Summer dormancy and winter growth: root survival strategy in a perennial monocotyledon.
Here, we tested the alternation of root summer dormancy and winter growth as a critical survival strategy for a long-lived monocotyledon (Restionaceae) adapted to harsh seasonal extremes of Mediterranean southwest Western Australia. Measurements of growth and the results of comparative studies of the physiology, water content, metabolites, osmotic adjustments, and proteomics of the dormant and growing perennial roots of Lyginia barbata (Restionaceae) were assessed in field-grown plants. Formation of dormant roots occurred before the onset of summer extremes. They resumed growth (average 2.3 mm d(-1)) the following winter to eventually reach depths of 2-4 m. Compared with winter-growing roots, summer dormant roots had decreased respiration and protein concentration and c. 70% water content, sustained by sand-sheaths, osmotic adjustment and presumably hydraulic redistribution. Concentrations of compatible solutes (e.g. sucrose and proline) were significantly greater during dormancy, presumably mitigating the effects of heat and drought. Fifteen root proteins showed differential abundance and were correlated with either winter growth or summer dormancy. None matched currently available libraries. The specific features of the root dormancy strategy of L. barbata revealed in this study are likely to be important to understanding similar behaviour in roots of many long-lived monocotyledons, including overwintering and oversummering crop species.
Shane
Michael W
MW
School of Plant Biology, M084, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
McCully
Margaret E
ME
Plant Industry, CSIRO, Canberra, ACT 2601, Australia.
Canny
Martin J
MJ
Functional Ecology Group, Research School of Biological Sciences, Australian National University, Canberra, ACT 0200, Australia.
Pate
John S
JS
School of Plant Biology, M084, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
Ngo
Hai
H
School of Plant Biology, M084, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
Mathesius
Ulrike
U
School of Biochemistry and Molecular Biology, Australian National University and Australian Research Council Centre of Excellence for Integrative Legume Research, Linnaeus Way, Canberra, ACT 0200, Australia.
Cawthray
Gregory R
GR
School of Plant Biology, M084, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
Lambers
Hans
H
School of Plant Biology, M084, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
D019069:Cell Respiration; D002980:Climate; D017753:Ecosystem; D019684:Magnoliopsida / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D012621:Seasons; D013395:Sucrose / Q000378:metabolism; D014867:Water / Q000502:physiology; D014904:Western Australia
D010940:Plant Proteins; D014867:Water; D013395:Sucrose; D011392:Proline