Page 1 - Geraci_al_2004

Genetic Resources and Crop Evolution 51: 137–146, 2004. 137
 2004 Kluwer Academic Publishers. Printed in the Netherlands.

Isozyme analysis of genetic diversity in wild Sicilian populations of
Brassica sect. Brassica in view of genetic resources management

Anna Geraci1,*, Anne-Marie Che`vre2, Isabelle Divaret2, Fre´de´rique Eber2 and Francesco
M. Raimondo1

1Dipartimento di Scienze Botaniche, Universita` di Palermo, via Archirafi 38 90123, Palermo, Italy; 2INRA
Station d’Ame`lioration, des Plantes Domaine de la Motte BP35327, 35653 Le Rheu, cedex, France; *Author
for correspondence; (e-mail: anna.geraci@infinito.it)

Received 13 March 2001; accepted in revised form 31 May 2002

Key words: Brassica sect. Brassica wild sicilian populations, Genetic resources, Genetic structure, Isozyme
diversity

Abstract

In Sicily and in the small surrounding islands the section Brassica of the genus Brassica comprises five species, B.
insularis Moris, B. incana Ten., B. macrocarpa Guss., B. rupestris Raf. and B. villosa Biv. These taxa represent a
genetic resource as relatives of kale crops but some populations are endangered or threatened, thus isozyme
analyses were performed to assess the genetic diversity degree at population and species levels in order to assist
the design of conservation management programs.

Eleven loci from five enzyme systems (aconitase, leucine aminopeptidase, 6-phosphogluconate dehydrogenase,
phosphoglucoisomerase phosphoglucomutase) were analyzed in sixteen natural population (fifteen from Sicily,
one from Calabria). Mean within-population genetic diversity was moderate (P 5 41%, A 5 1.54, H 5 0.16). In
some cases a great number of heterozygous individuals were detected, in other cases fixation index (F) deviated
significantly from Hardy-Weinberg genotypic expectations.

A total of 37 alleles was recognized, six of which resulted exclusive to single populations. The among-
population component of the total genetic diversity (Gst mean values) for each species was 0.30–0.37, indicating
genetic differentiation among populations.

Among B. villosa and B. rupestris populations genetic distance values resulted rather low and they resulted high
with B. incana and B. macrocarpa populations.

The results are discussed with regard to the distribution of the genetic diversity level and the genetic resources
management.

Introduction villosa, subsp. bivoniana (Mazzola et Raimondo)
Raimondo et Mazzola, subsp. drepanensis (Caruel)
Brassica sect. Brassica comprises ten species distrib- Raimondo et Mazzola, subsp. tinei (Lojac.) Raimondo
uted in Mediterranean area and eastern Atlantic coast- et Mazzola) and to B. rupestris (subsp. rupestris,
al areas (Brassica oleracea L., B. cretica Lam., B. subsp. hispida Raimondo et Mazzola, subsp. bre-
hilarionis Post, B. bourgeoui (Webb) O. Kuntze, B. visiliqua Raimondo et Mazzola) (Snogerup et al.
montana Pourret, B. incana Ten., B. insularis Moris, 1990; Raimondo and Mazzola 1997).
B. macrocarpa Guss., B. villosa Biv., B. rupestris
Raf.) (Diederichsen 2001). Different subspecies are This section, characterized by 2n 5 18, represents a
described as related to B. cretica (susbp. cretica, cytodeme (Harberd 1972) in which wild species and
subsp. aegaea (Heldr. et Hal.) Snog., Gust. et Both., cultivated forms of B. oleracea are interfertile in some
subsp. laconica Gust. et Snog.), to B. villosa (subsp. degrees (Kianian and Quiros 1992; Von Bothmer et al.
1995). The study and the conservation of wild rela-