Origination and selection of ABCDE and AGL6 subfamily MADS-box genes in gymnosperms and angiosperms

BACKGROUND: The morphological diversity of flower organs is closely related to functional divergence within the MADS-box gene family. Bryophytes and seedless vascular plants have MADS-box genes but do not have ABCDE or AGAMOUS-LIKE6 (AGL6) genes. ABCDE and AGL6 genes belong to the subgroup of MADS-box genes. Previous works suggest that the B gene was the first ABCDE and AGL6 genes to emerge in plant but there are no mentions about the probable origin time of ACDE and AGL6 genes. Here, we collected ABCDE and AGL6 gene 381 protein sequences and 361 coding sequences from gymnosperms and angiosperms and reconstructed a complete Bayesian phylogeny of these genes. In this study, we want to clarify the probable origin time of ABCDE and AGL6 genes is a great help for understanding the role of the formation of the flower, which can decipher the forming order of MADS-box genes in the future. RESULTS: These genes appeared to have been under purifying selection and their evolutionary rates are not significantly different from each other. Using the Bayesian evolutionary analysis by sampling trees (BEAST) tool, we estimated that: the mutation rate of the ABCDE and AGL6 genes was 2.617 × 10-3 substitutions/site/million years, and that B genes originated 339 million years ago (MYA), CD genes originated 322 MYA, and A genes shared the most recent common ancestor with E/AGL6 296 MYA, respectively. CONCLUSIONS: The phylogeny of ABCDE and AGL6 genes subfamilies differed. The APETALA1 (AP1 or A gene) subfamily clustered into one group. The APETALA3/PISTILLATA (AP3/PI or B genes) subfamily clustered into two groups: the AP3 and PI clades. The AGAMOUS/SHATTERPROOF/SEEDSTICK (AG/SHP/STK or CD genes) subfamily clustered into a single group. The SEPALLATA (SEP or E gene) subfamily in angiosperms clustered into two groups: the SEP1/2/4 and SEP3 clades. The AGL6 subfamily clustered into a single group. Moreover, ABCDE and AGL6 genes appeared in the following order: AP3/PI → AG/SHP/STK → AGL6/SEP/AP1. In this study, we collected candidate sequences from gymnosperms and angiosperms. This study highlights important events in the evolutionary history of the ABCDE and AGL6 gene families and clarifies their evolutionary path.

Genetic analysis of Penthorum chinense Pursh by improved RAPD and ISSR in China

Background: Penthorum chinense Pursh (P. chinense) is a well-known traditional Chinese medicine (TCM) plant, which has long been used for the prevention and treatment of hepatic diseases. This study aimed to genetically characterize the varieties of P. chinense from different geographic localities of China by random amplification of polymorphic DNA (RAPD)-PCR technique and verified with inter-simple sequence repeat (ISSR) markers. Results: The P. chinense samples were collected from nine different geographic localities. Previously improved RAPD and ISSR markers were utilized for genetic analysis using DNA amplification. The genetic relationship dendrogram was obtained by conducting cluster analysis to the similarity coefficient of improved RAPD and ISSR markers. Improved RAPD yielded 185 scorable amplified products, of which 68.6% of the bands were polymorphic, with an average amplification of 9.25 bands per primer. The ISSR markers revealed 156 alleles with 7.8 bands per primers, where 59.7% bands were polymorphic. Furthermore, the similarity coefficient ranges of RAPD and ISSR markers were 0.71­0.91 and 0.66­0.89, respectively. Conclusions: This study indicated that improved RAPD and ISSR methods are useful tools for evaluating the genetic diversity and characterizing P. chinense. Our findings can provide the theoretical basis for cultivar identification, standardization, and molecular-assisted breeding of P. chinense for medicinal use.

Phylogenetic overdispersion of plant species in southern Brazilian savannas / Dispersão filogenética de espécies de plantas em savanas no Sudeste do Brasil

Ecological communities are the result of not only present ecological processes, such as competition among species and environmental filtering, but also past and continuing evolutionary processes. Based on these assumptions, we may infer mechanisms of contemporary coexistence from the phylogenetic relationships of the species in a community. We studied the phylogenetic structure of plant communities in four cerrado sites, in southeastern Brazil. We calculated two raw phylogenetic distances among the species sampled. We estimated the phylogenetic structure by comparing the observed phylogenetic distances to the distribution of phylogenetic distances in null communities. We obtained null communities by randomizing the phylogenetic relationships of the regional pool of species. We found a phylogenetic overdispersion of the cerrado species. Phylogenetic overdispersion has several explanations, depending on the phylogenetic history of traits and contemporary ecological interactions. However, based on coexistence models between grasses and trees, density-dependent ecological forces, and the evolutionary history of the cerrado flora, we argue that the phylogenetic overdispersion of cerrado species is predominantly due to competitive interactions, herbivores and pathogen attacks, and ecological speciation. Future studies will need to include information on the phylogenetic history of plant traits.

Comunidades ecológicas resultam não somente de processos ecológicos atuais, como a competição e os filtros ambientais, mas também de processos evolutivos passados e contínuos. Com base nessas premissas, podemos inferir mecanismos de coexistência contemporânea a partir das relações filogenéticas das espécies em uma comunidade. Estudamos a estrutura filogenética das comunidades de plantas de quatro áreas de cerrado, no Sudeste do Brasil. Calculamos duas medidas das distâncias filogenéticas das espécies amostradas. Estimamos a estrutura filogenética comparando suas distâncias observadas com a distribuição dessas distâncias em comunidades nulas. Obtivemos comunidades nulas aleatorizando as relações filogenéticas do banco regional de espécies. Encontramos uma dispersão filogenética de espécies de cerrado. Há várias explicações para essa dispersão, dependendo da história filogenética dos traços e das interações ecológicas contemporâneas. Entretanto, com base nos modelos de coexistência entre árvores e gramíneas, nas forças ecológicas dependentes da densidade e na história evolutiva da flora do cerrado, argumentamos que a dispersão filogenética das espécies do cerrado é predominantemente devida às interações competitivas, aos ataques de herbívoros e patógenos e à especiação ecológica. Estudos futuros precisarão incluir informações sobre a história filogenética dos traços das plantas.

