Pisum Genetics
2010-Volume 42
Brief Communication
Mapping the st locus in respect to three molecular markers on Linkage Group III
Bogdanova, V.S. and Institute of Cytology and Genetics, Siberian Department
Yadrikhinskiy, A.K. of the Russian Academy of Sciences, Novosibirsk, Russia
The overwhelming majority of genetic studies in recent years have been based on DNA markers. Polymerase chain reaction (PCR)-based DNA markers have been recognized to be powerful tools for rapid construction of genetic maps. However, morphological markers still remain very convenient due to their ease of scoring and allowing larger plant numbers to be analyzed.
A pea consensus linkage map was published in 1998 (1) which included mainly morphological and isozyme data known to date. integration of new molecular, biochemical and morphological data (2) into existing maps has been possible through the use of a number of anchor genes (3). The st gene on Linkage Group III is a convenient genetic marker manifested as reduced stipules (4) that is clearly seen in young seedlings. The recommended anchor markers in LGIII are Aat-c, Adh-1, M, st, b,Lap-1 (3). In the present work, we mapped the st locus with respect to the morphological marker b and three molecular markers based on the following DNA sequences available from public databases: AF255058 Pisum sativum 33 kDa ribonucleoprotein gene, complete cds; AF280748 Pisum sativum phospholipase C gene; and AJ832139 Pisum sativum sym7 gene for GRAS family protein.
The latter gene is defined in the database as " sym7" (5); however, it seems to be different from the marker with the same designation "sym7" described by (6) and mapped on LGIII distally to b (1). To avoid confusion we designate it here as AJ832139, while the former two markers are designated as Rnp33 and PhlC as in (7, 8). The molecular markers used were assessed with the use of CAPS (9) and the following primers and restriction enzymes were used:
One hundred twenty-two plants of an F2 population from the cross, WL1072/VIR320, where WL1072 carried st (reduced stipules) and b (pink flowers), were analyzed for the genotype with respect to Rnp33, PhlC and AJ832139, as judged on fragment lengths formed after endonuclease treatment of PCR-products and characterized for st and b. Approximately 10 seeds collected from St- plants were sown to assess the allelic state of the st locus. The F2 progenitors of the F3 families segregating for normal/reduced stipules
Pisum Genetics
2010-Volume 42
Brief Communication
clearly seen in young seedlings were regarded as heterozygous. Mapmaker 3.0 software was used to construct the genetic map of the LGIII segment in Figure 1.
Figure 1 Fragment of the linkage map of LGIII.
In this study we mapped three molecular markers closely linked to st. One marker, AJ832139, had not been previously mapped. The choice of st was due to its ease in scoring and convenient use in mapping experiments related to the central region of LGIII. The b locus appears to be quite distant to st in our population.
This work was supported by the Russian Foundation for Fundamental Research, Grant 10-04-00230-a. References
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