Evaluation of seed-shattering degree of substitution lines having two non-shattering loci from cultivated rice (Oryza sativa) in the genetic background of wild rice (O. rufipogon)

Abstract

It is known that the common cultivated rice, Oryza sativa, was domesticated from Asian wild rice, O. rufipogon. Loss of seed-shattering is one of the most important traits during rice domestication. In order to better understand the genetic control of seed shattering, chromosome segment substitution lines were prepared by introgressing non-shattering qSH1 and sh4 alleles from cultivated rice, O. sativa cv. Nipponbare, in the genetic background of wild rice. The degree of shattering was examined to evaluate the genetic interaction of two loci. The results showed that the backcross plants individually having Nipponbare homozygous alleles at either shattering locus (qSH1 or sh4) shed all the seeds. These results indicated that two cultivated non-shattering alleles were not sufficient to express full non-shattering behavior in the genetic background of wild rice. Probably some other minor loci are still involved in the control of seed-shattering in wild rice.