Question

do you think that VOCs signaling evovled before or after the evolution of vascular tissue? explain your reasoning and use specific examples and or/facts to support your argument

Answer 1

In plant kingdom, the vascular tissues first appeared in Pteridophytes, which includes ferns. Ferns were also the first plants to develop proper stems, leaves and roots. The two lowest groups of plant kingdom- the thallophytes and bryophytes do not have vascular tissues and hence come under the non-vascular plants.

To investigate VOC signalling in non-vascular plants, plant-plant signalling was studied in bryophytes. Peatland moss, Hamatocaulis vernicosus were exposed to VOC of its common competitor Sphagnum flexuosum in an air flow system of connected containers under artificial light. When exposed to VOCs, shoots of H vernicosus elongated and emitted six times higher amounts of certain chemical compounds which are used by vascular plants in stress signalling and allelopathy. This was the first evidence of plant-plant VOCs interaction in non-vascular plants, similar to that in vascular plants.

Source - Scientific Reports 10, Article number: 7405 [2020]

Hence, the above research proves that VOC signalling in plant evolved before the evolution of vascular tisuues.