Showing posts with label orchid science. Show all posts
Showing posts with label orchid science. Show all posts

Friday, August 21, 2020

Epipactis helleborine (Michigan's Upper Peninsula)

Epipactis helleborine in bloom
Epipactis helleborine

I came across this native orchid almost entirely by happenstance. I had stopped at a beach access point to look over at a placid Lake Michigan coastline.  Although many different flowers were growing along the coast, one particular shrub caught my eye.  There was something different, something familiar about it.  I jumped the fence to get close, and my suspicions were confirmedthis was, in fact, a wild orchid! Further observation identified it as Epipactis helleborine.

Lake Michigan Upper Penninsula coastline
Lake Michigan shoreline--E. helleborine was growing just to the left out of view

So what do we know about this species? E. helleborine is a terrestrial orchid species that grows in wooded areas, swamps and riverbeds around the world, including parts of Europe, Asia, Africa, and North America. In fact, in the US, it's sometimes known as the "weedy orchid" because of its propensity for invading lawns and flowerbeds.  An audacious little plant!

E. helleborine distribution in the US (Adapted from: https://plants.usda.gov/core/profile?symbol=EPHE)

A recent study (May et al (Micorrhiza) 2020) provides insight into how this species is so successful across many terrains.  Like many orchids, E. helleborine develops a symbiotic relationship with mycorrhizal fungi in its root system.  Mycorrhizal fungi supply the orchid seeds with nutrients essential for germination.  Later, these fungi provide the adult orchid with a carbon source to supplement photosynthesis (organisms that get their energy from multiple sources like this are called mixotrophs).  

In the study by May et al, the authors observed E. helleborine orchids that were transplanted into pots for up to 3 years. These transplanted orchids had to grow without the aid of mycorrhizal fungal networks, relying solely on autotrophic growth (i.e. deriving all their energy through photosynthesis). May et al found that E. helleborine orchids can thrive even without fungal symbiotes. The authors suggest that this ability of the orchid to acquire nutrients through either mixotrophic (supplemented by the fungal symbiotes) or autotrophic (purely through photosynthesis) modes of growth "adds to the ecological plasticity" of these plants.
 
weedy orchid closeup
E. helleborine closeup
Citation: 
May, M., Jąkalski, M., Novotná, A. et al. Three-year pot culture of Epipactis helleborine reveals autotrophic survival, without mycorrhizal networks, in a mixotrophic species. Mycorrhiza 30, 51–61 (2020). https://doi.org/10.1007/s00572-020-00932-4

Thursday, July 5, 2018

4 New Orchid Species Discovered in June

June has been a great month for new orchid species discoveries.  Check out these cool new flowers!


Odontochilus putaoensis

This terrestrial orchid was discovered in northern Myanmar by a group of botanists from the Chinese Academy of Sciences. The orchid has greenish-brown flowers that are about 1cm across.
Odontochilus putaoensis
Image credit: Aung et al, Phytokeys 2018
Odontochilus putaoensis closeup
Image credit: Aung et al, Phytokeys 2018


Pleurothallis hawkingii 

This is a epiphytic orchid from Costa Rica blooms with pale yellow to white flowers, which sometimes have a distinctive purplish hue. It was described by a pair of botanists from the Universidad de Costa Rica.
Pleurothallis hawkingii
Image credit: Adam Karremans and Jose Esteban Jimenez Phytotaxa 2018
Pleurothallis hawkingii
Image credit: Adam Karremans and Jose Esteban Jimenez, Phytotaxa 2018
Pleurothallis hawkingii purple variant
Image credit: Adam Karremans and Jose Esteban Jimenez, Phytotaxa 2018


Pleurothallis vide-vallis

Another Costa Rican Pleurothallis species described in the same paper as P. hawkingii, Pleurothallis vide-vallis is a small epiphytic species that blooms with yellow flowers that have ranging degrees of pink hues.
Pleurothallis vide-vallis
Image credit: Adam Karremans and Jose Esteban Jimenez, Phytotaxa 2018
Pleurothallis vide-vallis closeups of yellow and purple variants
Image credit: Adam Karremans and Jose Esteban Jimenez, Phytotaxa 2018


