Search

In this review, we present genetically modified (GM) horticultural events that have passed the regulatory process and have been approved for cultivation or food use in different countries. The first authorization or deregulation of a GM horticultural plant issued 25 years ago initiated a fast expansion of GM organisms (GMO) engineered by using gene transfer technology. The list of GM horticultural species comprises representatives of vegetables, fruit plants and ornamentals. We describe their unique characteristics, often not achievable by conventional breeding, and how they were developed, and the approval process. Information on the adoption of GM horticultural cultivars and sale is accessed if commercialization has occurred. The review comprises, among others, Flavr SavrTM and other tomato cultivars with delayed ripening and improved shelf-life, insect-resistant eggplant (or brinjal), as well as virus-resistant squash, melon and the common bean, and also fruit trees, plum and papaya. Cultivation of the latter was particularly valuable to farmers in Hawaii as it ensured restoration of papaya production devastated earlier by the Papaya ringspot virus (PRSV). In contrast, a plum resistant to sharka (Plum pox virus; PPV) deregulated in the USA is still awaiting commercialization. GM events with improved quality include the recently marketed non-browning apple and high-lycopene pineapple. We also present orange petunia, blue ‘Applause’ rose and Moon-series carnations with a modified purple and violet flower colour. Finally, we discuss prospects of GM horticultural plants, including their development using promising new breeding technologies relying on genome editing and considered as an alternative to the transgenic approach.

Background: Haploid plant material is considered as recalcitrant to organogenesis, propagation, and maintenance in vitro. However, sugar beet (Beta vulgaris L.) breeders utilizing doubled haploid (DH) technology in their breeding programs indicate that sugar beet haploids may be cultured in vitro as well as diploids. Thus in this paper the in vitro performance of haploid and the doubled haploid sugar beet of various origin was evaluated. The DHs were derived from haploids by diploidization and twelve such haploid and corresponding DH clone pairs were obtained thus the comparison included haploid and DH clones that had identical allelic composition and differed only in their ploidy level. Results: The genotypes differed in shoot morphology and susceptibility to blackening during culture in vitro, but no significant differences were observed between the haploids and DHs. The micropropagation rate was, on average, higher for the haploids than DHs. Viability of the midrib and petiole explants after a 6-week culture was highly genotype dependent, but not affected by explant ploidy level. However, regeneration efficiency depended on both the genotype and ploidy level. The explants of several haploids regenerated more frequently and developed more adventitious shoots than the corresponding DHs thus overall efficiency was higher for haploids. Conclusions: The results obtained indicate that most of the haploids used in the comparison performed similar to or even better than DHs. This suggests that sugar beet haploid material can be successfully used not only for the production of DHs, but also maintained in vitro and utilized in projects requiring haploid tissues as the source material. [ABSTRACT FROM AUTHOR]

The development of the Clustered Regularly Interspersed Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas9) system has advanced genome editing and has become widely adopted for this purpose in many species. Its efficient use requires the method adjustment and optimization. Here, we show the use of a model carrot callus system for demonstrating gene editing via CRISPR/Cas9 targeted mutagenesis. The system relies on the utilization of carrot tissue accumulating anthocyanin pigments responsible for a deep purple cell color and generation of knockout mutations in the flavanone-3-hydroxylase (F3H) gene in the anthocyanin biosynthesis pathway. F3H mutant cells targeted by Cas9/gRNA complexes are not able to synthesize anthocyanins and remain white, easily visually distinguished from purple wild-type cells. Mutations are either small indels or larger chromosomal deletions that can be identified by restriction fragment analysis and sequencing. This feasible system can also be applied for validating efficiency of CRISPR/Cas9 vectors.