摘要
用Flaveria属不同的C_4种和C_3-C_4中间型种杂交,鉴定了杂种F_1 C_4光合CO_2的交换特性。结果表明:F.brownii(C_4)和F.floridana(C_3-C_4)正反交F_1表观光合强度在两亲值之间,有的植株偏向C_4亲本,有的偏向C_3-C_4亲本。利用这种偏向分布可从F_1中选出高光合能力的材料。从F.palmeri(C_4)和F.pubescens(C_3-C_4);F.brownii(C_4)和F.floridana(C_3-C_4);F.palmeri(C_4)和F.floridana(C_3-C_4);F.trineroia(C_4)和F.anomala(C_3-C_4)的正反交,可以看出:用C_4作父本,杂种F_1具有类似C_4种的耐高温的光合特性。从O_2抑光合反应看,F_1接近中亲值,稍偏向C_3-C_4亲本。CO_2补偿点却与C_4亲本相似,不因正反交而发生偏向分布。通过遗传操作,有可能将C_4光合特性传递给C_2植物。
To understand the relationship of photosynthetic charactelistics in hybrids and their parents differing in photosynthetic types, systematical analysis was made on C_4 photosynthetic CO_2 exchange in terms of apparent photosynthesis, CO_2 compensation point, O_2 inhibition of photosynthesis and photosynthesis response to temperature. Four reciprocal crosses involving C_4 species (F. palmeri, F. brownii, F. trinervia) and C_3-C_44 intermediate species(F, floridana, F. anomala, F. pubescens) were used for this study.
It was found that the apparent photosynthesis in F_1 hybrids from reciprocal cross between F. brownii (C_4) and F. floridana (C_3-C_4) showed a wide range of variations from C_4 species to C_3-C_4 species (Fig 2), F_1 hybrids from cross using C_4 species as male parent exhibit C_4 photosynthesis. This tendency was very obvious, when the temperature-photosynthesis response was concerned in these crosses: F. pubescens (C_3-C_3)×F. palmeri (C_4); F. floridana (C_3-C_3)×F. brownii; F. floridana (C_3-C_3)×F. palmeri (C_4); F. anomala (C_3-C_3)×F. trinervia (C_4) (Fig 1. A, B, C). It was suggested that C, photosynthetic characteristics might be incorperated by convention hybridization. O_2 inhibition of photosynthesis in F_1 hybrids, however, was found to lie near the means of me parents species (Table 1), CO_2 compensation point in F_1 hybrids was always close to that of the C_4 species (Fig 3), irrespective of whether C_4 species was used as male or female parent in the cross, suggesting that this trait couId be easily manipulated in breeding.
Finally, discussions were given on the potential of transferring C_4 photosynthetic characteristics into C_3 plants by genetic manipulation for the improvement of plant productivity.
