Question

Plants continuously monitor environmental conditions and modify their growth and/or development in response to these conditions. List five distinct responses to environmental conditions and for each indicate:

a) the environmental property being monitored
b) if it is known, the receptor that perceives the environmental condition
c) what is known about the signaling pathway and mechanism of response d) the developmental and/or growth outcome of the response
e) the benefit of the response

Your list should include at least one response each for seeds, seedlings and plants.

Answer 1

Seeds sense light and dark condition if its dark it promoted photomorphogenesis of seedlings i.e. short hypocotyl and expanded cotyledons for photosynthesis. But if it's dark it elongates its hypocotyl in search out light and does not open the cotyledons called skotomorphogenesis. Seedlings consist of hypocotyl and cotyledons. the light is being perceived by photoreceptors called phytochromes. These phytochromes can sense the signal and initiates the downstream signaling and ultimately regulate the expression of genes responsible for cell elongation and development. this benefits the development of the plant.

Seed sense the absence of water a signal that initiates the ABA response and does not allow them to germinate in the absence of enough moisture in the soil. this benefits the survival of the embryo.

Plants can sense temperature, radiation, day length. Certain plants in long day conditions flower early and in short day conditions delays flowering. This response is again mediated by phytochrome and also the circadian rhythm in plants that judge the day length and allow the transcriptional regulation of the genes involved in flowering.