bryophyte Stomata
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Stomata are present across all plants excluding liverworts and are very similar, consisting of a pore surrounded by two guard cells. In all extant plants, stomata are found in the sporophyte. The origin and evolution of stomata in land plants is controversial. Moss guard cells have similar wall architecture and are less variable than tracheophytes guard cells. In reduced sporophytes (such as Ephemerum and Physcomitrella) capsule anatomy is modified and some stomata features are also reduced (Merced & Renzaglia 2013). We described the developmental pattern and distribution of stomata in the moss Funaria (Merced & Renzaglia 2016) and changes in pectin composition during guard cell development. We found that guard cell walls are thinner and rich in pectins during the short period where stomata can open and close (Merced & Renzaglia 2014). We hypothesize that during development of the sporophyte, stomata serves as passages for gas exchange and bringing up water into the expanding capsule, later stomata helps to dry the capsule and influence the release of spores.
The single origin of stomata is complicated by the absence of true stomata in early-divergent mosses, but Sphagnum has specialized epidermal cells, pseudostomata, that partially separate but do not form a pore. Pseudostomata may be related to stomata and share a common function to moss stomata (Merced 2015), with wall architecture and behavior specialized to facilitate capsule dehydration, shape change, and dehiscence. To have a better picture of stomata evolution we studied the ultrastructure, anatomy and composition of stomata of hornworts and proposed that they share a common architecture and fate to stomata of ancient plants (Renzaglia et al. 2017). It turns out that guard cell walls of hornworts lack some of the pectin components necessary for stomata movement that are present in angiosperms (Merced & Renzaglia 2019). In a review article we summarize and synthesize the knowledge acquire in the last few years about bryophyte stomata and future directions of study (Merced & Renzaglia 2017). |
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Bryophyte diversity and Ecology
Bryophytes are usually a neglected group of plants, being small they can be bypass without notice, but once you stop to look at them or better yet get ahold of a hand-lens or a microscope you will be able to see their beauty. Bryophytes is the collective name given to three groups of plants: mosses, liverworts and hornworts. I have been studying bryophytes since 2001.
I am working with the bryophytes of Puerto Rico, collecting and identifying bryophytes around the islands. In particular, focusing on the role of bryophytes in Puerto Rican forests and how they respond to anthropogenic and non-anthropogenic disturbances. I am also interested in urban and community forests that sustain bryophytes to understand how they are different to non-urban vegetations.
To better understand the distribution of bryophytes in a tropical forest, we are studying the presence and abundance of a common moss and liverwort in El Verde LTER. We are interested in learning what ecological factors influence the presence and size of these bryophytes, and how it compares to other plants.
I am working with the bryophytes of Puerto Rico, collecting and identifying bryophytes around the islands. In particular, focusing on the role of bryophytes in Puerto Rican forests and how they respond to anthropogenic and non-anthropogenic disturbances. I am also interested in urban and community forests that sustain bryophytes to understand how they are different to non-urban vegetations.
To better understand the distribution of bryophytes in a tropical forest, we are studying the presence and abundance of a common moss and liverwort in El Verde LTER. We are interested in learning what ecological factors influence the presence and size of these bryophytes, and how it compares to other plants.
OTHER PROJECTS
Southern Illinois was a great area for bryophytes. In collaboration with S. Jesselson, a SIU Plant Biology undergraduate student in the Renzaglia lab, we collected, identify and image mosses of the area. Here is a link to the project of some common mosses of southern Illinois and the poster.
As a research assistant in Dr. Shaw’s Bryology Lab at Duke University I worked on the virtual flora of the mosses of North Carolina. The key to the mosses of NE United States, created by Lewis Anderson and others, is illustrated with pictures of some of the species and important characters for the identification. Here is the link to the Mosses of North Carolina.
From 2005 to 2008 I worked at the UPRRP Herbarium (San Juan PR), where I was in charge of the database activities of the herbarium and supervision of students. There I collected and identify specimens for the bryophyte collection. Here is the link to the UPRRP herbarium database.
During the time I was at UPR Río Piedras I worked with two undergraduate students doing research in bryology. With S. Galva we collected and identified bryophytes of the Carite Forest Reserve, PR and prepared a preliminary list of bryophyte species with new records for the area. Here is a poster with our findings (in Spanish). Working with orchid expert Dr. J. Ackerman I learn to see orchids everywhere. Did you know that small orchids, like Lepanthes, are often found between bryophyte matts? As an undergrad student J.G. García Cancel, advised by Dr. Melendez-Ackerman, looked at the relationship between orchid distribution and bryophyte cover, this study found that in thick bryophyte cover adult orchids are more frequent than younger plants but that interactions between bryophytes and this orchid are dynamic during different life stages. This research resulted in a publication in the Caribbean Naturalist.
Southern Illinois was a great area for bryophytes. In collaboration with S. Jesselson, a SIU Plant Biology undergraduate student in the Renzaglia lab, we collected, identify and image mosses of the area. Here is a link to the project of some common mosses of southern Illinois and the poster.
As a research assistant in Dr. Shaw’s Bryology Lab at Duke University I worked on the virtual flora of the mosses of North Carolina. The key to the mosses of NE United States, created by Lewis Anderson and others, is illustrated with pictures of some of the species and important characters for the identification. Here is the link to the Mosses of North Carolina.
From 2005 to 2008 I worked at the UPRRP Herbarium (San Juan PR), where I was in charge of the database activities of the herbarium and supervision of students. There I collected and identify specimens for the bryophyte collection. Here is the link to the UPRRP herbarium database.
During the time I was at UPR Río Piedras I worked with two undergraduate students doing research in bryology. With S. Galva we collected and identified bryophytes of the Carite Forest Reserve, PR and prepared a preliminary list of bryophyte species with new records for the area. Here is a poster with our findings (in Spanish). Working with orchid expert Dr. J. Ackerman I learn to see orchids everywhere. Did you know that small orchids, like Lepanthes, are often found between bryophyte matts? As an undergrad student J.G. García Cancel, advised by Dr. Melendez-Ackerman, looked at the relationship between orchid distribution and bryophyte cover, this study found that in thick bryophyte cover adult orchids are more frequent than younger plants but that interactions between bryophytes and this orchid are dynamic during different life stages. This research resulted in a publication in the Caribbean Naturalist.
PLANT ANATOMY
In collaboration with B. Sanchez and supervised by Dr. Muñoz (UPR Mayaguez), we studied the anatomy of Goetzea elegans (Solanaceae) an endemic endangered plant of Puerto Rico. We described the anatomy of green and young woody stems, roots, leaves, flowers and fruits using paraffin embedded serial sections that were viewed in light and fluorescent microscope. Here is a poster (in Spanish).
In collaboration with B. Sanchez and supervised by Dr. Muñoz (UPR Mayaguez), we studied the anatomy of Goetzea elegans (Solanaceae) an endemic endangered plant of Puerto Rico. We described the anatomy of green and young woody stems, roots, leaves, flowers and fruits using paraffin embedded serial sections that were viewed in light and fluorescent microscope. Here is a poster (in Spanish).
