UBC Research Week

March 13, 2008

Staphylea holocarpa var. rosea

The series for UBC Research Week is coming to a close soon. Connor's helped assemble this entry:

Andrew Riseman, an Associate Professor in the Faculty of Land and Food Systems at UBC and Ornamental Plant Breeder at the UBC Botanical Garden, shares his research on the various means by which plants can prevent self-pollination.

These photographs were taken from a research project evaluating self incompatibility in the genus Staphylea. Self-incompatibility systems act in promoting outcrossing (i.e., increasing genetic diversity) by only allowing non-self pollen to complete fertilization. These systems can be morphological (e.g., imperfect flowers where male or female organs are absent), developmental (e.g., protandry when the anthers reach anthesis before the stigmatic surface is receptive), or genetic (e.g., gametophytic self- incompatibility (GSI) where pollen tube growth of only self-pollen is disrupted by pistil tissue). In Staphylea, a GSI system appears to be present. These images are from outcross pollinations (i.e., compatible) between two Staphylea holocarpa var. rosea accessions maintained at the UBC Botanical Garden. As expected from a compatible cross, pollen grains successfully germinate and penetrate the stigmatic surface (photo 1). Pollen tubes continue to grow through the style to the ovary with individual tubes reaching separate ovuals (photo 2). Once fertilization is complete, fruit containing the newly formed seeds are produced (photo 3). The fourth photo shows a Staphylea flower post-anther dehiscence.

Posted by Daniel Mosquin at 9:14 AM| Comments (4)

March 12, 2008

Post-Fire Management of Forests

Connor Fitzpatrick continues with the series for UBC Research Week:

Scott Black is a Botany grad student at UBC. He is researching the ecological effects of post-wildfire management practices on the interior douglas fir forests, Pseudotsuga menziesii, of Southern British Columbia.

Disturbances such as forest-fires were once thought to be purely destructive forces, however, now they are seen in a more positive light. Disturbance (PDF) is now considered an important factor in maintaining the biodiversity of many natural ecosystems. Study of the effects of disturbance on plant community structure and, resource levels has initiated many ecological theories including the competitive exclusion and intermediate disturbance hypotheses. Disturbances are essential to ecosystem composition, function and sustainability but how much disturbance is too much?

Post-wildfire management in BC includes salvage logging, grass seeding and stump flipping. These practices increase the disturbance frequency and can potentially alter a plant community’s response after wildfire (here is a study, PDF, evaluating the effects of grass seeding). With 187 plant species and 98 animal species living in the interior douglas fir forests that are either red or blue listed (via the BC Ministry of Environment), an understanding of the effect of post-wildfire management practices on ecosystem health is crucial.

Salvage logging (PDF) can reduce the species diversity of plant communities, and reduce the number of tree seedlings after a fire. Soil loss / compaction and an increase in invasive species are results of salvage logging. Furthermore, the removal of burnt logs reduces the number of habitats for certain wildlife, especially birds, and can create unfavourable conditions for native understory vegetation.

In 2003, BC had a total of 2473 fires consuming 265,053 ha of forest (from the BC Ministry of Forests and Range), and fire frequency is expected to increase with climate change. Scott is comparing the plant communities found in post-wildfire sites that have been salvage logged, grass seeded, and left untouched. By uncovering the relationship between plant community structure, environmental characteristics and post-fire forest management practices Scott hopes to increase the sustainability of BC’s interior forests.

The first picture shows the ubiquitous post-fire species, Chamerion angustifolium, amidst a stand of burnt interior douglas firs. Fireweed has very deep rhizomes that sprout after fire and wind dispersed seeds that quickly cover burnt areas. It is also used as an ingredient in the cosmetic industry. This picture was taken in the McGillivray Fire north of Chase, BC last summer. The second picture shows the salvage logging process. The picture is courtesy of the Ministry of Forests and Range and was taken near MClure BC, North of Kamloops

(Adapted from Scott's 2007 proposal)

Here (PDF) is a report on wildfire management practices in western America.

Posted by Daniel Mosquin at 1:56 PM| Comments (7)

March 11, 2008

Chytriomyces sp.

The series for UBC Research Week continues. Today's write-up and photos are courtesy of Toko Mori. Toko writes:

My name is Toko Mori, a first-year graduate student in the Berbee Lab at the University of British Columbia. I study chytrid fungi, microscopic fungi that mainly live in freshwater. I especially focus on the local chytrids that parasitize freshwater microscopic algae. My long-term research goal is to create a tree of life of chytrids that parasitize algae and to see if there is any coevolutionary relationship between the species of parasitic chytrids and those of their host algae. I collected this chytrid on an alga, Vaucheria, from Burnaby Lake (Burnaby, BC) in August 2007. I have cultured it on agar and also co-cultured it with Vaucheria since then.

