Polymorphisms in the AOX2 gene are associated with the rooting ability of olive cuttings

Abstract

Different rooting ability candidate genes were tested on an olive cross progeny. Our results demonstrated that only the AOX2 gene was strongly induced. OeAOX2 was fully characterised and correlated to phenotypical traits. The formation of adventitious roots is a key step in the vegetative propagation of trees crop species, and this ability is under strict genetic control. While numerous studies have been carried out to identify genes controlling adventitious root formation, only a few loci have been characterised. In this work, candidate genes that were putatively involved in rooting ability were identified in olive (Olea europaea L.) by similarity with orthologs identified in other plant species. The mRNA levels of these genes were analysed by real-time PCR during root induction in high- (HR) and low-rooting (LR) individuals. Interestingly, alternative oxidase 2 (AOX2), which was previously reported to be a functional marker for rooting in olive cuttings, showed a strong induction in HR individuals. From the OeAOX2 full-length gene, alleles and effective polymorphisms were distinguished and analysed in the cross progeny, which were segregated based on rooting. The results revealed a possible correlation between two single nucleotide polymorphisms of OeAOX2 gene and rooting ability.

Reviewing current knowledge on olive (Olea europaea L.) adventitious root formation

“…In such cases, it's shown that difficult-to-root cultivars struggle to control free auxin levels after the induction phase. The first results from genomic studies are now starting to emerge, with emphasis on the differential expression of AOX genes in easy-and difficult-to-root plants (Hedayati et al, 2015).…”

Alternative Oxidase Gene Family in Hypericum perforatum L.: Characterization and Expression at the Post-germinative Phase

“…These observations are highly promising for a perspective toward FM development. Sequence variability at intron level in AOX genes has been suggested as a good source for functional polymorphisms that could be useful for FM development (Cardoso et al, 2009 , 2011 ; Santos Macedo et al, 2009 ; Hedayati et al, 2015 ). In the present study, the identification of SSRs located at intronic regions of both HpAOX genes makes them genes of interest for further search for variability among genotypes that could be used for FM development.…”

AOX1-Subfamily Gene Members in Olea europaea cv. “Galega Vulgar”—Gene Characterization and Expression of Transcripts during IBA-Induced in Vitro Adventitious Rooting

“…Clifton et al [ 12 , 13 ] pointed to the importance of this alternative respiratory pathway as an early-sensing system for cell programming. The involvement of AOX in AR has been also taken as an important research topic, not only in view of understanding the role of the genes during the AR process, but also to further develop functional markers in order to be able to select genotypes that show efficient cell reprogramming [ 4 , 14 , 15 ].…”

“…In the context of AR in olive, the AOX2 -subfamily gene member has been the main focus of AOX research. In addition to understanding the involvement of AOX gene members in the AR process, and in view of the development of further functional markers that are able to discriminate between genotypes with different potential to develop adventitious roots, gene sequence variability has been investigated [ 4 , 14 , 15 ]. AOX sequence variability, located in the protein coding and non-coding regions, has been reported in different plant species [ 4 , 28 , 29 , 30 , 31 , 32 ].…”

“…Abe et al [ 34 ] were the first research group to indicate the relevance of AOX polymorphisms in abiotic stress tolerance by identifying in the Oryza sativa AOX1a a SNP that mapped to a region of a QTL for low temperature tolerance in anthers at the booting stage. More recently, Hedayati et al [ 15 ] reported the existence of two SNPs located at intron 3 of OeAOX2 that correlate with differences in rooting ability.…”