Pineapple, Ananas comosus (L.) Merr, is the third most important tropical F
ruit cultivated in all tropical and subtropical countries. Pineapple germpl
asm includes all seven species of the genus Ananas and the unique species o
f the related genus Pseudananas. A knowledge of its diversity structure is
needed to develop new breeding programs. Restriction fragment length polymo
rphism (RFLP was used to study molecular diversity in a set of 301 accessio
ns, most of which were recently collected. This sample was analysed using 1
8 homologous genomic probes. Dissimilarities were calculated by a Dice inde
x and submitted to Factorial Analysis. The same data were represented as a
diversity tree constructed with the score method. Pseudananas sagenarius di
splayed a high polymorphism and shares 58.7% of its bands with Ananas. With
in Ananas, variation appears continuous and was found mostly at the intrasp
ecific level, particularly in the wild species Ananas ananassoides and Anan
as parguazensis. As for the cultivated species, Ananas comosus appears rela
tively homogeneous despite its wide morphological variation and Ananas brac
teatus, which is grown as a fence and for fruit, appears still much less va
riable. By contrast Ananas lucidus, cultivated by the Amerindians for fiber
, displays a high polymorphism. This tree displayed a loose assemblage of n
umerous clusters separated by short distances. Most species were scattered
in various clusters, a few of these being monospecific. Some accessions whi
ch had not been classified, as they shared morphological traits typical of
different species, re-group with one or the other, and sometimes with both
species in mixed clusters. No re-productive barrier exists in this germplas
m and these data indicate the existence of gene flow, enhancing the role of
effective sexual reproduction in a species with largely predominant vegeta
tive multiplication.