''Utricularia gibba'', commonly known as the humped or floating bladderwort, is a small, mat-forming species of

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

aquatic

bladderwort ''Utricularia'', commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species (precise counts differ based on classification opinions; a 2001 publication lists 215 species).Salmon, Br ...

. It is found on all continents except Antarctica. ''U. gibba'' has an exceptionally small

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...

for a plant, despite having a typical number of

genes In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

. The sequencing of its DNA revealed only 3%

non-coding Non-coding DNA (ncDNA) sequences are components of an organism's DNA that do not encode protein sequences. Some non-coding DNA is transcribed into functional non-coding RNA molecules (e.g. transfer RNA, microRNA, piRNA, ribosomal RNA, and regula ...

material.

Description

''Utricularia gibba'' is an aquatic

carnivorous plant Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryot ...

that belongs to the genus ''

Utricularia ''Utricularia'', commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species (precise counts differ based on classification opinions; a 2001 publication lists 215 species).Salmon, Br ...

'', or bladderworts. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''gibba'' is Latin for "hump" or "swelling" – a reference to the inflated base of the lower lip of the corolla.Bruce Salmon (2001) ''"Carnivorous Plants of New Zealand"'' Ecosphere Publications It is a small- to medium-sized aquatic plant that can either be affixed to the substrate in shallow water or free-floating in the water column, however it will likely flower more if supported by a substrate beneath shallow water. It forms mats of criss-crossing, branching, thread-like

stolon In biology, stolons (from Latin '' stolō'', genitive ''stolōnis'' – "branch"), also known as runners, are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external s ...

s, each growing to approximately long or longer and 0.2–1 mm thick. What are sometime described as leaves or leaf-like organs – the actual distinction is difficult in the reduced morphology – are numerous and scattered along the length of the stolons and are long with a very short dichotomous branching pattern toward the tip of anywhere from one to eight branches but usually not more than four. The bladder traps take the place of some of these

distal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

branches on the leaf-like structures. The traps are ovoid and are attached to the leaf-like structure by a short stalk; each trap is 1–2.5 mm long and has two primary setiform branched appendages on top and some smaller appendages surrounded the entrance to the trap. The appendages are the trigger that sets the trap off and vacuums the prey that touched it into the bladder to be digested.Taylor, Peter. 1989. ''

The genus Utricularia - a taxonomic monograph ''The Genus Utricularia: A Taxonomic Monograph'' is a monograph by Peter Taylor on the carnivorous plant genus ''Utricularia'', the bladderworts. It was published in 1989 by Her Majesty's Stationery Office (HMSO) as the fourteenth entry in the '' ...

''. Kew Bulletin Additional Series XIV: London.

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. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

s are erect and typically emerge from the water to about tall, though in some cases they can be submerged and produce

cleistogamous Cleistogamy is a type of automatic self-pollination of certain plants that can propagate by using non-opening, self-pollinating flowers. Especially well known in peanuts, peas, and pansies, this behavior is most widespread in the grass family. How ...

flowers. Inflorescences can produce anywhere from one to twelve flowers but it is unusual to see anything other than two to six flowers per inflorescence. Individual flowers are yellow, often with reddish-brown nerves, and are split into two lips: the upper lip is almost circular and weakly separated into three lobes while the lower lip is slightly smaller, also circular, and has a rounded, bilobed swelling in the center. The

spur A spur is a metal tool designed to be worn in pairs on the heels of riding boots for the purpose of directing a horse or other animal to move forward or laterally while riding. It is usually used to refine the riding aids (commands) and to back ...

is narrowly conical or cylindrical and curves down below the flower, varying in length from being just shorter than to noticeably longer than the lower lip. ''Utricularia gibba'' will flower throughout the year whenever conditions are favorable. Flowers, specifically the corolla, vary in size across this species' large distribution from .Schnell, Donald. 2002. ''Carnivorous Plants of the United States and Canada''. Timber Press: Portland, Oregon. pp. 369–370. The

diploid chromosome number Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...

for ''U. gibba'' is 2n = 28.

