Jania (alga)
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| Jania | |
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| Jania rubens | |
Scientific classification  | |
| Clade: | Archaeplastida |
| Division: | Rhodophyta |
| Class: | Florideophyceae |
| Order: | Corallinales |
| Family: | Corallinaceae |
| Subfamily: | Corallinoideae |
| Genus: | Jania J.V. Lamouroux, 1812 [1] |
| Species | |
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See text | |
Jania is a genus of red macroalgae (or seaweeds) with hard, calcareous, branching skeletons in the family Corallinaceae.
The genus name of Jania is derived from the Greek water nymph called Ianeira (or Janeria).[2] It was first circumscribed by Jean Vincent Félix Lamouroux in 1812.[3] Based on a recent integrated taxonomic examination of the genus, and by extension its tribe Janieae, the members of Cheilosporum and Haliptilon have all been transferred under genus Jania[4]. As a result, there is currently around 55 confirmed species for this genus.[5]
Morphology
Jania is an articulated coralline algae characterized by having erect thalli with dichotomously-arranged branches composed of alternating segments of red or pink, calcified, cylindrical sections (intergeniculum) and white uncalcified sections (geniculum); that is attached to the substrate by small, stolon-like holdfasts.[6][5] Intergenicula of this genus can be cylindrical, subcylindrical or compressed and smooth, winged or lobed.[5][4]
Distribution
Jania species are well-distributed throughout the world.[5]
Ecology
Life history
Like most red seaweeds, Jania exhibit a triphasic life cycle wherein aside from the free-living haploid (gametophyte) and diploid (tetrasporophyte) generations, another diploid generation that is parasitic to the gametophyte, the carposporophyte. Tetrasporophyte (2N) generation would release four haploid spores (or tetraspores) that would later on develop into either the male and female gametophytes; moreover, the spermatium (N) produced by the spermatangia will be trapped by the trichogyne of the carpogonium (N) of the female gametophyte and later on fuse to form the zygote and subsequently develop into the carposporophyte (2N); lastly the carposporophyte will produce carpospores (2N) that will become the tetratsporophyte (2N).[5] The unique structure involved in coralline reproduction is the presence of the conceptacle, a calcified depression wherein the tetrasporangia, spermatangia, and carposporangia are formed.[9]
Exploitation/harvesting/cultivation
There is no known cultivation technology for this genus.
Chemical composition/natural products chemistry
Priming tomato seeds with Jania polysaccharides has shown to greatly improve the resistance of seedlings to soil-borne pathogens and consequently promote plant growth.[10]