RT Journal Article SR Electronic T1 A no hydrotropic response Root Mutant that Responds Positively to Gravitropism in Arabidopsis JF Plant Physiology JO Plant Physiol. FD American Society of Plant Biologists SP 536 OP 546 DO 10.1104/pp.011841 VO 131 IS 2 A1 Eapen, Delfeena A1 Barroso, Marı́a Luisa A1 Campos, Marı́a Eugenia A1 Ponce, Georgina A1 Corkidi, Gabriel A1 Dubrovsky, Joseph G. A1 Cassab, Gladys I. YR 2003 UL http://www.plantphysiol.org/content/131/2/536.abstract AB For most plants survival depends upon the capacity of root tips to sense and move towards water and other nutrients in the soil. Because land plants cannot escape environmental stress they use developmental solutions to remodel themselves in order to better adapt to the new conditions. The primary site for perception of underground signals is the root cap (RC). Plant roots have positive hydrotropic response and modify their growth direction in search of water. Using a screening system with a water potential gradient, we isolated ano hydrotropic response (nhr) semi-dominant mutant of Arabidopsis 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 nhr1roots 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. nhr1 seedlings had abnormal root cap morphogenesis and reduced root growth sensitivity to abscisic acid (ABA) and the polar auxin transport inhibitor N-(1-naphtyl)phtalamic acid (NPA). These results showed that hydrotropism is amenable to genetic analysis and that an ABA signaling pathway participates in sensing water potential gradients through the root cap.