Abstract
Cucumber seedlings have potential to develop a peg on each side of the transition zone between the hypocotyl and the root. However, seedlings grown in a horizontal position develop a peg on the lower side of the transition zone and fail to develop the peg on the upper side. To understand how the gravity response differentially suppresses the peg formation, we performed fluorescent differential display (FDD) and isolated CsGRP1 cDNA that encodes glycine-rich protein. The mRNA accumulated more in the non-peg side than that in the peg side of the transition zone when peg initiation occurs. Northern blotting showed that patterns of CsGRP1 mRNA accumulation corresponded to the results of FDD. However, gravitropically bending hypocotyls did not show such differential expression of CsGRP1. Our results suggest that CsGRP1 is possibly involved in the suppression of peg formation during gravimorphogenesis of cucumber seedlings.
