UV induced visual cues in grasses.
Grasses are traditionally considered as wind pollinated, however, field observations confirmed frequent insect visits to grass flowers, suggesting insect pollination. Fruit and seed predators inflict heavy losses to cereals and millets during their growth, maturation and storage. The actual factors guiding insects and predators to grass flowers, fruits and seeds are not clear. Here, we report attractive blue fluorescence emissions on grass floral parts such as glumes, lemma, palea, lodicules, staminal filaments, pollens and fruits in ultraviolet (UV) 366 nm, whereas the stigmatic portions were not blue, but red fluorescent. We characterized the blue fluorescent constituent in grass reproductive structures as ferulic acid (FA). Fluorescence spectra of blue-emitting grass floral, seed extracts and isolated FA on excitation at 366 nm showed their emissions at 420-460 nm. We propose these FA-based blue fluorescence emissions in grass reproductive structures as visual cues that attract pollinators, predators and even pests towards them.
1] Phytochemistry and Phytopharmacology Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram 695562, Kerala, India [2].
Sabulal
S
Baby
Anil John
AJ
Johnson
Balaji
B
Govindan
Sujith
S
Lukose
Bhaskaran
B
Gopakumar
Konnath Chacko
KC
Koshy
D000818:Animals; D003373:Coumaric Acids / Q000737:chemistry; D003463:Cues; D007313:Insecta; D018514:Plant Structures / Q000737:chemistry / Q000378:metabolism; D006109:Poaceae / Q000502:physiology* / Q000528:radiation effects*; D054817:Pollination; D012098:Reproduction; D014466:Ultraviolet Rays
D003373:Coumaric Acids; C004999:ferulic acid