Peng, Mingsheng , Hannam, Carol , Gu, Honglan , Bi, Yong-Mei , Rothstein, Steven J .
The RING-type Ubiquitin Ligase, NLA, Controls the Adaptability of Arabidopsis to Nitrogen Limitation.
Plant growth and development require abundant nitrogen nutrient, while abiotic and biotic consumption of soil nitrogen frequently creates a nitrogen limitation growth condition. To cope with this, plants have evolved a suite of adaptive responses to nitrogen limitation. However, the molecular mechanism governing the adaptability of plants to nitrogen limitation is totally unknown because no reported mutant defines this trait. In this study, we established a nitrogen-limited growth condition for Arabidopsis plants, and isolated an Arabidopsis mutant called the nitrogen limitation adaptation (nla). Supplied with insufficient nitrogen (nitrate of ammonium), the nla plants failed to develop the essential nitrogen limitation adaptive responses, but senesced much earlier and more rapidly than did wild type plants. The responsive gene, NLA, was identified through a map-based cloning approach. The presence of a RING domain in NLA and its capacity to interact with Arabidopsis ubiquitin conjugase 8 (AtUBC8) indicate that NLA is RING-type ubiquitin ligase. In the nla mutant, the RING domain was deleted from the NLA protein, which resulted in the impairment of the interaction between NLA and AtUBC8, and disruption of the adaptation of the nla plants to nitrogen limitation. These results demonstrate that the ubiquitination pathway involving the NLA protein is required to develop the adaptability of Arabidopsis to nitrogen limitation. To identify more molecular components in this ubiquitination pathway, we mutated the nla seeds with EMS, and screened for the nla suppressors which do not show the low nitrogen limitation induced early senescence phenotype. Five nla suppressors were isolated, one of which was found to be controlled by a recessive Mendalian gene and mapped to the low arm of the chromosome 3.
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1 - University of Guelph, Department of Molecular and Cellular Biology, Guelph, Ontario, N1G 2W1, Canada
2 - University of Guelph, Department of Molecular and Cellular Biology
Ubiquitin ligase NLA.
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM