Scientists uncover the 'romantic journey' of plant reproduction

Scientists uncover the ‘romantic journey’ of plant reproduction
A recent PMB study of the thale cress plant (Arabidopsis thaliana) has identified a previously unknown molecular process that serves as a method of communication during fertilization and reproduction. Credit: Chun Yan

Researchers in the Department of Plant and Microbial Biology (PMB) have uncovered the intricate molecular processes that precede reproduction in flowering plants.

Published July 6 in Nature, the findings document a previously unknown molecular process that serves as a method of communication during fertilization. According to Professor Sheng Luan, chair of the PMB department and the paper's senior author, the exact mechanism for signaling has previously eluded researchers.

"At the , this whole process is now more clear than ever before," he said.

Sending molecular 'love notes'

Flowers reproduce sexually through pollination, a process that involves the transfer of pollen from a flower's stamen (the male fertilizing organ) to the stigma on the pistil (the female reproductive organ). Once the pollen grain lodges on the stigma, a grows from the pollen grain to an ovule to facilitate the transfer of sperm to the egg.

Luan said researchers have previously recorded the presence of waves preceding the fertilization process and noted that "they knew the calcium signal is important but didn't know exactly how it is produced."

To analyze how the calcium wave was produced by the female cell, Luan and his co-authors introduced a biosensor to report calcium levels in the specific cell to look for signals from the male parts that trigger calcium waves.

They found that pollen tubes emit several —short chains of amino acids—that can be recognized by peptide receptors on the surface of the female cell. Once activated, these receptors recruit a to produce a calcium wave that guides the pollen tube to the ovule and initiates fertilization.

Green calcium waves "pulse" in this recording provided by the Luan Lab.

"You could compare this to a delivery service," Luan explained. "We know the small peptide molecule serves as a signal to the female part of the flower, almost like a knock on the door letting it know the pollen tube is here."

The calcium waves ultimately cause the tube to rupture and release the immobile sperm once it is inside the ovule, ensuring a successful fertilization process.

"In a way, they basically commit suicide to release the sperm," Luan said. "Sometimes the female reproductive cell also dies in order to expose the egg so they can meet and produce new life. It's kind of a romantic journey for plant reproduction."

Reinventing molecular messaging

According to Luan, understanding the intricate molecular processes of fertilization may help improve the commercial yields in flowering . Other researchers or plant geneticists might use the findings to break the interspecies barrier, potentially opening the door to the creation of new hybrid crop species through cross-pollination.

But, in addition to the potential commercial application, these findings further highlight plants' miraculous ability to communicate via molecular emissions. "From an evolutionary point of view, plants reinvented their own molecules specific to their unique communication process," he added.

The calcium channels identified in this study are unique to plants, suggesting they invented a way to produce signals that are different than those found in animals. Luan said researchers have studied for more than 30 years, uncovering how they confer resistance to (a that affects a wide variety of plants) or enable mechanical sensing in root systems.

Their biochemical role remained unknown until this study uncovered the specific channel activity. "Reinventing new channels to communicate in their own way, consistent with different lifestyles of plants and animals, is of general importance to biology," Luan said.

More information: Qifei Gao et al, A receptor–channel trio conducts Ca2+ signalling for pollen tube reception, Nature (2022). DOI: 10.1038/s41586-022-04923-7

Journal information: Nature

Citation: Scientists uncover the 'romantic journey' of plant reproduction (2022, July 11) retrieved 14 April 2024 from
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