Isolation and characterization of genetic elements related to periodicity and fruit detachment in olive
Özet
Periodicity and difficult fruit detachment in olive cause significantyield loss for olive growers. These features greatly differ fromcultivar to cultivar pointing the genetic factors’ roles with theseprocesses. The objective of this investigation was to isolate andcharacterize genetic elements associated with periodicity andthose with fruit detachment. For this purpose, multiple cDNAlibraries were constructed from the leaves of “on year” trees andthose of “off year” in July and November. For fruit detachmentanalysis, a cDNA library from the pedicels of an easy detachingcultivar and another library from that of a tight holder cultivarwere prepared. Several hundred arbitrarily selected colonies fromeach library were analysed and the inserts from the positiveclones were sequenced. All the cDNA seqeunces were first ana-lyzed and those that seemed to be associated with alternate bear-ing and/or fruit detachment were further characterised withrespect to temporal/spatial expression patterns, polymorphism,genomic copy number and biochemical function. Most of theinsert sequences from each library were homologs of organellesequences. rDNA sequences were abundant while their base com-positions were sigficantly different depending of their origin.cDNAs specific to each library were further analysed for theirfunctions. Two cDNAs were determined as dehydrins withincreased expressions under temperature stress. A metallothioneinisolated from fruited leaves in November accumulated multiplemetals when expressed in bacteria. Another cDNA isolated from unfruited leaves in November displayed multiple open readingframes. cDNAs from pedicels yielded homologs of genes with cellwall degrading functions along with many transposons. Detailedfunctional analysis of these genes and their transcription controlmechanism will greatly help devicing genetic solutions againstalternate bearing and hard fruit detachment that are significanteconomical value for olive growers.
