Poster: Tropisms

Abs # 411: Genetic Approach for analyzing hydrotropism in Arabidopsis

Presenter:	Cassab, Gladys I, gladys@ibt.unam.mx
Authors	Cassab, Gladys I (A)   Eapen, Delfeena  (A)   Barroso, María Luisa  (A)   Campos, María Eugenia  (A)   Ponce, Georgina  (A)
Affiliations:	(A): National University of Mexico

The sessile plant requires a morphological and developmental pattern that enables exploitation of local minerals, light and water if proper growth is to be achieved. Roots are capable to construct a three-dimensional perspective of their local space by sensing and responding to a variety of stimuli. By doing this, plants actively forage resources from their environment. The primary site for perception of underground signals is the root cap. Roots have positive hydrotropic response and modify their growth direction in search of water overcoming their positive gravitropic response. Using a screening system with a water potential gradient, we isolated a no hydrotropic response (nhr) semi-dominant mutant of Arabidopsis thaliana that continued to grow downwardly into the medium with the lowest water potential contrary to the positive hydrotropic and negative gravitropic response seen in wild type-roots. The lack of hydrotropic response of nhr1 roots was confirmed in a system with a gradient in air moisture. The root gravitropic response of nhr1 seedlings was significantly faster in comparison with those of wild type. The frequency of the waving pattern in nhr1 roots was increased compared to those of wild type. The enhanced gravitropic and waviness response of nhr1 roots might suggest that the reduction in the strength of hydrotropism increases the net effectiveness of both differential growth responses. Supported by project 36071-N, Consejo Nacional de Ciencia y Tecnología.