The rose INFLORESCENCE DEFICIENT IN ABSCISSION-LIKE genes, RbIDL1 and RbIDL4, regulate abscission in an ethylene-responsive manner.

RbIDL1 and RbIDL4 are up-regulated in an ethylene-responsive manner during rose petal abscission and restored the Arabidopsis ida-2 mutant abscission defect suggesting functional conservation of the IDA pathway in rose. Abscission is an ethylene-regulated developmental process wherein plants shed unwanted organs in a controlled manner. The INFLORESCENCE DEFICIENT IN ABSCISSION family has been identified as a key regulator of abscission in Arabidopsis, encoding peptides that interact with receptor-like kinases to activate abscission. Loss of function ida mutants show abscission deficiency in Arabidopsis. Functional conservation of the IDA pathway in other plant abscission processes is a matter of interest given the discovery of these genes in several plants. We have identified four members of the INFLORESCENCE DEFICIENT IN ABSCISSION-LIKE family from the ethylene-sensitive, early-abscising fragrant rose, Rosa bourboniana. All four are conserved in sequence and possess well-defined PIP, mIDa and EPIP motifs. Three of these, RbIDL1, RbIDL2 and RbIDL4 show a three-fourfold increase in transcript levels in petal abscission zones (AZ) during ethylene-induced petal abscission as well as natural abscission. The genes are also expressed in other floral tissues but respond differently to ethylene in these tissues. RbIDL1 and RbIDL4, the more prominently expressed IDL genes in rose, can complement the abscission defect of the Arabidopsis ida-2 mutant; while, promoters of both genes can drive AZ-specific expression in an ethylene-responsive manner even in Arabidopsis silique AZs indicating recognition of AZ-specific and ethylene-responsive cis elements in their promoters by the abscission machinery of rose as well as Arabidopsis.