Oryza australiensis is a wild rice species native to monsoonal northern Australia.[2] Also known as Australian rice or Australian Wild Rice,[3][4] it is a perennial plant that uses the C3 photosynthesis pathway.[5] O. australiensis is unique among other Oryza for its resistance to abiotic stresses, particularly from heat, and having the largest genome in the genus.

Oryza australiensis
Wild plants near Townsville
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Poales
Family: Poaceae
Genus: Oryza
Species:
O. australiensis
Binomial name
Oryza australiensis
(Domin, 1915)
Distribution of O. australiensis

Description

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Appearance wise, O. australiensis is categorised as long paddy rice with short grain.[6] It is a perennial (lives for longer than 2 years), rhizomatous grass. It has straight culms, which are between 0.8 metres (2.6 ft) and 2.5 metres (8.2 ft) tall. It also has a panicle inflorescence that is either open or partially contracted, and between 13 centimetres (5.1 in) and 45 centimetres (18 in) long. Its lemma awns are between 10 millimetres (0.39 in) and 60 millimetres (2.4 in) long.[4] Leave colour varies between either a grey-green or a dark-green colour.[7]

O. australiensis is more slender than domesticated rice, and has a high gelatinization temperature and content of amylose, meaning it doesn't stick together after cooking.[8][9] Alongside this, it has a higher content of protein than cultigen rice.[8]

Habitat

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O. australiensis is a wild relative of other rice species and endemic to the tropical regions of northern Australia. Three other wild Oryza species are distributed across and endemic to northern Australia.[8] Within northern Australia, it is found in wet areas near or on the edge of fresh water. It grows in the open in black, clay, or red loam soil.[7]

Its habitat range experiences periods of heat and dryness, with the specie having developed a tolerance to heat. Heat shock experiments on O. australiensis have found that at 45 °C (113 °F), its ability to properly shoot biomass and leaf elongate was unaffected and soluble sugar concentrations tripled during the period of extreme heat, showing its robust carboxylation capacity and thermal tolerance. This is in contrast to other rice species, such as O. sativa, who didn't handle the heat as well as O. australiensis.[10] This is due to the plant's RuBisCO activase enzymes, which is thermally stable up to 42 °C (108 °F).[11] Other resistance to abiotic stresses include tolerance to salinity stress.[12] O. australiensis also has developed drought resistance, where photosynthesis efficiency was not affected by stress caused from drought conditions. It may contain a large number of novel stress responsive genes.[13] It survives the dry season through its rhizomes.[8] Due to its habitat and adaptions, the species has been described as an extremophile.[14] O. australiensis' resistance to abiotic stresses has also led to it being used in breeding programs.[12] It also carries genes that help it resist diseases, bacterial blights and insects such as brown planthoppers (BHP).[8]

Genetics

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O. australiensis is the only known member of the EE genome clade, and its genome is estimated to be 965 mega-base pairs (Mbp).[14] Its genome is in some cases double the size of other rice species, such as O. sativa ssp. japonica. Its size is due to long terminal repeat retrotransposon (LTR-RTs) families, which make up around 65% of its genome. This accumulation of over 90,000 LTR-RTs occurred within the last three million years after speciation. O. australiensis thus then has the largest genome within the genus Oryza.[15]

