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New Phytol. 2016 Jul;211(1):75-89. doi: 10.1111/nph.13898. Epub 2016 Mar 3.

Nitrogen remobilization and conservation, and underlying senescence-associated gene expression in the perennial switchgrass Panicum virgatum.

Author information

1
Plant Biology Division, the Samuel Roberts Noble Foundation, Ardmore, OK, 73401, USA.
2
BioEnergy Sciences Center (BESC), Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
3
Department of Plant Science, South Dakota State University, Brookings, SD, 57007, USA.
4
Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, 30602, USA.

Abstract

Improving nitrogen (N) remobilization from aboveground to underground organs during yearly shoot senescence is an important goal for sustainable production of switchgrass (Panicum virgatum) as a biofuel crop. Little is known about the genetic control of senescence and N use efficiency in perennial grasses such as switchgrass, which limits our ability to improve the process. Switchgrass aboveground organs (leaves, stems and inflorescences) and underground organs (crowns and roots) were harvested every month over a 3-yr period. Transcriptome analysis was performed to identify genes differentially expressed in various organs during development. Total N content in aboveground organs increased from spring until the end of summer, then decreased concomitant with senescence, while N content in underground organs exhibited an increase roughly matching the decrease in shoot N during fall. Hundreds of senescence-associated genes were identified in leaves and stems. Functional grouping indicated that regulation of transcription and protein degradation play important roles in shoot senescence. Coexpression networks predict important roles for five switchgrass NAC (NAM, ATAF1,2, CUC2) transcription factors (TFs) and other TF family members in orchestrating metabolism of carbohydrates, N and lipids, protein modification/degradation, and transport processes during senescence. This study establishes a molecular basis for understanding and enhancing N remobilization and conservation in switchgrass.

KEYWORDS:

gene expression; nitrogen remobilization; senescence; switchgrass (Panicum virgatum); transcription factors

PMID:
26935010
DOI:
10.1111/nph.13898
[Indexed for MEDLINE]
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