Botanical Studies最新文献

Background: Phalaenopsis is one of the important ornamental plants worldwide. It plays the most significant role in flower exportation in Taiwan. However, the yellow leaf disease caused by Fusarium spp. has reduced the orchid flower yield 10-50 % yearly. Varieties resistant to yellow leaf disease associated with Fusarium is urgently needed for orchid growers and breeders, and is the ultimate solution for the long-term goal. To achieve this, phenotyping is the first step and the most necessary information for further studies, such as resistance gene identification, quantitative trait loci identification, and genome-wide association study.

Results: The inoculation of Fusarium was performed in either abbreviated stem or detached leaf, and the pros and cons were compared. The former is the general method of phenotyping for estimating the tolerance to yellow leaf disease of Phalaenopsis, but it is time-consuming and spacy, and thus not suitable for the assessment of large numbers of samples. In contrast, the latter not only showed a similar trend of disease severity with time reduced to only one fourth of the former one but also less space needed.

Conclusions: This solution allows a better phenotyping approach for the fast detection of yellow leaf disease associated with Fusarium in a large number of Phalaenopsis samples.

Background: Halophytes are better than glycophytes at employing mechanisms to avoid salt injury, but both types of plants can undergo damage due to high soil salinity. Arbuscular mycorrhizal fungi (AMF) can mitigate the damage from salt stress in both halophytes and glycophytes by enhancing salt tolerance and improving energy efficiency. However, variations in mycorrhizal symbiotic efficiency between halophytes and glycophytes were still poorly understood. Therefore, we evaluated the magnitude of AMF effects on plant growth and determined the mechanisms that regulate the growth response of halophytes and glycophytes by performing a meta-analysis of 916 studies (from 182 publications).

Results: Arbuscular mycorrhizal fungi significantly enhance biomass accumulation, osmolytes synthesis (soluble sugar and soluble protein), nutrients acquisition (nitrogen, phosphorus, and potassium ion), antioxidant enzyme activities (superoxide dismutase and catalase), and photosynthetic capacity (chlorophyll and carotenoid contents, photosynthetic rate, stomatal conductance, and transpiration rate). AMF also substantially decreased sodium ion acquisition and malondialdehyde levels in both halophytes and glycophytes under salt stress conditions. Mycorrhizal halophytes deploy inorganic ions (potassium and calcium ions) and limited organic osmolytes (proline and soluble sugar) to achieve energy-efficient osmotic adjustment and further promote biomass accumulation. Mycorrhizal glycophytes depend on the combined actions of soluble sugar accumulation, nutrients acquisition, sodium ion exclusion, superoxide dismutase elevation, and chlorophyll synthesis to achieve biomass accumulation.

Conclusions: Arbuscular mycorrhizal fungi inoculation is complementary to plant function under salt stress conditions, not only facilitating energy acquisition but also redistributing energy from stress defence to growth. Glycophytes are more dependent on AMF symbiosis than halophytes under salt stress conditions.

Background: In the United States and Canada, ca. one-half of native orchid species are now threatened with extinction. A number of these species are restricted to tallgrass prairies of central North America, such as the Eastern Prairie Fringed Orchid, Platanthera leucophaea (Nutt.) Lindl.-a U.S. Federally threatened species.

Results: We provide new records of fungi recovered from roots of P. leucophaea and five other orchid species inhabiting prairie sites in Illinois and neighboring states during a 10-year period (2008-2017). A total of 39 fungal endophytes were isolated from Cypripedium candidum (1), Platanthera lacera (1), P. leucophaea (32), P. peramoena (3), Spiranthes lacera (1), and S. magnicamporum (1), 31 (79%) of which were assignable to Ceratobasidium and the remainder to Tulasnella. These fungi were acquired from 16 different sites, 13 of which are new records including two new state records (Iowa, Wisconsin). Molecular analysis revealed that some Ceratobasidium strains were virtually identical despite being geographically isolated by > 300 km.

Conclusions: This study, encompassing a decade of work, confirms that Platanthera leucophaea is a mycorrhizal specialist with heavy reliance on Ceratobasidium with the tallgrass prairie ecosystem of North America. Our isolation of Ceratobasidium from P. leucophaea spanning additional sites suggests that the association is widespread. Such information should provide conservationists and land managers with more confidence in developing protocols that facilitate the long-term conservation of this prairie orchid.

Background: A number of Xylaria species are exclusively associated with nests of macrotermitine termites. A nesting site of Odontotermes formosanus in eastern Taiwan, which is the only macrotermitine termite known on the island, had been inundated during the raining season of 2010, and hundreds of Xylaria stromata emerged from it thereafter. A thorough examination of these stromata showed that they represent a mixture of different species.