Distribution and habitat

''Utricularia gibba'' has a vast geographic range and is native to the eastern United States, southeastern Canada, Central America, the Caribbean, the western Mediterranean, Southern Africa and southern India. It is considered an

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

in Hawai'i, Australia, Japan, Brazil, New Zealand, Singapore, Serbia, Hungary and the United Kingdom. It grows in ponds and lakes or shallow water in ditches, pools, bogs, swamps, and marshes that may be still or slowly flowing. It can sometimes be found growing in deep water but will not flower unless the

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. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

s are supported near the surface by living or dead vegetation. The waters in which it grows are typically poor in available

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

and

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

Genetic efficiency

In 2013, the

of ''U. gibba'' was sequenced. At only 82

megabase A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...

s, the genome is exceptionally small for a multicellular plant and the main difference between other plant genomes and that of ''U. gibba'' is a drastic reduction in

non-coding DNA Non-coding DNA (ncDNA) sequences are components of an organism's DNA that do not encode protein sequences. Some non-coding DNA is transcribed into functional non-coding RNA molecules (e.g. transfer RNA, microRNA, piRNA, ribosomal RNA, and regul ...

. The discovery casts doubt on the idea that repetitive, non-coding DNA, popularly known as junk DNA, is necessary for life. ''Utricularia gibba'' and the

tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...

split from a common ancestor approximately 87 million years ago. Since that time, both plants have experienced episodes of

whole genome duplication Paleopolyploidy is the result of genome duplications which occurred at least several million years ago (MYA). Such an event could either double the genome of a single species (autopolyploidy) or combine those of two species (allopolyploidy). Bec ...

(WGD) in which the plants' DNA content doubled in size. Since then, it has lost most unneeded DNA, unlike the tomato, and now has a genome only a tenth as long as the tomato's. Compared to ''Arabidopsis'', the introns of ''Utricularia gibba'' are somewhat fewer in number per gene, and conserved ''cis''-acting elements of its promoters are compressed. Most critical genes have returned to single copy status. However, the

mitochondrial A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is use ...

and

plastid The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the Cell (biology), cells of plants, algae, and some other eukaryotic organisms. They are considered to be intracellular endosy ...

genomes of ''U. gibba'' do not appear to be compressed relative to those of other angiosperms. The compression of its nuclear DNA is thought to have occurred via both numerous microdeletions and some large-scale recombinant deletions. The presence of numerous GC-rich sequences throughout the nuclear genome of ''U. gibba'' is considered to have created a molecular mechanistic bias in favor of deletions, but this does not preclude the presence of a selection pressure to preserve such deletions. Trap formation is induced in ''U. gibba'' by low phosphorus but not low nitrogen, indicating that phosphorus availability is more limiting in its environment. It had also been previously proposed that an increased mutation rate due to greater environmental mutagen exposure could have increased natural selection for loss of unneeded DNA, but no evidence for this was found in the relative mutational diversities of ''U. gibba'' and ''Arabidopsis''. It is possible that the genome duplication events and low-phosphorus environment acted in concert with one another: that the three whole genome duplications that occurred in ''U. gibba'' enabled the selective pressure of a phosphorus poor environment to reduce total DNA without the deletion of important genes. Utricularia gibba and scenedesmus

Cultivation

''Utricularia gibba'' has the reputation of being one of the easier aquatic bladderworts to grow, often being described as a weed in cultivation. In his 1998 book '' The Savage Garden: Cultivating Carnivorous Plants'',

Peter D'Amato Peter D'Amato is an American author, businessman, and carnivorous plant authority. He is the owner of California Carnivores, located in Sebastopol, possibly the largest nursery of carnivorous plants in the world, and the author of '' The Savage ...

advised that successful cultivation could be achieved with ''U. gibba'' floating in a small cup or bowl, within waterlogged

peat Peat (), also known as turf (), is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. The peatland ecosystem covers and is the most efficien ...

, or even among the water-filled trays of other plants. It can also easily be grown in aquaria.D'Amato, Peter. 1998. '' The Savage Garden: Cultivating Carnivorous Plants''. Ten Speed Press: Berkeley, California. p. 231.

References

External links

{{Taxonbar, from=Q244015 Carnivorous plants of Africa Carnivorous plants of Asia Carnivorous plants of Australia Carnivorous plants of Central America Carnivorous plants of Europe Carnivorous plants of New Zealand Carnivorous plants of North America Carnivorous plants of South America Flora of New South Wales Flora of the North Island Flora of Queensland Flora of the Northern Territory Lamiales of Australia Plants described in 1753 Taxa named by Carl Linnaeus