Transcriptome analysis of Lolium temulentum exposed to a combination of drought and heat stress

Authors: Martin, Ruth; KRONMILLER, BRENT - Oregon State University; Dombrowski, James

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2021
Publication Date: 10/21/2021
Citation: Martin, R.C., Kronmiller, B., Dombrowski, J.E. 2021. Transcriptome analysis of Lolium temulentum exposed to a combination of drought and heat stress. Plants. 10(11). Article 2247. https://doi.org/10.3390/plants10112247.
DOI: https://doi.org/10.3390/plants10112247

Interpretive Summary: Grasses are found growing ubiquitously in almost every environment in the world, but many commercially important grasses are grown and utilized in temperate climates. However, even in normally temperate environments, plants are being exposed to more frequent extreme climatic events. In order to understand how grasses cope with concurrent heat and drought stress, it is important to identify not only what molecular processes the grasses mobilized in response to the stress, but also when these processes are activated over the course of the stress. Sequencing of the genes expressed in the model grass Lolium temulentum exposed to drought plus heat revealed over 20,000 up-regulated and 17,000 down-regulated differentially expressed genes. Analysis of the data revealed many genes that help the plant to recognize and respond to the stress. These include genes that help the plant to take care of or remove damaged proteins, respond to increased levels of oxidative stress, and alter plant growth. These data provide a valuable first step towards unraveling the temporal relationships and interconnections between the various molecular processes utilized by the grasses in order to survive simultaneous exposure to heat and drought stress. The knowledge gained of genes/pathways that grasses use to respond to the combination of heat/drought will be useful in developing approaches to generate multi-stress tolerant grasses.

Technical 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. Comparative transcriptome analysis of Lolium temulentum exposed to drought plus heat and control plants revealed 20,221 unique up-regulated and 17,034 unique down-regulated differentially regulated sequences. 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, ethylene/APETALA2, NAC, and WRKY transcription factors, and CCCH type Zinc Finger 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.