Sensing and signalling in plant stress responses: ensuring sustainable food security in an era of climate change

Abstract

Agriculture in the 21st century faces multiple challenges from biotic and abiotic stresses, which impose major constraints on crop yield. Under field conditions, the combined or sequential occurrence of environmental stresses poses a serious threat to global food security. Plants exhibit plasticity in their responses to environmental stresses, which may be attributed to their genetic and/or epigenetic make-up. One of the major challenges facing plant biology today concerns how gene regulatory networks function to generate morphological and adaptive diversity. Gaining a better understanding of the responses of crop plants to environmental stresses will allow the identification of improved genetic markers to increase yield stability and enhance productivity over a wide range of growth conditions. The availability of high-throughput sequencing technologies provides an opportunity to uncover the genetic/epigenetic basis of plant stress responses and adaptation. Furthermore, dissection of the molecular mechanisms underlying resilience will help us understand how plants cope with extreme environmental conditions, and ultimately lead to the development of climate-smart crops. Understanding the sensing and signalling mechanisms that plants use to perceive and respond appropriately to stress is crucial for the development of stress-resistant crops using current strategies and technologies. The Symposium ‘Sensing and signalling in plant stress response’ was organized in New Delhi, India, on the 15–17 April 2019 (Fig. 1) specifically to summarize and discuss current knowledge and the application of state of the art approaches and techniques to elucidate the sensing and signalling machinery operative in plants. The emblem of the India-EMBO Symposium depicts the various modules that plants use for sensing and signalling in the form of various leaf colours linked to the stem of a tree depicting the flow of knowledge towards ensuring food security in this era of climate change. The meeting attracted over 150 participants from 45 universities belonging to 16 countries across the globe (Fig. 2). In this report, we highlight emergent themes arising from the meeting and some of the fundamental biological questions that drive contemporary studies of stress signalling in plants. As sessile organisms, plants adapt to adverse environmental conditions through the coordinated regulation of a complex network of sensing mechanisms. At a cellular level, this includes both anterograde and retrograde signalling pathways. Furthermore, the cellular and developmental plasticity of plants can be harnessed to improve productivity under sub-optimal environmental conditions. In southeast Asia for example, flooding and drought impose frequent and increasing threat to staple food crops, such as rice. In her inaugural lecture, Julia Bailey-Serres (University of California, Riverside, CA, USA) discussed the importance of the SUB1A and AG1 loci in submergence tolerance, providing evidence of convergent signalling pathways that control metabolism during the transition from the oxygen-poor stressed state to air (Locke et al., 2018). Extending this discussion of the amelioration of stress tolerance and metabolism, Rashmi Sasidharan (Utrecht University, the Netherlands) presented data on the dynamics and interplay between ethylene, oxygen and nitric oxide (NO) signalling during hypoxia (Yeung et al., 2019). Using a functional genomics approach, Akhilesh Tyagi (University of Delhi, India) presented results demonstrating that stress-associated proteins in rice such as OsSAP1/11 that contain A20/AN1 zinc-finger domains interact with the receptor-like cytoplasmic kinase OsRLCK253 at the nuclear membrane and the plasma membrane in order to confer drought and salt tolerance (Giri et al., 2011). In addition, Ramesh V. Sonti (National Institute of Plant Genome Research, New Delhi, India) presented results showing that OsWRKY42 prevents cell wall damage and provides tolerance to s