Proceedings of the XLVI Italian Society of Agricultural Genetics - SIGA Annual Congress

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Poster Abstract - 3.09

STUDY OF WILD BETA (BETA VULGARIS L. SUBSP. MARITIMA (L) ARCANG.) POPULATIONS FROM PO DELTA BY AFLP

Mainolfi A.*, Moschella A.*, Stavanato P.**, Mandolino G.*, Biancardi F.**, Ranalli P.*

*) Istituto Sperimentale per le Colture Industriali, Bologna, Italy

**) Istituto Sperimentale per le Colture Industriali, S.O.P. Rovigo, Italy

wild beet, sugar beet, AFLP, gene flow, genetic similarity

The genus Beta is a morphologically and genetically variable one composed of wild, weedy, and cultivated forms that are used for sugar production or for vegetables. The crossing of different species of genus Beta has played a significant role in sugar beet breeding (Beta vulgaris L. subsp. vulgaris). Many successes have been obtained through hybridization with sea beet (Beta vulgaris L. subsp. maritima (L) Arcang.), considered to be the ancestor of the cultivated beets. In fact the resistance to cercospora leaf spot was obtained by introgression from sea beet populations in the area of the Po delta (Italy). Besides, some types of resistance to rizomania derived subsequently from such varieties. Selections are in progress to obtain from hybrids with sea beet the resistances to the nematode Heterodera shachtii Schm. and to abiotic stress. The genetic similarity made the sea beet the subject of researches aiming at targeting and isolating useful characters, which could then be transferred to cultivated varieties. Most of sugar beet multiplication fields are close to the area of Po delta, where several wild beet populations are also located. This proximity could cause gene flow between the two pools. There is the possibility that the hybridization of the wild beets through pollen released by the sugar beet crop could alter the original genetic structure of sea beets with a negative impact on the biodiversity of the wild subspecies. The survey of local populations, of their habitat characteristics, and of their genetic structure is therefore advisable. In the last few years, surveys were performed in order to locate the sea beet populations along the Adriatic coast between Trieste and Ancona (Italy). From a variable number of individual plants belonging to 12 different population, leaf samples were taken and genomic DNA was prepared. Each plant was then separately analysed using the AFLP technique. A total of 93 plants from 12 different localities were included in the AFLP analysis. For comparison, 20 Beta vulgaris L. subsp. maritima plants belonging to three accession of wild beet from Southern Italy, and 14 plants of two commercial sugar beet varieties (Puma and Contact) were grown in greenhouse, the genomic DNA prepared and analysed by the some AFLP primer combinations.

The genotypes were evaluated using 325 unambiguous bands (average 85% polymorphism rate) derived from five AFLP primer combinations after gel electrophoresis and autoradiography. Pairwise similarity estimates between 0.63 and 0.96 were found.

Cluster analysis yielded three distinct groups, including respectively all the plants from Po delta, the plants from southern Italy, and the commercial varieties. PCA analysis also confirmed the disinctness of these groups. 26 AFLP markers seem to be specific of the Po delta populations. Besides, a number of AFLP markers has been identified specifically present or absent in one of the Po delta populations, and are therefore potentially useful for monitoring gene flow.