phy·​to·​alex·​in ˌfī-tō-ə-ˈlek-sən How to pronounce phytoalexin (audio)
: any of various antimicrobial chemical substances produced by plants to combat infection by a pathogen (such as a fungus)

Word History


borrowed from German Phytoalexin, from phyto- phyto- + Alexin "complement (in immunology)," from Greek aléxein "to ward off, defend" + German -in -in entry 1; aléxein going back to Indo-European *h2lek-s- "ward off, defend" (whence also Sanskrit rákṣati "[s/he] defends"), suffixed form, with shifted ablaut vowel, of *h2elk- "ward off," hence Greek álalke "(s/he) warded off, turned away" (reduplicated aorist), alkḗ "defense, help," and perhaps Old English ealgian "to defend, protect" (going back to *algōjan-)

Note: The term Phytoalexin was introduced by the plant pathologists Karl Otto Müller (1872-1958) and Hermann Börger in "Experimentelle Untersuchungen über die Phytophora-Resistenz der Kartoffel," Arbeiten der Biologischen Reichsanstalt für Land- und Forstwirtschaft, Band 23 (1940), p. 223. The term Alexin (replaced by Komplement in German and complement in English) was introduced by the German bacteriologist Hans Buchner (1850-1902) in "Kurze Uebersicht über die Entwickelung der Bacterienforschung seit Naegeli's Eingreifen in dieselbe," Münchener medicinische Wochenschrift, 38. Jahrgang, No. 25, June 23, 1891, p. 437. The Indo-European base *h2elk- "ward off" has been connected to the Germanic noun represented by Old English ealh "temple," Old Saxon alah, Gothic alhs, with its Baltic congeners Lithuanian al͂kas "sacred grove on a hill," Latvian ȩ̀lka kalns "temple hill"; however, the semantic relationship is strained and the derivational relationship arbitrary.

First Known Use

1949, in the meaning defined above

Time Traveler
The first known use of phytoalexin was in 1949

Dictionary Entries Near phytoalexin

Cite this Entry

“Phytoalexin.” Dictionary, Merriam-Webster, Accessed 25 Sep. 2023.

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