DiscussionPlants encounter various stresses, change in temperature beingone of the most common. C. reinhardtii undergoes drastic changes inmetabolism and development when cold stress is applied (Valledoret al., 2013).Heat shock proteins are chaperones that play an impor-tant role in stress tolerance, including downshift in temperature(Timperio et al., 2008). The HSP70 genes encode for a group ofhighly conserved chaperone proteins across the living systemsencompassing bacteria, plants, and animals. The role of HSP70 inregulating the folding and functions of important cellular proteinsin C. reinhardtii (Schroda et al., 2015) has prompted us to investi-gate the expression of the HSP70 chaperone machines in this modelplant organism under cold shock conditions. The genes selectedencode chloroplast HSP70B, mitochondrial HSP70C and cytosolicHSP70A, i.e., chaperones from different cell compartments. More-over, expression levels of HSP70B and HSP70A interaction partnerswere analyzed.