ROOTINIT · Stem cell maintenance and reactivation in lateral root initiation
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2007-02-01 → 2009-01-31
- EU contribution
- €168,798
- Participants
- 1
- Scheme
- EIF
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Results in brief
Final Activity Report Summary - ROOTINIT (Stem cell maintenance and reactivation in lateral root initiation)
The correct integration of cell division in growth and development requires sensing of developmental and physiological signals by the cell cycle machinery. Proliferating cells in roots are concentrated at the root tip in meristems and are spatially separated from elongated non-dividing tissues. Specific tissues, such as the pericycle, maintain the capacity to reactivate division under hormonal stimulation and to form de novo lateral root meristems. D-type cyclins can stimulate entry into the mitotic cell cycle and respond to sucrose and plant hormones. Expressing d-type cyclin 2;1 (CYCD2;1) throughout the root meristem triggers cell division, as noted by Qi and John, 2007, but its function in root apical meristems remains enigmatic. In this project we showed that CYCD2;1 was induced by sucrose and was present in all meristematic tissues in the root apex. However, the intracellular distribution of CYCD2;1 was variable, as cells in regions marked by auxin maxima did not accumulate CYCD2;1 in the nucleus. The concentration of CYCD2;1 in the nucleus was dependent on kip-related protein 2 (KRP2), and KRP2 turnover itself was under auxin control. Furthermore, we demonstrated that CYCD2;1 contributed to the reactivation of pericycle cells by auxin. These results indicated that KRP2 sequestered CYCD2;1 in the nucleus and that CYCD2;1 activity stimulated auxin induced cell division in the pericycle integrating sucrose and auxin sensing, revealing an additional control mechanism for cell cycle regulation in the pericycle.
Data: CORDIS, © European Union
Project objective
Lateral roots are essential to form a dense root network allowing plants to take up water and minerals effectively from the soil. Laterals are initiated from a specific organogenic cell layer within the differentiated root known as the pericycle.The establishment and maintenance of the pericycle and the subsequent process of lateral root formation is an interesting model to study how stem-cells can be maintained within an otherwise differentiated and endoreduplicated tissue, and how these cells are re-activated into division in response to mitogenic signals.Recently the host laboratory has investigated in detail the expression patterns of D-type cyclin (CYCD) genes in roots. Whilst several CYCD genes are expressed during the establishment and proliferation of the new pericycle cells within the primary root meristem, only two are expressed in association with the mature pericycle or during early lateral root initiation.In particular, CYCD2;1 persists in the mature pericycle, but disappears on lateral root initiation, whereas CYCD1;1 is associated with proliferating primordial cells of lateral roots. In this project, I will investigate the hypothesis that the D-type cyclins CYCD2;1 and CYCD1;1 and their interactions with inhibitor proteins KRPs are important for maintaining the organogenic capacity of the pericycle and in the subsequent induction of lateral root induction.The proposed model is that CYCD2;1 maintains pericycle cells in a ready-to-go state until lateral root induction is triggered by auxin. Understanding the activity and control of these proteins is therefore of central importance to integrating an understanding of cell-cycle control with plant development.The host lab has the materials and the expertise in cell and developmental biology to carry out the proposal work and will provide both an excellent complement to the existing skills of the applicant in biochemical techniques and an international training environment.
Original text from CORDIS.
Participants
- University of Cambridge · CambridgeCoordinatorUnited Kingdom
Links
Data: CORDIS, © European Union