletions (Indels) were identified. Highly variable regions such as trnM-psaI, trnD-psbM, psbJ-psbB, psaA-trnQ, clpP-rpoA, rpl36-rps8, rpl16-rps3, and trnM-trnL intergenic spacers may be used as candidate markers for intraspecific differentiation. The Ka/Ks calculations showed that the two genes (psbJ and psbT) were strongly positively selected. Phylogenetic results reflected that the Vaccinium genus was clustered into two clades, and V. ashei was more closely related to V. uliginosum. These results provide a reference for the development of molecular markers, phylogeny, cp genome evolution and variety breeding of Vaccinium.

The knowledge about the level of genetic diversity and population structure in natural populations of Artemisia annua L. is a primary step in breeding programs for development of new cultivars with higher artemisinin level and better quality of secondary metabolites composition. We used PCR-based "retrotransposon-microsatellite amplified polymorphisms" (REMAPs) to study insertional polymorphism in A. annua genome to assess genetic variability and population structure in a collection of 118 accessions collected from north and northwest of Iran. Twenty-five primer combinations of 10 retrotransposon and seven ISSR primers amplified a total of 693 clear and unambiguous fragments in the studied accessions. The average number of bands, polymorphic bands, polymorphism, effective number of alleles, Shannon's information index and expected heterozygosity were 27.72, 24.76, 88.14%, 1.47, 0.42 and 0.28, respectively. The analysis of molecular variance revealed high genetic variation present within sampled geographical regions. Distance-based cluster analysis assigned the studied accessions into four clusters according to their geographical origin, which were also confirmed by principal coordinate analysis. In model-based Bayesian clustering, the maximum value of Δk was obtained when the collection of 118 assayed A. annua accessions assigned into two subgroups (K = 2). The results showed the high genetic variation in the collection of Iranian sweet wormwood which revealed by REMAP markers indicating the reliability and efficiency of this marker system for analysis of genetic diversity and population structure of A. annua.

Supplementary information: The online version contains supplementary material available at 10.1007/s40415-022-00860-x.

Boesenbergia rotunda (L.) Mansf. is a medically important ginger species of the family Zingiberaceae but its genomic information on molecular phylogeny and identification is scarce. In this work, the chloroplast genome of B. rotunda was sequenced, characterized and compared to the other Zingiberaceae species to provide chloroplast genetic resources and to determine its phylogenetic position in the family. The chloroplast genome of B. rotunda was 163,817 bp in length and consisted of a large single-copy (LSC) region of 88,302 bp, a small single-copy (SSC) region of 16,023 bp and a pair of inverted repeats (IRA and IRB) of 29,746 bp each. The chloroplast genome contained 113 unique genes, including 79 protein-coding genes, 30 transfer RNA (tRNA) genes and four ribosomal RNA (rRNA) genes. Several genes had atypical start codons, while most amino acids exhibited biased usage of synonymous codons. Comparative analyses with various chloroplast genomes of Zingiberaceae taxa revealed several highly variable regions (psbK-psbI, trnT-GGU-psbD, rbcL-accD, ndhF-rpl32, and ycf1) in the LSC and SSC regions in the chloroplast genome of B. rotunda that could be utilized as molecular markers for DNA barcoding and species delimitation. Phylogenetic analyses based on shared protein-coding genes revealed that B. rotunda formed a distinct lineage with B. kingii Mood & L.M.Prince, in a subclade that also contained the genera Kaempferia and Zingiber. These findings constitute the first chloroplast genome information of B. rotunda that could be a reference for phylogenetic analysis and identification of genus Boesenbergia within the Zingiberaceae family.

Supplementary information: The online version contains supplementary material available at 10.1007/s40415-022-00845-w.

Urochloa (syn.-Brachiaria s.s.) is one of the most important tropical forages that transformed livestock industries in Australia and South America. Farmers in Africa are increasingly interested in growing Urochloa to support the burgeoning livestock business, but the lack of cultivars adapted to African environments has been a major challenge. Therefore, this study examines genetic diversity of Tanzanian Urochloa accessions to provide essential information for establishing a Urochloa breeding program in Africa. A total of 36 historical Urochloa accessions initially collected from Tanzania in 1985 were analyzed for genetic variation using 24 SSR markers along with six South American commercial cultivars. These markers detected 407 alleles in the 36 Tanzania accessions and 6 commercial cultivars. Markers were highly informative with an average polymorphic information content of 0.79. The analysis of molecular variance revealed high genetic variation within individual accessions in a species (92%), fixation index of 0.05 and gene flow estimate of 4.77 showed a low genetic differentiation and a high level of gene flow among populations. An unweighted neighbor-joining tree grouped the 36 accessions and six commercial cultivars into three main clusters. The clustering of test accessions did not follow geographical origin. Similarly, population structure analysis grouped the 42 tested genotypes into three major gene pools. The results showed the Urochloa brizantha (A. Rich.) Stapf population has the highest genetic diversity (I = 0.94) with high utility in the Urochloa breeding and conservation program. As the Urochloa accessions analyzed in this study represented only 3 of 31 regions of Tanzania, further collection and characterization of materials from wider geographical areas are necessary to comprehend the whole Urochloa diversity in Tanzania.