The stringent response, also called stringent control, is a stress response of bacteria and plant chloroplasts in reaction to amino-acid starvation, fatty acid limitation, iron limitation, heat shock and other stress conditions and growth processes. The stringent response is signaled by the alarmone (p)ppGpp, and modulates transcription of up to 1/3 of all genes in the cell. This in turn causes the cell to divert resources away from growth and division and toward amino acid synthesis in order to promote survival until nutrient conditions improve.