Nucleotide polymorphism in the drought responsive gene Asr2 in wild populations of tomato
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The Asr gene family (named after abscicic acid [ABA], stress, ripening), exclusively present in plant genomes, is involved in transcriptional regulation. Its members are up-regulated in roots and leaves of water- or salt-stressed plants. In previous work, evidence of adaptive evolution (as inferred from synonymous and nonsynonymous divergence rates) has been reported for Asr2 in Solanum chilense and S. arcanum, two species dwelling in habitats with different precipitation regimes. In this paper we investigate patterns of intraspecific nucleotide variation in Asr2 and the unlinked locus CT114 in S. chilense and S. arcanum. The extent of nucleotide diversity in Asr2 differed between species in more than one order of magnitude. In both species we detected evidence of non-neutral evolution, which may be ascribed to different selective regimes, potentially associated to unique climatic features, or, alternatively, to demographic events. The results are discussed in the light of demographic and selective hypotheses.
KeywordsPolymorphism Asr genes Solanum Drought Selection
We thank the Tomato Genetics Resource Center (University of California, Davis, USA) for providing the seeds of the tomato wild populations and Gustavo Gudesblat for his valuable help with the experimental work in the laboratory. We also wish to thank Romina Piccinali and David Ardell for their help with technical issues of software usage, and two anonymous reviewers for their constructive comments and criticisms on a previous version of this manuscript. This work was supported by grants from Universidad de Buenos Aires (UBA), Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT) and Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Argentina. M.G. held a fellowship from UBA. N.F. held a fellowship from CONICET. N.D.I. and E.H. are members of the Carrera del Investigador Científico, CONICET, Argentina.
- Crandall KA, Templeton AR (1999) Statistical methods for detecting recombination. In: Crandall KA (ed) The evolution of HIV. The Johns Hopkins University Press, pp 153–176Google Scholar
- Hudson RR (1990) Gene genealogies and the coalescent process. Oxf Surv Evol Biol 7:1–44Google Scholar
- Jeanneau M, Gerentes D, Foueillassar X, Zivy M, Vidal J, Toppan A et al (2002) Improvement of drought tolerance in maize: towards the functional validation of the Zm-Asr1 gene and increase of water use efficiency by over-expressing C4-PEPC. Biochimie 84:1127–1135. doi: 10.1016/S0300-9084(02)00024-X PubMedCrossRefGoogle Scholar
- Kimura M (1983) The neutral theory of molecular evolution. Cambridge University Press, Cambridge, UKGoogle Scholar
- Peters S, Mundree SG, Thomson JA, Farrant JM, Keller F (2007) Protection mechanisms in the resurrection plant Xerophyta viscosa (Baker): both sucrose and raffinose family oligosaccharides (RFOs) accumulate in leaves in response to water deficit. J Exp Bot 58:1947–1956. doi: 10.1093/jxb/erm056 PubMedCrossRefGoogle Scholar
- Städler T, Roselius K, Stephan W (2005) Genealogical footprints of speciation processes in wild tomatoes: demography and evidence for historical gene flow. Evol Int J Org Evol 59:1268–1279Google Scholar