Short communication
Effect of rhizobia symbiosis on lignin levels and forage quality in alfalfa (Medicago sativa L.)

https://doi.org/10.1016/j.agee.2016.08.035Get rights and content

Highlights

  • Rhizobia symbiosis increased lignin content and reduced digestibility of alfalfa.

  • The symbiosis enhanced transcript levels of PAL, C4H, C3H, HCT and CCR genes.

  • The symbiosis increased Ca levels and decreased K levels in alfalfa.

Abstract

Many beneficial effects of symbiotic rhizobia on leguminous plants have been reported. Here we report a novel effect of rhizobia on forage quality in alfalfa. We found that nodulated alfalfa showed an increase in lignin content and a decrease in digestibility in comparison with non-nodulated plants. Detailed studies revealed that nodulation resulted in an increase in monolignol G unit and S unit. An overall increase in lignin content in nodulated alfalfa was associated with more lignified tissues in the stem and an upregulation of transcript levels of several lignin biosynthesis genes. We hypothesize that an increase in lignin content in nodulated alfalfa is a result of defensive response in plants to rhizobial invasion.

Graphical abstract

  1. Download : Download high-res image (64KB)
  2. Download : Download full-size image

An effect of rhizobia symbiosis on lignin level and forage quality in alfalfa. Rhizobia symbiosis increases lignin content and decreases forage digestibility. An increase in lignin content in nodulated alfalfa was associated with an upregulation of transcript levels of several lignin biosynthesis genes such as PAL, C4H, C3H, HCT and CCR. The upregulation of PAL gene may be linked to the increase of Ca level in alfalfa after nodulation. In addition, rhizobia symbiosis could also increase the levels of ADF, NDF and hemicellulose, resulting in a reduction in IVTD of alfafla. Therefore, forage quality was decreased due to the increase of lignin and other cell wall components (ADF, NDF and hemicellulose) induced by rhizobia symbiosis.

Section snippets

Acknowledgments

This work was supported by the Project of National Natural Science Foundation of China (31272490, 31572456), the major Project for Tibetan forage industry (Z2014C02N02), China Postdoctoral Science Foundation (2014M552496) and Technology system of Agricultural Industry in China (CARS-35). We acknowledge the South Dakota Agricultural Experiment Station at South Dakota State University for technical assistance and language editing.

References (27)

  • W. Boerjan et al.

    Lignin biosynthesis

    Annu. Rev. Plant Biol.

    (2003)
  • X.F. Chang et al.

    Rapid, microscale, acetyl bromide-based method for high-throughput determination of lignin content in Arabidopsis thaliana

    J. Agric. Food Chem.

    (2008)
  • F.D. Dakora

    Defining new roles for plant and rhizobial molecules in sole and mixed plant cultures involving symbiotic legumes

    New Phytol.

    (2003)
  • Cited by (9)

    • Functions of mineral-solubilizing microbes and a water retaining agent for the remediation of abandoned mine sites

      2021, Science of the Total Environment
      Citation Excerpt :

      These polymers are deposited predominantly in the walls of secondarily thickened cells, which makes them rigid and impervious (Vanholme et al., 2010). In this study, the addition of microbes increased the lignin content but decreased the content of cellulose, which was similar to previous studies (Zhang et al., 2016). However, further research is required to determine exactly which biosynthetic genes are affected by microbes that lead to changes in lignin, cellulose, and hemicellulose.

    View all citing articles on Scopus
    View full text