期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 108, 期 45, 页码 18524-18529出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1108684108
关键词
Systems analysis; root morphology; hormone
资金
- National Science Foundation Arabidopsis [MCB-0929338]
- National Institutes of Health [R01 GM032877, R01 GM078279]
- European-FP7-International Outgoing Fellowships (Marie Curie) [2008-220157]
- International Fulbright Science and Technology Doctorate Award
As sessile organisms, root plasticity enables plants to forage for and acquire nutrients in a fluctuating underground environment. Here, we use genetic and genomic approaches in a split-root framework-in which physically isolated root systems of the same plant are challenged with different nitrogen (N) environments-to investigate how systemic signaling affects genome-wide reprogramming and root development. The integration of transcriptome and root phenotypes enables us to identify distinct mechanisms underlying N economy (i.e., Nsupply and demand) of plants as a system. Under nitrate-limited conditions, plant roots adopt an active-foraging strategy, characterized by lateral root outgrowth and a shared pattern of transcriptome reprogramming, in response to either local or distal nitrate deprivation. By contrast, in nitrate-replete conditions, plant roots adopt a dormant strategy, characterized by a repression of lateral root outgrowth and a shared pattern of transcriptome reprogramming, in response to either local or distal nitrate supply. Sentinel genes responding to systemic N signaling identified by genome-wide comparisons of heterogeneous vs. homogeneous split-root N treatments were used to probe systemic N responses in Arabidopsis mutants impaired in nitrate reduction and hormone synthesis and also in decapitated plants. This combined analysis identified genetically distinct systemic signaling underlying plant N economy: (i) N supply, corresponding to a long-distance systemic signaling triggered by nitrate sensing; and (ii) N demand, experimental support for the transitive closure of a previously inferred nitrate-cytokinin shoot-root relay system that reports the nitrate demand of the whole plant, promoting a compensatory root growth in nitrate-rich patches of heterogeneous soil.
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