Many of the plants we know today have been created by man through the lengthy process of crossbreeding. We wouldn’t be able to enjoy a lot of fruit and vegetables without botanists and their selection methods. We asked Dr Piotr Klepacki from the JU Botanical Garden to elaborate on the issue.
Piotr Żabicki, www.nauka.uj.edu.pl: Let’s introduce the concept of plant crossbreeding to our readers. What exactly does it mean for a biologist?
Dr Piotr Klepacki, JU Botanical Garden: Crossbreeding means combining two different plants (of varying types, species, genera etc.) to produce offspring, usually through sexual reproduction. The aim of it is chiefly to create a hybrid that would possess the positive qualities of both parents, preferably without the negative ones. Other goals include increasing plant biodiversity for further crossbreeding and taking advantage of heterosis – i.e. increased function of any biological quality in a hybrid offspring – in order to obtain plants with higher growth, vitality, disease resistance, and so on.
When carrots were purple
Is it possible to determine which commonly grown plants are the product of crossbreeding?
A great many of today’s cultivated plants were developed by people. For some of them, we can point to their more or less distant relative, but in some cases it’s not possible, as they have evolved over the period of many centuries, stimulated by agriculture. Furthermore, the process of plant domestication was sometimes quite random. For instance, rye, now one of the main ingredients of our ‘daily bread’, was probably considered a weed in the past.
It’s difficult to say what percentage of plants don’t have a wild counterpart. However, it is certain that most crops with significant economic value were created through conscious crossbreeding. Plants were crossbred with one another, including the wild ones as well, giving rise to interspecies and even inter-genus hybrids. Some of them became economically important, like triticale. Today, crossbreeding is becoming more and more obsolete, instead being replaced by genetic engineering: from inducing desirable mutations to asexual reproduction techniques, or even further modifications allowing for an exchange of genes between organisms.
So when we’re strolling through Polish forests and meadows, we can stumble upon the predecessors of some cultivated plants? Are they edible?
Well, you can find currants: they’re pretty tasty, though their fruits are not too plentiful. In alder forests, you can spot blackcurrants, easily recognizable due to the scent of their leaves. The redcurrant, popular in gardens and allotments, is related to its wild counterpart or its hybrids (Ribes spicatum) from riverside riparian forests and the rock redcurrant (Ribes petraeum). Wild carrot (Daucus carota) is common on meadows and in urban green areas. Its root is not orange like in the case of the ordinary carrot, and isn’t as large, but it smells the same and it’s edible. It is worth mentioning that the carrot as we know it has been orange only for the last several centuries; previous varieties were purple and yellow. It was first domesticated in Central Asia, and later it spread to all of Europe through the Mediterranean.
‘Manmade’ plants are usually cultivated in certain conditions. Are they able to survive on their own, without our care?
Crops often spread out from their fields to the surrounding environment. It’s been known for a long time. There is a number of plant species that were once cultivated, but now are just an integral part of Polish flora. Some examples include wild parsnip (Pastinaca sativa), rampion bellflower (Campanula rampunculus) and possibly turnip-rooted chervil (Chaerophyllum bulbosum), known for its taste and nutritional value.
It’s becoming less and less surprising to see, for example, a tomato fruiting on a river bank. Indeed, some plants are so quick to adapt to new environments, particularly the ones transformed by man, that they start to dominate them. Because of this, they’re called invasive plants. They’re the reason we need to be extra careful when we introduce new species. The situation can get out of control quickly, as in the case of Sosnowsky’s hogweed (Heracleum sosnowskyi).
Are there any plants that people just started cultivating without trying to change them in any way?
Humans are impatient creatures. It’s difficult to find an example of a plant that wasn’t modified to suit our desires. There are, however, many plants that we just pick from the wild, such as the European blueberry (Vaccinium myrtillus) and the Brazil nut (Bertholletia excelsa). There are also some interesting plants, like horseradish (Armoracia rusticana), which are both cultivated (and sometimes just tolerated) and wild.
Many decorative plants can be categorised as having few to no modifications, as there is a large number of people interested in botany who like ‘purebred’ species. Nevertheless, starting a plantation of wild plants always involves selection of the best maternal genetic material and crossbreeding.
Nowadays, what we’re mostly interested in is not how similar plants are to their ancestors, but if local plants suited to low-intensity cultivation can survive in the future. They are an invaluable reservoir of genetic material: a set of characteristics that may be useful in the future. The 20th-century success in creating more and more fertile edible plants was based on increasing the potential of intensive industrial agriculture. Using traditional extensive agricultural techniques on many new types of plants have brought disappointing results. The older varieties are mostly preserved where the traditional farming methods are still used.
Original text: www.nauka.uj.edu.pl