Root growth in Arabidopsis requires gibberellin/DELLA signalling in the endodermis

Abstract

Gibberellins (GAs) are key regulators of plant growth and development. They promote growth by targeting the degradation of DELLA repressor proteins; however, their site of action at the cellular, tissue or organ levels remains unknown. To map the site of GA action in regulating root growth, we expressed gai, a non-degradable, mutant DELLA protein, in selected root tissues. Root growth was retarded specifically when gai was expressed in endodermal cells. Our results demonstrate that the endodermis represents the primary GA-responsive tissue regulating organ growth and that endodermal cell expansion is rate-limiting for elongation of other tissues and therefore of the root as a whole.

Environmental Nitrate Stimulates Abscisic Acid Accumulation in Arabidopsis Root Tips by Releasing It from Inactive Stores

“…Duan et al (2013) have shown that ABA is required within the root endodermis to regulate root growth in response to NaCl. This observation could reflect either increased ABA levels within the endodermis, increased sensitivity of the endodermis to ABA, resulting in the activation of ABA responses at a lower threshold, or a requirement for ABA solely within the endodermis, since endodermal cell expansion is rate-limiting for root elongation (Ubeda-Tomás et al, 2008); thus, ABA signaling in other root tissues may be irrelevant for root growth. Our observation that ABA accumulates particularly within the endodermis supports the hypothesis that increased ABA levels within the endodermis mediate root growth in response to NaCl and underscores the importance of the endodermis in root physiology.…”

Gibberellin-GID1-DELLA: A Pivotal Regulatory Module for Plant Growth and Development

“…site of GA-induced DELLA degradation for primary root elongation is in the endodermis (Ubeda-Tomas et al, 2008). Interestingly, recent studies showed that different phytohormones seem to act in distinct and not completely overlapping cell types (Jaillais and Chory, 2010).…”

Growth-induced hormone dilution can explain the dynamics of plant root cell elongation

“…1A): Cells divide in the meristem, which is located close to the root tip; after a number of divisions, cells then move through the elongation zone, where they rapidly increase in length with negligible change in radius; finally, cells stop growing on entering the mature zone. Gibberellin has been described as a key hormone in regulating both cell division in the root meristem (6) and cell elongation in the elongation zone (5).…”

“…A well-studied context for gibberellin growth regulation is provided by the primary root of the model species Arabidopsis thaliana (3,5,6). At the organ level, the Arabidopsis primary root classically presents three distinct morphological zones (ref.…”