LIBRO-CONGRESO-CITRUS

S06O01
Effect of male-female interaction and temperature variation in citrus pollen performance
Distefano G. 1 , Hedhly A. 2 , Las Casas G. 1 , La Malfa S. 1 , Cicala A. 1 , La Rosa G. 1 , Herrero M. 3 , and Gentile A. 1
1 University of Catania (DISPA), Department of Agriculture and Food Science, Italy; 2 University of Zurich, Institute of Plant Biology,
Switzerland and 3 Consejo Superior de Investigaciones Científicas (CSIC), Departmento de Pomología, Estación Experimental de Aula
Dei, Spain. gentilea@unict.it
Characterizing pollen performance is especially relevant for some economically important genus like Citrus,
in which failure of the sexual reproductive process resulting in parthenocarpic fruit development and
seedlessness is a prized character. Pollen-pistil interaction in the three ancestral true-type Citrus species
was characterized in order to determine the influence of the male and female genotypes, as well as of the
temperature regime on pollen performance. Specifically, temperature effect on pollen grain germination in
vitro, and on pollen tube growth either in vivo in cut flowers under controlled temperature chambers or in
planta under field temperature conditions was characterized. Results obtained showed that temperature
variation has a strong effect on pollen germination, on pollen tube kinetics, and on their population size
depending on the specific male-female combination. Furthermore, temperature appears to have an effect on
the self-incompatibility reaction by affecting the place where pollen tubes are arrested. Overall, our results
show that pollen performance is not only an inherent characteristic of the pollen genotype, but is largely
dependent on the particular male-female combination and on genotype-temperature interactions.
S06O02
Abscission of reproductive structures in citrus and its control with brassinosteroids and girdling
Pérez M.C. 1 , Almenares G. 2 , Torres W. 3 , Aranguren M. 2 , Betancourt M. 2 , García M.E. 2 , Núñez M. 3 , Llauger R.E. 4 ,
Mahouachi J. 5 , Iglesias D.J. 6 , and Talón M. 6
1Instituto Nacional de Ciencias Agrícolas (INCA), Dirección General, Cuba; 2Instituto de Investigaciones en Fruticultura Tropical
(IIFT), Fisiología, Cuba; 3Instituto Nacional de Ciencias Agrícolas (INCA), Fisiología, Cuba; 4Instituto de Investigaciones en Fruticultura
Tropical (IIFT), Dirección General, Cuba; 5Instituto Canario de Investigaciones Agrarias (ICIA), España; and 6Instituto Valenciano de
Investigaciones Agrarias (IVIA), Genómica, España. mcperez@inca.edu.cu
A study was done to characterize the abscission of reproductive structures under tropical conditions using
brassinosteroids and girdling for its control. The trial included ‘Valencia Late’ and ‘Washington’ navel orange
trees. The tendency to abscise was determined since the early stage of flower development until the end of
fruit-set. Fallen reproductive structures were classified through the BBCH scale, foliar levels of gibberellins
during fruit-set were also determined and the effect of foliar sprays of analogues of brassinosteroids during
petal fall and branch girdling from the anthesis until petal fall on fruit-set, foliar gibberellin levels and yield
were also evaluated. Results indicate that the abscission of reproductive structures was interrupted since
the beginning by flower development until the end of fruit-set with a maximum during the stage 69 of the
BBCH scale, when abscission is high and the fall of reproductive structures is increased in initial phenological
stages, the sink capacity reduces, foliar gibberellin levels rise and vice versa. The spray of the analogue of
brassinosteroid BB-6 (0.1 mg∙L -1 ) reduced the accumulated abscission in 9% and increased yield in 38%, while
branch girdling also reduced accumulated abscission and increased yield in 54%. This girdling was preceded
by a reduction of total carbohydrates and increased gibberellin levels in leaves during the stage II of fruit
growth and development.
S06O03
“To fall or not to fall, that’s the question!” Molecular mechanisms underlying organ abscission in
citrus
Tadeo F.R., Agustí J., Merelo P., Estornell L.H., Cercós M., Terol J., Domingo C., and Talón M.
Instituto Valenciano de Investigaciones Agrarias (IVIA), Genómica, España. tadeo_fra@gva.es
During their life cycle, citrus plants can experience different processes involving separation of cells by
dissolution of cell adhesion materials and breakdown of cell walls at specific sites on the plant body. Abscission
enables both vegetative and reproductive organs to be shed in response to developmental, hormonal and
XII INTERNATIONAL CITRUS CONGRESS 2012 - 95
S06