Since it seems that this is the first entry of chytrids in the Botany Photo of the Day, let me explain what they are. Chytrids are fungi, although they look quite different from mushrooms and molds, which we often think of as fungi. There are about one thousand species of chytrids which form the Phylum Chytridiomycota. Being the only group of fungi which reproduce by motile cells called zoospores (shown in picture 4), chytrids are considered to have diverged from the other fungi very early in their evolutionary history. Having motile spores gives them reproductive advantage in water. However, this is a double-edged sword; chytrids are unable to reproduce without moisture and thus bound to aquatic habitats.

Chytrids have recently attracted public attention as a cause for the population decline of amphibians. However, not all the chytrids are amphibian pathogens. To the contrary, many chytrid species are decomposers of organic matter in ponds and lakes, or parasites of microscopic invertebrates or algae, as in this case. Not much is known about their ecological roles.

Now let me explain these pictures. You are witnessing the moment of zoospore release, the highlight of their life history. The small round structure on the algal filament in picture 1 is a mature sporangium, where zoospores are produced. (The big bulge at the right end is a part of the alga, which I will explain later.) You can see the sporangium filled with small dots, each representing a zoospore. Five minutes later, the zoospores start to leave the sporangium, probably triggered by the sudden change in temperature caused by the intense light from the microscope. The change in pH of the surrounding water (when transferred from culture to a drop of distilled water on a slide) may also be the trigger. For a few minutes after the release, zoospores swarm just outside of the sporangium, until they start to swim away as in picture 3. As you may see in picture 4, the zoospores (ca. 4µm in diameter) have a flagellum like that of animal sperm. Eventually these zoospores stop swimming, retract their flagellum and encyst on a suitable substratum if they find one. Then they themselves will grow into a new sporangium, produce zoospores inside by mitosis, and start a new cycle of asexual reproduction.

A note for this alga. To co-culture this chytrid with its host, I received the culture of the host algal species, Vaucheria sessilis, from the Canadian Center for the Culture of Microorganisms at UBC. Vaucheria is unusual in that it lacks cell walls except when making reproductive structures; this entire filament seen here is one cell. The bulging end was formerly a spore, from which this algal filament grew.

Species identification is an important part of my research. Correct identification is the first step to making a tree of life. However, species identification of chytrids can be often difficult due to their simple body structure - there are not many morphological characters to study, at least on the light microscopy level. These days researchers combine molecular data and electron microscopy, together with traditional morphology. I have identified this chytrid down to the genus Chytriomyces, based on the light microscopic level morphology and molecular data.

Posted by Daniel Mosquin at 2:13 PM| Comments (13)

March 10, 2008

Amelanchier alnifolia

Connor Fitzpatrick continues with the series for UBC Research Week: Dr. Shannon Cowan is an Assistant Professor in the Faculty of Land and Food Systems. She shares her research today.

Dr. Shannon Cowan is conducting community-based plant research with B.C. First Nations in Nlaka'pamux Siska Band and Boston Bar Band.

Traditional food is associated with "healthy eating and living" in Aboriginal Canadian communities (here is an article, second from top, exemplifying this point). Current dietary practices in Aboriginal communities are also inextricably tied to cultural traditions and norms, which have seen significant shifts in Canada in the last few decades. Traditional food resources themselves are changing based on political and physical modification of environments including climate change, industrial development and contamination. There is a lack of research evidence regarding traditional food plant knowledge / beliefs and practices and how that affects traditional food consumption and health in Aboriginal communities.

Interdisciplinary research linking ecological knowledge, dietary knowledge and practices is needed to improve nutritional status in Aboriginal Canadians, and must be informed by an understanding of contemporary patterns of food procurement, preparation and distribution.

The Siska-UBC research team includes a Siska Community Research Committee (H. Michell, C. Michell, B. Munro, M. Williams), Siska Traditions Society Board Members, Siska Chief F. Sampson, UBC graduate student N. MacPherson, community member researchers and participants, and Dr. S.E. Cowan (UBC Faculty of Land and Food Systems, Botanical Garden and Center for Plant Research).

