Theoretical and Applied Genetics

, Volume 122, Issue 6, pp 1039–1049

An analysis of sequence variability in eight genes putatively involved in drought response in sunflower (Helianthus annuus L.)

Authors

  • T. Giordani
    • Genetics Section, Department of Crop Plant BiologyUniversity of Pisa
  • M. Buti
    • Genetics Section, Department of Crop Plant BiologyUniversity of Pisa
  • L. Natali
    • Genetics Section, Department of Crop Plant BiologyUniversity of Pisa
  • C. Pugliesi
    • Genetics Section, Department of Crop Plant BiologyUniversity of Pisa
  • F. Cattonaro
    • Istituto di Genomica Applicata, Parco Scientifico e Tecnologico Luigi Danieli
  • M. Morgante
    • Istituto di Genomica Applicata, Parco Scientifico e Tecnologico Luigi Danieli
    • Department of Crop and Environmental SciencesUniversity of Udine
    • Genetics Section, Department of Crop Plant BiologyUniversity of Pisa
Original Paper

DOI: 10.1007/s00122-010-1509-0

Cite this article as:
Giordani, T., Buti, M., Natali, L. et al. Theor Appl Genet (2011) 122: 1039. doi:10.1007/s00122-010-1509-0

Abstract

With the aim to study variability in genes involved in ecological adaptations, we have analysed sequence polymorphisms of eight unique genes putatively involved in drought response by isolation and analysis of allelic sequences in eight inbred lines of sunflower of different origin and phenotypic characters and showing different drought response in terms of leaf relative water content (RWC). First, gene sequences were amplified by PCR on genomic DNA from a highly inbred line and their products were directly sequenced. In the absence of single nucleotide polymorphisms, the gene was considered as unique. Then, the same PCR reaction was performed on genomic DNAs of eight inbred lines to isolate allelic variants to be compared. The eight selected genes encode a dehydrin, a heat shock protein, a non-specific lipid transfer protein, a z-carotene desaturase, a drought-responsive-element-binding protein, a NAC-domain transcription regulator, an auxin-binding protein, and an ABA responsive-C5 protein. Nucleotide diversity per synonymous and non-synonymous sites was calculated for each gene sequence. The πa/πs ratio range was usually very low, indicating strong purifying selection, though with locus-to-locus differences. As far as non-coding regions, the intron showed a larger variability than the other regions only in the case of the dehydrin gene. In the other genes tested, in which one or more introns occur, variability in the introns was similar or even lower than in the other regions. On the contrary, 3′-UTRs were usually more variable than the coding regions. Linkage disequilibrium in the selected genes decayed on average within 1,000 bp, with large variation among genes. A pairwise comparison between genetic distances calculated on the eight genes and the difference in RWC showed a significant correlation in the first phases of drought stress. The results are discussed in relation to the function of analysed genes, i.e. involved in gene regulation and signal transduction, or encoding enzymes and defence proteins.

Copyright information

© Springer-Verlag 2010