Recent Advances of In Vitro Culture for the Application of New Breeding Techniques in Citrus

Abstract

Citrus is one of the most important fruit crops in the world. This review will discuss the recent findings related to citrus transformation and regeneration protocols of juvenile and adult explants. Despite the many advances that have been made in the last years (including the use of inducible promoters and site-specific recombination systems), transformation efficiency, and regeneration potential still represent a bottleneck in the application of the new breeding techniques in commercial citrus varieties. The influence of genotype, explant type, and other factors affecting the regeneration and transformation of the most used citrus varieties will be described, as well as some examples of how these processes can be applied to improve fruit quality and resistance to various pathogens and pests, including the potential of using genome editing in citrus. The availability of efficient regeneration and transformation protocols, together with the availability of the source of resistance, is made even more important in light of the fast diffusion of emerging diseases, such as Huanglongbing (HLB), which is seriously challenging citriculture worldwide.

SuperSour: A New Strategy for Breeding Superior Citrus Rootstocks

“…Some progress has also been made in efforts to use genome editing to improve disease resistance ( Peng et al, 2017 ; Jia et al, 2019 ; Wang et al, 2019 ). Although numerous groups have made very large investments of resources into Agrobacterium -mediated transformation and genome editing of citrus ( Poles et al, 2020 ), as of now, no citrus rootstocks derived from GMO technology or genome editing have become commercially available. While new technologies offer abundant options for continuing work, none has yet proven successful in creating rootstocks of commercial importance, and it seems likely that conventional breeding will continue to have the primary role in the development of the next generation of citrus rootstocks in the coming decade.…”

De Novo Transcriptome Sequencing of Rough Lemon Leaves (Citrus jambhiri Lush.) in Response to Plenodomus tracheiphilus Infection

“…In this context, next-generation high-throughput sequencing techniques have become an increasingly useful tool for exploring whole plant genomes, providing a means for analyzing plant molecular regulatory mechanisms in specific abiotic and biotic stress conditions. The identification of candidate genes is a prerequisite for the application of new genome editing techniques by which targeted genetic modifications can lead to the introduction of precise changes directly into the genome of commercial varieties, offering an alternative to traditional methods of genetic improvement [ 19 , 20 , 21 ]. Different authors in the last years conducted transcriptomic analysis to better understand Citrus plants response to biotic stress caused by pathogens [ 22 , 23 , 24 , 25 , 26 , 27 ].…”

Effects of Foliar Spraying with Different Concentrations of Selenium Fertilizer on the Development, Nutrient Absorption, and Quality of Citrus Fruits

“…Citrus fruits are one of the most important fruits, ranking first among the four major fruits in the world; their production is mainly distributed across 135 countries and the tropical and subtropical regions (Poles et al, 2020). As the origin and the main producing area of citrus, China ranks first in the cultivation area and output in the world, with a long history of citrus cultivation (Liu et al, 2019).…”