Organelle variation
Often we assume that genes responsible for phenotypic variation resides in the nuclear genome. Now a group of international researchers show in PNAS that also genes located in organelles are contributing to phenotypic variation.
Organelles like mitochondria and chloroplasts contain genetic material, remnants of ancient symbiotic ancestors. Genes essential for function of the organelles that did not find a place in the genome. The researchers decided to study the influence of the organelle genetic material on photosynthetic activity in more detail.
First they analysed the actual amount of variation in organelle DNA. This they did through comparing the DNA sequence of 1541 different tale cress variations. The researchers noticed that there was a similar number of mitochondria variants as there were tale cress variants. While there were about 4 times as much chloroplast variants as there were mitochondria variants.
Organellair genetic variation contributes to photosynthetic efficiency
Subsequently the researchers studied the influence of the chloroplast and mitochondria DNA on photosynthesis. In order to do this they combined 53 chloroplast/mitochondria DNA variants with 4 genome variations. Resulting in a population of 232 plants.
Those 232 plants the researchers grew in three different environments. Whereby they varied temperature and daylength. They noticed that the observed contribution of the organelle DNA on photosynthesis was strongly dependent on the growth conditions of the plant.
There was for example one variant, Bur-0, which in two of the three growth conditions did not stand out from the rest. But in an environment with strong fluctuating light Bur-0 quicker adapted to the change from hight to low light intensity, like when a cloud suddenly covers the sun.
Organelle genetic material like that of mitochondria and chloroplast, thus contributes to differences seen in photosynthetic capacity. Not only in specific circumstances like the situation described above. But also more in general. The genetic variation of organelles can therefore be an important contributor for improving crops.
Literature
T.P.J.M. Theeuwen, et al., (2024) Species-wide inventory of Arabidopsis thaliana organellar variation reveals ample phenotypic variation for photosynthetic performance, Proc. Natl. Acad. Sci. U.S.A. 121 (49) e2414024121, https://doi.org/10.1073/pnas.2414024121.
Plant en Zo 