Transcriptome Analysis of Lolium temulentum Exposed to a Combination of Drought and Heat Stress.

Ruth C Martin,Brent A Kronmiller,James E Dombrowski

doi:10.3390/plants10112247

Abstract

Drought and heat are two major stresses predicted to increase in the future due to climate change. Plants exposed to multiple stressors elicit unique responses from those observed under individual stresses. A comparative transcriptome analysis of Lolium temulentum exposed to drought plus heat and non-stressed control plants revealed 20,221 unique up-regulated and 17,034 unique down-regulated differentially regulated transcripts. Gene ontology analysis revealed a strong emphasis on transcriptional regulation, protein folding, cell cycle/parts, organelles, binding, transport, signaling, oxidoreductase, and antioxidant activity. Differentially expressed genes (DEGs) encoding for transcriptional control proteins such as basic leucine zipper, APETALA2/Ethylene Responsive Factor, NAC, and WRKY transcription factors, and Zinc Finger (CCCH type and others) proteins were more often up-regulated, while DEGs encoding Basic Helix-Loop-Helix, MYB and GATA transcription factors, and C2H2 type Zinc Finger proteins were more often down-regulated. The DEGs encoding heat shock transcription factors were only up-regulated. Of the hormones, auxin-related DEGs were the most prevalent, encoding for auxin response factors, binding proteins, and efflux/influx carriers. Gibberellin-, cytokinin- and ABA-related DEGs were also prevalent, with fewer DEGs related to jasmonates and brassinosteroids. Knowledge of genes/pathways that grasses use to respond to the combination of heat/drought will be useful in developing multi-stress resistant grasses.

Highlights

Forage and turf grasses are exposed to many biotic and abiotic stresses that impact yields and the quality of forage, seed yield, and turfgrass utility
This paper describes the transcriptomic response of Lolium temulentum (Lt) to the combined effects of heat/drought stresses, with an emphasis on transcription factors and hormone-related processes
In order to understand how grasses cope with concurrent heat and drought stress, it is important to identify what molecular processes the grasses mobilized in response to the stress, and when these processes are activated over the course of the stress

Summary

Introduction

Forage and turf grasses are exposed to many biotic and abiotic stresses that impact yields and the quality of forage, seed yield, and turfgrass utility. Drought and heat are two major stressors predicted to increase in the future due to the changing climate [1]. In the US, there have been nine drought related disasters since 2010, four of which were concurrent with major heat events. With the increasing likelihood of these events in the future, it is important to understand how the grasses respond to these combined heat/drought disasters to facilitate the development or identification of crops that can perform better under these increasingly extreme conditions. Heat stress negatively impacts many aspects of crop production including germination, biomass accumulation, and floral and seed development, all of which can affect forage and seed yields. Damage to proteins, membranes, mitochondria, photosynthetic machinery, and chloroplasts, and increases in reactive oxygen species (ROS)

Methods

Results

Conclusion