Long-Term Overgrazing-Induced Memory Decreases Photosynthesis of Clonal Offspring in a Perennial Grassland Plant

Abstract

Previous studies of transgenerational plasticity have demonstrated that long-term overgrazing experienced by Leymus chinensis, an ecologically dominant, rhizomatous grass species in eastern Eurasian temperate grassland, significantly affects its clonal growth in subsequent generations. However, there is a dearth of information on the reasons underlying this overgrazing-induced memory effect in plant morphological plasticity. We characterized the relationship between a dwarf phenotype and photosynthesis function decline of L. chinensis from the perspective of leaf photosynthesis by using both field measurement and rhizome buds culture cultivated in a greenhouse. Leaf photosynthetic functions (net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration, and transpiration rate) were significantly decreased in smaller L. chinensis individuals that were induced to have a dwarf phenotype by being heavily grazed in the field. This decreased photosynthetic function was maintained a generation after greenhouse tests in which grazing was excluded. Both the response of L. chinensis morphological traits and photosynthetic functions in greenhouse were deceased relative to those in the field experiment. Further, there were significant decreases in leaf chlorophyll content and Rubisco enzyme activities of leaves between bud-cultured dwarf and non-dwarf L. chinensis in the greenhouse. Moreover, gene expression patterns showed that the bud-cultured dwarf L. chinensis significantly down-regulated (by 1.86- to 5.33-fold) a series of key genes that regulate photosynthetic efficiency, stomata opening, and chloroplast development compared with the non-dwarf L. chinensis. This is among the first studies revealing a linkage between long-term overgrazing affecting the transgenerational morphological plasticity of clonal plants and physiologically adaptive photosynthesis function. Overall, clonal transgenerational effects in L. chinensis phenotypic traits heavily involve photosynthetic plasticity.

Leaf gas exchange and photosynthesis curves of Elymus nutans and Potentilla anserina under fencing and grazing conditions in the Qilian Mountains, Northwest China

“…Five years fencing significantly improved the photosynthetic capacity in both species. In addition, fencing increased the daily mean P N values in both species, which is consistent with the previous research (Zhang et al, 2009;Zlatev and Fernando, 2012;Tao et al, 2015;Ren et al, 2017). However, the patterns of P N under both regimes varying across the three observation dates were different in E. nutans and P. anserina, which was likely attributed to the different adaptions of the two species.…”

Leymus chinensis Tolerates Mowing Disturbance by Maintaining Photosynthesis in Saline-Alkali Heterogeneous Habitats

“…With the increase of grazing intensity, in order to better adapt to grazing, plants not only change morphological indicators but also change physiological indicators such as photosynthesis and redistribution of nutrients in plants [28,29]. Grazing reduces the leaf area of plants, directly affects photosynthesis [30], and even directly impairs some functions of plants [31]. In addition, grazing can affect the water situation in plants, thus changing the relationship between net photosynthetic rate and water, leading to the decline of net photosynthetic rate [30].…”

“…Grazing reduces the leaf area of plants, directly affects photosynthesis [30], and even directly impairs some functions of plants [31]. In addition, grazing can affect the water situation in plants, thus changing the relationship between net photosynthetic rate and water, leading to the decline of net photosynthetic rate [30]. However, many studies have found that moderate grazing and mowing can stimulate plants to produce compensatory growth, thus restoring their lost biomass, and even produce more biomass.…”

Effects of Urtica cannabina to Leymus chinensis Ratios on Ruminal Microorganisms and Fiber Degradation In Vitro

“…L. chinensis is a perennial herb, which is one of the favorite forages of large herbivores because of its high palatability and proper nutritional values [4]. However, long-term livestock farming, dominated by sheep and goats, causes severe degradation by reducing canopy cover significantly [5]. Therefore, alternative forage sources are needed as a substitute for L. chinensis to reduce grassland degradation dominated by L. chinensis and to alleviate vacancies in high-quality forage.…”