Chemosystematics of the Rosiflorae / Quimiossistemática de Rosiflorae

The superorder Rosiflorae (sensu Dahlgren, 1980) belongs to the Angiospermae. It comprises twelve orders and thirty-eight families formed of species with varied habits widely distributed in temperate regions. The chemistry of Rosiflorae species is highly diversified; nevertheless it shows clearly phylogenetic affinity among the orders, except for Buxales. Flavonoids and triterpenoids are the real taxonomic markers for the superorder, due not only to the great number of occurrences, but also to the high structural diversity. On the other hand, the alkaloids are suitable as chemical markers only for the order Buxales. For orders and families of Rosiflorae, analysis of correlations among chemical parameters based on flavonoids and triterpenoids, with themselves and with the morphological and chemo-morphological parameters, showed evolutionary gradients among these taxa in which Trochodendrales occupy a primitive position while Saxifragales have the outpost. According to the types of flavonoids found in the superorder, there is clearly a higher incidence of flavonols than flavones, suggesting a primitive status of the Rosiflorae. Evolutionary advancement parameters relative to flavonoid hydroxyl protection show preferential protection mechanisms of glycosylation against methylation as well as a high percentage of free hydroxyl groups. The order Buxales has an isolated position in the superorder Rosiflorae with a high alkaloid production, which is quite exclusive to this taxon.

A superordem Rosiflorae (sensu Dahlgren, 1980), Angiospermae, é composta por doze ordens e trinta e oito famílias. Em geral são plantas de hábito variado e muito freqüentes em regiões temperadas. A química das espécies de Rosiflorae é muito diversificada, mas evidencia a proximidade filogenética entre as ordens, com exceção de Buxales. Os flavonóides e os triterpenóides mostram-se como verdadeiros marcadores quimiossistemáticos em nível de superordem, devido, não somente ao seu grande número de ocorrências, mas também pela sua elevada diversidade estrutural; contudo os alcalóides são os marcadores para Buxales. Avaliação das correlações dos parâmetros químicos entre si e com os parâmetros morfológico e químico-morfológico, para ordens e famílias de Rosiflorae, com base nos seus flavonóides e triterpenóides, evidenciaram uma grande proximidade filogenética entre esses táxons, além de mostrar gradientes evolutivos, em que Trochodendrales e Saxifragales são posicionadas como a ordem mais primitiva e a ordem mais evoluída, respectivamente. Com relação aos tipos flavonoídicos produzidos na superordem, verifica-se uma maior produção de flavonóis em relação às flavonas, o que acarreta uma baixa relação favona/flavonol, confirmando o posicionamento primitivo da superordem, indicado pelos índices morfológico e químico-morfológico. A proteção das hidroxilas flavonoídicas mostra uma nítida preferência na proteção por glicosilação e desproteção em detrimento à proteção por metilação. A ordem Buxales praticamente encontra-se isolada na superordem com grande produção de alcalóides muito característicos, sendo bastante diferenciada da produção alcaloídica relativamente pobre da superordem.

Morphogenetic responses of six Philodendron cultivars in vitro.

In vitro morphogenic response of nodal explants from six cultivars of Philodendron viz, blue mistic, painted lady, pink prince, pluto, royal queen and green emperor was studied. Frequency and number of shoot formation depend on the cultivars and concentration of BAP. High frequency and number of shoot formation were obtained w hen the nodal explants were cultured in Nitsch medium supplemented with BAP (6.8-11.8 microM), sucrose (2%) and agar (0.45%), initially in the dark for 8-10 weeks followed by 16 hr photoperiod. Regenerated shoots were rooted on medium without growth regulators. After two weeks of hardening, rooted and rootless shoots were established in the soil with more than 90 and 65% survival rates respectively, while the unhardened plantlets showed a much lower percentage (20%) establishment. A standard protocol for the rapid multiplication of Philodendron is presented.

Pleiotropic morphological and abiotic stress resistance phenotypes of the hyper-abscisic acid producing Abo- mutant in the periwinkle Catharanthus roseus.

The pleiotropic properties of a abo abo (Abo-) gamma-ray induced mutant of Catharanthus roseus cv. Nirmal, selected among the M2 generation seeds for ability to germinate at 45 degrees C, are described. The mutant produced seeds possessing tricotyledonous embryos, unlike the typically dicotyledonous embryos present in the wild type Abo+ seeds. In comparison to Abo+ adults, the mutant plants had short stature and lanceolate leaves. The vascular bundles in the leaves and stem were poorly developed. Leaf surfaces were highly trichomatous, epidermal, cortex and mesophyll cells were small sized and a large majority of stomata were closed. Besides high temperature, the mutant was salinity and water-stress tolerant. The abscisic acid (ABA) content in the leaves was about 500-fold higher. The genetic lesion abo responsible for the above pleiotropy was recessive and inherited in Mendelian fashion. The seedlings and adult plants of the mutant accumulated higher proline than Abo+ plants. The phenotypes of abo abo mutants permitted the conclusions that (i) the mutant synthesizes ABA constitutively, (ii) both ABA-dependent and ABA independent pathways for proline and betaine accumulation are functional in the mutant, and (iii) cell division, elongation and differentiation processes in embryo and adult plant stages are affected in the mutant