Gastrodia kachinensis

Gastrodia are a genus of parasitic orchids, which grow primarily underground.  They have no leaves, do not photosynthesize, and instead feed on the fungi that grow around their roots. Gastrodia kachinensis is a new species discovered in Myanmar by a pair of botanists from the Chinese Academy of Sciences.
Left: A Gastrodia kachinensis inflorescencees, barely visible against the forest floor.  Right: closeup of G. kachinensis
Image credit: Ye Lwin Aung and Xiao-hua Jin, Phytokeys 2018

Wednesday, May 30, 2018

Coelogyne victoria-reginae: new orchid species discovered in Myanmar

Coelogyne victoria-reginae
Image credit: Zhou et al. PhyotKeys 2018 (https://phytokeys.pensoft.net/article/23298/)
A group of botanists from the Chinese Academy of Sciences, in collaboration with HponkanRazi Wildlife Sanctuary in Myanmar and the Forest Department Ministry of Environmental Conservation and Forestry in China have described a new species of Coelogyne which grows in the Nat Ma Taung (Mt.Victoria) National Park.
Coelogyne victoria-reginae
Image credit: Zhou et al. PhytoKeys 2018 (https://phytokeys.pensoft.net/article/23298/)
This epiphytic orchid produces brownish-red flowers that are about 0.5 inches in length (1.2 cm). It blooms in April and May. The species is named after the Mount Victoria region of Myanmar where it was found.
Coelogyne victoria-reginae
Image credit: Zhou et al. PhytoKeys 2018 (https://phytokeys.pensoft.net/article/23298/)
Authors: Shi-Shun Zhou, Yun-Hong Tan, Xiao-Hua Jin, Kyaw Win Maung, Myint Zyaw, Ren Li, Rui-Chang Quan, Qiang Liu
Published in: PhytoKeys (May 18, 2018)
Coelogyne victoria-reginae (Orchidaceae, Epidendroideae, Arethuseae), a new species from Chin State, Myanmar

Monday, May 21, 2018

New orchid species discovered in Thailand: Dendrobium Obchantiae

Dendrobium obchantiae
Image Credit: Department of Botany, Faculty of Science, Chulalongkorn University (Image Link)

There are an estimated 30,000 species of orchids, and hundreds of new orchid species are discovered each year. A group from Chulalungkorn University in Thailand and the Department of National Park Wildlife and Plant Conservation published a paper in April describing a new species of dendrobium which grows in the mixed deciduous forests of northern Thailand.

Dendrobium obchantiae full plant view
Photo by W. Buddhawong
Image Credit: Department of Botany, Faculty of Science, Chulalongkorn University (Image Link)
Dendrobium obchantiae closeup
Image Credit: Department of Botany, Faculty of Science, Chulalongkorn University (Image Link)

Authors: Phattaravee Prommanut, Somran Suddee, Manit Kidyoo
Published in Phytotaxa (April 27, 2018)

Saturday, January 7, 2017

What causes a phalaenopsis to grow a keiki?

Phalaenopsis keikis: Noid Phal keiki on left, Phal Gold Tris keiki on right
Happy 2017 everyone! December/January tend to be a colorful time for orchids in my terrarium.  The shorter, colder days of September provide the perfect signal to induce my Phals to spike.  The flower spikes generally develop over the next two months, and come into full bloom around the turn of the new year.

However, this year, some of my spikes started growing aerial plantlets (or keikis) in addition to flower buds.  The keiki on my noid phal looks like a leaf growing off the side of a new flower spike.  Meanwhile, Phal Gold Tris produced a tiny plantlet at the tip of an old spike that bloomed over the Summer.

I have written about growing and separating phalaenopsis keikis in the past, but this time I was curious about what caused my orchids to produce keikis in the first place.

What causes a phalaenopsis to grow a keiki?

The internet has many claims about what causes an orchid to make a keiki, but offers little evidence in support.  And even in the research literature, I struggled to find a definitive answer.

So what do we know about Phalaenopsis keikis?  I found a common claim that if a phalaenopsis with a new spike (<4 inches) is exposed to temperatures above 28C (82F), then the spike will develop keikis instead of flower buds.  

