Doubled Haploid Production In Perennial Ryegrass

The ability to produce doubled haploid (DH) plant material, which is 100% homozygous at every genomic locus, is of great benefit to both research and breeding. Among the advantages of homozygous genotypes are the fact that they are stable over generations (immortal), ensure a homogeneous crop and simplify investigations into the genetic make-up of a species. As parents of hybrid breeding programs DHs allow for the most effective exploitation of heterosis, the increased vigor observed in progenies of a cross between two inbred parents.

Using either in vivo or in vitro methods to double the chromosomes of a haploid individual or cell containing a single chromosome set (n), doubled haploids can be created in a single generation. The traditional way of generating homozygosity by repeatedly self-fertilizing single plants is both laborious and time-consuming and cannot efficiently be performed on those species that have self-incompatibility mechanisms in place to reject their own pollen or suffer from inbreeding depression. Production of DHs has therefore only become routine in the breeding programs of crops for which methods are cost-effective and scalable, such as maize, barley, and rapeseed. As a consequence, significant and measurable increases in the speed of yield gain have thus been achieved and doubled haploid or hybrid cultivars dominate the seed markets.

freshly plated anthers (Credit: Rachel Begheyn)

We investigated doubled haploid production in perennial ryegrass (Lolium perenne L.), an important forage crop in temperate agriculture with a highly effective self-incompatibility system. All potential benefits associated with the ability to generate doubled haploid material may thus be unlocked for this economically important species. In the ‘80s and ‘90s, in vitro, DH production protocols based on the cultivation of immature pollen grains, or microspores, have been developed for use in perennial ryegrass.

putative dh regenerants (Credit: Rachel Begheyn)

Under the right circumstances, a switch in the developmental pathway can be induced in haploid, immature pollen cells so that embryogenesis and subsequent plant regeneration occurs instead of the production of mature pollen. This process, known as microspore embryogenesis, can give rise to haploid or, via spontaneous chromosome doubling, diploid plants.

A suitable pre-culture stress treatment, in this case, a cold shock, as well as appropriate culture conditions are paramount to the success of in vitro DH induction. Despite the availability of a protocol for perennial ryegrass microspore culture, the response to the procedure is highly genotype-dependent and individuals with a good response are very rare. In addition, tissue culture-related albinism, common in all members of the grass family, further complicates efficient doubled haploid production in this species.

putative dh regenerants in soil (Credit: Rachel Begheyn)

Our work, therefore, aimed to investigate the genetic basis of the response to in vitro DH production in perennial ryegrass, so that targeted manipulations of relevant genetic factors can be undertaken to increase the capacity for doubled haploid induction in breeding material. In our paper, we report the responses to in vitro doubled haploid production of several multi-parental populations of perennial ryegrass. These populations were created by crossing parental plants with contrasting doubled haploid induction abilities so that their progeny segregated for such traits as embryo production, plant regeneration and percentage of albino plants produced. We describe the populations’ responses in detail and hypothesize about the inheritance of the distinct component traits important for efficient doubled haploid production.

Ultimately, the plant material investigated in our study proved to be an excellent resource to 1) select highly responsive individuals from, which may, for example, be used to produce DHs for a further investigation of their performance, 2) introduce beneficial genetic factors into unresponsive plant material through targeted crossing programs, and 3) perform genotyping and genetic mapping studies to further elucidate the genetic control of the response to in vitro DH induction and identify relevant genetic loci.

Close up single putative dh regenerant (Credit: Rachel Begheyn)

These findings are described in the recently published article entitled Inheritance patterns of the response to in vitro doubled haploid induction in perennial ryegrass (Lolium perenne L.), in the journal Plant Cell, Tissue and Organ Culture. This work was led by Rachel Begheyn from the Institute of Agricultural Sciences, ETH, Zurich.

For more information see:

  • Begheyn RF, LĂźbberstedt T, Studer B (2016a) Haploid and doubled haploid techniques in perennial ryegrass (Lolium perenne L.) to advance research and breeding. Agronomy 6:60

About The Author

Rachel Begheyn

Rachel Begheyn is an Associate Scientist Product Support and Training at Tecan. Her areas of expertise are plant breeding, plant biotechnology, plant cell biology, plant genetics and genomics, plant tissue culture, doubled haploids, perennial ryegrass. She received her Ph.D. in plant sciences from ETH Zurich in 2017. 

 

Speak Your Mind!

READ THIS NEXT

Bio-inspired Slim Polymer Films With Wide Fields Of View And Multiple Imaging Capabilities

Inspired by the behaviour of light-harvesting ommatidia – biological waveguides composed of a lens, crystalline cone and rhabdom – found in the compound eyes of arthropods, the Saravanamuttu Research Group at McMaster University has developed a fundamentally new class of intelligent thin films: Waveguide Encoded Lattices (WELs) possess enhanced panoramic fields of view (FOV) as […]

Map Of Florida East Coast: Beaches And Cities

The map of Florida’s east coast is dotted with beautiful beaches and fun lively cities. The maps below give you a sense of just how populated the coast is and how difficult it can be to decide on your next warm vacation. The state of Florida has over 300 miles of beautiful coastline, but arguably […]

Researchers Study How Long Microorganisms Can Survive On Mars

By the year 2026, Russia and the United States hope to begin the construction of a space station to orbit the Moon. This project would mark the beginning of a new age of space exploration as the station will be used as an intermediary between Earth and the rest of the solar system. With the […]

Light Activated “Quantum Dots” Make Anti-Biotic Resistant Bacteria Vulnerable Once More

One of the biggest emerging threats in the world today is the proliferation of drug-resistant superbugs. In the attempts to find ways to fight drug-resistant infections, a research group from the University of Colorado has made a promising discovery. Synthetic nanoparticles can be used to undercut the defenses of antibiotic-resistant bacteria, making traditional antibiotics effective […]

Measuring Noise Emissions During Aircraft Take-Off

During the last decades, the use of air transport has dramatically increased generally due to globalization, which has caused a rising need for mobility. Consequently, aviation-noise exposure has continued to deteriorate mostly for people living in urban areas near airport surroundings. Although many noise-abatement measures have been developed to counter this phenomenon, further actions against […]

Centrosome Function: Plant Vs. Animal Cell

The centrosome is an intracellular organelle whose primary function is to organize the microtubules of the cell. Microtubules can be thought of as the cell’s skeleton, so centrosomes are the organelles that serve as the lynchpin and scaffolding that organizes and anchors the cellular skeleton. Centrosomes also play a role in cellular mitosis—the process by which a […]

Can Bell’s Theorem Be Disproved?

Bell’s theorem (BT) was formulated in 1964 as a continuation of the 1935 Einstein, Podolski, Rosen (EPR) criticism on the completeness of quantum mechanics (QM). Based on the principle of locality, i.e., instantaneous spooky actions at a distance are not allowed, EPR showed through a thought experiment that QM was an incomplete theory in the […]