Aquaporins in the wild: natural genetic diversity and selective pressure in the PIP gene family in five Neotropical tree species.
BACKGROUND
Tropical trees undergo severe stress through seasonal drought and flooding, and the ability of these species to respond may be a major factor in their survival in tropical ecosystems, particularly in relation to global climate change. Aquaporins are involved in the regulation of water flow and have been shown to be involved in drought response; they may therefore play a major adaptive role in these species. We describe genetic diversity in the PIP sub-family of the widespread gene family of Aquaporins in five Neotropical tree species covering four botanical families.


RESULTS
PIP Aquaporin subfamily genes were isolated, and their DNA sequence polymorphisms characterised in natural populations. Sequence data were analysed with statistical tests of standard neutral equilibrium and demographic scenarios simulated to compare with the observed results. Chloroplast SSRs were also used to test demographic transitions. Most gene fragments are highly polymorphic and display signatures of balancing selection or bottlenecks; chloroplast SSR markers have significant statistics that do not conform to expectations for population bottlenecks. Although not incompatible with a purely demographic scenario, the combination of all tests tends to favour a selective interpretation of extant gene diversity.


CONCLUSIONS
Tropical tree PIP genes may generally undergo balancing selection, which may maintain high levels of genetic diversity at these loci. Genetic variation at PIP genes may represent a response to variable environmental conditions.
Audigeos
Delphine
D
INRA UMR 0745 EcoFoG (<< Ecologie des forêts de Guyane >>), Campus Agronomique, 97387 Kourou, French Guiana, France.
Buonamici
Anna
A
Belkadi
Laurent
L
Rymer
Paul
P
Boshier
David
D
Scotti-Saintagne
Caroline
C
Vendramin
Giovanni G
GG
Scotti
Ivan
I
D000595:Amino Acid Sequence; D020346:Aquaporins / Q000235:genetics*; D017931:DNA Primers; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant; D008957:Models, Genetic; D008969:Molecular Sequence Data; D005810:Multigene Family; D011110:Polymorphism, Genetic; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D014197:Trees / Q000235:genetics*; D014329:Tropical Climate
D020346:Aquaporins; D017931:DNA Primers; D018742:DNA, Chloroplast; D018744:DNA, Plant