Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The evolution of grain yield – Decoding the genetic basis of floret fertility in wheat

22.02.2019

A high grain yield is undoubtedly a desirable trait in cereal crops. Floret fertility is a key factor which determines the number of grains per inflorescence of cereals such as bread wheat or barley. Nonetheless, until recently little was known about its genetic basis. Whilst investigating floret fertility, a group of researchers from Japan, Germany and Israel have now discovered the locus Grain Number Increase 1 (GNI1), an important contributor to floret fertility.

Even though the consequent gene GNI-A1 itself results in a lower grain yield, the researchers showed that its mutation, the reduced-function allele of GNI-A1, leads to an increased number of fertile florets and to a higher grain count. Due to this positive effect, the mutated allele has been under selection over the course of wheat domestication.


Spikelet morphology of bread wheat cv. Bobwhite and of a transgenic derivative harboring a GNl1-RNAi construct.

Kazuhiko Sugimoto, Taiichi Ogawa

The large tribe of Triticeae encompasses several important cereal crops, including bread wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). One of the major outcomes of the domestication process of selected Triticae species has been the increased number of grains per inflorescence in modern cultivars – due to a boost in the crop’s floret fertility.

All Triticeae plants produce an unbranched inflorescence, referred to as a spike. In wheat, the spike is made up of several spikelets, which each generate an indeterminate number of grain-producing florets. At the floral developmental stage called “white anther”, each wheat spikelet normally produces up to 12 potentially fertile floret primordia.

However, more than 70% of the florets abort during their development. Whilst it is known that the number of grains set per spikelet is determined by the fertility of each floret, the genetic basis for floret fertility was recently still widely unidentified.

An international group of researchers, including several scientists from the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK Gatersleben), have now collaborated in an effort to decode the genetic basis of floret fertility in wheat.

The researchers focussed on the quantitative trait loci (QTL) responsible for an enhanced grain number per spikelet, which was previously identified by a genome-wide association analysis of European winter bread wheat. They were able to map the QTL and identified the gene Grain Number Increase 1 (GNI-A1), which had evolved in the Triticeae through gene duplication, on chromosome arm 2AL.

The scientists showed that the resulting GNI-A1 encoded a homeodomain leucine zipper class I (HD-Zip I) transcription factor. The expression of the transcription factor resulted in the inhibition of the growth and development of the wheat rachilla, the axis bearing the florets within the spikelets, therefore negatively affected floret fertility and grain yield.

Over the course of domestication, a decrease of GNI1 expression had led to more fertile florets and an increase in grains per spikelet. However, through the additional analysis of high-yielding bread wheat cultivars, the researchers were able to reveal a reduced-function allele of the GNI-A1 gene. This mutated allele was found in modern wheat with higher floret fertility, implying that it increased floret fertility and that a selection for wheat cultivars carrying the reduced-function allele had taken place during further wheat-domestication.

The first author of the study, Dr. Shun Sakuma (Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany and Tottori University, Japan), who had started this work under the supervision of Dr. Takao Komatsuda at the National Institute of Agrobiological Sciences (presently National Agriculture and Food Research Organization (NARO), Japan), emphasises that “this study shows for the first time a direct association between increased floret fertility, higher grain number per spike, and higher plot yields of field-grown wheat”.

The project had been continued when Dr. Sakuma had joined the research group of Dr. Thorsten Schnurbusch at the IPK Gatersleben. Further experiments were performed in collaboration with members of three additional IPK research groups as well as scientists from the Israeli Hebrew University of Jerusalem.

As a further result of the international collaboration, GNI-A1 proved to be an orthologue of the barley Vrs1 gene, which controls lateral floret fertility and leads to inhibited floret development. Similar to the reduced-function allele of GNI-A1, the loss-of-function mutants of Vrs1 led to an increased grain yield.

Having previously also contributed to elucidating the molecular basis of barley Vrs1, Dr. Komatsuda (NARO) now is “very pleased that we have discovered what GNI1 actually does in wheat”. The appearance of GNI1/Vrs1 and the parallel selection of the mutated alleles seem to be in line with the genetic hotspot hypothesis, which implies that evolutionary relevant mutations tend to accumulate in specific genes and at specific positions within genes.

The identification and understanding of the genetic basis of floret fertility now opens new options for further investigation of plant architecture and for grain yield improvement in wheat. And, as noted by Dr. Schnurbusch (IPK), “this knowledge may help in finding related genes working in the same direction to further improve cereal breeding to fulfil needed demands.”

- Floret fertility is a key determinant of the number of grains per inflorescence in cereals but little is known regarding the genetic basis of floret fertility in wheat (Triticum sp.).
- Identification of the locus Grain Number Increase 1 (GNI1), which evolved due to gene duplication, resulting in the gene GNI-A1.
- GNI-A1 encodes a homeodomain leucine zipper class I (HD-Zip I) transcription factor. The expression of the gene negatively affects floret fertility by inhibiting rachilla growth.
- A subsequently evolved reduced-function allele of GNI-A1 contrastingly increases floret fertility and leads to the increased number of fertile florets per spikelet. This mutation, favouring increased grain production, has been under selection during wheat domestication.
- Collaboration of researchers from Japan, Germany and Israel
- Publication in PNAS

Wissenschaftliche Ansprechpartner:

Dr. Thorsten Schnurbusch
Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben
Tel.: +49 39482 5486,
E-mail: schnurbusch@ipk-gatersleben.de

Originalpublikation:

Unleashing floret fertility in wheat through the mutation of a homeobox gene” PNAS in press, https://doi.org/10.1073/pnas.1815465116

Regina Devrient | idw - Informationsdienst Wissenschaft
Further information:
http://www.ipk-gatersleben.de

More articles from Life Sciences:

nachricht Rising water temperatures could endanger the mating of many fish species
03.07.2020 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

nachricht Moss protein corrects genetic defects of other plants
03.07.2020 | Rheinische Friedrich-Wilhelms-Universität Bonn

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electrons in the fast lane

Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.

Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....

Im Focus: The lightest electromagnetic shielding material in the world

Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.

Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...

Im Focus: Gentle wall contact – the right scenario for a fusion power plant

Quasi-continuous power exhaust developed as a wall-friendly method on ASDEX Upgrade

A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...

Im Focus: ILA Goes Digital – Automation & Production Technology for Adaptable Aircraft Production

Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...

Im Focus: AI monitoring of laser welding processes - X-ray vision and eavesdropping ensure quality

With an X-ray experiment at the European Synchrotron ESRF in Grenoble (France), Empa researchers were able to demonstrate how well their real-time acoustic monitoring of laser weld seams works. With almost 90 percent reliability, they detected the formation of unwanted pores that impair the quality of weld seams. Thanks to a special evaluation method based on artificial intelligence (AI), the detection process is completed in just 70 milliseconds.

Laser welding is a process suitable for joining metals and thermoplastics. It has become particularly well established in highly automated production, for...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International conference QuApps shows status quo of quantum technology

02.07.2020 | Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

 
Latest News

Rising water temperatures could endanger the mating of many fish species

03.07.2020 | Life Sciences

Risk of infection with COVID-19 from singing: First results of aerosol study with the Bavarian Radio Chorus

03.07.2020 | Studies and Analyses

Efficient, Economical and Aesthetic: Researchers Build Electrodes from Leaves

03.07.2020 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>