KARRIKIN INSENSITIVE2 regulates leaf development, root system architecture and arbuscular‐mycorrhizal symbiosis in Brachypodium distachyon

Root system architecture (RSA) is used to describe the spatial configuration of a root system in the soil, which substantially determines the capacity of a plant to take up nutrients and water. The present study was to assess if arbuscular mycorrhizal fungi (AMF), Glomus mosseae, G. versiforme, and Paraglomus occultum would alter RSA of peach (Prunus persica L. Batsch) seedlings, and the alteration due to mycorrhization was related to allocation of glucose/sucrose to root (Aglucose/sucrose). Inoculation with G. mosseae and G. versiforme significantly increased leaf, stem, root and total fresh weights, compared with non-AMF treatment. Mycorrhizal alterations of RSA in peach plants were dependent on AMF species, because only G. mosseae and G. versiforme but not P. occultum markedly increased root length, root projected area, root surface area and root volume. For the distribution of root length classes, AMF mainly increased 0-1 and 3-4 cm root length classes, which is AMF species dependent. Inoculated seedlings with Glomus species recorded significantly higher root sucrose and leaf and root glucose concentrations and lower root sucrose concentrations than un-inoculated control. Compared with the non-AMF treatment, G. mosseae and G. versiforme generally increased the Aglucose and Asucrose, but P. occultum significantly decreased the Aglucose and Asucrose. Asucrose or Aglucose was significantly positive correlated with root length, root projected area and root surface area. The results suggest that AMF modified variables of RSA in peach, which is AMF species dependent and related to Aglucose and Asucrose.

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Transcriptome diversity among rice root types during asymbiosis and interaction with arbuscular mycorrhizal fungi

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1504142112 ◽

2015 ◽

Vol 112 (21) ◽

pp. 6754-6759 ◽

Cited By ~ 44

Author(s):

Caroline Gutjahr ◽

Ruairidh J. H. Sawers ◽

Guillaume Marti ◽

Liliana Andrés-Hernández ◽

Shu-Yi Yang ◽

...

Keyword(s):

Root System ◽

System Architecture ◽

Arbuscular Mycorrhizal ◽

Root Systems ◽

Root System Architecture ◽

Adaptive Plasticity ◽

Functional Relationships ◽

Am Symbiosis ◽

Crown Roots ◽

Root Types

Root systems consist of different root types (RTs) with distinct developmental and functional characteristics. RTs may be individually reprogrammed in response to their microenvironment to maximize adaptive plasticity. Molecular understanding of such specific remodeling—although crucial for crop improvement—is limited. Here, RT-specific transcriptomes of adult rice crown, large and fine lateral roots were assessed, revealing molecular evidence for functional diversity among individual RTs. Of the three rice RTs, crown roots displayed a significant enrichment of transcripts associated with phytohormones and secondary cell wall (SCW) metabolism, whereas lateral RTs showed a greater accumulation of transcripts related to mineral transport. In nature, arbuscular mycorrhizal (AM) symbiosis represents the default state of most root systems and is known to modify root system architecture. Rice RTs become heterogeneously colonized by AM fungi, with large laterals preferentially entering into the association. However, RT-specific transcriptional responses to AM symbiosis were quantitatively most pronounced for crown roots despite their modest physical engagement in the interaction. Furthermore, colonized crown roots adopted an expression profile more related to mycorrhizal large lateral than to noncolonized crown roots, suggesting a fundamental reprogramming of crown root character. Among these changes, a significant reduction in SCW transcripts was observed that was correlated with an alteration of SCW composition as determined by mass spectrometry. The combined change in SCW, hormone- and transport-related transcript profiles across the RTs indicates a previously overlooked switch of functional relationships among RTs during AM symbiosis, with a potential impact on root system architecture and functioning.

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High-throughput imaging and analysis of root system architecture in Brachypodium distachyon under differential nutrient availability

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2011.0241 ◽

2012 ◽

Vol 367 (1595) ◽

pp. 1559-1569 ◽

Cited By ~ 32

Author(s):

Paul A. Ingram ◽

Jinming Zhu ◽

Aabid Shariff ◽

Ian W. Davis ◽

Philip N. Benfey ◽

...

Keyword(s):

Root Growth ◽

Root System ◽

High Throughput ◽

Nutrient Availability ◽

System Architecture ◽

Brachypodium Distachyon ◽

Root System Architecture ◽

Vital Role ◽

P Deficiency ◽

Genetic Components

Nitrogen (N) and phosphorus (P) deficiency are primary constraints for plant productivity, and root system architecture (RSA) plays a vital role in the acquisition of these nutrients. The genetic determinants of RSA are poorly understood, primarily owing to the complexity of crop genomes and the lack of sufficient RSA phenotyping methods. The objective of this study was to characterize the RSA of two Brachypodium distachyon accessions under different nutrient availability. To do so, we used a high-throughput plant growth and imaging platform, and developed software that quantified 19 different RSA traits. We found significant differences in RSA between two Brachypodium accessions grown on nutrient-rich, low-N and low-P conditions. More specifically, one accession maintained axile root growth under low N, while the other accession maintained lateral root growth under low P. These traits resemble the RSA of crops adapted to low-N and -P conditions, respectively. Furthermore, we found that a number of these traits were highly heritable. This work lays the foundation for future identification of important genetic components of RSA traits under nutrient limitation using a mapping population derived from these two accessions.

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