Can Ethylene Inhibitors Enhance the Success of Olive Somatic Embryogenesis?

Muhammad Ajmal Bashir,Eddo Rugini,Cristian Silvestri,Samanta Zelasco,Amelia Salimonti,Valerio Cristofori

doi:10.3390/plants11020168

Muhammad Ajmal Bashir, Eddo Rugini + Show 4 more

Open Access

https://doi.org/10.3390/plants11020168

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Abstract

An efficient in vitro morphogenesis, specifically through somatic embryogenesis, is considered to be a crucial step for the application of modern biotechnological tools for genetic improvement in olive (Olea europaea L.). The effects of different ethylene inhibitors, i.e., cobalt chloride (CoCl2), salicylic acid (SA), and silver nitrate (AgNO3), were reported in the cyclic somatic embryogenesis of olive. Embryogenic callus derived from the olive immature zygotic embryos of the cultivar Leccino, was transferred to the expression ECO medium, supplemented with the ethylene inhibitors at 20 and 40 µM concentrations. Among these, the maximum number of somatic embryos (18.6) was obtained in media containing silver nitrate (40 µM), followed by cobalt chloride (12.2 somatic embryos @ 40 µM) and salicylic acid (40 µM), which produced 8.5 somatic embryos. These compounds interfered on callus traits: white friable embryogenic calli were formed in a medium supplemented with 40 µM cobalt chloride and salicylic acid; in addition, a yellow-compact embryogenic callus appeared at 20 µM of all the tested ethylene inhibitors. The resulting stimulatory action of silver nitrate among all the tested ethylene inhibitors on somatic embryogenesis, clearly demonstrates that our approach can efficiently contribute to the improvement of the current SE protocols for olive.

Highlights

Olive (Olea europaea L.) plants belong to the family Oleaceae, and are one of the most popular species of the genus Olea, which is commonly grown in the Mediterranean region and used for food purposes [1]
The findings of this study demonstrate that ethylene inhibitors, AgNO3 and to a lesser extent CoCl2 and salicylic acid (SA), enhanced the somatic embryogenic ability in olive explants (Table 3)
An efficient and rapid protocol was developed for a more efficient somatic embryogenesis by using ethylene inhibitors, which has paved a path to overcome the double regeneration technique that has been previously adopted for mature tissues of olive cultivars [11]

Summary

Introduction

Olive (Olea europaea L.) plants belong to the family Oleaceae, and are one of the most popular species of the genus Olea, which is commonly grown in the Mediterranean region and used for food purposes [1]. More than 750 million olive trees are cultivated worldwide. Among the more than one thousand known varieties, of which there are about 600 in Italy, very few are suitable for modern cultivation systems, and the development of novel cultivars is often hampered by the most commonly used breeding techniques that are time-consuming [2]. In vitro morphogenesis through somatic embryogenesis is considered as the fundamental step for the application of different biotechnological tools for unconventional breeding in many fruit species, including olives [1]. Somatic embryogenesis has been achieved from mature tissues [1,11,12,13,14,15]. The induction and regeneration of somatic embryos are highly sensitive to culture conditions, such as the medium composition, physical environment of the culture, and the genotype and explant source, especially in olives [1,2,15,16]

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