Abstract: Chlorophyll deficiency mutants are ideal materials to study photosynthetic mechanism, pathways of chlorophyll biosynthesis and degradation, and genes related to photosynthesis. The chlorophyll-deficient wheat (Triticum aestivum L.) mutant Mt135, induced by space mutagenesis, was investigated on main agronomic traits and photosynthesis characteristics with a comparison to its wild type. The leaf color of the Mt135 showed albino, stripe, and green phenotypes. The albino plants with entire albino leaves died at seedling stage, while plants with green-and-white striped leaves usually matured 5–7 d later than the wild type, and the plant height, spike length, grains and grain weight per plant, and 1000-grain weight were lower. The green plants were not significantly different from the wild type. Preliminary genetic analysis showed that the inheritance model of Mt135 was nucleo-cytoplasmic interaction. When exposed to photosynthetic active radiation (PAR) of 110 μmol m^-2 s^-1, the green tissue of striped plants (S-G) and the wild plant had no significant difference on the value of maximum photosystem II quantum yield, but the potential activity of photosystem II was significantly lower in the S-G plants than in the wild plant. The changes of the photochemical quenching, non-photochemical quenching, effective quantum yield, regulated non-photochemical energy dissipation, and non-regulated energy dissipation were different at various growth stages. In addition, the differences of the electron transport rate, photochemical quenching, and effective quantum yield between S-G plant and wild plant varied under different PAR conditions. The white tissue of striped plant and the albino plant completely lose the photosynthetic function. As a result, the photosynthesis of Mt135 was greatly restricted. High photosynthetic active radiation had tremendous impact on the mutant at elongation stage and relatively weak impact at heading stage. The changes of photosynthetic function of striped plant are in accordance with the reduction of their plant height, spike length, and yield related traits.

Key words: Triticum aestivum L., Space mutagenesis, Chlorophyll-deficient mutant, Agronomic traits, Chlorophyll fluorescence kinetic parameters