Environmental effects on seedling identity recognition

Abstract

<p>Adaptive plasticity is important for plants. For example, plants can respond to light by elongating their stem or to low nutrients by increasing root proliferation. Kin recognition in plants is a type of phenotypic plasticity, but to relatives versus non-relatives. Recently kin recognition has been demonstrated for the first time in a plant species using the annual plant Cakile edentula. Plants responded to kin recognition only when sharing a pot where the roots could interact. This indicates that plants were responding to the identity of their neighbours through touch, a volatile chemical, or a soluble chemical.</p> <p>Dr.Harsh Bais has developed a methodology to test whether kin recognition occurs through plant exudates without physical contact. Arabidopsis seedlings responded differentially to an exudate source belonging to kin or strangers. Using this methodology we proposed to determine if Chenopodium album seedlings and Arabidopsis thaliana seedlings respond to kin recognition from exudates sources under different environmental conditions. For Chenopodium seedlings we manipulated the nutrient treatments, as per a previous experiment where juvenile Chenopodium demonstrated kin recognition under differing nutrient treatments. For Arabidopsis seedlings we changed the irradiance and quality of light for seedlings exposed to different exudate sources to see if it changed the response. The goal was to find a repeatable, reliable assay for kin recognition.</p> <p>Chenopodium albunt and Arabidopsis thaliana both demonstrated kin recognition. Chenopodium responses were consistent with juvenile plants, where seedlings in scarce nutrients displayed an increased root shoot ratio compared to those in regular nutrients which had a low rootshoot ratio and were overall larger seedlings. Seedlings placed in exudates belonging to kin in regular nutrient conditions had a higher root shoot ratio than those exposed to stranger exudates, indicating that those in stranger exudates had more aboveground growth. Arabidopsis displayed inconsistent kin recognition, with responses varying between different environmental conditions and among families . There was significant genetic variability among families which resulted in a change in response to exudate source within trials and between trials.</p> <p>Both Chenopodium album and Arabidopsis thaliana respond to an exudate source and demonstrate kin recognition. However, more work needs to be done to find a reliable, repeatable assay for Arabidopsis seedlings.</p>