Scientists shed new light on pollen tube growth in plants

September 01, 2020

New insight on how an enzyme ensures the correct growth of pollen tubes in flowering plants has been published today in the open-access journal eLife.

The study reveals an unexpected role of KATANIN in moderating the mechanical properties of the papilla cell wall in Arabidopsis thaliana (A. thaliana), thereby preventing disordered pollen tube growth and allowing the tube to find its correct path to the underlying female plant tissues. These findings suggest that KATANIN has likely played a major role in the success of flowering plants on earth more widely.

Seeds are produced in flowering plants when male and female germ cells called gametes fuse together. Male gametes are contained in the pollen grain while female gametes are found in the ovules, which are embedded in a female reproductive organ called the pistil. For successful seed production to happen, pollen grains need to meet with the surface of the pistil, which is composed of a layer of elongated cells called papillae. When a pollen grain lands on a papilla, it rehydrates and then produces a tube that will carry the male gametes toward the ovules.

Pollen tubes grow first within the papilla cell wall, exerting a physical pressure on the cell. After crossing the papilla layer, they then grow in the intercellular space of underlying tissues. The pistil then produces compounds that guide the pollen tube to the ovules where it reaches the female gametes. But how the tube orients itself when it emerges from the pollen at the papilla surface remains unknown.

"It is striking that, whatever the position of the flower and hence the pistil on the stem, the pollen tube grows to the base of the papilla in the direction of the ovules. We wanted to explore the mechanisms that allow for this proper orientation of pollen tubes on the papilla cells," says lead author Lucie Riglet, who was a PhD student in senior author Thierry Gaude's lab at the Laboratory of Plant Reproduction and Development, ENS Lyon, France, at the time the study was carried out, and is now a postdoctoral researcher at the Sainsbury Laboratory, University of Cambridge, UK.

Mechanical forces are known to play a major role in plant cell shape by controlling the orientation of cortical microtubules, which in turn mediate the deposition of cellulose microfibrils. For their study, Riglet and her team combined imaging, genetic and chemical approaches to show that the enzyme KATANIN, which cuts microtubules, also acts on cellulose microfibril orientation and confers mechanical properties to the papilla cell wall that allow for correct pollen tube orientation.

"By forcing the pollen tubes to take the right direction from their early places in the papilla, KATANIN has likely played a major role in the success of flowering plants on earth by promoting fertilisation," explains senior author Thierry Gaude, Group Leader at the Laboratory of Plant Reproduction and Development, ENS Lyon. "As KATANIN is found in most organisms, including humans, it is possible that the enzyme plays a role in regulating mechanical properties in other processes - but this is a fascinating question that remains to be explored."
-end-
Reference

The paper 'KATANIN-dependent mechanical properties of the stigmatic cell wall mediate the pollen tube path in Arabidopsis' can be freely accessed online at https://doi.org/10.7554/eLife.57282. Contents, including text, figures and data, are free to reuse under a CC BY 4.0 license.

Media contact

Emily Packer, Media Relations Manager
eLife
e.packer@elifesciences.org
01223 855373

About eLife

eLife is a non-profit organisation created by funders and led by researchers. Our mission is to accelerate discovery by operating a platform for research communication that encourages and recognises the most responsible behaviours. We work across three major areas: publishing, technology and research culture. We aim to publish work of the highest standards and importance in all areas of biology and medicine, including Plant Biology, while exploring creative new ways to improve how research is assessed and published. We also invest in open-source technology innovation to modernise the infrastructure for science publishing and improve online tools for sharing, using and interacting with new results. eLife receives financial support and strategic guidance from the Howard Hughes Medical Institute, the Knut and Alice Wallenberg Foundation, the Max Planck Society and Wellcome. Learn more at https://elifesciences.org/about.

To read the latest Plant Biology published in eLife, visit https://elifesciences.org/subjects/plant-biology.

eLife

Related Flowering Plants Articles from Brightsurf:

When plants attack: parasitic plants use ethylene as a host invasion signal
Researchers from Nara Institute of Science and Technology have found that parasitic plants use the plant hormone ethylene as a signal to invade host plants.

Shifts in flowering phases of plants due to reduced insect density
A research group of the University of Jena and the iDiv has discovered that insects have a decisive influence on the biodiversity and flowering phases of plants.

210 scientists highlight state of plants and fungi in Plants, People, Planet special issue
The Special Issue, 'Protecting and sustainably using the world's plants and fungi', brings together the research - from 210 scientists across 42 countries - behind the 2020 State of the World's Plants and Fungi report, also released today by the Royal Botanic Gardens, Kew.

Dodder uses the flowering signal of its host plant to flower
Researchers from the Chinese Academy of Sciences and the Max Planck Institute for Chemical Ecology have investigated how the parasitic dodder Cuscuta australis controls flower formation.

Research reveals function of genetic pathway for reproductive fitness in flowering plants
A research collaboration has demonstrated the function of a genetic pathway for anther development, with this pathway proven in 2019 work to be present widely in the flowering plants that evolved over 200 million years ago.

Bumblebees speed up flowering
When pollen is in short supply, bumblebees damage plant leaves in a way that accelerates flower production, as an ETH research team headed up by Consuelo De Moraes and Mark Mescher has demonstrated.

The revolt of the plants: The arctic melts when plants stop breathing
A joint research team from POSTECH and the University of Zurich identifies a physiologic mechanism in vegetation as cause for Artic warming.

Bumble bee disease, reproduction shaped by flowering strip plants
Flowering strips -- plants used to augment bee foraging habitats -- can help increase bee reproduction but may also increase pathogen infection rates.

Study reveals important flowering plants for city-dwelling honey bees
Trees, shrubs and woody vines are among the top food sources for honey bees in urban environments, according to an international team of researchers.

Water lily genome expands picture of the early evolution of flowering plants
The newly reported genome sequence of a water lily sheds light on the early evolution of angiosperms, the group of all flowering plants.

Read More: Flowering Plants News and Flowering Plants Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.