Nav: Home

Hydrogen peroxide assists sexual reproduction in spruce

May 16, 2018

Plant physiologists from MSU proved for the first time that dangerous reactive oxygen species that are often considered as by-products of energy generation in cells, are required by the conifers to fertilize the egg cell. Experiments with pollen of blue spruce (Picea pungens) helped to find a protein that makes the whole system work. The scientists believe that the obtained data will lead to the optimization of conifer forests restoration. The results of the study were published in the Plant Reproduction journal.

"The study of sexual reproduction in conifers is on its early stage, and many of it`s aspects are practically unknown," - says the co-author of the article Maria Breygina, a senior scientific researcher at the department of plant physiology, Faculty of Biology, MSU, and a scientific fellow of the electrophysiology lab at Pirogov Russian National Research Medical University. - "These studies are of high fundamental importance, as the pollen of conifers is a more ancient object with directional growth compared to that of flowering plants."

Flowering plants have flowers with stamens distributing the pollen and pistils where it has to get for fertilizing. Cross pollination is usually more advantageous for a plant, as it helps to increase genetic diversity. The seeds in flowering plants are formed inside an ovary which, in turn, forms a fruit (that is why flowering plants are also called angiosperms). However, gymnosperms (of which conifers are the best-known group) also have mechanisms for cross pollination. In conifers these are cones that are actually modified sprouts. The cones of conifers are diclinous; male ones are relatively small and produce pollen that is distributed by wind, and female ones are bigger and form seeds. After reaching the female cone, pollen sticks to special liquid (in pines and spruce) or small hairs (as in Douglas fir).

Having landed in the right place (on a pistil in flowering plants or under a seed scale in gymnosperms), pollen starts to grow forming a pollen tube. Through this tube sperm cells reach to egg cell to fertilize it. In flowering plants the second sperm fuses with a central cell to form endosperm (a nutritional part of the seeds, for example, as in wheat seeds). That is why this fertilization type is called double fertilization.

All these processes were described long ago, but modern science is focused on their molecular and biochemical aspects. It has been recently established that reactive oxygen species (ROS) play a key role in pollen germination in angiosperms. ROS are neutral or negatively charged particles in which oxygen has an unpaired electron. ROS include peroxides (in particular, hydrogen peroxide) and radicals, such as superoxide radical O2-.

An unpaired electron makes ROS highly reactive. If a lot of ROS is formed within a cell, the consequences may be severe. These compounds may affect the balance of complex biochemical reactions, damage membranes, DNA, and other parts of cells. That is why, regardless of their origin, ROS are often considered dangerous by-products that need to be neutralized as quickly as possible. Still, certain cells synthesize them in small quantities and use as a messenger. Due to the ambiguous nature of these compounds, it is extremely important to study the useful functions of ROS, such as their role in plant fertilization.

Plant physiologists from MSU were the first to study the role of ROS in pollen germination in conifers (namely, blue spruce) and found out that pollen grains secrete hydrogen peroxide and O2- into the environment before germinating. Later on hydrogen peroxide gradient is formed in the pollen tube, i.e. its concentration is increased in the tip. This gradient seems to be necessary for the tube to grow to the egg cell, as well as to support the membrane potential (negative charge) gradient (which is described in conifers for the first time), though these gradients do not seem to be related directly.

The scientists also found out what protein regulates this process. It turned to be NADPH-oxidase located in cell membranes. This protein is in charge of moving electrons out of the cell and the formation of extracellular superoxide. ROS interconvert quite quickly, O2- turns into peroxide that re-enters the cell. Due to this process hydrogen peroxide is distributed gradiently in the pollen tube. Experiments have shown that after NADPH oxidase suppression pollen grains do not germinate, and pollen tubes become unable to grow. Therefore, fertilization doesn't take place.

"The results of this and further studies may be used to optimize forest restoration, especially fir trees, cedars, pines, and silver-firs, as well as their selection and forming a collection of forest breeds in Russia," -- commented Maria Breygina.