See examples:
if a plant with a young inflorescence (less than 4 inches or 10 cm) is subsequently grown at 82 F (28 C) or higher, a spike can form a vegetative air plantlet known as a “keiki” instead of flower buds, buds may abort or both. (Phals article from AOS.org).  
"if a plant with an inflorescence <10cm is subsequently grown at 28C or higher for extended periods, a spike can form a vegetative air plantlet referred to as a "keiki" instead of flower buds, buds may abort, or the stem may elongate indefinitely without open flowers [Sakanishi et. al 1980]"  (Roberto G. Lopez and Erik S. Runkle, 2005)
However, when I tried to find the original source for this claim, its evidence is weak.  Sakanishi et al is a 1980 paper describing the Effect of Temperature on Growth and Flowering of Phalaenopsis amabilis. However, this paper never actually reported any keikis!

In fact, the authors found that high temperatures caused flower spikes to abort growth and flowering.
With the object of determining the effect of high temperature treatment started from the different stages of stalk elongation, 12 plants in the greenhouse were shifted to minimum 28C at each time when flower stalks reached a length of 5, 10, 21-30, and 41-50 cm.  The high temperature from the 5cm stage caused the abortion of florets or the stunted growth of the flower stalks. After the stalks elongated more than 10cm, every stalk normally developed into flower even at the high temperature.
 In the closing remarks, the paper references an even older study on Phalaenopsis schilleriana, which makes the claim about keikis being triggered by temperature.
At ...(maximum temperature 29-34C; minimum temperature 24-25C), [Phalaenopsis schilleriana]  adult plants develop a stalk, which remains vegetative and develops an adventive plant.           (De Vries JT, 1953)
This paper "On the flowering of Phalaenopsis schilleriana" dates back to 1953, and is not available online.  Thus we only have a second-hand description of its findings from the Sakanishi paper.  However, it appears to be the sole parent of all the claims regarding temperature control inducing keiki formation.

What does keiki paste do?

A number of companies sell a product called "keiki paste" which when applied to a dormant node on a flower spike can help induce growth of a keiki.  The active ingredient of keiki paste is a chemical called BAP, or benzyl adenine.  BAP is a synthetic plant growth hormone.  It stimulates activity from flower spikes, and can produce either flowers or keikis depending on environmental conditions.

Which still does not answer our original question about what conditions make a Phalaenopsis develop a keiki instead of flowers.

The final verdict?

I don't think we actually really know the answer to this question. 

Orchid research is not particularly interested in this question. Commercial growers optimize conditions to produce flowers, not keikis.  And keikis are an inefficient way to reproduce orchids on a commercial scale, leaving little incentive to study keikis when there are important questions to be worked out in meristem cloning and in vitro seed germination techniques. 

If anyone reading this has come across a different claim about phalaenopsis keikis, I'd be happy to look into whether it has a scientific backing.  However, in the meantime, I don't think we know what cocktail of light/temperature/water/nutrients is the Goldilocks recipe to trigger keiki growth.

Wednesday, May 11, 2016

Orchid Science Update: Studying biodiversity of two Floridian orchid species

Encyclia tampensis
Photo Credit: (Wikimedia commons image) Andrea Westmoreland (Flickr gallery)

This reports comes out of the Million Orchid Project, an orchid reintroduction program in south Florida. The authors of the study completed a genetic characterization of two Floridian orchid species in order to help inform conservation efforts.


Encyclia tampensis, pictured above, is an epiphytic orchid native to south Florida, Cuba and the Bahamas, where it grows in cypress swamps and tropical hammocks.  Florida law regulates collection of wild-grown E. tampensis due to threat of commercial exploitation.



Cyrtopodium punctatum
Photo Credit: (Wikimedia commons image) Everglades National Park (Flickr gallery)
Cyrtopodium punctatum, or Cowhorn orchid, is another epiphytic orchid species from Florida. This orchid used to be widespread, but due to intense harvesting is now categorized as "Near Threatened".

Low genetic diversity can result when the numbers of a given species dwindle. This can hamper preservation efforts, as the species becomes more susceptible to diseases and the problems of inbreeding.  In order to asses the genetic diversity of E. tampensis and C. punctatum, this study collected genetic samples from orchids in the wild and from cultivation, and identified 10 microsattelite markers in each species that showed variation between individual orchids. 

Future conservation efforts and breeding programs will be able to use these microsattelite markers to make sure that they are maintaining a healthy genetic diversity in the species.




