SENESCENCE-INDUCED EXPRESSION OF A HOMOLOG OF DELTA-9 DESATURASE IN ROSE PETALS

cDNAs for senescence-inducible genes were isolated by differential hyb ridization from a cDNA library derived from mRNAs from the petals of r ose flowers. The amino acid sequence deduced from these cDNAs exhibite d significant homology to those of Delta 9 acyl-lipid desaturases of c yanobacteria and of Delta 9 acyl-CoA desaturases of a yeast and mammal s. There was no amino-terminal sequence indicative of a leader peptide for targeting to the chloroplasts or to mitochondria. Northern blot a nalysis indicated that the transcripts of the cDNAs were expressed spe cifically in petals at late developmental stages and during senescence . It is proposed that a Delta 9 desaturase in the senescing petals pla y an important role in the degradation of saturated fatty acids of mem brane lipids.