All the authors of the article study or work at MSU. Maria was in charge of drafting the article and processing experimental data obtained by PhD student Nikita Maksimov and undergraduate student Anastasiya Evmenyeva. The idea was developed by Igor Ermakov, Doctor of Biology, professor of the plant physiology department, and the coordinator of the study.
-end-


Lomonosov Moscow State University

Related Protein Articles:

Hi-res view of protein complex shows how it breaks up protein tangles
A new, high-resolution view of the structure of Hsp104 (heat shock protein 104), a natural yeast protein nanomachine with six subunits, may show news ways to dismantle harmful protein clumps in disease.
Breaking the protein-DNA bond
A new Northwestern University study finds that unbound proteins in a cell break up protein-DNA bonds as they compete for the single-binding site.
FASEB Science Research Conference: Protein Kinases and Protein Phosphorylation
This conference focuses on the biology of protein kinases and phosphorylation signaling.
Largest resource of human protein-protein interactions can help interpret genomic data
An international research team has developed the largest database of protein-to-protein interaction networks, a resource that can illuminate how numerous disease-associated genes contribute to disease development and progression.
STAT2: Much more than an antiviral protein
A protein known for guarding against viral infections leads a double life, new research shows, and can interfere with cell growth and the defense against parasites.
A protein makes the difference
It is well-established knowledge that blood vessels foster the growth of tumors.
Nuclear protein causes neuroblastoma to become more aggressive
Aggressive forms of neuroblastoma contain a specific protein in their cells' nuclei that is not found in the nuclei of more benign forms of the cancer, and the discovery, made through research from the University of Rochester Medical Center, could lead to new forms of targeted therapy.
How a protein could become the next big sweetener
High-fructose corn syrup and sugar are on the outs with calorie-wary consumers.
High animal protein intake associated with higher, plant protein with lower mortality rate
The largest study to examine the effects of different sources of dietary protein found that a high intake of proteins from animal sources -- particularly processed and unprocessed red meats -- was associated with a higher mortality rate, while a high intake of protein from plant sources was associated with a lower risk of death.
Protein in, ammonia out
A recent study has compiled and analyzed data from 25 previous studies.

Related Protein Reading:

Proteins (Explore the molecules of life)
by Tali Lavy (Author), Ofir Corcos (Illustrator)

Protein Power: The High-Protein/Low Carbohydrate Way to Lose Weight, Feel Fit, and Boost Your Health-in Just Weeks!
by Michael R. Eades (Author), Mary Dan Eades (Author)

Clean Protein: The Revolution that Will Reshape Your Body, Boost Your Energy—and Save Our Planet
by Kathy Freston (Author), Bruce Friedrich (Author)

The Perfect Protein: The Fish Lover's Guide to Saving the Oceans and Feeding the World
by Andy Sharpless (Author), Suzannah Evans (Author), Bill Clinton (Foreword)

Janeva's Ideal Recipes: A Personal Recipe Collection for the Ideal Protein Phase 1 Diet [Revised Version 1]
by Janeva Caroline Eickhoff (Author)

The High-Protein Vegetarian Cookbook: Hearty Dishes that Even Carnivores Will Love
by Katie Parker (Author), Kristen Smith (Author)

The Protein Power Lifeplan
by Michael R. Eades (Author), Mary Dan Eades (Author)

Plant-Protein Recipes That You'll Love: Enjoy the goodness and deliciousness of 150+ healthy plant-protein recipes!
by Carina Wolff (Author)

The Protein Counter 3rd Edition
by Jo-Ann Heslin M.A. R.D. CDN (Author), Karen J Nolan Ph.D. (Author)

Proteins: Concepts in Biochemistry
by Paulo Almeida (Author)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Hacking The Law
We have a vision of justice as blind, impartial, and fair — but in reality, the law often fails those who need it most. This hour, TED speakers explore radical ways to change the legal system. Guests include lawyer and social justice advocate Robin Steinberg, animal rights lawyer Steven Wise, political activist Brett Hennig, and lawyer and social entrepreneur Vivek Maru.
Now Playing: Science for the People

#495 Earth Science in Space
Some worlds are made of sand. Some are made of water. Some are even made of salt. In science fiction and fantasy, planet can be made of whatever you want. But what does that mean for how the planets themselves work? When in doubt, throw an asteroid at it. This is a live show recorded at the 2018 Dragon Con in Atlanta Georgia. Featuring Travor Valle, Mika McKinnon, David Moscato, Scott Harris, and moderated by our own Bethany Brookshire. Note: The sound isn't as good as we'd hoped but we love the guests and the conversation and we wanted to...