Tuesday, May 3, 2016

April Orchid Science




INTERBREEDING OF BEE ORCHIDS CREATES SPECIES CONFUSION

Bee or Orchid? (Ophrys apifera)
Photo credit: © Copyright Andrew Curtis and licensed for reuse under this Creative Commons Licence







































Ophrys, or "bee orchids" have a clever reproduction strategy. These orchids look so similar to female insects, that males are fooled into mating with the flowers, thereby pollinating them. These flowers not only look strikingly similar to their insect pollinators; they also produce specialized scents, called allomones, which copy the pheromones emitted by an insect seeking mates.

The Ophrys genus is large, containing over 2000 species, subspecies and natural hybrids.  These orchids grow all over Europe, North Africa, and the Middle East, and related species can form many naturally occurring hybrids.

Scientists in this study looked at hybridization among three Ophrys species (Ophrys lutea, Ophrys fusca, Ophrys dyris). They recorded photographs of flowers and gathered DNA samples from Bee Orchids in various parts of Portugal. Afterwards, they performed genetic analysis to examine which orchids contained DNA from related species.
Three Ophrys orchid species featured in this study
Photo credits:
Ophrys dyris and Ophrys lutea by Luis Nunes Alberto (Wikimedia commons)
Ophrys fusca, by Orchi (Wikimedia commons) 
What they found was that O. dyris and O. fusca were so intermixed in the wild, that even with the help of all the genetic data, it was not always possible to identify which of the two species a given flower belonged to.  Finding a population of pure O. dyris orchids was rare.

Looking at the image of these two orchids (above), I can easily see why.  The flowers look incredibly similar, and if you told me that both images were the same species, I would not hesitate to believe it.

The authors also report extensive hybridization and introgression (backcrossing of hybrids with parent species) among O. fusca and O. lutea. However those two species are more distinct from one another than O. fusca and O. dyris.

Authors: Cotrim H, Monteiro F, Sousa E, Pinto MJ, Fay MF
Published In: American Journal of Botany , April 7, 2016
Marked hybridization and introgression in Ophrys sect. Pseudophrys in the western Iberian Peninsula.

A NEW PROPAGATION METHOD MAY PROTECT ENDANGERED ORCHID SPECIES (SATYRIUM NEPALENSE)

Satyrium nepalense
Photo Credit: L. Shyamal (Wikimedia commons image
Satyrium nepalense, is a rare terrestrial orchid which grows at high altitudes in India and South-Central China. This orchid species is threatened due to habitat destruction and over-collection. Various parts of the orchid have been used since ancient times as a dietary supplement to treat various ailments. (However, modern medical research to validate these medicinal properties is lacking.)

This paper describes a protocol for large-scale propagation of Satyrium nepalense in a lab setting. The paper also describes a method for extracting phenol compounds from the roots and leaves of the orchid for biochemical analysis.

Authors: Babbar SB, Singh DK
Published In: Methods in molecular biology, April 24

Monday, March 28, 2016

March Orchid Science: Orchids in Medicine, Conservation, Evolution, and Symbiosis

Hey guys, lately I've been interested in learning more about what goes on in the world of orchid research.  I'd like to try a column where I summarize science articles about orchids.  Some of these studies are more technical than others, and I will do my best to convey their findings in an understandable manner.

As the end of March is approaching, here is a wrap-up of this month's orchid science news.

GENETIC STUDY SHOWS HOW GASTRODIA ELATA ORCHID MAKES MEDICINAL COMPOUND 

    Gastrodia elata orchid
    Photo Credit
    Qwert1234, Wikimedia commons

    Gastrodia elata is an orchid species used in Sichuan cuisine and traditional Chinese medicine. It is a rootless, leafless plant, which grows from an underground tuber that produces a flowering stalk as shown in the image above. 

    Gastrodin is a chemical compound produced by Gastrodia elata, which is responsible for some of its medicinal properties. Studies have investigated gastrodin's medical potential in a variety of contexts, including everything from anxiety to diabetes and dementia. We know that Gastrodia elata produces high levels of gastrodin during growth of juvenile tubers, but we don't know how the plant synthesizes this chemical.

