— To generate phylogenetic trees and investigate relationships between organisms, scientists usually look for similarities and differences in the DNA. Plant scientists were confounded by the fact that the DNA extracted from the plants’ green chloroplasts sometimes showed the greatest similarities when related species grew in the same area. They tried to explain the phenomenon with the assumption that every once in a while those normally sexually incompatible species crossed and produced offspring with a new combination of nuclear and chloroplast genomes.
They coined the term “chloroplast capture” to illustrate what they thought was happening. Now, scientists around Ralph Bock from the Max Planck Institute of Molecular Plant Physiology in Potsdam discovered that a transfer of entire chloroplasts, or at least their genomes, can occur in contact zones between plants. Inter-species crossing is not necessary. The new chloroplast genome can even be handed down to the next generation and, thereby, give a plant with new traits. These findings are of great importance to the understanding of evolution as well as the breeding of new plant varieties.
Many wooden plants, especially fruit and rose trees, are deliberately damaged by gardeners. They chop off branches or cut dents into the bark in order to put parts of another plant into the slots. The plant whose roots touch the soil is called stock, whereas scion is the technical term for the branch that is put onto it. The reason behind the gardener’s atrocities is to reproduce varieties with an especially high yield without the Mendelian Laws messing with their business. According to Mendel, only parts of the progeny show the same traits as their parents. The rest of the offspring will most likely be less valuable. By putting one branch of a successful apple variety onto a new stock, the desired apple tree is easily cloned. But graft junctions do not always have to be human-made. Plants that simply grow in close vicinity to each other can fuse (…full text)