UBC-Siska Research Goal: Addressing health and education needs through community-based revitalization of Ecological Knowledge and Practices with Traditional Food and Medicine Plants.

Saskatoon (s/cáqw-m) has been identified as one of the dominant shrub species in the harvesting area under the Siska Forest and Range Agreement. Through the Traditional Knowledge for Health Research Project, the Siska-UBC Research Team is conducting cross-generational community-based research and education that involves this food plant resource through a traditional food survey (dietary interviews and traditional food guide creation), harvest training research and education, traditional food practices (berry jam making that bridges youth-elder generations), and a youth traditional food interview video project.

Concurrently there is a non-UBC project underway (Siska Researchers, M Keefer & Teal Jones Group) that is designed to test different strategies for enhancing saskatoon and other key cultural plant species on sites that have been in decline (see: Measuring success in managing for Saskatoon berries and other traditionally important plants). Timber management in the area, and the absence of traditional management techniques such as pruning and fire has been hypothesized as being directly related to the decline. Ecologically, saskatoon is known to be a key browse species (ungulates and bears), and some experiments have been designed to enhance the resource for wildlife habitat. However, there is a gap in the literature concerning management of saskatoon stands for berry production as a traditional food resource. Results of the UBC-Siska and the Keefer et al. projects will be integrated for economic and food security in Siska Band, traditional use plant species abundance, improved harvest yields, biodiversity and compatible management of forests for berries and trees, climate change mitigation and wildlife enhancement.

The first two photographs show saskatoon in fruit and flower, while the third shows M. Keefer working with a Siska youth.

Here (PDF) are the proceedings of a workshop, which included Siska Chief F. Sampson, at Royal Roads University concerning native plants and First Nation people

Posted by Daniel Mosquin at 9:27 AM| Comments (19)

March 9, 2008

Populus

Continuing the series for UBC Research Week, Connor introduces the next entry: Today we feature UBC Dept. of Forest Sciences Professor and Head, Robert D. Guy from the Faculty of Forestry. He shares with BPotD a collaborative project involving multiple labs.

Poplars Popular at UBC (an article from the Faculty of Forestry newsletter, Branchlines)

There is much interest in afforestation (PDF) as a strategy to help mitigate climate change by sequestering carbon and, ultimately, providing feedstock for renewable biofuels. These opportunities are likely to be greatest in intensively managed stands of rapidly growing trees. In Canada, there are several million hectares of marginal agricultural lands potentially available, mostly in the prairie provinces. But what’s actually available to plant? Not much it seems. Most of the available hybrid poplars currently planted in Canada are derived from species or populations adapted to relatively mild climates. While some of these "mild climate" clones are suitable to southern Ontario and southwestern British Columbia, few can survive on the prairies. There is, however, within our native forests, a tremendous untapped genetic resource, pre-adapted to the Canadian climate.

Ignoring aspens, Canada supports four of five North American poplar species. For example, balsam poplar is found in every province, from the US border to Inuvik, while black cottonwood occurs throughout British Columbia and adjacent areas of Yukon and Alberta. Appropriate selections and new hybrids could greatly increase the potential area that can be successfully planted to poplar.

Several researchers at UBC are studying genotypic variation in adaptive traits in poplar. To this end, some 750+ genotypes of balsam poplar (Populus balamifera) and black cottonwood (Populus trichocarpa), plus a wide selection of hybrids (including crosses with eastern cottonwood) are now springing up, in somewhat patchy fashion, at UBC’s Totem field (see photo). This “forest” might not last long, given the rate of campus development, but many of these genotypes grow so rapidly that if left uncontrolled there would be a continuous canopy within just a few years. Most of the clones come from two range-wide provenance collections – the BC MoF black cottonwood collection originally put together by Dr. C.C. Ying, and the new AgCanBaP balsam poplar collection compiled by scientists at the Prairie Farm Rehabilitation Administration (PFRA) Shelterbelt Centre, at Indian Head, SK. The AgCanBaP collection consists of some 15 individual clones from each of 43 populations.

