Vigorous growth and high yielding of rice (Oryza sativa) introgression lines and transformants carrying a PRR37 allele from wild rice O. longistaminata

Wild rice species are expected to possess genes that are potentially useful for rice breeding. Backcross inbred lines (BILs) derived from a cross of a japonica rice 'Shiokari' and a progeny line from a cross of a japonica 'Taichung 65' and Oryza longistaminata MwM were examined for agronomic traits. Some BILs showed vigorous growth and increased yield relative to 'Shiokari'. One of such BILs was further analysed using QTL mapping followed by map-based cloning to identify the causal gene. An allele of OsPRR37, which encodes a pseudo response regulator protein, in O. longistaminata was found responsible for the traits and named OlPRR37. OlPRR37 was expressed more than an OsPRR37 allele from a japonica 'Nipponbare' in the heterozygotes of the two alleles. The genomic clone of OlPRR37 and the coding sequences of both OlPRR37 and the 'Nipponbare' allele driven by the promoter of OlPRR37 similarly functioned as high-yielding genes in transgenic rice. Thus, higher expression of PRR37 by the OlPRR37 promoter likely conferred the increased yield. Accordingly, OlPRR37 may be used to improve rice productivity.