    In this study, the authors used a technique called de novo transcriptome sequencing to compare gene expression levels in germinated seeds versus juvenile plants. This is the first time that anyone has done a comprehensive genetic study of this orchid. 

    The resulting data gives us information about which genes are active in Gastrodia elata at different stages of the orchid's early growth. The authors then proceeded to identify two novel genes which encode for enzymes that may be involved in the biosynthesis of gastrodin.


    Authors: Tsai CC, Wu KM, Chiang TY, Huang CY, Li SJ, Chiang YC.
    Published in BMC Genomics (March 9, 2016)
    Comparative transcriptome analysis of Gastrodia elata (Orchidaceae) in response to fungus symbiosis to identify gastrodin biosynthesis-related genes


    STUDY OF EPICACTIS ORCHIDS SHOWS THAT EACH SPECIES HAS A DISTINCT COMMUNITY OF SYMBIOTIC FUNGI

      Epicactis orchid species examined in Jacquemyn et al 2016
      Photo Credits:
      Epicactis helleborine, by Amadej Trnkoczy (Flickr gallery)
      Epicactis are a genus of terrestrial orchids; these species are hardy and can survive in a broad range of environments. Epicactis helleborine, originally a European species, has spread across Asia, northern Africa and North America.  It is increasingly considered invasive in parts of the US, earning it the moniker "weed orchid."

      This study looked at mycorrhizal fungus communities associated with three epicactis species (Epipactis helleborineEpipactis neerlandica, and Epipactis palustris).  Many orchid species require the presence of symbiotic root fungi (mycorrhiza) throughout life for optimal growth and development. Terrestrial orchids rely on specific fungi to trigger seed germination and/or initiate development of orchid seedlings. 

      Epicactis helleborine and Epicactis neerlandica have only recently evolved to be separate species.  However, they occupy extremely different environments; E. helleborine grows primarily in forests, and E. neerlandica is found almost exclusively in coastal dunes.  E. palustris is an evolutionarily more distant species that also grows in coastal dune habitats.

      This study found a total of 105 different kinds (taxa) of mycorrhizal fungi among the roots of these three orchid species. Each orchid species had a unique mycorrhizal community. Out of the 105 types of fungus identified in the study, only 8 were shared among all three orchid species. The differences were the most pronounced between the forest-growing orchid (E. helleborine) and the two dune species (E. neerlandica and E. palustris).


      Figure 3. A. from Jacquemyn et al 2016 
      This venn diagram depicts how many taxa of mycorrhizal fungi are unique to each orchid species, and how many are shared between them.

      Authors: Jacquemyn H, Waud M, Lievens B, Brys R
      Published in Annals of Botany (March 5, 2016)
      Differences in mycorrhizal communities between Epipactis palustris, E. helleborine and its presumed sister species E. neerlandica.


      POLLINATION OF PHALAENOPSIS APHRODITE IS A 2 MONTH PROCESS 
      Phalaenopsis aphrodite var formosana
      Photo Credit: Orchi (wikimedia commons image)

      Pollination and seed maturation works differently in orchids than it does in most flowers.  Like most other things, it is slower.  Much slower.  In most flowers, the ovule structure and the embryo sac have fully developed by the time the flower opens.  Once a flower is pollinated, the pollen reaches the ovule within hours, fertilizing the embryo, which then develops into a seed.

      Orchid flowers, on the other hand, will not even begin developing an ovule until after pollination has occurred.  This is an energy-saving strategy by the plant, which will only put in resources to develop the ovule if pollination has already occurred.

      One consequence of this delay is that the ovule must have enough time to mature after the orchid first senses pollination. As a result, orchids can have a delay of days, or even months between pollination and fertilization. In Vanda suavis, pollen can take up to 10 months to fertilize the flower.

      The authors in this study observed the timing of pollination and fertilization in Phalaenopsis aphrodite var. foromsana. They purchased seedlings from a commercial supplier.  The orchids produced flower stalks after about 2 months of cultivation, and the first flowers opened 1-2 months after that.

      The authors hand-pollinated these flowers and observed how the flower developed in response to pollination. They found that the pollen grains did not even begin to germinate until 3 days after pollination.  After that, it took 60-65 days for the pollen to reach the ovules deep in the body of the flower, and complete fertilization.  The timing of this 2-month journey for the pollen matched the timing of ovule maturation.

