Genlisea margaretae
Encyclopedia
Genlisea margaretae is a carnivorous
species in the genus
Genlisea
(family Lentibulariaceae
) native to areas of Madagascar
, Tanzania
, and Zambia
. It has pale bundles of root-like organs up to about 20 cm long under ground that attract, trap, and digest protozoa
ns. These organs are subterranean leaves
, which lack chlorophyll
. It possesses the smallest known genome
of any flowering plant
.
composed of nearly linear leaves about 2 mm wide. Leaves are typically 5-50 mm in length, but most of that length, including the petiole
, is hidden beneath the soil. It has no true roots and instead has highly modified subterranean leaves that act as the carnivorous trapping mechanism.
The inflorescence
s, which can grow to be 20-60 cm tall, emerge from the center of the rosette and produce mauve
or violet-colored flowers. Each inflorescence can produce more than 10 flowers on a congested raceme
. The upper part of the inflorescences is densely covered with glandular trichome
s while the lower part has fewer trichomes and is often glabrous. Individual flowers have rounded upper lips on the corolla instead of being lobed and a relatively straight spur
.
The genome
s of several species in the genus Genlisea were studied in 2006 along with other members of the Lentibulariaceae
family. According to the study, prior to its publication the smallest known angiosperm (flowering plant) genome was that of Arabidopsis thaliana
at 157 Megabase pairs
(Mbp). With a diploid chromosome
number of around 40 (2n = ca.
40), G. margaretae now holds the distinction of having the smallest known angiosperm genome size
at 63.4 Mbp, just 0.2 Mbp lower than that of Genlisea aurea
. The smallest individual chromatid
s from mitotic
anaphase
are just 2.1 Mbp and therefore have a size smaller than some bacterial chromosomes, such as the approximate 4 Mbp of Escherichia coli
. G. margaretae and G. aurea also both appear to be polyploid species with the unusual circumstances of having a high chromosome number with extremely small chromosomes. Other species in the genus Genlisea and the family Lentibulariaceae have much lower chromosome numbers and larger genome sizes, affirming that one characteristic of this botanic family is rapid molecular evolution. G. margaretae in particular may be helpful in research aimed at understanding the mechanisms behind genome downsizing.
At least one natural hybrid among the African species that involves G. margaretae has been described. Genlisea margaretae × glandulosissima is a product of G. margaretae and G. glandulosissima.
. It has been discovered in Tanzania
and Zambia
and is the only Genlisea species reported to exist in Madagascar
. Its typical oligotroph
ous habitat includes inselbergs, ferricrete
s, and swamps.
that attracts, traps, kills, and digests prey, which are typically protozoans. Evidence of this behavior had been postulated ever since Charles Darwin
's time and has mostly relied on circumstantial findings of the occasional dead aquatic invertebrate in the utricle (digestion chamber). In 1975, however, British botanist Yolande Heslop-Harrison discovered digestive enzyme
activity in G. africana. Later, in 1998, Wilhelm Barthlott
and his colleagues concluded through experimentation that Genlisea attracts prey chemotactically
, traps them in the corkscrew "lobster pot" trap, digests them with enzymes produced by the plant, and then absorbs the nutrients. This study represented the first conclusive evidence that G. margaretae was carnivorous.
Carnivorous plant
Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous plants appear adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic...
species in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Genlisea
Genlisea
Genlisea is a genus of carnivorous plants also known as corkscrew plants. The 21 species grow in wet terrestrial to semi-aquatic environments distributed throughout Africa and Central and South America. The plants use highly modified underground leaves to attract, trap and digest minute...
(family Lentibulariaceae
Lentibulariaceae
Lentibulariaceae is a family of carnivorous plants containing three genera, Genlisea, the corkscrew plants, Pinguicula, the butterworts, and Utricularia, the bladderworts....
) native to areas of Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
, Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
, and Zambia
Zambia
Zambia , officially the Republic of Zambia, is a landlocked country in Southern Africa. The neighbouring countries are the Democratic Republic of the Congo to the north, Tanzania to the north-east, Malawi to the east, Mozambique, Zimbabwe, Botswana and Namibia to the south, and Angola to the west....
. It has pale bundles of root-like organs up to about 20 cm long under ground that attract, trap, and digest protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
ns. These organs are subterranean leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
, which lack chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
. It possesses the smallest known genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
of any flowering plant
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
.
Characteristics
G. margaretae is a perennial herb that forms small, compact rosettesRosette (botany)
In botany, a rosette is a circular arrangement of leaves, with all the leaves at a single height.Though rosettes usually sit near the soil, their structure is an example of a modified stem.-Function:...
composed of nearly linear leaves about 2 mm wide. Leaves are typically 5-50 mm in length, but most of that length, including the petiole
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
, is hidden beneath the soil. It has no true roots and instead has highly modified subterranean leaves that act as the carnivorous trapping mechanism.
The inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
s, which can grow to be 20-60 cm tall, emerge from the center of the rosette and produce mauve
Mauve
Mauve is a pale lavender-lilac color, one of many in the range of purples. The color mauve is named after the mallow flower....
or violet-colored flowers. Each inflorescence can produce more than 10 flowers on a congested raceme
Raceme
A raceme is a type of inflorescence that is unbranched and indeterminate and bears pedicellate flowers — flowers having short floral stalks called pedicels — along the axis. In botany, axis means a shoot, in this case one bearing the flowers. In a raceme, the oldest flowers are borne...
