Functional Identification of Salt-Stress-Related Genes Using the FOX Hunting System from Ipomoea pes-caprae

Ipomoea pes-caprae is a seashore halophytic plant and is therefore a good model for studying the molecular mechanisms underlying salt and stress tolerance in plant research. Here, we performed Full-length cDNA Over-eXpressor (FOX) gene hunting with a functional screening of a cDNA library using a salt-sensitive yeast mutant strain to isolate the salt-stress-related genes of I. pes-caprae (IpSR genes). The library was screened for genes that complemented the salt defect of yeast mutant AXT3 and could grow in the presence of 75 mM NaCl. We obtained 38 candidate salt-stress-related full-length cDNA clones from the I. pes-caprae cDNA library. The genes are predicted to encode proteins involved in water deficit, reactive oxygen species (ROS) scavenging, cellular vesicle trafficking, metabolic enzymes, and signal transduction factors. When combined with the quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analyses, several potential functional salt-tolerance-related genes were emphasized. This approach provides a rapid assay system for the large-scale screening of I. pes-caprae genes involved in the salt stress response and supports the identification of genes responsible for the molecular mechanisms of salt tolerance.