TITLE:
Maternal Environment Effects on Phenolic Defenses in Abutilon theophrasti Seeds
AUTHORS:
Brian J. Schutte, Sam E. Wortman, John L. Lindquist, Adam S. Davis
KEYWORDS:
Environmental Maternal Effect; Growth-Differentiation Balance Hypothesis; ortho-Dihydroxyphenols; Seed Defense, Seed Protein
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.4 No.5,
May
29,
2013
ABSTRACT: A class of
phenolic compounds, ortho-dihydroxyphenols
(hereafter “o-DHP”), has been
implicated with seed survival. Based on expectations of the
growth-differentiation balance hypothesis, we predicted that seed o-DHP concentration exhibits a
curvilinear response to increasing resource availability in the maternal
environment, with maximum o-DHP
occurring at moderate resource levels. To test this hypothesis, Abutilon theophrasti seeds were produced
under field conditions at two locations. Each location included twelve maternal
environments established through factorial combinations of soil compost (+/-), species assemblage (A. theophrasti with and without maize), and soil nitrogen
fertilizer (0, 0.5× or 1× local
recommendations for maize). Resource availability with respect to A. theophrasti growth was summarized by
above-ground biomass at seed harvest (maternal biomass). Results indicated that
seed o-DHP concentrations increased
then decreased in response to increasing maternal biomass. This relationship
was modeled with a unimodal function specific to location (Location 1, y = 1.18 + 0.03xe-0.02x, pseudo-R2 = 0.59, p = 0.003; Location 2, y = 1.40 + 0.006xe-0.005x;
pseudo-R2 = 0.34, p = 0.05). Seed
protein concentrations remained constant across maternal biomass levels. Because
inherent vulnerability to predation and decay is considered a consequence of
chemical protection relative to nutritional offering, our results suggest that A. theophrasti seed susceptibility to lethal
attack is influenced by resource levels in the maternal environment. More
broadly, our results suggest that the growth-differentiation
balance hypothesis can be extended to maternal effects on seed phenolics.