How do plants know when to flower? The answer to this ancient question is that they actually have multiple mechanisms. A discovery that explains one of them could provide a pathway to sustaining the viability of crops in a warming world.
Although plants use the shortening of the nights as a trigger telling them it is time to flower, this is far from the whole story. "A plant doesn't necessarily treat temperature, light, food, and so on as separate cues, but these are integrated," Dr. Sureshkumar Balasubramanian of Monash University in Melbourne told IFLScience.
"A plant doesn't flower the first day after germination even if it has enough light. It has internal control that takes into account its developmental state as well as environmental cues such as temperature, light, and so on. For us to understand how this integration works we have to study each."
In attempting to unravel the temperature aspect of the trigger, researchers have previously found that two proteins, Flowering Locus M (FLM) and Short Vegetative Phase (SVP), function together to block the production of florigen, the molecule produced in leaves that, when transferred to buds, instigates flowering. The decay of these two opens the door to florigen.
In Nature Plants Balasubramanian reported that the FLM decay is controlled by "Nonsense-mediated mRNA decay," a mechanism more widely used to destroy aberrant messenger RNA to prevent the replication of damaging mutations.
Warmer temperatures prompt this decay. One of the notable effects of global warming is the way that plants are flowering earlier in response to higher spring temperatures. This can often have negative effects, either by getting out of sync with pollinators, or because even in a warmer climate early flowering can expose plants to damaging frosts.
"This is very exciting as our understanding of how these genetic mechanisms work together opens up whole new possibilities for us to be able to develop technology to control when plants flower under different temperatures," Balasubramanian said in a statement. "These mechanisms are present in all organisms, so we may be able to transfer this knowledge to crop plants, with very promising possibilities for agriculture,"
Balasubramanian noted to IFLScience that many species have varieties that flower at quite different temperatures, and it may be possible to manipulate regulatory proteins such as FLM and SVP of those that flower at undesirable temperatures to bring them into line with their new climate. “We’re getting very hypothetical,” he said. “However, it may eventually become possible to convince a plant that it is growing at 23 degrees when it is actually 26.”
Last year Balasubramanian revealed that some varieties of Arabidopsis thaliana, the model plant also used in the most recent research, completely cease growing in temperatures 3 to 4 °C (5 to 7 °F) higher than they are used to, even when conditions are otherwise suitable. He told IFLScience: "Temperature affects plants at almost every stage of development. If we hope to understand temperature effects, we need to study it at all stages. Sometimes we find different mechanisms, but the proteins are relevant."