#80 - Sept 2024 - Garden Stuff - © Sandy Lang - slang@xtra.co.nz GENE SONGSSeptember/October: Early/mid-spring. Pruning done. New perennials in the ground. New seeds germinating. On/off: Plants have from 20,000 to 40,000 genes (see mulchpile.org/78/). But most of the time, most genes are switched off. Why? Think a piano: If all notes are played at once there’s a horrid noise. It‘s by not playing most of them, most of the time, you can hear the ones that are played. You hear chords. By changing the ones played, you hear melody. Gene expression: When a gene is turned on, it is ‘expressed’. This means a particular section of code in the cell’s DNA, is being copied (transcribed) to produce a particular protein that will do some useful job in the cell. Transcription factors (TFs): Living organisms use TFs to control gene expression. These adjust the rate of transcription of genetic information - turning genes on or off, faster or slower. So, while genes contain the codes, it’s TFs that orchestrate how their coded information is used. It is this orchestration that allows a plant to survive and thrive by expressing the right genes, at the right times, in the right cells, to the right amounts, throughout its life. Development: So, it’s the TFs that control plant development, by controlling the behaviour of each cell, and so the formation of different tissues (skin, vascular tissues, cortex) and different organs (leaves, stems, roots). Behaviour: TFs also control the behaviour of the plant with time. The process of aging and its response to changes in season (spring flowering, autumn leaf drop). An example is the TFs triggered by hormones from organs that detect time of year by measuring daylength. Acclimatisation: Unlike animals, plants can’t seek shelter from environmental extremes. So, they are masters at adjusting to these. They do it by adjusting their internal chemistry to best align with the new environment. As an environmental change occurs, their TFs express a different set of genes. This new expression pattern offsets problems from too much or too little of something – hot /cold, light /shade, drought /flooding. Also, from stress factors like disease and salinity. This explains why it takes a few days for a plant to adjust to an environmental change (see mulchpile.org/63/). The plant must first sense the change and then adjust the balance of genes turned on /off via the TFs. ___________________________________