LIBRO-CONGRESO-CITRUS

S05
stoma density, size and opening differences between the genotypes were not enough to cause the reaction
variability related to Xac infection. In conclusion, citron ‘C-05’ is actively resistant to Canker disease.
S05O08
Genetic transformation of citrus species aiming to increase tolerance to drought stress
Carlos E.F., Ariyoshi C., Felício M.S., Shimizu P., Souza G.V., Kudo S.A., Silva L.M., Silva A.J.M., Cação S.M.B., and Vieira L.G.E.
Instituto Agronômico do Paraná (IAPAR), Laboratory of Biotechnology, Brazil. efcarlos@iapar.br
Most of the citrus trees grown in Brazil are extensively managed with no irrigation, leaving trees more
vulnerable to extended dry season, which may reach 90 days without rain in some areas. Thus, utilization
of rootstocks more tolerant to drought, such as ‘Rangpur’ lime (Citrus limonia), is widely employed, while
other rootstocks are not. Our laboratory has produced ‘Carrizo’ and ‘Swingle’ rootstocks that accumulate the
osmoprotectant aminoacid proline, and the present work has continued those efforts aimed to obtain new
transgenic rootstocks and scions more tolerant to drought stress. We employed Agrobacterium tumefaciens
carrying a gene encoding a mutant enzyme of P5CS (D1-pyrroline-5-carboxylate synthetase), a key enzyme
in the biosynthesis of proline, from Vigna aconitifolia, under control of either the constitutive CaMV 35S
promoter, or the stress induced RD29A promoter. We worked with sweet orange cultivars (Citrus sinensis)
and trifoliate rootstocks (Poncirus trifoliata cv. ‘Flying Dragon’ and P. trifoliata cv. ‘Rubidoux’). Two sweet
orange plantlets were micropropagated and further acclimated in greenhouse conditions. One of these trees
was PCR positive for the transgenes and presented a concentration of free proline 2.6 times higher than
its non-transgenic control plant. Four plantlets of juvenile ‘Flying Dragon’ were also obtained and trifoliate
‘Rubidoux’ plantlets are now under selection procedures.
S05O09
Targeted cybridization in citrus and transcript profiling of a male sterile cybrid pummelo
containing cytoplasm from satsuma mandarin
Guo W.W. 1 , Zheng B.B. 1 , Xiao S.X. 1 , Grosser J.W. 2 , and Deng X.X. 1
1 Huazhong Agricultural University, Key Laboratory of Horticultural Plant Biology, Ministry of Education, China; and 2 University of
Florida, Citrus Research and Education Center, USA. guoww@mail.hzau.edu.cn
Seedlessness is an elite fruit quality trait. By symmetric fusion of embryogenic callus protoplasts of satsuma
mandarin and mesophyll protoplasts of elite seedy cultivars, diploid cybrid plants containing sterile cytoplasm
from satsuma were regenerated and characterized from several fusions, and the cybrid pummelo between
satsuma ‘Guoqing No. 1’ and ‘Hirado Buntan’ pummelo showed male sterile trait. To gain new insight into
the underlying mechanism, the nuclear gene expression profiles of floral buds of the cybrid with that of
fertile pummelo were compared by RNA-Seq. Gene expression profiles which identified a large number of
differentially expressed genes were captured at both petal and stamen primordia distinguishable stages. In
addition, agreeable with flower morphology of the cybrid, expression of PISTILLATA (PI) was reduced in stamenlike
structures, even though it was restricted to correct floral whorls. Down-regulated expression of APETALA3
(AP3) coincided with that of PI. These finding indicated that, due to their whorl specific effects in flower
development, citrus class-B MADS-box genes likely constituted ‘perfect targets’ for CMS retrograde signaling,
and that dysfunctional mitochondria seemed to cause male sterile phenotype in the cybrid pummelo.
S05O10
In vitro anther culture of several cultivars of Citrus sinensis and Citrus clementina
Cardoso J.C. 1 , Abdelgallel A. 2 , Chiancone B. 2 , Rocha Latado R. 3 , Lain O. 4 , Testolin R. 4 , and Germanà M.A. 2
1 Centro APTA Citros Sylvio Moreira - Instituto Agronômico, Cordeirópolis, Centro de Energia Nuclear na Agricultura - Universidade
de Sao Paulo, Brasil; 2 Facoltà di Agraria. Università degli Studi di Palermo, Dipartimento DEMETRA, Italy; 3 Centro APTA Citros Sylvio
Moreira - Instituto Agronômico, Cordeirópolis, Instituto Agronômico de Campinas, Brasil; and 4 Università degli Studi di Udine.
Dipartimento di Scienze Agrarie e Ambientali, Italy. mariaantonietta.germana@unipa.it
Citrus breeding goals can be achieved by traditional (hybridization, selection, mutation) or biotechnological
methods. Efficient procedures of in vitro regeneration are required, in conjunction with the recent techniques
of cellular and molecular biology, to achieve significant improvement in a brief time. Moreover, particularly in
78 - VALENCIA CONFERENCE CENTER, 18th-23rd NOVEMBER 2012