Abiotic and Biotic Stresses Interaction in Fabaceae Plants. Contributions from the Grain Legumes/Soilborne Vascular Diseases/Drought Stress Triangle Susana T. Leitão, Susana Araújo, Diego Rubiales, and Maria Carlota Vaz Patto Abstract As sessile organisms, plants are constantly exposed to simultaneously abi- otic and biotic stresses that impact growth thus resulting in significant yield losses. An example is drought and root infecting pathogens, which combined cause greater damage to plants than the stresses individually. Substantial information is available on the physiological, molecular, and metabolic changes in Fabaceae plants exposed to individual stresses, but little is known about how plants respond to multiple stresses. This is of primary importance for the development of breeding approaches based on the trade-off between plant defense response mechanisms, and high and consis- tent yield under field conditions. A better knowledge of the mechanisms by which legume plants perceive and transduce simultaneous or sequential combination of stress signals to initiate diverse adaptive responses is essential for breeding multiple stress-tolerant crop cultivars. In this chapter, we assess the relevance of understand- ing legume combined responses to abiotic and biotic stresses for production and breeding, focusing on soilborne vascular diseases and drought interaction in grain legumes. Particular attention is given to the crosstalk between signaling pathways of the “stress triangle” pathogen/host/environment interactions and to the application of integrated breeding methods aiming at multiple stress-resistant legume crops better adapted to climate change. Keywords Abiotic/biotic interaction · Grain legumes · Drought · Soilborne vascular diseases · Climate change S. T. Leitão · S. Araújo · M. C. Vaz Patto (B ) Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Oeiras,Portugal e-mail: cpatto@itqb.unl.pt D. Rubiales Institute for Sustainable Agriculture, CSIC, Córdoba, Spain © Springer Nature Singapore Pte Ltd. 2020 M. Hasanuzzaman et al. (eds.), The Plant Family Fabaceae, https://doi.org/10.1007/978-981-15-4752-2_9 237