C4 photosynthetic pathway and morphological functional types were determined for 104 species in 45 genera and 10 families from the deserts of China. 67 C4 species (64.4 %) were found in Dicotyledoneae (e.g. Chenopodiaceae, Polygonaceae, and Amaranthaceae), the other 37 species were in Monocotyledoneae (e.g. Gramineae, Cyperaceae, and Commelinaceae). 36.5 % of the Chenopodiaceae species (predominantly members of the genera Anabasis, Atriplex, Kochia, Salsola, and Suaeda) identified in the desert regions were found with C4 photosynthesis, which was about 48 % of the total C4 species. Many C4 species (58.7 %) were annuals (e.g. Amaranthus, Atriplex, Digitaria, Eragrostis, Kochia, and Salsola) and experienced long-term droughts, high temperature, and high irradiance. Relatively more shrub C4 species (28 species of 104) were found in Chenopodiaceae (e.g. Anabasis, Camphorosma, Haloxylon, and Salsola) and Polygonaceae (e.g. Calligonum) in the desert regions. Most of shrub C4 species with small leaf area were no more than 1 m in height and distributed in sandy soils. Composition of relatively more annual species, shrubs, and Chenopodiaceae C4 species was the primary characteristic for the C4 species occurrence in deserts, and this was remarkably related with the arid environmental conditions.
The effects of the diurnal variations in ambient temperature on some C3 and C4 enzymes in the Salsola dendroides and Suaeda altissima species of Chenopodiaceae family were studied during the intensive vegetation period. Activities of phosphoenolpyruvate carboxylase (PEPC) and cytosolic aspartate aminotransferase (AsAT) were shown to decrease in both species in the afternoon and evening. The activity of the mitochondrial AsAT decreased in S. altissima, remained relatively constant in S. dendroides during the day. The activity of alanine aminotransferase was high in the S. dendroides species in the morning and evening and decreased in the S. altissima species by the evening. Glucose-6-phosphate activated PEPC in both species throughout the day. The study of the redox status-regulated C3 enzymes showed temperature-related increases in NADP-glyceraldehyde 3-phosphate dehydrogenase activity in both plants, in fructose-2,6-bisphosphatase activity in the S. altissima species, and in NADP-MDH activity in the S. dendroides species in the afternoon., T. Y. Orujova, S. M. Bayramov, U. A. Gurbanova, H. G. Babayev, M. N. Aliyeva, N. M. Guliyev, Y. M. Feyziyev., and Obsahuje bibliografii