**6. Olive**

levels

Gene transformation to olive cultivars is considered as a difficult task due to recalcitrant nature of their tissues to regeneration process in vitro condition; however, it stays the most promising technique in respect to conventional and unconventional and even some biotechnological methods such as protoplast and somaclonal variation techniques. Classical methods of the olive breeding are more time-consuming, with very low efficient, due to lengthy seedling juvenile phase, alternation bearing, low fruitfulness, and low seed germinability [41–43].

The same as the other tropical fruit trees, the most of olive gene transformation studies were conducted using *Agrobacterium*-mediated transformation. However, there are few reports on the gene transformation by means of biolistic method in which most of them were down to optimization of scorable and selectable marker genes. Successfully transferred *gus* gene under the control of sunflower ubiquitin promoter in to small somatic embryos of Canino olive cultivar by biolistic method was reported by [44]. Afterward [45] bombarded the embryogenic tissues of Picual cultivar with three different plasmid constructs harboring *gus* gene under control of 35S, 35S with enhancer and sunflower ubiquitin promoters, and found that the ubiquitin promoter could significantly enhance the *gus* gene expression in olive.

**Author details**

Mousa Mousavi1

Ahvaz, Ahvaz, Iran

**References**

University of Ahvaz, Ahvaz, Iran

DOI: 10.4236/ajps.2016.71019

DOI: 10.20546/ijcmas.2018.707.312

2017.608.241

4614-0920-5\_5

Biology. 2002;**40**:1387-1392

\* and Mohsen Brajeh Fard2

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1 Department of Horticulture Science, Faculty of Agriculture, Shahid Chamran University of

Genetic Improvement of Tropical and Subtropical Fruit Trees via Biolistic Methods

http://dx.doi.org/10.5772/intechopen.81373

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2 Department of Agronomy and Plant Breeding, Faculty of Agriculture, Shahid Chamran

\*Address all correspondence to: m.mousavi@scu.ac.ir

More recently, [41] introduced an optimized protocol for transformation of olive cv. Picual embryogenic callus with *gus* gene under the control of sunflower ubiquitin promoter and *npt*II selective gene (**Table 1**) and achieved 72.7% transformation efficiency for embryogenic calli.
