Nucleotide polymorphism in the drought responsive gene Asr2 in wild populations of tomato

MARIANO I. GIOMBINI; NICOLÁS FRANKEL; NORBERTO D. IUSEM; ESTEBAN HASSON

GENETICA

SPRINGER

Año: 2009 vol. 136 p. 13 - 25

0016-6707

The Asr gene family (named after abscicic acid[ABA], stress, ripening), exclusively present in plant genomes,is involved in transcriptional regulation. Its membersare up-regulated in roots and leaves of water- or saltstressedplants. In previous work, evidence of adaptiveevolution (as inferred from synonymous and nonsynonymousdivergence rates) has been reported for Asr2 inSolanum chilense and S. arcanum, two species dwelling inhabitats with different precipitation regimes. In this paperwe investigate patterns of intraspecific nucleotide variationin Asr2 and the unlinked locus CT114 in S. chilense and S.arcanum. The extent of nucleotide diversity in Asr2 differedbetween species in more than one order ofmagnitude. In both species we detected evidence of nonneutralevolution, which may be ascribed to differentselective regimes, potentially associated to unique climaticfeatures, or, alternatively, to demographic events. Theresults are discussed in the light of demographic andselective hypotheses.