So what are we doing with them at UBC? Several projects are underway or have been completed. In collaboration with Richard Pharis at the University of Calgary, Rob Guy and Shawn Mansfield (Faculty of Forestry) are investigating plant hormone profiles, fiber properties, carbon isotope composition, photosynthesis, and several other physiological parameters in black cottonwood, balsam poplar and various hybrids. This work forms the basis of thesis projects for Virginie Pointeau (Guy Lab) and Faride Unda (Mansfield Lab). In addition, Raju Soolanayakanahally (Guy lab) has been working closely with Dr. Salim Silim at the PFRA, both in Saskatchewan and at UBC, to characterize growth potential, photosynthetic rates, resource-use efficiencies and single-nucleotide polymorphism (SNP) variation in the complete AgCanBap collection. Using a subset of clones from the BCMoF collection, Hannah Buschhaus (Guy lab) recently completed her MSc thesis on variation in nitrogen isotope discrimination. Activity is not restricted to just the Faculty of Forestry. Quentin Cronk (Faculty of Land & Food Systems) and colleagues in Botany, for example, have been studying morphological variation, phenology and SNPs in the black cottonwood collection.

Physiology and other fancy stuff aside, the single most important attribute dictating the rate of biomass accretion is the length of the active growing season (i.e. the period from bud break to leaf drop). Timing of bud break in the spring is largely controlled by temperature. There is genetic variation in this trait but, in the main, when trees from different locations are planted in a common garden they generally flush out within a few days of each other. The same is generally true of cottonwoods, but a notable exception we’ve noticed at the UBC common garden is that trees from very high latitude can break bud in what we locally consider to be the depth of winter (December or January!). They also set bud several months too early (during our spring) because they are sensitive to the relatively short photoperiods encountered in Vancouver. Unlike bud break, bud set and (later) leaf drop are under tight photoperiodic control, and for these traits there are very strong latitudinal clines. In a common garden, genotypes from lower latitudes are in better synchrony with local conditions and remain active over a much greater portion of the available season, and they consequently accumulate far more biomass.

Although trees representative of northern populations generally do not grow as much as those from the south over any given summer, they can in fact possess higher photosynthetic rates. Indeed, they may also show the more rapid growth if measured over just a few weeks at the height of summer. We recently reported that light-saturated photosynthetic rates increased with latitude of origin in provenances of black cottonwood. This variation was well correlated with foliar nitrogen, stomatal conductance, and stomatal density.

The cline towards increased photosynthesis with latitude may be a generalised phenomenon among deciduous trees in North America. A similar trend is found in paper birch and Sitka alder and we see the same pattern in the AgCanBaP poplar collection. We speculate that northern provenances may have inherently high photosynthetic rates to compensate for the reduced leaf longevity associated with shorter growing seasons. Indeed, under an extended photoperiod in the greenhouse, where free growth is maintained, the fastest growing balsam poplar clones are from the far north. Clearly, the intrinsic growth rate must be assessed separately from the realized growth that occurs in a common garden. In other words, the largest individuals do not necessarily have the greatest growth potential if photoperiodic adaptation is unaccounted for. This raises the intriguing prospect of breeding trees from high latitude with trees of the same species from low latitude to combine high photosynthetic rates with a longer growing season. Using balsam poplar, such crosses have now been performed by collaborators at the PFRA and the “hybrid” progeny are undergoing assessment at Indian Head.

Posted by Daniel Mosquin at 12:19 PM| Comments (4)

March 8, 2008

Guizotia abyssinica

Fifth in a series celebrating UBC Research Week, again organized by Connor Fitzpatrick:

Scott Black, a Dept. of Botany M.Sc. student supervised by Dr. Gary Bradfield, and Hannes Dempewolf, a Ph.D. student co-supervised by Dr. Quentin Cronk and Dr. Loren Rieseberg, are researching the crop species noug, Guizotia abyssinica. Scott provided the photograph and Hannes adapted the write-up from this brochure on noug (PDF) that he co-authored (published by the Global Facilitation Unit for Underutilized Species).

What is noug?

Noug is an oil-seed crop, indigenous to Ethiopia and holds significant promise for improving rural livelihoods in Sub-Saharan Africa. The species is used in intercropping systems, grows on poor but also extremely wet soils, and contributes to soil conservation. While not fully domesticated, and suffering from low yields and susceptibility to insect herbivores, it contributes up to 50% of the Ethiopian oil-seed crop. Noug belongs to the Compositae family and is closely related to sunflower. It differs from domesticated sunflower mainly due to its high level of branching, numerous flower heads and small seeds. The oil content of noug seed varies from 30 to 50%. The fatty acid composition is typical for seed oils of the Compositae family with linoleic acid being the dominant component.

