Recent advances in strawberry (Fragaria x ananassa) breeding helped to improve productivity, quality, and sustainability of cultivation worldwide, providing producers and consumers with an ever-widening range of high-quality cultivars characterized by distinctive traits, adaptability to different soils, climates, and cultivation systems. The optimization of all the steps in strawberry breeding programs and the implementation of new biotechnological tools aimed at characterizing and selecting the best genotypes are essential. This includes hybridizations, seed germination protocols, phenotypic selection, genotypic selection, and tailored propagation methods to ensure the stability of desired cultivar traits. This experimental work was focused on the improvement of different critical steps characterizing a strawberry breeding program, starting from seed germination to propagation of new genotypes. The Ph. D. dissertation describes four main experimental trials. The first experiment was focused on a scarification and germination protocol, implemented to obtain a higher germination rate of strawberry seeds. The scarified seeds, belonging to three different genotypes, were compared to non-treated seeds. The scarification treatment was done through H2SO4 use, followed by sterilization in NaCl solution. All seeds, scarified and non-treated controls, were placed to germinate in three different germination media (peat, filter sterile paper, MS in vitro medium) and then phenotypically characterized, at the plantlet stage. The scarified seeds gave a higher germination rate without differences among genotypes and germination media. Seed germination in peat led to the best results in vegetative plant development. The second part of the work was focused on the increase of genetic variability, in a private breeding program, through the production of new hybrid progenies. This trial consisted of different phases: i) selection of relatives, ii) their controlled hybridization, iii) germination of the new seeds obtained, iv) subjective evaluation of seedlings obtained, and v) subjective and objective assessments of the first-level selections. The analysis of the data individuated the best genotypes from first-level selections, which represent useful material for the next steps of the breeding program. The third research topic of this dissertation describes the phenotypic characterization of six strawberry crossing populations, based on subjective and objective parameters. Data collected revealed significant differences in terms of quality and production parameters, giving information about the combinatorial ability of relatives. This plant material will be exploited for high-throughput genotypic analysis, to be associated with the collected phenotypic information. This study will allow the in-depth evaluation of the most important strawberry traits, useful to improve fruit quality and satisfy consumer preferences. The fourth trial was conducted at Genson quality plants, in the Netherlands, where different cultivation systems were evaluated on two different varieties to determine the most appropriate method for plant propagation. In particular, different pot sizes, plant propagation origins, and treatments for fungal disease control, were tested. Results highlighted that pot size, the genotype, and the origin of plant propagation material significantly influenced the quality of the plants. This study emphasized the importance of genetic diversity within breeding programs, and the improvement of critical steps, to ensure the sustainability and competitiveness of the strawberry industry by allowing cultivars with improved traits. The key findings of Ph. D. experimental work were: The optimized and standardized strawberry seeds scarification protocol, can contribute to the efficiency of the seed germination process in breeding programs or for other purposes, i.e. open the door of gamic propagation in strawberries, facilitating the F1 hybrids propagation thanks to the over-binding of germination critical step. The wide genetic variability of new breeding material is useful as new breeding lines for future breeding programs, for patenting, as new commercial varieties, or for exploitation of interesting new breeding traits. The massive phenotypic characterization is useful for the calibration of high-throughput genomic tools, in order to embrace the molecular breeding of strawberry. Through phenotypic and genotypic analyses, future breeding programs can produce resilient cultivars with high-quality fruit, improving sustainability and competitiveness for growers.
I recenti progressi nel breeding della fragola (Fragaria x ananassa) hanno contribuito a migliorare la produttività, la qualità e la sostenibilità della coltivazione in tutto il mondo, fornendo a produttori e consumatori una gamma sempre più ampia di cultivar di alta qualità caratterizzate da tratti distintivi, adattabilità a diversi terreni, climi e sistemi di coltivazione. L'ottimizzazione di tutte le fasi dei programmi di selezione e l'implementazione di nuovi strumenti biotecnologici, finalizzati alla caratterizzazione e alla selezione dei migliori genotipi, sono essenziali. Ciò include ibridazioni, protocolli di germinazione dei semi, selezione fenotipica, selezione genotipica e metodi di propagazione personalizzati per garantire la stabilità dei tratti desiderati della cultivar. Questo lavoro sperimentale è incentrato sul miglioramento delle diverse fasi critiche che caratterizzano un programma di breeding della fragola, a partire dalla germinazione dei semi fino alla propagazione di nuovi genotipi. Il protocollo di scarificazione e germinazione implementato in questo lavoro ha portato a un alto tasso di germinazione di tutti i genotipi di fragola testati. Il substrato più efficiente è stato la torba, che ha anche indotto il miglior sviluppo vegetativo della pianta, seguito da un terreno di coltura in vitro MS. Questo protocollo ottimizzato può contribuire all'efficienza del processo di germinazione dei semi nei programmi di riproduzione o per altri scopi. La seconda parte del lavoro si è concentrata sull'aumento della variabilità genetica in un programma di breeding privato attraverso la produzione di nuove progenie ibride. La valutazione fenotipica delle caratteristiche di piante e frutti ha mostrato variazioni tra le diverse popolazioni incrociate, indicando la capacità combinatoria dei parenti utilizzati. Le valutazioni soggettive e oggettive delle selezioni di primo livello hanno fornito risultati promettenti. La caratterizzazione fenotipica di sei popolazioni di incrocio ha rivelato differenze significative nei parametri di qualità e produzione, fornendo informazioni sulla capacità combinatoria dei parentali. L'analisi genotipica ad alto rendimento sarà implementata utilizzando le informazioni fenotipiche raccolte, consentendo una valutazione approfondita e mettendo in evidenza il potenziale di strategie di selezione mirate per ottimizzare i tratti qualitativi dei frutti e soddisfare le preferenze dei consumatori. Questo studio ha sottolineato l'importanza della diversità genetica all'interno dei programmi di selezione e il miglioramento delle fasi critiche, per garantire la sostenibilità e la competitività del settore fragolicolo, consentendo di ottenere cultivar con caratteristiche migliori. Attraverso analisi fenotipiche e genotipiche, i futuri programmi di selezione potranno produrre cultivar resilienti con frutti di alta qualità, migliorando la sostenibilità e la competitività per i coltivatori.
