Proto-Kranz plants represent an initial phase in the evolution from C₃ to C₃–C₄ intermediate to C₄ plants. The ecological and adaptive aspects of C₃–C₄ plants would provide an important clue to understand the evolution of C₃–C₄ plants. We investigated whether growth temperature and nitrogen (N) nutrition influence the expression of C₃–C₄ traits in Chenopodium album (proto-Kranz) in comparison with Chenopodium quinoa (C₃). Plants were grown during 5 weeks at 20 or 30 °C under standard or low N supply levels (referred to as 20SN, 20LN, 30SN, and 30LN). Net photosynthetic rate and leaf N content were higher in 20SN and 30SN plants than in 20LN and 30LN plants of C. album but did not differ among growth conditions in C. quinoa. The CO₂ compensation point (Γ) of C. album was lowest in 30LN plants (36 µmol mol^–1), highest in 20SN plants (51 µmol mol^–1), and intermediate in 20LN and 30SN plants, whereas Γ of C. quinoa did not differ among the growth conditions (51–52 µmol mol^–1). The anatomical structure of leaves was not considerably affected by growth conditions in either species. However, ultrastructural observations in C. album showed that the number of mitochondria per mesophyll or bundle sheath (BS) cell was lower in 20LN and 30LN plants than in 20SN and 30SN plants. Immunohistochemical observations revealed that lower accumulation level of P-protein of glycine decarboxylase (GDC-P) in mesophyll mitochondria than in BS mitochondria is the major factor causing the decrease in Γ values in C. album plants grown under low N supply and high temperature. These results suggest that high growth temperature and low N supply lead to the expression of C₃–C₄ traits (the reduction of Γ) in the proto-Kranz plants of C. album through the regulation of GDC-P expression.

_{Proto-Kranz 植物代表了从 C 3}到 C ₃ –C ₄中间到 C ₄植物进化的初始阶段。_{C 3 -C 4 植物的生态和适应性方面将为了解 C 3} -C ₄植物_的进化_提供重要线索。我们研究了生长温度和氮 (N) 营养是否影响藜(proto-Kranz) 与藜麦(C _{3 ) 中 C 3} –C ₄性状的表达。）。在标准或低 N 供应水平（称为 20SN、20LN、30SN 和 30LN）下，植物在 20 或 30°C 下生长 5 周。20SN和30SN植物的净光合速率和叶片氮含量高于20LN和30LN植物，但在藜麦生长条件下没有差异。C. album的 CO ₂补偿点 ( Γ )在 30LN 植物中最低 (36 µmol mol ^–1 ), 在 20SN 植物中最高 (51 µmol mol ^–1 ), 在 20LN 和 30SN 植物中居中,而C.藜麦在生长条件（51–52 µmol mol ^–1）。叶子的解剖结构不受这两种植物生长条件的显着影响。然而，在C. album中的超微结构观察表明，20LN 和 30LN 植物中每个叶肉或束鞘 (BS) 细胞的线粒体数量低于 20SN 和 30SN 植物。免疫组织化学观察表明，在低氮供应和高温下生长的C. album植物中，甘氨酸脱羧酶 (GDC-P) P 蛋白在叶肉线粒体中的积累水平低于在 BS 线粒体中的积累水平是导致Γ值降低的主要因素。这些结果表明，高生长温度和低氮供应导致 C ₃ -C ₄性状的表达（减少Γ ) 在C. album的 proto-Kranz 植物中通过调节 GDC-P 表达。