Comparison of leaf structure and photosynthetic characteristics of C₃ and C₄Alloteropsis semialata subspecies

Abstract

Alloteropsis semialata (R. Br.) Hitchcock includes both C 3 and C 4 subspecies: the C 3 subspecies eckloniana and the C 4 subspecies semialata . We examined the leaf structural and photosynthetic characteristics of these plants. A. semialata ssp. semialata showed high activities of photosynthetic enzymes involved in phosphoenolpyruvate carboxykinasetype C 4 photosynthesis and an anomalous Kranz anatomy. Phosphoenolpyruvate carboxylase; pyruvate, Pi dikinase and glycine decarboxylase (GDC) were compartmentalized between the mesophyll (M) and inner bundle sheath cells, whereas ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) occurred in both cells. A. semialata ssp. eckloniana also showed an anomalous non-Kranz anatomy, in which the mestome sheath cells included abundant chloroplasts and mitochondria. Rubisco and GDC accumulated densely in the M and mestome sheath cells, whereas the levels of C 4 enzymes were low. The activity levels of photorespiratory enzymes in both subspecies were intermediate between those in typical C 3 and C 4 plants. The values of CO 2 compensation points in A. semialata ssp. semialata were within the C 4 range, whereas those in A. semialata ssp. eckloniana were somewhat lower than the C 3 range. These data suggest that the plants are C 3 -like and C 4 -like but not typical C 3 and C 4 , and when integrated with previous findings, point to important variability in the expression of C 4 physiology in this species complex. A. semialata is therefore an intriguing grass species with which to study the evolutionary linkage between C 3 and C 4 plants.

Introgression and repeated co-option facilitated the recurrent emergence of C4photosynthesis among close relatives

“…S1), which implies some Rubisco activity in these cells, confirming previous reports (Ueno and Sentoku 2006; Lundgren et al. 2016).…”

The activities of PEP carboxylase and the C4 acid decarboxylases are little changed by drought stress in three C4 grasses of different subtypes

“…Therefore, special care was taken to include the appropriate components in the extraction medium to maximise the extraction and recovery of the enzyme activities. The methods adopted in the present study were similar to those recently reported by other authors (Bailey et al 2007;Marshall et al 2007;Sudderth et al 2007), and the values obtained for the activities of the three C 4 acid decarboxylases are in the same range as previously reported for grass species (Gutierrez et al 1974;Hatch et al 1975Hatch et al , 1982Prendergast et al 1987;Ueno and Sentoku 2006).…”

Inheritance of C3―C4Intermediate Photosynthesis in Reciprocal Hybrids BetweenMoricandia Arvensis(C3―C4) andBrassica Oleracea(C3) That Differ in Their Genome Constitution

“…Br.) Hitchcock (Ueno and Sentoku, 2006), bridge the genetic gap between C 3 and C 4 species. Currently, attempts have been made to genetically manipulate photosynthesis by introducing the genes for C 4 photosynthetic enzymes into C 3 plants (reviewed in Surridge, 2002).…”