Establishment of standard experimental strains through pure-line selection in major weeds in Japan

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For establishing the scientific foundation to principles on breeding the standard experimental strains in Japanese major weeds, 1267 accessions of gramineus species from different local area were collected with voucher herbarium specimens. Inbreeding by panicle-bagging and bulk maintaining of seeds were conducted with DNA polymorphism evaluation. Bred accessions and previously bred strains were performed in physio-ecological evaluation. Programs were scheduled all the processes from seed collection through breeding and selection of representative strains to seed production of established strain. Practices of all the process were thoroughly evaluated. In Echinochloa weed, as a model taxon, molecular genetic skills were applied for species identification and tagging of experimental strains. Molecular discrimination practice was established by the PCR-RFLP in Echinochloa crus-gslli and E. otyzicola. Eight mJcrosatellites were established using one accession of Echinochba. Since four of th … More em were polymorphic in Echinochloa weeds, their applicability was tested by evaluation of inbred strains. As a result 44 accessions of third inbred generation were selected as mother strains of standard experimental strains of which identities and uniqueness were proved by microsatellite variations. Flowering habit, precocity, seed production ability and genetic variation for chemical tolerance were evaluated in established strains in several species of arable (Rumex obtsusifolius, Rorripa islandica), paddy (Echinochloa crus-galii and E. otyzicola), subtropical (Digitaria, Echinochloa, Poa, Paspalum) and aquatic (Eichhornia crassipes) weeds. In general ecophysiological teaits were much variable among strains, but RAPD variation was narrow and AFLP diversity showed geographical gradient. In particular Japanese populations of Echinochloa showed no herbicide-tolerance. The selected strains including standard strains will be provided freely for academic scientific research upon request as informed at an international conference. Less