References

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  1. ^ Phillips, J.; Yang, L. (2017). "Oryza australiensis". IUCN Red List of Threatened Species. 2017: e.T21346627A21413475. Retrieved 22 September 2024.
  2. ^ Atlas of Living Australia'
  3. ^ "Australian Rice". IUCN Red List. Retrieved 22 September 2024.
  4. ^ a b Hooker, Nanette B. (2016). Grasses of Townsville. Townsville, QLD, Australia: James Cook University. ISBN 978-0-9942333-3-2.
  5. ^ Brian Atwell (2012). "Plant of the Week: Australian 'Native' or 'Wild' Rice". Macquarie University. Retrieved 2 February 2015.
  6. ^ Tikapunya, Tiparat; Fox, Glen; Furtado, Agnelo; Henry, Robert (29 March 2016). "Grain physical characteristic of the Australian wild rices". Plant Genetic Resources. 15 (5): 409–420. doi:10.1017/S1479262116000083. ISSN 1479-2621. S2CID 87676451.
  7. ^ a b "Wild Rice Taxonomy" (PDF). 2004.
  8. ^ a b c d e Abdelghany, Gehan; Wurm, Penelope; Hoang, Linh Thi My; Bellairs, Sean Mark (25 December 2021). "Commercial Cultivation of Australian Wild Oryza spp.: A Review and Conceptual Framework for Future Research Needs". Agronomy. 12 (1): 42. doi:10.3390/agronomy12010042. ISSN 2073-4395.
  9. ^ "Rice 101: Nutrition facts and health effects". www.medicalnewstoday.com. 2020-05-15. Retrieved 2024-09-23.
  10. ^ Phillips, Aaron L.; Scafaro, Andrew P.; Atwell, Brian J. (2022-11-01). "Photosynthetic traits of Australian wild rice (Oryza australiensis) confer tolerance to extreme daytime temperatures". Plant Molecular Biology. 110 (4): 347–363. doi:10.1007/s11103-021-01210-3. ISSN 1573-5028. PMC 9646608. PMID 34997897.
  11. ^ Scafaro, Andrew P.; Gallé, Alexander; Van Rie, Jeroen; Carmo-Silva, Elizabete; Salvucci, Michael E.; Atwell, Brian J. (5 May 2016). "Heat tolerance in a wild Oryza species is attributed to maintenance of Rubisco activation by a thermally stable Rubisco activase ortholog". New Phytologist. 211 (3): 899–911. doi:10.1111/nph.13963. ISSN 0028-646X. PMID 27145723.
  12. ^ a b Yichie, Yoav; Brien, Chris; Berger, Bettina; Roberts, Thomas H.; Atwell, Brian J. (2018-12-22). "Salinity tolerance in Australian wild Oryza species varies widely and matches that observed in O. sativa". Rice. 11 (1): 66. doi:10.1186/s12284-018-0257-7. ISSN 1939-8433. PMC 6303227. PMID 30578452.
  13. ^ Hamzelou, Sara; Kamath, Karthik Shantharam; Masoomi-Aladizgeh, Farhad; Johnsen, Matthew M.; Atwell, Brian J.; Haynes, Paul A. (19 August 2020). "Wild and Cultivated Species of Rice Have Distinctive Proteomic Responses to Drought". International Journal of Molecular Sciences. 21 (17): 5980. doi:10.3390/ijms21175980. ISSN 1422-0067. PMC 7504292. PMID 32825202.
  14. ^ a b Phillips, Aaron L.; Ferguson, Scott; Watson-Haigh, Nathan S.; Jones, Ashley W.; Borevitz, Justin O.; Burton, Rachel A.; Atwell, Brian J. (2022-06-25). "The first long-read nuclear genome assembly of Oryza australiensis, a wild rice from northern Australia". Scientific Reports. 12 (1): 10823. doi:10.1038/s41598-022-14893-5. ISSN 2045-2322.
  15. ^ Piegu, Benoit; Guyot, Romain; Picault, Nathalie; Roulin, Anne; Saniyal, Abhijit; Kim, Hyeran; Collura, Kristi; Brar, Darshan S.; Jackson, Scott; Wing, Rod A.; Panaud, Olivier (2006-10-01). "Doubling genome size without polyploidization: Dynamics of retrotransposition-driven genomic expansions in Oryza australiensis, a wild relative of rice". Genome Research. 16 (10): 1262–1269. doi:10.1101/gr.5290206. ISSN 1088-9051. PMC 1581435. PMID 16963705.