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Title: Evaluation of a M-202x Oryza nivara advanced backcross population for seedling vigor, agronomic traits, yield components, yield and grain quality

item Eizenga, Georgia
item NEVES, PERICLES - Embrapa
item Bryant, Rolfe
item AGRAMA, HESHAM - University Of Arkansas
item Mackill, David - Dave

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2015
Publication Date: 12/17/2015
Citation: Eizenga, G.C., Neves, P.C., Bryant, R.J., Agrama, H.A., Mackill, D.J. 2015. Evaluation of a M-202x Oryza nivara advanced backcross population for seedling vigor, agronomic traits, yield components, yield and grain quality. Euphytica. 208:157–171. doi: 10.1007/s10681-015-1613-y.

Interpretive Summary: Oryza nivara, a rice wild relative, has the potential to improve seedling vigor and the grain yield of cultivated rice. Improved seedling vigor and cold tolerance at planting would allow rice to be planted earlier in the growing season, improve stand establishment when rice is broadcast seeded into cold water, and increase the weed competitiveness of rice after planting. Other reports have shown O. nivara (O. rufipogon), the undomesticated, wild species progenitor of cultivated rice, has the potential to improve the yield of cultivated rice, O. sativa. Using DNA markers, the chromosomal location of potential genes underlying the traits evaluated were identified using a segregating population derived from M202 (O. sativa) and O. nivara. Potential genes attributed to the O. nivara parent included those for increased coleoptile and shoot length which improves seedling vigor, and increased number of panicles per plant, kernel length and grain weight for potentially improving grain yield. Nine lines were identified with improved seedling vigor and these can be used for improving vigor in new rice cultivars. Knowing the genes that affect yield components like the number of panicles per plant, percent seed set, grain weight and kernel size will impact selection for improved rice yields.

Technical Abstract: Oryza nivara, the ancestral species of cultivated rice (O. sativa) is the source of novel alleles for resistance to biotic and abiotic stress lost during domestication, including those for improved yield. Interspecific advanced backcross (ABC) populations permit both the introgression of desirable alleles from the wild donor into O. sativa and allows these traits to be mapped to chromosome region by QTL mapping. An ABC population was developed by crossing M-202, a California medium grain, temperate japonica cultivar with O. nivara (IRGC100195). The population has 177 BC2F2 progeny lines and was evaluated for 20 traits including seedling vigor (mesocotyl, coleoptile, shoot and root lengths), agronomic traits (days to heading, plant height, plant type, panicle type), yield components (panicles per plant, panicle length, florets and grains per panicle, 100-grain weight), yield, and grain quality [kernel length and width, apparent amylose content (AAC), alkali spreading value (ASV)]. Most QTLs identified were validated in other interspecific ABC populations. The O. nivara parent improved seedling vigor by increasing both the coleoptile and shoot lengths. The wild donor alleles increased the panicles per plant, but M-202 alleles improved fertility and yield. The O. nivara alleles accounted for increased kernel length even though this parent had shorter kernels than M-202. The AAC mapped to the Waxy gene and ASV to the Alk gene, with most progeny being similar to M-202 for these quality traits. Selected progeny lines will be useful for improving seedling vigor. This interspecific population is the first in the background of a U.S. temperate japonica rice cultivar.