Ethiopia is well known as centre of diversity for several crops, including teff, enset and Ethiopian mustard. As a result, it has been suggested as Africa's independent origin of domestication. Noug diversity is greatest in Ethiopia and Eritrea and local farmers are able to distinguish many different land-races. The process of noug domestication is incomplete, probably due to frequent interbreeding with its co-occurring wild relatives. Apart from Africa (Ethiopia, Sudan, Uganda, Democratic Republic of Congo, Tanzania, Malawi, Zimbabwe), noug is also cultivated in parts of South Asia (India, Nepal, Bangladesh, Bhutan) where it was introduced several thousand years ago, and the West Indies.

The Rieseberg lab at UBC's Department of Botany is at the centre of an international collaborative research effort that has been launched in order to understand and manage the genetic diversity of noug for its improvement. The challenge of the project (2007-2010) is to show how modern molecular breeding efforts can be adapted and implemented for neglected and underutilized species, such as noug, through research on their diversity. This approach is especially powerful when conducted in the context of genomic information and tools that have already been developed for related major crops, in this case sunflower and lettuce.

This requires:

collection, characterization and conservation of ecologically and genetically diverse germplasm
initiation or re-orientation of existing breeding and crop deployment programs to capitalize on this diversity
transfer of knowledge and technology to breeders and farmers in Ethiopia

With funds from the Canadian International Development Agency (CIDA), scientists from UBC's Department of Botany in collaboration with researchers from Addis Ababa University, the Ethiopian Institute of Agricultural Research and Bioversity International have initiated this project last year and have already completed several components, such as the collection and characterization of several noug cultivars in Ethiopia. Currently, scientists are working in the laboratory to assess the genetic diversity and population structure of noug and its wild relatives.

Posted by Daniel Mosquin at 11:38 AM| Comments (7)

March 7, 2008

Arabidopsis thaliana

Today's entry, organized by Connor Fitzpatrick, is the fourth in a BPotD series for UBC Research Week. The photographs and write up come courtesy of Dr. Fred Sack, Professor and Head, Department of Botany.

Each leaf contains thousands of pores, stomata, which allow gas exchange between the atmosphere and the shoot. Stomata are cellular valves central to plant survival because they allow carbon dioxide to enter leaves where it is used to make sugars in photosynthesis. Stomata are also adaptive because they close down when water loss becomes too great. Efficient gas exchange seems to require that valves be spaced apart from each other since it is rare in nature to find two stomata in direct contact.

My lab pioneered the discovery of genes required for stomatal formation and spacing. We first determined how stomata develop and are distributed in the model eudicot Arabidopsis. As in all plants, stomatal formation requires an initial division that is unequal in size and fate, generating a smaller cell and a larger cell. After the smaller cell becomes oval in profile, it divides equally thus producing the two young guard cells that develop into the stoma. Meanwhile the larger cell produced by the unequal division can in turn divide asymmetrically. Normally this “piggyback” (iterative) division is oriented so that the new small precursor cell does not contact the previously formed one, a placement that generates the minimal one-celled separation between stomata. This placement probably requires intercellular communication, a conclusion reinforced when we identified the TOO MANY MOUTHS gene which encodes a probable receptor. Defects in TMM induce spacing violations, suggesting that it normally receives spatial cues used to correctly orient “piggyback” divisions. TOO MANY MOUTHS acts exclusively in the cells that form stomata as shown by the distribution of green fluorescent protein in the accompanying picture (red shows the cell walls; note that stomata are still forming in this picture; reproduced from Nadeau and Sack, Science). Thus this gene, which is conserved in monocots as well, controls the division behavior of islands of stem cells distributed throughout the epidermis of the developing shoot.

We also found that a different gene, FOUR LIPS, is required to ensure that there is only one equal division of the GMC (the guard mother cell is a precursor to guard cells). Mutations in FLP induce extra, abnormal, equal divisions resulting in four guard cells (lips) in a row (“stoma” comes from the Greek for “mouth”). We found that FLP is a transcription factor that regulates genes involved in cell cycling. Additional genes in this pathway are being identified in collaboration with Erich Grotewold at Ohio State University. It is likely that restricting GMC divisions to one (failsafe) would be strongly selected for in evolution since the control of water loss and the efficiency of carbon dioxide uptake are critical for plant survival.

The first photograph was taken using cryoscanning electron microscopy. The second photograph was taken using confocal laser scanning microscopy. The red channel shows the cell outlines (cell walls labeled with propidium iodide), and the green channel shows where the gene TMM is expressed.

Posted by Daniel Mosquin at 10:09 AM| Comments (10)

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Botany Photo of the Day and all associated images are licensed under a Creative Commons License.