Genetic mapping of salt tolerance gene in soybean cultivar Fiskeby III

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Salinity in the parts of the southern USA causes injury in soybeans. As a result many farmers prefer varieties that are tolerant to excess sodium and chloride to grow under these conditions. Present varieties grown in the southern USA with salt tolerance are primarily derived from the single dominant gene from the ancestral line S100 via the maturity group VI cultivar Lee and its derivatives. The maturity group 000 ancestral soybean varieties Fiskeby and Fiskeby III were also identified as having salt tolerance. The purpose of this study was to determine the inheritance of salt tolerance in Fiskeby III and to map the gene(s) related to its tolerance and their possible relationships with the salt tolerance gene found in S100. DNA was extracted from leaf tissue from individual F[SUBSCRIPT 2] plants from cross of Williams 82 x Fiskeby III. Each plant was then phenotyped for salt tolerance in a salt solution. A genetic ratio of 3 tolerant (T) : 1 susceptible (S) indicating a single dominant gene was responsible for tolerance. Forty five (45) F[SUBSCRIPT 2] and 113 F4:7 Recombinant Inbred Lines (RILs) from cross of Holladay (salt tolerance from S100) x Fiskeby III were developed and each line was phenotyped for salt reaction. A segregation ratio of 15 tolerant (T): 1 susceptible (S) from screening of F[SUBSCRIPT 2] individual plants from Holladay x Fiskeby III indicated presence of a new allele for salt tolerance in Fiskeby III. However, no segregation was detected in F4:7 RILs of Holladay x Fiskeby III. Thus, the new salt gene in Fiskeby III was inherited with Ncl gene together. To determine if the salt tolerance from Fiskeby III was located in the same or a different chromosome region than the gene for tolerance in S100, DNA from the F[SUBSCRIPT 2] plants from cross of Williams 82 (S) and Fiskeby III (T) was used to map the gene. Genotyping was conducted with 13 SSR markers in proximity to the Ncl gene on chromosome 3. The salt gene in Fiskeby III was detected between SSR marker Satt312 and GMABAB which is near to the Ncl locus. This salt tolerance gene in Fiskeby III is probably not the same as Ncl allele but, is located in the same region of soybean chromosome 3.