Premium
Gravity control of growth form in Brassica rapa and Arabidopsis thaliana (Brassicaceae): Consequences for secondary metabolism
Author(s) -
Allen Joan,
Bisbee Patricia A.,
Darnell Rebecca L.,
Kuang Anxiu,
Levine Lanfang H.,
Musgrave Mary E.,
Loon Jack J. W. A.
Publication year - 2009
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.0800261
Subject(s) - brassica rapa , pith , hypergravity , biology , brassicaceae , brassica , arabidopsis thaliana , botany , context (archaeology) , biochemistry , astrobiology , paleontology , gene , mutant
How gravity influences the growth form and flavor components of plants is of interest to the space program because plants could be used for food and life support during prolonged missions away from the planet, where that constant feature of Earth's environment does not prevail. We used plant growth hardware from prior experiments on the space shuttle to grow Brassica rapa and Arabidopsis thaliana plants during 16‐d or 11‐d hypergravity treatments on large‐diameter centrifuge rotors. Both species showed radical changes in growth form, becoming more prostrate with increasing g ‐loads (2‐ g and 4‐ g ). In Brassica , height decreased and stems thickened in a linear relationship with increasing g ‐load. Glucosinolates, secondary compounds that contribute flavor to Brassica , decreased by 140% over the range of micro to 4‐ g , while the structural secondary compound, lignin, remained constant at ∼15% (w/w) cell wall dry mass. Stem thickening at 4‐ g was associated with substantial increases in cell size (47%, 226%, and 33% for pith, cortex, and vascular tissue), rather than any change in cell number. The results, which demonstrate the profound effect of gravity on plant growth form and secondary metabolism, are discussed in the context of similar thigmostresses such as touch and wind.