. The upper part of the inflorescences is densely covered with glandular trichome
Trichome
Trichomes are fine outgrowths or appendages on plants and certain protists. These are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae.- Algal trichomes :...
s while the lower part has fewer trichomes and is often glabrous. Individual flowers have rounded upper lips on the corolla instead of being lobed and a relatively straight spur
Spur (biology)
A spur in botany is a spike, usually part of a flower.In certain plants, part of a sepal or petal develops into an elongated hollow spike extending behind the flower, containing nectar which is sucked by long-tongued animals . Plants with such structures include Delphinium, Aquilegia, Piperia, and...
.
The genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
s of several species in the genus Genlisea were studied in 2006 along with other members of the Lentibulariaceae
Lentibulariaceae
Lentibulariaceae is a family of carnivorous plants containing three genera, Genlisea, the corkscrew plants, Pinguicula, the butterworts, and Utricularia, the bladderworts....
family. According to the study, prior to its publication the smallest known angiosperm (flowering plant) genome was that of Arabidopsis thaliana
Arabidopsis thaliana
Arabidopsis thaliana is a small flowering plant native to Europe, Asia, and northwestern Africa. A spring annual with a relatively short life cycle, arabidopsis is popular as a model organism in plant biology and genetics...
at 157 Megabase pairs
Base pair
In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
(Mbp). With a diploid chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
number of around 40 (2n = ca.
Circa
Circa , usually abbreviated c. or ca. , means "approximately" in the English language, usually referring to a date...
40), G. margaretae now holds the distinction of having the smallest known angiosperm genome size
Genome size
Genome size is the total amount of DNA contained within one copy of a single genome. It is typically measured in terms of mass in picograms or less frequently in Daltons or as the total number of nucleotide base pairs typically in megabases . One picogram equals 978 megabases...
at 63.4 Mbp, just 0.2 Mbp lower than that of Genlisea aurea
Genlisea aurea
Genlisea aurea is one of the largest carnivorous species in the genus Genlisea . It has pale bundles of root-like organs up to about 15 cm long under ground that attract, trap, and digest protozoans. These organs are subterranean leaves, which lack chlorophyll. G. aurea is endemic to Brazil, where...
. The smallest individual chromatid
Chromatid
A chromatid is one of the two identical copies of DNA making up a duplicated chromosome, which are joined at their centromeres, for the process of cell division . They are called sister chromatids so long as they are joined by the centromeres...
s from mitotic
Mitosis
Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets, in two separate nuclei. It is generally followed immediately by cytokinesis, which divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly...
anaphase
Anaphase
Anaphase, from the ancient Greek ἀνά and φάσις , is the stage of mitosis or meiosis when chromosomes move to opposite poles of the cell....
are just 2.1 Mbp and therefore have a size smaller than some bacterial chromosomes, such as the approximate 4 Mbp of Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
. G. margaretae and G. aurea also both appear to be polyploid species with the unusual circumstances of having a high chromosome number with extremely small chromosomes. Other species in the genus Genlisea and the family Lentibulariaceae have much lower chromosome numbers and larger genome sizes, affirming that one characteristic of this botanic family is rapid molecular evolution. G. margaretae in particular may be helpful in research aimed at understanding the mechanisms behind genome downsizing.
At least one natural hybrid among the African species that involves G. margaretae has been described. Genlisea margaretae × glandulosissima is a product of G. margaretae and G. glandulosissima.
Distribution and habitat
G. margaretae is one of the several Genlisea species native to Southeast AfricaAfrica
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. It has been discovered in Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
and Zambia
Zambia
Zambia , officially the Republic of Zambia, is a landlocked country in Southern Africa. The neighbouring countries are the Democratic Republic of the Congo to the north, Tanzania to the north-east, Malawi to the east, Mozambique, Zimbabwe, Botswana and Namibia to the south, and Angola to the west....
and is the only Genlisea species reported to exist in Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
. Its typical oligotroph
Oligotroph
An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments...
ous habitat includes inselbergs, ferricrete
Ferricrete
Ferricrete is a hard, erosion-resistant layer of material at the land surface that consists of near surface sediments cemented by iron oxide in to a duricrust. Ferricretes contains sediments and other non-indigenous materials, which have been transported from outside the immediate area in which it...
s, and swamps.
Carnivory
G. margaretae, like all Genlisea species, is a carnivorous plantCarnivorous plant
Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous plants appear adapted to grow in places where the soil is thin or poor in nutrients, especially nitrogen, such as acidic...
that attracts, traps, kills, and digests prey, which are typically protozoans. Evidence of this behavior had been postulated ever since Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
's time and has mostly relied on circumstantial findings of the occasional dead aquatic invertebrate in the utricle (digestion chamber). In 1975, however, British botanist Yolande Heslop-Harrison discovered digestive enzyme
Digestive enzyme
'Digestive enzymes' are enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption by the body. Digestive enzymes are found in the digestive tract of animals where they aid in the digestion of food as well as inside the cells,...
activity in G. africana. Later, in 1998, Wilhelm Barthlott
Wilhelm Barthlott
Wilhelm Barthlott is German botanist and the head of the Nees-Institute for Biodiversity of Plants and director of the Botanical Gardens of the University of Bonn.- External links :*...
and his colleagues concluded through experimentation that Genlisea attracts prey chemotactically
Chemotaxis
Chemotaxis is the phenomenon in which somatic cells, bacteria, and other single-cell or multicellular organisms direct their movements according to certain chemicals in their environment. This is important for bacteria to find food by swimming towards the highest concentration of food molecules,...
, traps them in the corkscrew "lobster pot" trap, digests them with enzymes produced by the plant, and then absorbs the nutrients. This study represented the first conclusive evidence that G. margaretae was carnivorous.