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

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

 

Poster Abstract

 

 

GENETIC STRUCTURE OF COMMON BEAN (PHASEOLUS VULGARIS L.) LANDRACES FROM SOUTHERN ITALY REVEALED BY SSR AND AFLP MOLECULAR MARKERS

 

MASI P., SPAGNOLETTI ZEULI P. L.

 

Dept. Biologia Difesa e Biotecnologie Agro-forestali, Università degli Studi della Basilicata, I-85100 Italy

bio346@unibas.it

 

 

common bean landrace, SSR and AFLP marker, genetic diversity

 

The amount and distribution of genetic diversity must be assessed to facilitate conservation and utilisation of plant genetic resources.

 

The characterisation of three landraces “Poverella”, “a’ Marrozzo” and “Verdolino” of common bean (Phaseolus vulgaris L.) collected in Southern of Italy was carried out using two different second generation DNA marker systems. Genetic diversity within and among three landraces was evaluated over 30 microsatellites (SSRs) and 8 primer combinations for amplified restriction polymorphisms (AFLPs) using a total of 73 individuals.

 

The level of genetic diversity at multiple and single loci was assess by calculating the mean number of alleles, the observed and expected heterozygosity. The distribution of variation within and among population was calculated by AMOVA. Cluster analysis (Dice’s genetic diversity matrices) visualised the relationships among genotypes within landrace, and among landraces for both SSR and AFLP markers.

 

Considerable variation was found at the microsatellite loci analysed with an average number of 2.6 alleles per locus and 4.9 alleles per polymorphic locus. “A’ Marrozzo” was the landrace with highest value of Ap (3.5) and He (0.38) and Ho (0.01). Analysis of three landraces with 8 AFLP primers revealed a total of 1318 bands: the total number of polymorphic fragment detected by individual primer varied from 8 to 36. “Poverella” was the landrace with highest number of polymorphic bands (228). As expected, microsatellite markers showed a higher degree of variation in terms of percentage of polymorphism (80%) than did AFLPs (40.5%).

 

In addition, the observed values of Nei diversity index expressed as average genetic diversity (AGD) per loci were higher for SSR (0.393) than for AFLP (0.103).

 

From the AMOVA of SSRs, the percentage of genetic variation explained by differences within the three landraces was consistently higher (64.9%) than the percentage of genetic variation explained by differences among each landrace (35.1%), while for AFLP the opposite was observed (20.6% vs 79.4%). AFLP markers differentiated the three races more effectively than SSR and this was confirmed by displayed UPGMA dendrograms.

 

This study showed that SSR and AFLP markers were informative descriptors of genetic structure and global variation of common bean landraces and that they can be used to design further studies and plan strategies for conserving Phaseolus vulgaris L. germplasm.