Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/36244
Title: STUDY OF LATERAL ROOT DEVELOPMENT DURING SALT STRESS IN ARABIDOPSIS
Authors: DUAN LINA
Keywords: lateral root, salt stress, quiescence, endodermis, ABA, Arabidopsis
Issue Date: 22-Aug-2012
Source: DUAN LINA (2012-08-22). STUDY OF LATERAL ROOT DEVELOPMENT DURING SALT STRESS IN ARABIDOPSIS. ScholarBank@NUS Repository.
Abstract: In a taproot system, the development of lateral roots (LRs) from the primary root (PR) is an essential factor in shaping the whole root system architecture. Under environmental stress, such as high salinity, the patterning of LRs along the longitudinal axis of PR and the post-emergence growth of LRs are disrupted. In this thesis, we describe the detailed analysis of these two aspects of LR development in Arabidopsis during salt stress. When facing high salinity environment, PRs and LRs show distinct intrinsic programing in controlling growth. We report that salt stress induces an extended quiescence phase in post-emergence lateral roots (LRs) whereby the rate of growth is suppressed for several days before recovery begins. Quiescence is correlated with sustained Abscisic Acid (ABA) response in LRs and is dependent upon genes necessary for ABA biosynthesis, signaling and transcriptional regulation. Here we show that high salinity, an environmental stress widely impacting agricultural land, regulates growth of the root system through a signaling network operating primarily in the endodermis. Gibberellic Acid (GA) signaling, which antagonizes the ABA pathway, also acts primarily in the endodermis and we define the cross talk between these two hormones. The antioxidant genes, peroxidases, could be the potential targets of both ABA and GA signaling in the endodermis in controlling LR growth. Our results define the endodermis as a gateway with an ABA-dependent guard, which prevents root growth into saline environments. Besides the post-emergent growth, the early LR patterning determination is also disrupted by salt stress. We reveal salt stress affects LR initiation through signaling to the primary root tip. The maintenance of LR pre-branch sites is largely disrupted during salt stress, indicated by the disrupted pattern of the auxin responsive reporter, DR5::Luciferase. This study provides the first evidence on the mechanism of early LR patterning disruption during salt stress.
URI: http://scholarbank.nus.edu.sg/handle/10635/36244
Appears in Collections:Ph.D Theses (Open)

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