Epigenetic traits in plants

V prvi polovici 20. stol. sta bili genetika in razvojna biologija ločeni disciplini. Besedo »epigenetika« je prvi uporabil Conrad Waddington leta 1942. Skoval jo je iz grške besede »epigenesis«, ki je izvirno pomenila vpliv genetskih procesov na razvoj. Danes epigenetsko regulacijo genov lahko definiramo kot spremembe v genski aktivnosti, ki se dedujejo skozi mitotske in/ali mejotske celične cikle brez sprememb v zaporedju DNA. Vsaj trije biološki sistemi, med njimi DNA metilacija, modifikacija histonov in z nekodirajočimi RNA-povezano gensko utišanje, začenjajo, vzdržujejo ali spreminjajo epigenetske zapise. Ker epigenetske spremembe niso povezane s spremembami v zaporedju DNA, je njihovo dedovanje povezano z možnostjo določene stopnje reverzibilnosti. Ta stopnja pa je odvisna od posameznega mehanizma, ki je epigenetske spremembe povzročil. Primer epigenetske genske regulacije pri rastlinah je vernalizacija – sposobnost rastline, da razvije generativne organe pod vplivom nizkih temperatur. Pred vernalizacijo, je cvetenje zavrto z ekspresijo gena FLC (Flowering Locus C). Ko je rastlina nekaj časa izpostavljena nizkim temperaturam, se ekspresija gena FLC utiša skozi modifikacijo strukture kromatina na tem genskem lokusu.In the first half of the 20th century, genetics and developmental biology were considered separate disciplines. The word "epigenetics" was coined by Conrad Waddington in 1942. He formed it from the Greek word "epigenesis", which initially stood for the effect of genetic processes on development. Today the epigenetic regulation of genes can be defined as changes in gene activity, which are inherited through mitotic and/or meiotic cell cycles, without changes in DNA sequence. It is currently considered that at least three biological systems start, maintain, or alter epigenetic codeincluding DNA methylation, histone modification, and gene silencing with implementation of non-coding RNA. Since epigenetic alterations are not tied to changes in DNA sequence, the inheritance thereof is connected to a probability of reversibility to a certain degree. The aforementioned degree, however, relies on the very same mechanism that caused the epigenetic changes. An example of plant’s epigenetic gene regulation is vernalization – the ability of a plant to develop generative organs when influenced by low temperatures. Before vernalization, flowering is suppressed with the expression of the FLC gene (Flowering Locus C). After the plant has been exposed to low temperatures for some time, the expression of the FLC gene is silenced through the modification of chromatine structure in this gene locus