A new strawberry (Fragaria x ananassa) breeding program to advance critical steps and obtain new resilient and high-quality cultivars / Giovanetti, Giammarco. - (2024 Jun 19).
A new strawberry (Fragaria x ananassa) breeding program to advance critical steps and obtain new resilient and high-quality cultivars
GIOVANETTI, GIAMMARCO
2024-06-19
Abstract
Recent advances in strawberry (Fragaria x ananassa) breeding helped to improve productivity, quality, and sustainability of cultivation worldwide, providing producers and consumers with an ever-widening range of high-quality cultivars characterized by distinctive traits, adaptability to different soils, climates, and cultivation systems. The optimization of all the steps in strawberry breeding programs and the implementation of new biotechnological tools aimed at characterizing and selecting the best genotypes are essential. This includes hybridizations, seed germination protocols, phenotypic selection, genotypic selection, and tailored propagation methods to ensure the stability of desired cultivar traits. This experimental work was focused on the improvement of different critical steps characterizing a strawberry breeding program, starting from seed germination to propagation of new genotypes. The Ph. D. dissertation describes four main experimental trials. The first experiment was focused on a scarification and germination protocol, implemented to obtain a higher germination rate of strawberry seeds. The scarified seeds, belonging to three different genotypes, were compared to non-treated seeds. The scarification treatment was done through H2SO4 use, followed by sterilization in NaCl solution. All seeds, scarified and non-treated controls, were placed to germinate in three different germination media (peat, filter sterile paper, MS in vitro medium) and then phenotypically characterized, at the plantlet stage. The scarified seeds gave a higher germination rate without differences among genotypes and germination media. Seed germination in peat led to the best results in vegetative plant development. The second part of the work was focused on the increase of genetic variability, in a private breeding program, through the production of new hybrid progenies. This trial consisted of different phases: i) selection of relatives, ii) their controlled hybridization, iii) germination of the new seeds obtained, iv) subjective evaluation of seedlings obtained, and v) subjective and objective assessments of the first-level selections. The analysis of the data individuated the best genotypes from first-level selections, which represent useful material for the next steps of the breeding program. The third research topic of this dissertation describes the phenotypic characterization of six strawberry crossing populations, based on subjective and objective parameters. Data collected revealed significant differences in terms of quality and production parameters, giving information about the combinatorial ability of relatives. This plant material will be exploited for high-throughput genotypic analysis, to be associated with the collected phenotypic information. This study will allow the in-depth evaluation of the most important strawberry traits, useful to improve fruit quality and satisfy consumer preferences. The fourth trial was conducted at Genson quality plants, in the Netherlands, where different cultivation systems were evaluated on two different varieties to determine the most appropriate method for plant propagation. In particular, different pot sizes, plant propagation origins, and treatments for fungal disease control, were tested. Results highlighted that pot size, the genotype, and the origin of plant propagation material significantly influenced the quality of the plants. This study emphasized the importance of genetic diversity within breeding programs, and the improvement of critical steps, to ensure the sustainability and competitiveness of the strawberry industry by allowing cultivars with improved traits. The key findings of Ph. D. experimental work were: The optimized and standardized strawberry seeds scarification protocol, can contribute to the efficiency of the seed germination process in breeding programs or for other purposes, i.e. open the door of gamic propagation in strawberries, facilitating the F1 hybrids propagation thanks to the over-binding of germination critical step. The wide genetic variability of new breeding material is useful as new breeding lines for future breeding programs, for patenting, as new commercial varieties, or for exploitation of interesting new breeding traits. The massive phenotypic characterization is useful for the calibration of high-throughput genomic tools, in order to embrace the molecular breeding of strawberry. Through phenotypic and genotypic analyses, future breeding programs can produce resilient cultivars with high-quality fruit, improving sustainability and competitiveness for growers.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
