Gravitropism in plants is key for orienting organs such as the Darwin＇s description of the opposite growth direction of roots and shoots in his book The Power of Movement in Plants more than 100 years ago （Darwin, 1880）. The gravitropic response of an oriented plant is divided into three sequential phases： gravity sensing, signal transmission, and the growth response. As the initial phase of gravitropism, gravity sensing （the conversion of the mechanical stimulus into a biochemical signal） has been intensively studied, but much is still unknown. The statoliths are vital for sense of balance and response to gravity, e.g. in statocytes for invertebrates and in inner ears for vertebrates.
Zhongyu ZhengJunjie ZouHanhai LiShan XueYuren WangJie Le
One of the important questions in space biology is the mechanisms underlying plant responses to an outer space environment,i.e.,how gene expression is altered in space.In this study,the transcriptome of Arabidopsis thaliana seedlings was analyzed as a part of Germany SIMBOX(science in microgravity box)spaceflight experiment on Shenzhou 8 spacecraft.This experiment involved the following treatments:spaceflight with microgravity(Fμg),spaceflight with 1g centrifugal force(F 1g),and ground 1g control(G 1g).Gene chips were used to screen gene expression differences in Arabidopsis thaliana seedlings among these treatments.Microarray analysis revealed that 621 genes were differentially expressed in samples Fμg vs.G 1g,249 genes in samples F 1g vs.G 1g,and 368 genes in samples Fμg vs.F 1g.Gene ontology analysis indicated that the genes were involved in metabolism of stress response,gravitropic response,and DNA damage and repair,suggesting that plants adjust these metabolic pathways to space environmental stress,microgravity,and radiation.
LI HuaShengLU JinYingZHAO HuiSUN QiaoYU FuTongPAN YiCHEN YuSU LiangLIU Min
