Fast-Track Breeding Strategies for Targeted Genotype Development in Fruit Crops
摘要
Traditional fruit breeding is a protracted and slow process primarily because of extended juvenility, higher heterozygosity, intricate reproductive biology, incomplete understanding of horticultural trait inheritance, higher field maintenance costs, and the necessity of large populations for effective selection. Incorporating resistance genes from wild fruit species is also time-intensive, involving multiple rounds of backcrossing with proficient donor parents. The development of a new apple cultivar that expresses traits from wild apples, with fruit quality competitive on a global scale, demands a period exceeding 50 years. Various techniques have been tried to shorten the juvenile phase in hybrid fruits across different crops, yet reducing this phase to less than 18 months has proven unattainable. To address these challenges, expedited breeding methods have emerged to compress breeding cycles. These strategies circumvent prolonged juvenility in fruit trees through transgenic expression of target genes. Compared to conventional approaches, the breeding duration for fruit trees can be reduced to one-fifth of the time. The introduction of the Arabidopsis LFY gene into fruit trees has successfully accelerated breeding processes. In transgenic citrus plants, significant reductions in the juvenile phase have been achieved. Similarly, suppression of TERMINAL FLOWER 1 homolog MdTFL1 in apple has notably curtailed the juvenile period, with successful applications in plum as well. Efforts to hasten breeding cycles are facilitated by diverse technologies including intense genotyping, marker-assisted selection, high throughput phenotyping, gene editing, genomic selection, and re-domestication. Integration of these technologies with speed breeding supports plant breeders in adapting to a changing climate and meeting the food demands of rapidly growing global population. Although still in its infancy for many fruit crops, the fast-track or speed breeding system warrants exploration to accelerate overall breeding processes, particularly in perennial fruit/plantation crops, thereby enhancing precision breeding for nationally significant fruits such as mango, walnut, citrus, banana, among others.