Royero N. 1,5, Mejía-Jiménez A. 2, Sánchez I. 3, Saavedra R. 4, Gallego G. 2, Duque MC. 2, Tohme J. 2
1
Annonaceae is a pantropical
family of about 130 genera and
2000 species. Its plants are
mainly trees with simple,
alternate leaves, bisexual
flowers with numerous stamens
and carpels and monocarpus
fruits. They are useful as
ornamental and medicinal
plants. They are source of edible
fruits as well as cosmetic
extracts too.
Corporación BIOTEC, CIAT, n_royero@yahoo.com; 2 Centro Internacional de Agricultura Tropical - CIAT A.A. 6713, Cali, Colombia
; 3Corporación Colombiana de Investigaciones Agropecuarias – Corpoica, CIAT, Colombia; 4C.I. Corpoica, Palmira, Colombia;
5Universidad Nacional de Colombia, Palmira
Cherimoya (Annona cherimola) and
Atemoya (A. squamosa x A.
cherimola) are the most consumed
around the world.
There are other species of local
importance that could reach
international markets once their
delicious taste and nutritive
properties are promoted (Fig.1).
Soursop is the most important
Annona species for industrial
purposes. It is consumed fresh or
processed as juice, ice cream,
yogurt or desserts. It has a
characteristic sour flavor and is very
tasty.
A
Figure 1 Horticulturally
important Annonaceae:
A) Atemoya; B) Cherimoya
(“Chirimoya”); C) “Anón
amazónico” (Rollinia
mucosa); D) Sweetsop
(“Anona Blanca” – Annona
squamosa); E), F) Bullock´s
heart (“Anona colorada”– A. reticulata); G)
soursop “Guanábana”).
Most of the horticulturally
important species belong to the
tropical genera Annona and
Rollinia and have syncarpous
fruits (Fig. 1).
Soursop like most Annona and Rollinia species has a neo-tropical
origin. This is why in countries of northern South America a great
genetic variability of soursop may be found. However, its genetic
resources have not been systematically studied, neither is the
genetic variability known, variability which is useful for selecting
high yields or pest resistant cultivars.
Soursop is a fruit crop in Colombia,
Ecuador, Venezuela, Costa Rica
and Brazil, offering high incomes to
farmers. Nevertheless it is
cultivated on a small area,
producing low yields.
Table 1. Variability parameters of the Annonaceae and soursop
accessions based on AFLP fingerprintings with two primers
combinations.
Accessions
Annonaceae
(global analysis)
Soursop
(specific
analysis)
Total
Polymorphic Percentage of Similarity
fragments fragments polymorphism
496
486
98
0.07-0.99
241
87
36
0.75-0.95
Gene
Diversity
0.21569
Soursop accessions (G5) showed low similarity with the other
Annonaceae species (≤ 0.22). This may explain why no fertile
hybrids have been produced up to now between soursop and any
of the species here evaluated. Conventional breeding through
interspecific hybridization with these species may be limited.
0.09049
Colombian Corpoica guards the only Annonaceae live germplasm
bank of Andean countries that could be used to breed soursop
planting material. Some agro-morphological characteristics of this
bank have been evaluated recently (Mejía et al., 2002).
Molecular markers are a huge universe of genetic information that
are not modified by the environment. They could be use to
assess the divergence between organism. Our objective in this
study was to characterize the genetic variability of soursop and
related Annonaceae species accessions of the Corpoica
germplasm bank using AFLP markers.
Plant Materials:
39 accessions of Annonaceae species (global analysis); and 37 soursop
accessions (specific analysis) sampled from several agroecological zones of
Colombia
Primer combinations E-AGC/M-CTC and E-AGC/M-CAA
detected high polymorphism in Annonaceae accessions. Primer
combinations E-ACT/M-CAA and E-AGC/M-CTC revealed a
polymorphism of 36% in the soursop accessions (Table 1). In
either of the analysis, polymorphism was higher than the one
found previously by allozymic markers.
Between accessions no equal AFLP pattern was found, then
there were not duplicates within the germplasm bank (Figure 2).
AFLP methodology:
DNA extraction (Dellaporta et al., 1983)
AFLP fingerprinting with two selective primer pairs (Vos et al., 1995)
AFLP fragment separation on silver stained 6 % polyacrylamide gels
Data Analysis:
AFLP bands scored as present (1) or absent (0) in each accession
Estimate of genetic similarity based on Nei-Li (1979) coefficient
Cluster analysis
Estimate of genetic diversity based on Nei heterozygosity parameters
In the global analysis nine genetic groups were detected
(G1-G9), each one corresponding to at least one Annonaceae
species. Low similarity (≤ 0.30) was revealed between them.
Sweetsop (G9) and cherimoya (G8) accessions were the
closest groups, they unified at 0.53 of similarity and included
their atemoya hybrids (Figure 3).
A. glabra
Pond apple
Rollinia sp.
Biriba
A. montana
Mountain
soursop
A. muricata
Soursop
Figure 2.
Silver stained
polyacrylamide gel
displaying AFLP
fingerprints detected in
37 soursop accessions
using primer
combination
E-ACT/M-CAA. (O)
outgroups; (WM) 10 bp
and 25 bp ladders
Figure 4. Dendrogram of 37 soursop accessions revealed by UPGMA
analysis based on AFLP fingerprintings with two primer pairs.
2Outgroups (see Fig 3)
Gene diversity for soursop accessions was low (0.09) and no
organized groups were found according to their geographical source
(Table 1). This homogeneity could arise because soursop
accessions were sampled from cultivated zones and there was an
interchange of seeds between indigenous people and farmers since
prehispanic times. Another reason could be that the samples
evaluated were not representative for all the extant variability.
The Colombian collection of soursop showed low genetic variability.
To collect and characterize new soursop germplasm from its whole
distribution area is recommended to assess the extant diversity and
evaluate the representativeness of the collection analysed. Also it
would be necessary to study the variability of new soursop related
species. That way, new useful characters such as high yield and
disease resistance would be available for soursop breeding.
A. reticulata
Custard apple
A. cherimola
cherimoya
A. squamosa
Sweetsop
Figure 3. Dendrogram of 39 Annonaceae accessions revealed by
UPGMA analysis based on AFLP fingerprintings with two
primer pairs. Nine groups were detected (G1-G9).
G2 – species unidentified and G6 – maybe A. purpurea are
not illustrated. 2Cadmia (Cananga odorata) was an
outgroup.
This work is financially supported by COLCIENCIAS-BID,
Ginés-Mera grants of CBN and the participating institutions
Corporación BIOTEC, CIAT and Corpoica. We thank Dr. J Cabra and
professor JE Muñoz for recommendations.
Mejía-Jiménez, A et al., 2002, Final report of the project “Molecular and agromorphological
characterization of the genetic variability of native soursop (Annona muricata L.) and related
Annonaceae species”.
Vos, P et al. 1995 AFLP: a new technique for DNA fingerprinting. Nucleic Acids Res 23:
4407 – 4414.