Abstract:

Genetic improvement of tofu and soymilk output is interested by both farmers and processors. The objective of the present study was to reveal the genetic system and map QTLs of tofu and soymilk output for improvement of the traits. The RIL population NJRISX consisting of 176 families was derived from a cross Su88-M21×Xinyixiaoheidou and was tested in two cropping years (2005 and 2006). A genetic linkage map, containing 131 SSR markers, spanning 24 linkage groups (LG) at a total length of 2 044.6 cM, with an average distance of 15.6 cM between the flanking markers was constructed by using MAPMAKER 3.0. Genetic analysis was performed under main gene plus polygene mixed inheritance model for the P1, P2, and RIL population and QTLs were mapped with both composite interval mapping (CIM) and multiple interval mapping (MIM) of the software Win QTL Cartographer Version 2.5 on output of dried tofu, wet tofu and dried soymilk. The main QTL qODT-A2-1 associated with dried tofu output, explaining 15.7%-28.2% of the total phenotypic variation was identified between Satt424 and Sat_162 on LG A2; the main QTL qODS-A2-1 related to dried soymilk output, explaining 30.0%-34.8% of the phenotypic variation was also between Satt424 and Sat_162 on LG A2; and two main QTLs qOWT-A2-1 and qOWT-L associated with wet tofu output, explaining 20.7%-30.7% and 19.0%-27.4% of the total phenotypic variation were identified between Satt424 and Sat_162 on LG A2 and between Satt481 and Sat_397 on LG L, respectively. The results from segregation analysis showed that dried tofu and soymilk output were dominated by one main gene plus polygenes and wet tofu output was by two unlinked main genes plus polygenes. In comparison, the number of main genes, the phenotypic variation proportion explained by the main genes, and the relative contribution of main gene vs. ploygene from both segregation analysis and QTL mapping were similar, and two genetic analyses could be used for verification each other. From described above, it was inferred that breeders for tofu and soymilk output should pay attention to both main genes and polygenes.

Key words:

Soybean, Recombinant inbred line (RIL), Tofu, Soymilk, Output, Segregation analysis, QTL mapping