Anatomical, biochemical, and photosynthetic responses to recent allopolyploidy in Glycine dolichocarpa (Fabaceae).
OBJECTIVE
Previous studies have shown that polyploidy has pronounced effects on photosynthesis. Most of these studies have focused on synthetic or recently formed autopolyploids, and comparatively little is known about the integrated effects of natural allopolyploidy, which involves hybridity and genome doubling and often incorporates multiple genotypes through recurrent origins and lineage recombination.


METHODS
Glycine dolichocarpa (designated T2) is a natural allotetraploid with multiple origins. We quantified 21 anatomical, biochemical, and physiological phenotypes relating to photosynthesis in T2 and its diploid progenitors, G. tomentella (D3) and G. syndetika (D4). To assess how direction of cross affects these phenotypes, we included three T2 accessions having D3-like plastids (T2(D3)) and two accessions having D4-like plastids (T2(D4)).


RESULTS
T2 accessions were transgressive (more extreme than any diploid accession) for 17 of 21 phenotypes, and species means differed significantly in T2 vs. both progenitors for four of 21 phenotypes (higher for guard cell length, electron transport capacity [J(max)] per palisade cell, and J(max) per mesophyll cell; lower for palisade cells per unit leaf area). Within T2, four of 21 parameters differed significantly between T2(D3) and T2(D4) (palisade cell volume; chloroplast number and volume per unit leaf area; and J(max) per unit leaf area).


CONCLUSIONS
T2 is characterized by transgressive photosynthesis-related phenotypes (including an ca. 2-fold increase in J(max) per cell), as well as by significant intraspecies variation correlating with plastid type. These data indicate prominent roles for both nucleotypic effects and cytoplasmic factors in photosynthetic responses to allopolyploidy.
Department of Plant Biology, Cornell University, Ithaca, New York 14853, USA. jec73@cornell.edu
Jeremy E
JE
Coate
Amelia K
AK
Luciano
Vasu
V
Seralathan
Kevin J
KJ
Minchew
Tom G
TG
Owens
Jeff J
JJ
Doyle
D002452:Cell Count; D048429:Cell Size; D002678:Chimera; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000502:physiology; D018744:DNA, Plant / Q000235:genetics; D004579:Electron Transport; D007887:Fabaceae / Q000166:cytology / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D059646:Genome Size; D058503:Mesophyll Cells / Q000502:physiology; D010641:Phenotype; D010788:Photosynthesis / Q000502:physiology*; D019441:Plant Epidermis / Q000166:cytology / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D011123:Polyploidy; D012641:Selection, Genetic; D013045:Species Specificity
D018744:DNA, Plant; D002734:Chlorophyll