Druse (botany)

Crystals found in plants

Druses in onion scales (100x magnification)

For other uses, see Druse.

A druse is a group of crystals of calcium oxalate,[1] silicates, or carbonates present in plants, and are thought to be a defense against herbivory due to their toxicity. Calcium oxalate (Ca(COO)2, CaOx) crystals are found in algae, angiosperms and gymnosperms in more than 215 families. These plants accumulate oxalate in the range of 3–80% (w/w) of their dry weight[2][3] through a biomineralization process in a variety of shapes.[4] Araceae have numerous druses, multi-crystal druses and needle-shaped raphide crystals of CaOx present in the tissue.[5] Druses are also found in leaves and bud scales of Prunus, Rosa,[6] Allium, Vitis, Morus and Phaseolus.[7][8]

## Formation

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A number of biochemical pathways for calcium oxalate biomineralization in plants have been proposed. Among these is the cleavage of isocitrate, the hydrolysis of oxaloacetate, glycolate/glyoxylate oxidation, and/or oxidative cleavage of L-ascorbic acid.[9] The cleavage of ascorbic acid appears to be the most studied pathway.[10][11][12][13] The specific mechanism controlling this process is unclear. Still, it has been suggested that a number of factors influence crystal shapes and growth, such as proteins, polysaccharides, and lipids or macromolecular membrane structures.[14][15][16] Druses may also have some purpose in calcium regulation.

## See also

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* Idioblast
* Raphide
* Phytolith
* Plant defense against herbivory

## References

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1. ^ Franceschi VR, Nakata PA (2005). "Calcium oxalate in plants: formation and function". Annu Rev Plant Biol. 56 (1): 41–71\. Bibcode:2005AnRPB..56...41F. doi:10.1146/annurev.arplant.56.032604.144106. PMID 15862089.
2. ^ Zindler-Frank E. (1976). "Oxalate biosynthesis in relation to photosynthetic pathways and plant productivity: a survey". Z. Pflanzenphysiol. 80 (1): 1–13\. doi:10.1016/S0044-328X(76)80044-X.
3. ^ Libert B, Franceschi VR (1987). "Oxalate in crop plants". J Agric Food Chem. 35 (6): 926–938\. Bibcode:1987JAFC...35..926L. doi:10.1021/jf00078a019.
4. ^ McNair JB (1932). "The interrelation between substances in plants: essential oils and resins, cyanogen and oxalate". Am J Bot. 19 (3): 255–271\. doi:10.2307/2436337. JSTOR 2436337.
5. ^ Prychid CJ, Jabaily RS, Rudall PJ (2008). "Cellular ultrastructure and crystal development in Amorphophallus (Araceae)". Ann. Bot. 101 (7): 983–995\. doi:10.1093/aob/mcn022. PMC 2710233. PMID 18285357.
6. ^ Lersten NR, Horner HT (2006). "Crystal macropattern development in Prunus serotina (Rosaceae, Prunoideae) leaves". Ann. Bot. 97 (5): 723–729\. doi:10.1093/aob/mcl036. PMC 2803424. PMID 16513655.
7. ^ Jáuregui-Zúñiga D, Reyes-Grajeda JP, Sepúlveda-Sánchez JD, Whitaker JR, Moreno A (2003). "Crystallochemical characterization of calcium oxalate crystals isolated from seed coats of Phaseolus vulgaris and leaves of Vitis vinifera". J Plant Physiol. 160 (3): 239–245\. Bibcode:2003JPPhy.160..239J. doi:10.1078/0176-1617-00947. PMID 12749080.
8. ^ Katayama H, Fujibayashi Y, Nagaoka S, Sugimura Y (2007). "Cell wall sheath surrounding calcium oxalate crystals in mulberry idioblasts". Protoplasma. 231 (3–4): 245–248\. Bibcode:2007Prpls.231..245K. doi:10.1007/s00709-007-0263-x. PMID 17922267. S2CID 29944485.3–4&rft.pages=245-248&rft.date=2007&rft_id=info:doi/10.1007/s00709-007-0263-x&rft_id=https://api.semanticscholar.org/CorpusID:29944485#id-name=S2CID&rft_id=info:pmid/17922267&rft_id=info:bibcode/2007Prpls.231..245K&rft.aulast=Katayama&rft.aufirst=H&rft.au=Fujibayashi,+Y&rft.au=Nagaoka,+S&rft.au=Sugimura,+Y&rfr_id=info:sid/en.wikipedia.org:Druse+(botany)" class="Z3988">
9. ^ Hodgkinson A (1977). "Oxalic acid metabolism in higher plants". In A Hodgkinson (ed.). Oxalic Acid Biology and Medicine. Vol. 101\. New York: Academic Press. pp. 131–158\. doi:10.1016/0014-5793(79)81066-2. ISBN 9780123517500. `{{cite book}}`: `|journal=` ignored (help)
10. ^ Yang J, Loewus FA (1975). "Metabolic conversion of L-ascorbic acid in oxalate-accumulating plants". Plant Physiol. 56 (2): 283–285\. doi:10.1104/pp.56.2.283. PMC 541805. PMID 16659288.
11. ^ Nuss RF, Loewus FA (1978). "Further studies on oxalic acid biosynthesis in oxalate-accumulating plants". Plant Physiol. 61 (4): 590–592\. doi:10.1104/pp.61.4.590. PMC 1091923. PMID 16660342.
12. ^ Li XX, Franceschi VR (1990). "Distribution of peroxisomes and glycolate metabolism in relation to calcium oxalate formation in Lemna minor L.". Eur J Cell Biol. 51 (1): 9–16\. PMID 2184039.
13. ^ Keates SA, Tarlyn N, Loewus FA, Franceschi VR (2000). "L-Ascorbic acid and L-galactose are sources of oxalic acid and calcium oxalate in Pistia stratiotes". Phytochemistry. 53 (4): 433–440\. Bibcode:2000PChem..53..433K. doi:10.1016/S0031-9422(99)00448-3. PMID 10731019.
14. ^ Horner HT, Wagner BL (1980). "The association of druse crystals with the developing stomium of Capsicum annuum (Solanaceae) anthers". Am J Bot. 67 (9): 1347–1360\. doi:10.2307/2442137. JSTOR 2442137.
15. ^ Arnott HJ, Webb MA (1983). "Twin crystals of calcium oxalate in the seed coat of the kidney bean". Protoplasma. 114 (1): 23–34\. Bibcode:1983Prpls.114...23A. doi:10.1007/BF01279865. S2CID 180834.
16. ^ Webb MA (1999). "Cell-mediated crystallization of calcium oxalate in plants". Plant Cell. 11 (4): 751–761\. doi:10.1105/tpc.11.4.751. PMC 144206. PMID 10213791.