Results: Five Xylaria species were identified from the stromata collected from the nesting site, including two undescribed species, which are newly described as X. insolita and X. subescharoidea herein, and three known species X. brunneovinosa, X. escharoidea, and X. furcata.

Conclusion: Totally, there are 28 Xylaria species growing on termite nests or ground in the world. Although O. formosanus is the only macrotermitine species known in Taiwan, the Xylaria diversity associated with its nests is fairly high; the species number has reached 12 with X. furcata, X. insolita, and X. subescharoidea added to the Taiwan mycobiota.

Background: Phalaenopsis orchids are one of the most common potted orchids sold worldwide. Most Phalaenopsis cultivars have long inflorescences that cause shipping problems and increase handling costs. Miniaturization of Phalaenopsis orchids not only reduces overall production costs but also can expand the appeal of the orchids to a different group of consumers who prefer to keep flowers on desks or tabletops. Although some miniature Phalaenopsis plants can be obtained via hybridization or mutation, they are unpredictable and limited in variety. We therefore used the transgenic approach of overexpressing gibberellin 2-oxidase 6 (OsGA2ox6), a rice GA deactivation gene, to investigate its functional effect in miniaturizing Phalaenopsis and to create a stable miniaturization platform to facilitate a supply for the potential demands of the miniature flower market.

Results: A commercial moth orchid, Phalaenopsis Sogo Yukidian 'SPM313', was transformed with the plasmid vector Ubi:OsGA2ox6 and successfully overexpressed the OsGA2ox6 gene in planta. The transgenic lines displayed darker-green, shorter, and wider leaves, thicker roots and much shorter flower spikes (10 cm vs 33 cm) than the nontransgenic line with a normal flower size and blooming ability and are therefore an ideal miniaturized form of Phalaenopsis orchids.

Conclusions: We demonstrated that the ectopic expression of OsGA2ox6 can miniaturize Phalaenopsis Sogo Yukidian 'SPM313' while preserving its blooming ability, providing an alternative, useful method for miniaturizing Phalaenopsis species. This miniaturization by a transgenic approach can be further expanded by using GA2ox genes from different plant species or different gene variants, thereby expanding the technical platform for miniaturizing Phalaenopsis species to meet the potential demands of the miniature Phalaenopsis flower market.

Background: Fritillaria cirrhosa, an important Chinese medicinal herb, is a Class-III protected and highly exploited species by pharmaceutical industry. Dwindling wild populations of species are unable to meet market demand. Therefore, this study was carried out to develop an in vitro propagation method for bulblet production. Also, the study aimed to carry out LC-MS/MS analysis of tissue culture-derived bulblets and callus for the presence of isosteroidal alkaloids (peimissine, verticine, and verticinone), and compare its quantities with commercially available crude drug samples.

Results: In vitro seed germination (91%) of F. cirrhosa was achieved on Murashige and Skoog's basal medium (MSBM) supplemented with 6-benzylaminopurine (1 mg L^-1) and α-naphthalene-acetic-acid (0.4 mg L^-1). On transfer of germinated seeds from Petri-dishes to glass bottles containing hormone-free MSBM, 37.5% of seedlings developed bulblets after 3 months of incubation. Regeneration and multiplication of bulblets were achieved by culture of transverse sections of bulblets on 1/2 X MSBM. By repeated subcultures at an interval of 2 months, 3072 bulblets weighing 1270 g could be produced at the end of 5th subculture. LC-MS/MS analysis showed a significant presence of peimissine in in vitro bulblets while callus incubated in the dark showed presence of peimissine and verticine.

Conclusion: The study reports an efficient in vitro propagation method of bulblets production of F. cirrhosa and presence of some isosteroidal alkaloids in tissue culture-derived bulblets and callus. The study could be of immense help in production of F. cirrhosa bulblets and callus under laboratory conditions round the year. Also, these results can be used further to investigate production of isosteroidal alkaloids in bioreactors at commercial scale using liquid and cell suspension cultures. Thus, we not only can reduce our dependence on collections from natural habitats, but also can help in in situ conservation of this important species.

Background: N-acyl-homoserine lactones (AHLs) are the quorum sensing (QS) signal molecules to coordinate the collective behavior in a population in Gram-negative bacteria. Recent evidences demonstrate their roles in plant growth and defense responses.

