Defense response enhancement in strawberry via elicitors

Abstract

In this study, cell-suspension culture of strawberry (Fragaria × ananassa), cultivars Camarosa, and Sweet Charlie has been established. Embryogenic callus was induced by incubating the in vitro juvenile leaf explants on medium, containing 2-mg/l picloram at dark. Suspension culture was initiated from 4-week-old embryogenic calli in the liquid MS medium with 1-mg/l 2,4-D and 2-mg/l picloram. Suspension culture was maintained by sub-culturing each 3 weeks into a fresh medium. At week 9 after third sub-cultures, torpedo and cotyledonary embryo stages were observed. Embryos were then developed into shoots on medium 1 mg/l of each BA and IBA. Obtained shoots were successfully rooted on 1-mg/ml GA3, 0.5-mg/ml BA, and 1-mg/ml IBA. To enhance the resistance availability in strawberry plants, elicitation was applied by adding the JA and SA elicitors to the suspension culture with two doses (0.5 and 1 mM) individually and in combination, in addition to the fungal homogenate of Macrophomina phasiolena at concentration of 10⁶ spor/ml. The fawrky-1-Camarosa gene, which has defense-related function, was detected in the different elicited strawberry tissues and isolated via RT-PCR. The isolated gene was submitted to GenBank with accession number (KX096885).

Keywords: Elicitors; Jasmonic acid; Salicyilic acid fawrky gene; Strawberry cell-suspension culture.

Fig. 1

Somatic embryogenesis via cell-suspension culture in strawberry: a callus formation, b big cell-aggregates produced in cell-suspension culture, c small cell-aggregates and single cells in suspension culture, d developed embryo on medium MS4, e regenerated shoots on medium MS4, and f rooted shoots

Fig. 2

RT-PCR results of the elicited strawberry tissues with different elicitors and concentrations right: M ladder 1 Kb, elicited tissues with 1 1.0-M SA/0.5-M JA, 2 1.0 -M SA, 3 1.0-M JA, and 4 negative control. left: M ladder 1 Kb, elicited tissues with 1 1.0-M JA/0.5-M SA and 2 0.5-M SA

Fig. 3

Blast x alignment shows 98 % homology with Fararia vesca subsp. Vescaprotein, 186 identical amino acids of a total 190. In faWRKY_1 (our sequence) Threonine (T) at position 6 was changed to Alanine (A), Serine (S) at position 36 was changed to Glycine (G), (A) was at position 48 changed to Glutamic acid (E) and Pheylalanine (F) to Leucine (L) at position 190