LIBRO-CONGRESO-CITRUS

S02O06
Citrus breeding in South Africa: the latest developments in the programme run by the ARC-
Institute for tropical and subtropical crops.
Sippel A.D., Bijzet Z., Froneman I.J., Combrink N.K., Maritz J.G.J., Hannweg K.F., Severn-Ellis A.A., and Manicom B.Q.
Agricultural Research Council - Institute for Tropical and Subtropical Crops (ARC - ITSC), Plant Improvement, South Africa.
arthur@arc.agric.za
The South African Agricultural Research Council’s Citrus Plant Improvement Programme run by the Institute
for Tropical and Subtropical Crops consists of a number of separate projects. These involve conventional scion
breeding to improve productivity and quality, rootstock breeding for soil adaption, disease resistance and
improved yields, mutation breeding, and evaluation of both scions and rootstocks in different climatic zones.
These projects are also supported through the Citrus Improvement Programme, a vast germplasm collection,
various biotechnology techniques such as embryo rescue and ploidy manipulation, and the use of molecular
markers to distinguish between, at this stage citrus mandarin selections. This paper will give a short overview
of the research activities within each of the projects, as well as the most important results achieved by each.
S02O07
Highlights of the University of Florida, Citrus Research and Education Center’s comprehensive
citrus breeding and genetics program
Grosser J.W., Gmitter Jr. F.G., Ling P., and Castle W.S.
University of Florida, Institute of Food and Agricultural Sciences (IFAS), Citrus Research and Education Center (CREC), USA.
jgrosser@ufl.edu
A comprehensive citrus breeding and genetics program was established at the UF/CREC during the mid-1980’s
combining conventional breeding with tools provided by tissue culture, emerging biotechnologies, molecular
genetics and genomics. Scion Improvement: The Florida citrus industry is 90% processing sweet oranges. A
major goal has been to develop new cultivars for Not From Concentrate juice production with emphasis on
increasing juice quality and expanding seasonal availability. Improved clones from seedling introductions,
budwood irradiation and somaclonal variation will be discussed. The fresh fruit industry in Florida is dominated
by grapefruit and seedy mandarins. Primary objectives for fresh fruit improvement include expanding
seasonal availability, development of Canker tolerant and low furanocoumarin grapefruit, and development
of seedless, easy-peeling mandarins. The focus of our program has been on parent development, and
seedless triploid production via interploid crosses; strategies and successes will be discussed. Rootstock
Improvement: Initial focus was on improving soil adaptation, tree-size control to facilitate harvesting and
cold-protection, and disease resistance, especially to blight, CTV induced quick decline and Phytophthora.
Breeding objectives have since been expanded to include tolerance of the Diaprepes/Phytophthora complex
and HLB, and development of rootstocks that facilitate advanced citrus production systems (ACPS). Progress
from conventional breeding (both 2x and 4x) and somatic hybridization will be discussed. Genetic Engineering
and Genomics: Due to the HLB and Canker epidemics, focus has been on disease resistance gene discovery,
transformation, and evaluation of transgenic plants; progress will be discussed.
S02O08
Advance in S allele determination, S allele frequencies and S-genotyping in citrus
Wakana A., Handayani E., Kim J.H., Miyazaki R., Mori T., Sato M., and Sakai K.
Kyushu Univesity, Horticultural Science, Japan. wakana@agr.kyushu-u.ac.jp
Gametophytic self-incompatibility (SI) is known in pummelo, mandarin and cultivars with pummelo in their
pedigrees. Despite the importance of SI for citrus cultivation and breeding, little is known about the SI
genotypes of citrus cultivars. In this study, homozygous S 1 seedlings for the S gene were produced through
bud self-pollination of five monoembryonic SI cultivars, i.e., ‘Banpeiyu’ and ‘Hirado Buntan’ pummelos
(Citrus grandis), clementine (Citrus clementina) and ‘Ellendale’ mandarins and ‘Hassaku’ (Citrus hassaku).
The homozygosity of S 1 seedlings for S gene was determined by pollen tube penetration in the stylar base 8
XII INTERNATIONAL CITRUS CONGRESS 2012 - 39
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