      Authors: Chen JC, Fang SC


      CYNORKIS PURPUREA SEEDLINGS NEED SYMBIOTIC FUNGI FOR OPTIMAL GROWTH

      This study looked at seed germination and seedling development of Cynorkis purpurea in a lab setting.  Cynorkis purpurea is a terrestrial orchid that generally lives only in gallery forests in the Central Highlands of Madagascar.  

      The authors of this study wanted to understand how various symbiotic fungi influence seed germination and seedling development of Cynorkis purpurea.  They collected seeds from wild orchids in Madagascar, and attempted to grow them in the lab.  Some seeds were grown in the presence of orchid mycorrhizal fungi, while other seeds were grown in conditions without fungi.

      One of the things I was struck by in this study, was how slowly orchid seeds develop, even under optimal conditions.  Panel "d" in the image below shows what a 'successfully developed' seedling looked like after 3 months of growth.  At less than 1/2 a millimeter in diameter, the seedling is still nearly microscopic.

      Figure from Rafter et al, 2016, showing the germination stages of Cynorkis purpurea seeds


      a. What a Cynorkis purpurea seed looks like before germination 
      b. A successfully germinated seed (2-4 weeks)
      c. A fully germinated orchid seed shows fungal tendrils growing along its surface 
      d. After 12 weeks, seeds grown in favorable conditions will have developed the start of a shoot

      The study found that while Cynorkis purpurea seeds do not require symbiotic fungi for germination, seedlings developed dramatically better when they were paired with symbiotic fungi. The authors compared three different genera of fungus, and found that sebacina fungi were the most effective at promoting orchid seedling development. 

      One of the control conditions, which added sucrose to the growth media to simulate the effect of fungal presence, also significantly boosted seed germination and development. 


      Authors: Rafter M, Yokoya K, Schofield EJ, Zettler LW, Sarasan V.
      Published in Micorrhiza (March 17, 2016)
      Non-specific symbiotic germination of Cynorkis purpurea (Thouars) Kraezl., a habitat-specific terrestrial orchid from the Central Highlands of Madagascar

      CHANGE IN EXPRESSION LEVEL OF KEY GENES HELPED ORCHID SPECIES ADAPT TO HOT, DRY CLIMATES

      Example of 4 orchid species that use CAM photosynthesis
      Photo Credits:
      Dendrobium terminale, (C) by G. Meyer 1990, Swiss Orchid Foundation at the Herbarium Jany Renz. Botanical Institute, University of Basel, Switzerland.
      Crassulacean acid metabolism, or CAM photosynthesis, is an adaptation that allows some plants to conserve water in arid conditions.  It is mostly found in succulents.  However, among approximately 25,000 known species of orchids, about 10,000 are estimated to use CAM photosynthesis.  

      Photosynthesis requires that plants take in carbon dioxide (CO2) from the air. However, when a plant opens its pores (stoma) to intake carbon dioxide, it also loses water through evaporation. In order to survive in water-scarce environments, some plants have evolved a way to take in CO2 at night, when temperatures are cooler and evaporation is less of a problem.  CAM photosynthesis is a method by which some plants can accumulate and store CO2 at night for use in photosynthesis during daytime.  Plants that use CAM photosynthesis can require as much as 80% less water than other kinds of plants.

      Scientists are interested in studying plants which use CAM photosynthesis, because it can be useful for developing drought-resistant crops.  This study did the first comparative genetics look at CAM in orchids. The authors examined CAM-related genes from 4 orchid species that had the CAM adaptation (Cymbidium atropurpureum,  Phalaenopsis mannii, Phalaenopsis equestris, and Dendrobium terminale), 9 orchid species that did not have CAM, and 12 other non-orchid species.

      The authors concluded that CAM may have evolved in orchids through changes in expression level of a few key genes involved in carbon fixation during photosynthesis.


      Authors: Zhang L, Chen F, Zhang GQ, Niu S, Xiong JS, Lin Z, Cheng ZM, Liu ZJ
      Published in The Plant Journal (March 9, 2016)
      Origin and mechanism of crassulacean acid metabolism in orchids as implied by comparative transcriptomics and genomics of the carbon fixation pathway.