Citrus rootstock breeding for adaptation to climate change and to sustainable production systems

Last update: 16 March 2018

Citrus fruits, which originate from Asia, are now grown between the 40th parallels North and South in highly varied production and marketing systems. These different Citrus growing systems have to cope with increasing biotic and abiotic stress linked to climate change, and with the strong expectations of society in terms of environmental friendliness and input reduction. Traits of adaptation to these varied and changing environments, and traits of resistance to various diseases, are mainly sought in rootstocks.

Breeding objectives

Resistance to Phytophthora and to the Tristeza virus are essential criteria for all the production basins (Ollitrault and Navarro, 2012). The consequences of global warming make tolerance of salinity and water stress a major breeding target. Tolerance of iron chlorosis on calcareous sols is also very important in the Mediterranean Basin.  Lastly, for most tropical regions, the selection of rootstocks less affected by Citrus greening, a bacterial disease that causes considerable damage, has become a core objective.

Breeding strategies and methods

Given the increased plasticity traits displayed by tetraploid citrus fruits, rootstock breeding at SEAPAG focuses on creating tetraploid rootstocks by somatic hybridization (Ollitrault et al., 2007; Dambier et al., 2011), through the selection of spontaneous doubled diploids (Aleza et al., 2011) or by sexual hybridization at tetraploid level.

Achievements

An allotetraploid hybrid obtained by somatic hybridization (FLHORAG1: C. deliciosa + Poncirus trifoliata) displays some very worthwhile traits for constraints in the Mediterranean Basin (resistance to the Tristeza virus and to Phytophthora, tolerance of calcareous soils, fruit quality of the grafted varieties; Dambier et al., 2011). Several doubled diploid rootstocks (tetraploid Citrumelo 4475, Citrandarin Cleopatra x Poncirus, in particular) are also promising and, along with FLHORAG1, are entering multi-site assessment in a network with different partner countries. Several hundred sexual tetraploid hybrids of intergeneric origin (Citrus/Poncirus) have been created and are entering assessment in Guadeloupe for the main constraints in tropical citrus fruit systems.

References cited

  • Aleza P., Froelicher Y., Schwarz S., Agusti M., Hernandez M., Juarez J., Luro F., Morillon R., Navarro L., Ollitrault P. (2011) Tetraploidization events by chromosome doubling of nucellar cells are frequent in apomictic citrus and are dependent on genotype and environment. Annals of Botany, 108 (1) : p. 37-50.
  • Dambier D., Benyahia H., Pensabene-Bellavia G., Aka Kacar Y., Froelicher Y., Belfalah Z., Beniken L., Handaji N., Printz B., Morillon R., Yesiloglu T., Navarro L., Ollitrault P. (2011) Somatic hybridization for citrus rootstock breeding: An effective tool to solve some important issues of the Mediterranean citrus industry. Plant Cell Reports, 30 (5) : p. 883-900.
  • Ollitrault P., Guo W. and Jude Grosser W. (2007) Recent Advances and Evolving Strategies in Citrus Somatic Hybridization. In Citrus Genetics, Breeding and Biotechnology. I. Khan Edit. CABI publishing. 235-260.
  • Ollitrault, P., Navarro, L. (2012) Citrus. In: Badenes, M.L.B., D.H (ed. Fruit breeding. New-York, USA: Springer, p. 623-662.  (Handbook of Plant Breeding, vol. 8). http://dx.doi.org/10.1007/978-1-4419-0763-9_16

Last update: 16 March 2018