title: Are contents of Rubisco, soluble protein and nitrogen in flag leaves of rice controlled by the same genetics?
abstract: Genetic relations among the contents of Rubisco, soluble protein and total leaf nitrogen (N) in leaves of rice (Oryza sativa L.) were studied by quantitative trait loci (QTL) analysis with a population of backcross inbred lines (BILs) of japonica Nipponbarexindica Kasalath. The ratio of Rubisco to total leaf N in leaves is the main target in improving photosynthetic N-use efficiency in plants. QTLs controlling Rubisco content were not detected near QTLs for total leaf N content. These results indicate that contents of Rubisco and total leaf N are controlled by different genetics. QTLs that controlled the ratio of Rubisco to total leaf N (CORNs) were detected. These results suggest that some mechanism(s) may be involved in determining this ratio, while the contents of Rubisco and total leaf N are controlled in other ways. In elite BILs, the ratios of Rubisco to total leaf N were higher than those of both parents. These results suggest a good possibility of improving N-use efficiency by CORNs in cultivated rice. A QTL controlling Rubisco content was mapped near a QTL for soluble protein content on chromosome 8 at 5 d after heading and on chromosome 9 at 25 d. In each chromosome region, the peaks of both QTLs overlapped accurately, giving a high possibility of pleiotropic effects by the same genes. Different QTLs controlling soluble protein or Rubisco were detected from those detected at 5 d or 25 d after heading. This suggests that these traits are genetically controlled depending on the growth stages of leaves.
authors.affiliation: National Institute of Agrobiological Sciences, 2-1-2, Kannondai, Tsukuba, Ibaraki 305-8602, Japan. kenshi@nias.affrc.go.jp
authors.forename: K
authors.initials: K
authors.lastname: Ishimaru
authors.forename: N
authors.initials: N
authors.lastname: Kobayashi
authors.forename: K
authors.initials: K
authors.lastname: Ono
authors.forename: M
authors.initials: M
authors.lastname: Yano
authors.forename: R
authors.initials: R
authors.lastname: Ohsugi
mesh_terms: D002874:Chromosome Mapping; D003433:Crosses, Genetic; D017343:Genes, Plant; D009584:Nitrogen / Q000378:metabolism*; D012275:Oryza / Q000235:genetics* / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D019655:Quantitative Trait, Heritable; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics* / Q000378:metabolism; D012995:Solubility
chemical_list: D010940:Plant Proteins; D012273:Ribulose-Bisphosphate Carboxylase; D009584:Nitrogen