Title: Root morphology and exudate availability are shaped by particle size and chemistry in Brachypodium distachyon

Abstract

Root morphology and exudation define a plants' sphere of influence in soils. In turn, soil characteristics influence plant growth, morphology, root microbiome, and rhizosphere chemistry. Collectively, all these parameters have significant implications on the major biogeochemical cycles, crop yield, and ecosystem health. However, how plants are shaped by the physiochemistry of soil particles is still not well understood. We explored how particle size and chemistry of growth substrates affect root morphology and exudation of a model grass. We grew Brachypodium distachyon in glass beads with various sizes (0.5, 1, 2, 3 mm), as well as in sand (0.005, 0.25, 4 mm) and in clay (4 mm) particles and in particle-free hydroponic medium. Plant morphology, root weight, and shoot weight were measured. We found that particle size significantly influenced root fresh weight and root length, whereas root number and shoot weight remained constant. Next, plant exudation profiles were analyzed with mass spectrometry imaging and liquid chromatography-mass spectrometry. Mass spectrometry imaging suggested that both, root length and number shape root exudation. Exudate profiles were comparable for plants growing in glass beads or sand with various particles sizes, but distinct for plants growing in clay for in situ exudate collection. Clay particles were found to sorbmore » 20% of compounds exuded by clay-grown plants, and 70% of compounds from a defined exudate medium. The sorbed compounds belonged to a range of chemical classes, among them nucleosides, organic acids, sugars, and amino acids. Some of the sorbed compounds could be desorbed by a rhizobacterium (Pseudomonas fluorescens WCS415), supporting its growth. This study demonstrates the effect of different characteristics of particles on root morphology, plant exudation and availability of nutrients to microorganisms. These findings further support the critical importance of the physiochemical properties of soils when investigating plant morphology, plant chemistry, and plant-microbe interactions.« less

Authors:

Sasse, Joelle  ^[1];

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Kosina, Suzanne M. ^[2]; Raad, Markus ^[2]; Jordan, Jacob S. ^[3]; Whiting, Katherine ^[2]; Zhalnina, Kateryna ^[2]; Northen, Trent R. ^[3]

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+ Show Author Affiliations

1. Environmental Genomics and Systems Biology Lawrence Berkeley National Laboratory Berkeley CA USA, Department of Plant and Microbial Biology University of Zurich Zurich Switzerland
2. Environmental Genomics and Systems Biology Lawrence Berkeley National Laboratory Berkeley CA USA
3. Environmental Genomics and Systems Biology Lawrence Berkeley National Laboratory Berkeley CA USA, Joint Genome Institute Lawrence Berkeley National Laboratory Berkeley CA USA

Publication Date:

Thu Jul 02 00:00:00 EDT 2020

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER); National Science Foundation (NSF)

OSTI Identifier:

1635742

Alternate Identifier(s):

OSTI ID: 1635744; OSTI ID: 1756344

Grant/Contract Number:  

AC02-05CH11231; 1617020

Resource Type:

Published Article

Journal Name:

Plant Direct

Additional Journal Information:

Journal Name: Plant Direct Journal Volume: 4 Journal Issue: 7; Journal ID: ISSN 2475-4455

Publisher:

Wiley and American Society of Plant Biologists and Society for Experimental Biology

Country of Publication:

United Kingdom

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Brachypodium distachyon; particle chemistry; particle size; Pseudomonas fluorescens; rhizosphere; root exudation; root morphology