Results: In present study, we show that the treatment of plant roots with N-3-oxo-hexanoyl-homoserine lactone (3OC6-HSL), one molecule of AHLs family, resulted in enhanced salt tolerance in Arabidopsis and wheat. We found that the growth inhibition phenotype including root length, shoot length and fresh weight were significantly improved by 3OC6-HSL under salt stress condition. The physiological and biochemical analysis revealed that the contents of chlorophyll and proline were increased and the contents of MDA and Na⁺ and Na⁺/K⁺ ratios were decreased after 3OC6-HSL treatment in Arabidopsis and wheat under salt stress condition. Molecular analysis showed that 3OC6-HSL significantly upregulated the expression of salt-responsive genes including ABA-dependent osmotic stress responsive genes COR15a, RD22, ADH and P5CS1, ABA-independent gene ERD1, and ion-homeostasis regulation genes SOS1, SOS2 and SOS3 in Arabidopsis under salt stress condition.

Conclusions: These results indicated that 3OC6-HSL enhanced plant salt tolerance and ABA-dependent and ABA-independent signal pathways and SOS signaling might be involved in the induction of salt resistance by 3OC6-HSL in plants. Our data provide a new insight into the plant-microbe inter-communication.

In the publication of this article (Liu et al. 2019), there was an error in the method and ethics declarations sections which were published with incorrect animal experiment approval number. The error: 'These animal experimental protocols have been reviewed and approved by the Institutional Animal Care and Use Committee of Taipei Medical University (LAC-99-0142).' Should instead read: These animal experimental protocols have been reviewed and approved by the Institutional Animal Care and Use Committee of Taipei Medical University (LAC-2016-0340).

Background: Most plant cytochrome P450 (P450) proteins need to be supplied with electrons from a redox partner, e.g. an NADPH-cytochrome P450 reductase (CPR), for the activation of oxygen molecules via heme. CPR is a flavoprotein with an N-terminal transmembrane domain, which transfers electrons from NADPH to the P450 via coenzymes flavin adenine dinucleotide and flavin mononucleotide.

Results: In this study, a novel CPR (SdCPR) was isolated from a tropical medicinal plant Scoparia dulcis L. The deduced amino acid of SdCPR showed high homology of > 76% with CPR from higher plants and belonged to the class II CPRs of dicots. Recombinant SdCPR protein reduced cytochrome c, ferricyanide (K₃Fe(CN)₆), and dichlorophenolindophenol in an NADPH-dependent manner. To elucidate the P450 monooxygenase activity of SdCPR, we isolated a cinnamic acid 4-hydroxylase (SdC4H, CYP73A111) gene from S. dulcis. Biochemical characterization of SdCPR/SdC4H demonstrated that SdCPR supports the oxidation step of SdC4H. Real-time qPCR results showed that expression levels of SdCPR and SdC4H were inducible by mechanical wounding treatment and phytohormone elicitation (methyl jasmonate, salicylic acid), which were consistent with the results of promotor analyses.

Conclusions: Our results showed that the SdCPR and SdC4H are related to defense reactions, including the biosynthesis of secondary metabolites.

Background: Grass phytoliths are the most common phytoliths in sediments; recognizing grass phytolith types is important when using phytoliths as a tool to reconstruct paleoenvironments. Grass bulliform cells may be silicified to large size parallelepipedal or cuneiform shaped phytoliths, which were often regarded as of no taxonomic value. However, studies in eastern Asia had identified several forms of grass bulliform phytoliths, including rice bulliform phytolith, a phytolith type frequently used to track the history of rice domestication. Identification with a higher level of taxonomic resolution is possible, yet a systematic investigation on morphology of Poaceae bulliform phytoliths is lacking. We aimed at providing a morphological description of bulliform phytoliths of Poaceae from Taiwan based on morphometric measurements in anatomical aspect. The results are important references for paleo-ecological studies.

Result: The morphology of grass bulliform phytoliths is usually consistent within a subfamily; the end profile is relatively rectangular in Panicoideae and Micrairoideae, whereas cuneiform to nearly circular in Oryzoideae, Bambusoideae, Arundinoideae, and Chloridoideae. Bulliform phytoliths were seldom observed in Pooideae. Certain morphotypes are limited to plants growing in specific environments. For example, large, thin, and pointed bulliform phytoliths are associated with wet habitat; Chloridoideae types are mostly from C4 plants occupying open arid places.

Conclusion: Grass bulliform phytoliths can be identified at least to the subfamily level, and several forms were distinguished within large subfamilies. Previously un-reported silicified cell types, i.e., arm cells and fusoids, and two special trichome phytolith types associated with bulliform phytoliths, were described. Morphometric methods were great tools for delimiting morphotypes; with refined morphological classification the association between forms and habit/habitats was revealed. The knowledge provides new ways to interpret phytolith assemblage data, and it is especially useful when the sediments are enriched in large blocky phytoliths.