几种 C_4和 CAM 植物光合亚途径的鉴别

THE IDENTIFICATION OF PHOTOSYNTHETIC SUBPATHWAYS OF SOME C_4 AND CAM PLANTS

C_4.植物鼠尾粟(Sporobolus indicus),金色狗尾草(Setaria glauca)、细叶结缕草(zoysia tenuifolia)、千金子(Leptochloa chinensis)和 CAM 植物芦荟(Aloe vera)属PEP 羧激酶亚型。C_4双子叶植物飞扬草(Euphorbia hirta)则为 NAD 苹果酸亚型。前面4种 PEP 羧激酶型的 C_4草本植物的维管束鞘细胞叶绿体呈均匀分布,与已知的该型的离心排列不同。认为这可为 C_4植物三种光合亚型的演化关系提供新的证据。

The photosynthetic subpathways of five C_4 plants and one CAM plant were distinguished according to their chemical,physiological and cytological characteristics.Based on C_4 acid decarboxylation enzymes,four C_4 plants of Setaria glauca,Sporobolus indicus,Zoysia tenuifolia and Leptochloa chinensis all exhibited the functional high activities of PEP carboxykinase and aspartate aminotransferase as seen in the known PEP-CK subtype.The δ^(13)C value of-12.43% in leaves of L.chinensis was also consistent with that range among PEP-CK subtype.So,these species were classified into PEP-CK subtype.However,their chloroplasts in bundle sheath cells were evenly distributed,not as that displayed centrifugally or centripetally in three typical subtypes.The even arrangement of chloroplasts in bundle sheath cells was likely to be an evolutional intermediate from centripetal (NAD-ME type) to centrifugal types.(NADP-ME and most PEP-CK types). The high activities of NAD-malic enzyme and aspartate aminotransferase,accompanied with the centripetally located chloroplasts,0.057 of quantum yield and the δ^(13)C value of-15.3% in leaves of C_4 dicot Euphobia hirta indicated characteristics of NAD-ME subtype.Moreover, CAM plant Aloe vera clearly fell into PEP-CK sybtype because of its high activity of PEP-CK both in whole leaf and green tissue.