Screening Auxin Response, In Vitro Culture Aptitude and Susceptibility to Agrobacterium-Mediated Transformation of Italian Commercial Durum Wheat Varieties

Wilma Sabetta,Alexandra Soltész,Cinzia Montemurro,Cristina Crosatti,Valentina Di Rienzo

doi:10.3390/molecules21111440

Abstract

The development of a robust Agrobacterium-mediated transformation protocol for a recalcitrant species like durum wheat requires the identification and optimization of factors affecting T-DNA delivery and plant regeneration. The purpose of this research was to compare the behavior of diverse durum wheat genotypes during in vitro culture and Agrobacterium tumefaciens-mediated transformation, using immature embryos as explants. Apart from plant genotype, two of the main influencing factors for a successful genetic transformation have been examined here, i.e., auxin source (Dicamba and 2,4-D) and duration of the pre-culture period (one, seven and 21 days). The addition of Dicamba to the media in combination with seven days pre-cultivation resulted in a general enhancement of T-DNA delivery for most of the analyzed cultivars, as revealed by β-glucuronidase (GUS) histochemical assay. Although all genotypes were able to produce calli, significant differences were detected in regeneration and transformation efficiencies, since only two (Karalis and Neolatino) out of 14 cultivars produced fertile transgenic plants. The estimated transformation efficiencies were 6.25% and 1.66% for Karalis and Neolatino, respectively, and χ2 analysis revealed the stable integration and segregation of the gus transgene in T1 and T2 progenies. This research has demonstrated that, among the influencing factors, genotype and auxin type play the most important role in the success of durum wheat transformation.

Highlights

Wheat is certainly one of the most important and widespread crops in the world
A total of 3360 embryos dissected callus induction production capacity of immature several Italian durumwere wheat cultivars,and twothe auxins were tested: rate was calculated at the end of the pre-culture period, i.e.,were at the was observed that all the
Two types of synthetic auxin were tested: Dicamba and 2,4-D, which have distinct effects on the induction of cell division, proliferation and further regeneration, to exposure time and concentration [20,21,31]. Both auxins seemed to influence the formation of calli, since each wheat genotype responded in a comparable way to both treatments; the only exception was shown by cv Ancomarzio, whose callus formation was only extremely promoted by Dicamba

Summary

Introduction

Wheat is certainly one of the most important and widespread crops in the world. In particular, tetraploid durum wheat (Triticum turgidum L. var. durum) is mainly used to produce pasta and semolina for human consumption, while soft wheat (Triticum aestivum) is more widely cultivated for flour and bread-making. Wheat improvement has received considerable attention from plant breeders, whose efforts have mainly focused on increasing the yield potential, quality characteristics, resistance to biotic stresses and tolerance to abiotic stresses, depending on the regional requirement of the crop [1,2]. Scientific approaches have their history in conventional breeding techniques, principally based on the processes of crossing, back crossing and selection, which have the related disadvantages. This was how the first durum wheat transgenic and fertile plant, resistant to the broad spectrum herbicide

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