Leaf anatomy and C₄ photosynthetic enzymes in three reed ecotypes

Abstract

Differences in leaf interveinal distances, chloroplasts distribution in bundle sheath cells (BSC) and activities of C 4 photosynthetic enzymes in the leaves of three ecotypes of Phragmites communis Trinius, namely swamp reed (SR), heavy salt meadow reed (HSMR) and dune reed (DR), occurring in the desert region of northwest China were investigated. The two terrestrial ecotypes, DR and HSMR, had denser vascular system, more and longer BSC chloroplasts and higher capacity of CO 2 concentrating mechanism of NAD-ME subtype as compared with the SR ecotype. The enhanced NADP-ME pathway in the HSMR might contribute to its adaptation to the salinity habitat.

Physiological and Proteomic Analyses of Different Ecotypes of Reed (Phragmites communis) in Adaption to Natural Drought and Salinity

“…The Kranz anatomy and high density of veins in leaves were the typical structures of the C 4 plants (Schlüter and Weber, 2020 ). P. communis was a C 3 hydrophytic species, however, investigations of leaf structures, δ 13 C, and C 4 photosynthetic enzymes in different ecotypes of reed showed an obvious evolution tendency from C 3 to C 4 in adaptation to long-term natural drought and salinity habitats (Zheng et al, 1993 ; Zhu et al, 2012 ). Consistent with the previous studies, our confocal laser scanning micrograph results confirmed a Kranz anatomy-like structure with mesophyll cells and chloroplast-containing BSCs, especially in DR and HSMR, they both had more and bigger chloroplasts in their BSCs in comparison with the swamp ecotype, SR ( Supplementary Figure 1 ).…”

“…Phragmites communis is a hydrophytic species thriving across the world, whose typical habitats are fresh and brackish swamps, riverbanks, and lakesides. However, the reed can adapt to adverse terrestrial habitats, and various ecotypes exhibiting genetic differences have evolved resistance to drought and salinity (Matoh et al, 1988 ; Zhu et al, 2001 , 2003a , b , 2012 ; Eller et al, 2017 ). Due to high intraspecific diversity and phenotypic plasticity, reed has an extensive ecological amplitude and a great capacity to acclimate to adverse environmental conditions, which therefore offers valuable insights into plant responses to natural stresses (Eller et al, 2017 ).…”

“…Stable variations of morphological and physiological characteristics in response to drought and salinity and genetic diversity analysis on these reed ecotypes confirmed that they diverged from a common ancestor, which offers valuable insights into plants within one species in response to changing habitats with different soil water levels and soil salinity (Wang et al, 1998 ; Lin et al, 2007 ; Eller et al, 2017 ; Li et al, 2017 ). Over 20 years, comparative researches on these different ecotypes of reed in morphology, ultrastructure, physiological, and molecular distinctions have been extensively investigated (Chen and Zhang, 1991 ; Wang et al, 1998 ; Zhu et al, 2001 , 2003b , c , 2012 ; Chen et al, 2003 ; Lin et al, 2007 ). These results show that water availability and soil salinity are important factors related to the high intraspecific diversity and phenotypic plasticity of these reed ecotypes; however, the specific mechanisms of two terrestrial ecotypes in adaption to drought and salinity habitats remain unclear.…”

“…Due to the sessile lifestyle, the plants often simultaneously suffer from various stresses in natural conditions. For example, in addition to water deficiency, plants growing in the desert regions are always accompanied by other stress factors as well, such as high temperature and high irradiance (Zhu et al, 2001(Zhu et al, , 2003c. A variety of evidence indicates that combined stress factors impact plant growth and development more severely than a single one (Pandey et al, 2017;Sengupta et al, 2021).…”

Cosmopolitan Species As Models for Ecophysiological Responses to Global Change: The Common Reed Phragmites australis

“…However, due to the lack of chloroplasts in this layer, there is no functional correlation with true C 4 plants ( Henriques and Webb, 1989 ). Doubts about the photosynthetic pathway of P. australis have also emerged due to relatively high PEPcase activities, higher activities of the decarboxylating NADP-dependent malic enzyme (NADP-ME), and a possible C 3 –C 4 intermediate pathway associated with ecotypes from arid or salt-affected habitats ( Rintamaki and Aro, 1985 ; Zheng et al, 2000 ; Zhu et al, 2012 ). Most of the known C 4 species occur in the Poaceae, in which C 4 -evolution has occurred independently several times and, thus, genes are present in P. australis that can rapidly develop C 4 functions including the gene coding for NADP-ME ( Christin et al, 2009 ).…”