Comparative Study Reveals Insights of Sheepgrass (Leymus chinensis) Coping With Phosphate-Deprived Stress Condition.

Lingyu Li,Peng Liu,Lianwei Peng,Jirui Gong,Fang Huang,Weibo Ren,Xinhong Wu,Haomeng Yang

doi:10.3389/fpls.2019.00170

Abstract

Sheepgrass [Leymus chinensis (Trin.) Tzvel] is a valuable forage plant highly significant to the grassland productivity of Euro-Asia steppes. Growth of above-ground tissues of L. chinensis is the major component contributing to the grass yield. Although it is generally known that this species is sensitive to ecosystem disturbance and adverse environments, detailed information of how L. chinensis coping with various nutrient deficiency especially phosphate deprivation (-Pi) is still limited. Here, we investigated impact of Pi-deprivation on shoot growth and biomass accumulation as well as photosynthetic properties of L. chinensis. Growth inhibition of Pi-deprived seedlings was most obvious and reduction of biomass accumulation and net photosynthetic rate (Pn) was 55.3 and 63.3%, respectively, compared to the control plants grown under Pi-repleted condition. Also, we compared these characters with seedlings subjected to low-Pi stress condition. Pi-deprivation caused 18.5 and 12.3% more reduction of biomass and Pn relative to low-Pi-stressed seedlings, respectively. Further analysis of in vivo chlorophyll fluorescence and thylakoid membrane protein complexes using 2D-BN/SDS-PAGE combined with immunoblot detection demonstrated that among the measured photosynthetic parameters, decrease of ATP synthase activity was most pronounced in Pi-deprived plants. Together with less extent of lipid peroxidation of the thylakoid membranes and increased ROS scavenger enzyme activities in the leaves of Pi-deprived seedlings, we suggest that the decreased activity of ATP synthase in their thylakoids is the major cause of the greater reduction of photosynthetic efficiency than that of low-Pi stressed plants, leading to the least shoot growth and biomass production in L. chinensis.

Highlights

Phosphorus (P) is a major nutrient essential to plant growth and development
Since no difference in the intercellular CO2 concentrations (Ci) was observed between control and phosphate anion (Pi)-stressed plants (Figure 5C), and the reduced portion of ATP synthase activity was largely comparable to the decreased photosynthetic rate (Pn) between Pi-deprived and low-Pi-stressed plants (Figure 5), we suggest that the greater growth/biomass reduction of Pi-deprived L. chinensis seedlings could be largely attributable to the reduced capability of ATP production catalyzed by ATP synthase in the thylakoids
We have investigated growth and photosynthetic characteristics of the dominant forage species L. chinensis in response to Pi-deprivation

Summary

Introduction

Phosphorus (P) is a major nutrient essential to plant growth and development. It is estimated that that 30% of the agricultural soils worldwide are Pi deficient and concentration of Pi in soil solutions is generally lower than 10 μM, which is far below the critical level required for the optimal performance of crops, resulting in severe yield limitations (Batjes, 1997; Abel et al, 2002; MacDonald et al, 2011). Over-addition of Pi exists in some other regions, causing eutrophication of lakes and seas (MacDonald et al, 2011) as well as agricultural runoff (Abel et al, 2002; Niu et al, 2013). It is imperative to increase Pi utilization efficiency of plants toward sustaining global vegetation productivity with reduced Pi fertilizers (López-Arredondo et al, 2014)

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