Wild Pea Explored for Better Understanding of Seed Dormancy

The variability of pea seeds. Photo: Miroslav Hýbl
monday 8. august 2016, 12:46 - Text: Martina Šaradínová

Plant geneticists, botanists, and geoinformaticists from the UP Faculty of Science and the Olomouc’s branch of the Czech Crop Research Institute (CRI) will investigate the seed dormancy of the wild pea and Medicago truncatula in the context of evolutionary adaptation. Seed dormancy is a plant’s ability to stop or reduce physiological processes in order to better survive unfavourable conditions. Scientists will use a unique collection from various locations in the world – the seeds of 150 pea species and 260 alfalfa species with GPS coordinates tracing them back to their original place of harvest.

The current cultivated varieties have been, throughout the process of cultivation, ridden of a number of their properties, such as seed dormancy and pod shattering in bean plants and brittle rachis in cereal crops. These two traits are considered crucial in the process of plant domestication.

“In nature, these traits have their significance, however they would be harmful in cultivated varieties, because part of the harvest would be left in the field or the seeds would not germinate after sowing. Dormancy, or swelling of the legume seeds, is a practical thing too. It allows us to cook the seeds and digest them. During domestication and cultivation we have gotten rid of a large part of the variability, including certain traits and new factors having impact on the plants due to climate changes. If we understand dormancy in the wild species, then we may improve our cultivated varieties too,” said the main investigator, Petr Smýkal from the Department of Botany, concerning their novel project.

Work in the fields and experiments

The research began in April 2016, within a three-year project called “Ecological genomic approaches to uncovering the adaptive significance of seed dormancy in legumes”. Researchers will first reproduce the seeds and then get down to experiments. The geoinfomaticists will provide data on climatic conditions in the place of the seeds’ origin. This data will serve for experimental testing of dormancy, in other words the germination of seeds in the regime of oscillating temperatures typical for natural conditions, including a simulation of varying precipitation amounts. With the help of geoinformatics and statistics, the link between the degree of dormancy, environmental conditions, and DNA will be tested. Such a fusion of genomics and geoinformatics is a current trend in ecological genomics, a discipline that helps understand the process of adaptation to environment.

“We will investigate, for example, what portion of the seeds will germinate in various conditions. Genetic data will be available too. The alfalfa genome has been sequenced, and the pea genome should be made available this year. Thanks to bioinformatics, we will try to reveal the segment of the genome that is associated with the traits we are focussing on. That could result in the development of more productive and adaptable varieties,” added Smýkal.

Importance for the Czech gene bank

Miroslav Hýbl from CRI deems the project helpful for adding wild pea varieties from many countries, such as Armenia, Syria, Turkey, and Iran, into the Czech collection of genetic resources of the pea. Czech scientists will have at their disposal an unparalleled collection of wild pea seeds from various altitudes. “Such a collection cannot be found anywhere else – everything at one place, systematically described and analysed. It comprises a great variability of traits, as opposed to the cultivated lines,” said Hýbl who is in charge of the pea collection in the Olomouc genomic library. The collection of pea species in the Czech Republic comprises 2 508 genetic resources.

The seeds come from foreign genomic banks. They contain about 1500 species of wild pea, but only 150 to 200 of them are archived with reliable GPS information. Alfalfa was selected as a model plant – its genome is ten times smaller than that of peas, and it still behaves like a wild species.

There are several types of seed dormancy, however legumes and bean plants have physical dormancy, provided by the impervious seed coat which prevents the seeds from absorbing water, swelling, and germinating. Investigators already looked into the dormancy mechanism in a similar project for the Czech Science Foundation.

The scientists from the Departments of Botany and of Cell Biology and Genetics are also engaged in the European project Legume Futures (LEGATO, 2014–2017). The aim of researchers from 12 countries is to support the use of legumes in crop systems in Europe. Their objective is to develop introgression lines, where chromosome segments of cultivated pea types will be substituted with chromosome segments of the wild pea, namely Pisum fulvum and Pisum elatius. This will enable them to utilise the genetic diversity of the wild types, which were lost or not used during the process of domestication and subsequent cultivation. A collection of lines with molecular maps of their chromosome segments will be available as the outcome of the project. The first fifty lines have been selected and tested in the fields this year.