Differential Expression of Genes Regulated in Response to Drought or Salinity Stress in Sunflower

Abstract

Structural and functional characterization of environmental stress-induced genes has contributed to a better understanding of how plants respond and adapt to different abiotic stresses. Differential display was used to compare overall differences in gene expression between drought- or salinity-stressed and unstressed (control) plants of sunflower, Helianthus annuus L. Five drought-regulated cDNAs and 12 salinity-regulated cDNAs were cloned and sequenced. Thirteen of these cDNAs were confirmed to be expressed differentially in response to drought or salinity stress by quantitative reverse transcriptase polymerase chain reaction (RT-PCR). Regulation of the expression of these 13 genes was analyzed in leaves of drought-stressed plants, and in roots and shoots of drought- and salinity-stressed seedlings. Results showed that certain genes respond to both stresses, while others are uniquely regulated either in terms of the stress stimulus or the plant tissue. Sequence analysis of these clones identified five with homology to known genes [guanylate kinase (signal transduction), lytB (antibiotic/drug resistance), selenium-binding protein (heavy metal stress), polyprotein (reverse transcriptase), and AC-like transposable element]. The possible functions of these genes in plant stress-response are discussed.