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REGENERATION OF THE SUNFLOWER CAPITULUM AFTER CYLINDRICAL WOUNDING OF THE RECEPTACLE
Author(s) -
Hernandez Luis F.,
Palmer John H.
Publication year - 1988
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1988.tb14185.x
Subject(s) - receptacle , biology , achene , bract , epidermis (zoology) , regeneration (biology) , anatomy , helianthus annuus , petal , botany , leaflet (botany) , meristem , sunflower , inflorescence , horticulture , microbiology and biotechnology , shoot
Using the young capitulum of Helianthus annuus L., a cylindrical plug of undifferentiated receptacle tissue, 1 mm in diameter, was isolated from lateral communication with the rest of the receptacle surface by a vertical circular wound cut, while retaining continuity with the subapical meristem. Within 24 hr, active cell division was induced at the inner and outer surfaces of the wound and in the receptacle epidermis bordering the wound edges, creating a rounded rim at the top of the wound. Within 3–6 days, floral initials, spaced 133–166 μ m apart appeared on the flanks of both rims and later on the top of the plug and surrounding receptacle surface. The first formed initials developed into involucral bracts or ray florets and the later ones into disc florets which were organized into contact parastichies, the number of which did not conform with the Fibonacci series. The base of the plug developed into a stem‐like structure completing the regeneration of a fully formed functional capitulum. This operation was demonstrated for two sunflower cultivars and occurred in both long and short daylengths.