New light shed on internal processes that decide the architecture of plants

New light shed on internal processes that decide the architecture of plants

The physical traits of plants are shaped by internal processes prompted by environmental signals, which include the length of days and presence of nutrients. 

These processes help to control the growth of a plant’s flowers, roots and branches. A better understanding of these processes could therefore enable new strategies for improved growth.

A research team from the University of Pennsylvania recently published a report in the journal Nature Communications, detailing investigations into two near-identical proteins already known to influence plant form and the timing of developmental transitions.

The two groups of proteins studied have competing functions. Terminal Flower 1 (TLF1) proteins promote branch formation, and where it is repressed, flowers can grow. Conversely, Flowering Locus T (FT) proteins promote flowering, in response to seasonal cues.

Biologist Doris Wagner from the School of Arts and Sciences at the University of Pennsylvania said these two protein types hold ‘significance galore’.

"Besides flowering, they're involved in tuberisation in potatoes, bulb formation in onions, tendril formation in grapes, growth cessation in trees, lots of things," explained Wagner.

It has long been theorised that the workings of these proteins could have the potential to be manipulated to the advantage of growers. 

The team’s initial testing found that TFL1 acts by binding itself to something known as transcription factor FD. Once bound, it regulates the plant’s LEAFY gene, which is understood to support flower development through protein production.

Unsurprisingly the scientists found the areas within the plant where TFL1 was bound to be consistent with the suppression of flowering and gene expression. Following this, the team mutated the areas where TFL1 was present, and found that LEAFY proteins were now present alongside TFL1 which would not usually have been the case.

An additional finding that came as a surprise was that following this mutation, LEAFY proteins were found to be absent from the areas of the plant specifically responsible for flowering. This indicated an unknown factor relating to FD could be responsible for activating the LEAFY gene in the flowering areas of plants. 

The team therefore turned its attention to the FT protein, because of the important role it plays in promoting flower growth. By experimentally boosting FT expression, they found this protein also needed to bind itself to the FD transcription factor in order to act upon LEAFY and promote flower formation.

Noting that FT and TFL1 both require access to FD, the team worked to understand the nature of the relationship between the two proteins by eliminating FD altogether.

"We wanted to really test its biological contribution: What does it mean to the plant to lose this?" Wagner said.

They noted that in the absence of FD, plants with a normal amount of FT failed to flower, even under conditions where they would normally be expected to do so.

"It made it very clear to us that FT and TFL1 compete for this FD factor binding site," said Wagner.

The team is keen to find out more about the mechanisms used by TFL1 and FT and the competitive nature of their relationship. Future work will focus on discovering exactly how these proteins respond to the various different environmental cues, as well as how the plant’s responses might be controlled.

The team hopes the outcomes of this research will ultimately be used to help growers adapt plants to best suit the environments in which they are planted.

"These elements could even play a role in rational solutions for climate change, breeding plants that are specifically adapted for new conditions," concluded Wagner.

Source: Science Daily

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