83rd Annual Meeting of the Botanical Society of Japan

Description

Symposium: Beyond Fibonacci patterns and the golden angle: phyllotactic variations and their cellular origin
Invited speaker: Developmental patterning of head-like inflorescences in Asteraceae

Abstract:
Developmental patterning of head-like inflorescences in Asteraceae
Teng Zhang1, Mikolaj Cieslak2, Feng Wang1, Suvi K. Broholm1, Teemu H. Teeri1, Przemyslaw Prusinkiewicz2, Paula Elomaa1
1Department of Agricultural Science, Viikki Plant Science Centre, University of Helsinki, P.O. Box 27, FIN-00014 Helsinki, Finland
2University of Calgary, 2500 University Dr NW, Calgary T2N 1N4, Canada.

The key question in biology is how organisms generate reproducible patterns in a highly precise manner. In plants, the regularity is visible in the architecture of inflorescences that may vary from a single flower to large flower clusters, and is thus one of the major determinants of crop yield and reproductive success of plants. The unique feature in the large Asteraceae plant family is that their inflorescence forms a pseudanthium, or a false flower. While the inflorescence superficially mimics a solitary flower, it is actually composed of multiple morphologically and structurally distinct types of flowers packed into a single head-like structure. Intriguingly, the individual flowers emerge in highly regular, left and right winding spirals (parastichies), whose number follow the two consecutive numbers in a mathematical Fibonacci series (1, 1, 2, 3, 5, 8, 13 …). We have resolved the growth dynamics of flower heads in a model plant Gerbera hybrida using scanning electron microscopy and micro-CT imaging. Our data indicates that the phyllotactic pattern is templated by involucral bracts initiated at the rim of the meristem during early development. The pattern is driven by expansion of the meristem, and simultaneous emergence of multiple new primordia that quickly leads to high Fibonacci numbers. We have produced transgenic gerbera lines with DR5 reporter indicating a major role for auxin in defining the position of emerging flower primordia. We have integrated the experimental data into a computational model to demonstrate how phyllotactic patterning is established in Asteraceae flower heads.

Period	15 Sept 2019 → 17 Sept 2019
Event type	Conference
Conference number	83
Location	Sendai, JapanShow on map
Degree of Recognition	International