CRISPR/Cas as a Genome-Editing Technique in Fruit Tree Breeding.

CRISPR (short for "Clustered Regularly Interspaced Short Palindromic Repeats") is a technology that research scientists use to selectively modify the DNA of living organisms. CRISPR was adapted for use in the laboratory from the naturally occurring genome-editing systems found in bacteria. In this work, we reviewed the methods used to introduce CRISPR/Cas-mediated genome editing into fruit species, as well as the impacts of the application of this technology to activate and knock out target genes in different fruit tree species, including on tree development, yield, fruit quality, and tolerance to biotic and abiotic stresses. The application of this gene-editing technology could allow the development of new generations of fruit crops with improved traits by targeting different genetic segments or even could facilitate the introduction of traits into elite cultivars without changing other traits. However, currently, the scarcity of efficient regeneration and transformation protocols in some species, the fact that many of those procedures are genotype-dependent, and the convenience of segregating the transgenic parts of the CRISPR system represent the main handicaps limiting the potential of genetic editing techniques for fruit trees. Finally, the latest news on the legislation and regulations about the use of plants modified using CRISPR/Cas systems has been also discussed.

Responses of Persian walnut on foliar applications of different biostimulants.

Biostimulants have different effects on plants. The aim of this paper is to determine responses of the 'Alsószentiváni 117' walnut cultivar on foliar applications of different biostimulants (Wuxal Ascofol, Kondisol, Alga K Plus). The nut traits (nut length, nut diameter, nut weight, kernel weight) and some phenolic compounds of the kernel were measured and detected. In 2020, during warmer early spring weather conditions under pistillate flowering receptivity, chlorogenic acid and quercetin content of kernels treated with Kondisol were higher than in control. All biostimulants influenced positive effects on catechin and rutin content, as well as treatments made with Wuxal Ascofol and Kondisol increased the juglon content of the kernel. In 2021, when the spring weather was typical for that period, only the Kondisol treatments had increasing effects on the catechin and chlorogenic acid content, than the control. The rutin and quercetin concentrations reached the highest value in this trial by Alga K Plus applications. The juglon content decreased in this year compared to the control. The pirocathecin, cinnamic acid, and gallic acid (except Wuxal Ascofol treatment in 2021) content decreased in all treatments in both observed years. Responses of woody fruit species on biostimulants applications depend on the weather conditions. Biostimulants had positive effects on the nut size characteristics in both observed years.

Effects of Phenolic Compounds on Walnut Bacterial Blight in the Green Husk of Hungarian-Bred Cultivars.

The Persian walnut (Juglans regia L.) is the most grown nut tree crop in Central Europe. The aim was to study the full Hungarian walnut assortment with a distinct early spring phenology to detect the difference in phenolic profile in their green husks. Furthermore, the relationship between the presence and concentration of phenolic compounds and the tolerance/resistance of the observed cultivars to walnut bacterial blight was investigated. Examining the samples, significant differences were found between the concentrations of the different groups of phenolic compounds. Walnut blight immunity tests were also performed to clarify the role of phenolic compounds in the nut derived from a non-irrigated orchard. The Hungarian-bred local cultivars contained phenolic compounds in higher concentrations than the domesticated ones. There was a significant correlation between the budburst, as well as the pistillate flowers' receptivity and the concentration of juglone. Cultivars with a low concentration of phenolic compounds were the most susceptible to walnut bacterial blight, except 'Bonifác'.

Is "Esterhazy II", an Old Walnut Variety in the Hungarian Gene Bank, the Original Genotype?

The old walnut (Juglans regia L.) genotype called "Esterhazy II" was well-known in the Austro-Hungarian Monarchy before World War II, and it can still be found in the Austrian, German and Swiss backyard gardens today. Unfortunately, nowadays, vegetatively propagated progenies of the original "Esterhazy II" are not available anymore around the world because walnut grafting started later than this genotype had become well-known. Although various accessions with "Esterhazy II"-"blood" are available, it is difficult to determine which one can be considered true or the most similar to the original one. In this paper, phenological and nut morphological characteristics of an "Esterhazy II" specimen planted in a Hungarian gene bank were compared to the varieties "Milotai 10" and "Chandler". Examined characteristics were: budbreak, blossom time, type of dichogamy, ripening time, nut and kernel features. An additional SSR fingerprinting was used to identify identical genotypes and to demonstrate the relatedness of the analyzed "Esterhazy II" genotype to the other Hungarian walnut cultivars. It can be concluded that under the name "Esterhazy II", several different genotypes can be observed. All the checked characteristics except budbreak fitted well with the previous descriptions. Our results confirmed that the examined "Esterhazy II" genotype shows high similarity to the "original" "Esterhazy II" described in the literature.