Participation of cytokinins in plant response to competitors

Abstract

An attempt was made to look into participation of cytokinins in regulation of stomatal behavior and growth response of plants to the presence of competitors in the neighborhood. The plants of tobacco (Nicotiana tabacum L.) and lettuce (Lactuca sativa L.) were accommodated by one or several plants per pot. In rival plants growing by two or three per pot, the level of transpiration considerably fell, accumulation of shoot biomass decelerated, and leaf area decreased as compared with single plants. Reduction in transpiration and plant biomass was accompanied by a decrease in the content of endogenous cytokinins. When the plants were grown in the presence of competitors for a long time, an increase in the content of hormones in transgenic tobacco plants as a result of heat induction of ipt-gene and inoculation of lettuce plants with bacteria Bacillus subtilis, strain IB-22, producing cytokinin, reduced suppression of transpiration and shoot growth in competing plants. This suggests that cytokinins participate in late stages of plant adaptation to competitors.