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Plant Cell Rep (2011) 30:883900 DOI 10.1007/s00299-010-1000-z
ORIGINAL PAPER
Somatic hybridization for citrus rootstock breeding: an effective tool to solve some important issuesof the Mediterranean citrus industry
Dominique Dambier Hamid Benyahia Giovanni Pensabene-Bellavia Yildiz Aka Kaar
Yann Froelicher Zina Belfalah Beniken Lhou Najat Handaji Bruno Printz
Raphael Morillon Turgut Yesiloglu Luis Navarro Patrick Ollitrault
Received: 29 October 2010 / Revised: 29 December 2010 / Accepted: 30 December 2010 / Published online: 12 January 2011 Springer-Verlag 2011
Abstract The prevalence of sour orange rootstock in the southern and eastern part of the Mediterranean Basin is presently threatened by the spread of Citrus Tristeza Virus (CTV) and its main vector Toxoptera citricida, combined with abiotic constraints such as drought, salinity and alkalinity. The search for alternative CTV-resistant rootstocks that also withstand the other constraints is now considered an urgent priority for a sustainable citrus industry in the area. Complementary progenitors can be found in citrus germ-plasm to combine the desired traits, particularly between Poncirus and Citrus genera. The production of somatic hybrids allows cumulating all dominant traits irrespective of
their heterozygosity level, and would appear to be an effective way to solve the rootstock challenge facing the Mediterranean citrus industry. This paper presents the results obtained during a regional collaborative effort between ve countries, to develop new rootstocks by somatic hybridization. New embryogenic callus lines to be used for somatic hybridization have been created. Protoplast fusions have been performed at CIRAD and IVIA laboratories, focusing on intergeneric combinations. Analysis of ploidy level by ow cytometry and molecular markers conrmed the acquisition of new interesting tetraploid somatic hybrids for six combinations. Diploid cybrids with intergeneric (Citrus 9 Poncirus) nucleus and C. reticulata or C. aurantifolia mitochondria were also identied for four combinations. The agronomical performance of a preexisting somatic hybrid between Poncirus trifoliata and Citrus reticulata was validated in calcareous soils in Morocco. Somatic hybridization is now integrated into the breeding programs of the ve Mediterranean countries.
Keywords Somatic hybridization Rootstock Citrus
Poncirus Allotetraploid
Introduction
The citrus industry is one of the main components of Mediterranean agriculture, covering 1.1 million hectares in 2009 (FAOStat 2010), and helping to guarantee incomes in underprivileged rural zones. Furthermore, citrus fruits provide the main source of vitamin C in the Mediterranean Basin,...