Mechanical touch responses of Arabidopsis TCH1-3 mutant roots on inclined hard-agar surface**

Abstract

The gravity-induced mechanical touch stimulus can affect plant root architecture. Mechanical touch responses of plant roots are an important aspect of plant root growth and development. Previous studies have reported that [Arabidopsis TCH]1-3 genes are involved in mechano-related events, how-ever, the physiological functions of [TCH]1-3 genes in [Arabidopsis] root mechanoresponses remain unclear. In the present study, we applied an inclined hard agar plate method to produce mechanical touch stimulus, and provided evidence that altered mechanical environment could influence root growth. Furthermore, [tch]1-3 [Arabidopsis] mutants were investigated on inclined agar surfaces to explore the functions of [TCH]1-3 genes on [Arabidopsis] root mechanoresponses. The results showed that two [tch2] mutants, [cml]24-2 and [cml]24-4, exhibited significantly reduced root length, biased skewing, and decreased density of lateral root. In addition, primary root length and density of lateral root of [tch]3 ([cml]12-2) was significantly decreased on inclined agar surfaces. This study indicates that the [tch]2 and [tch]3 mutants are hypersensitive to mechanical touch stimulus, and [TCH]2 ([CML]24-2 and [CML]24-4) and [TCH]3 ([CML]12-2) genes may participate in the mechanical touch response of [Arabidopsis] roots.