Physiological and transcriptomic analyses of drought stress response in Ilex paraguariensis St. Hil.

SANSBERRO, P.

Foz do Iguazu

Conferencia; XV Brazilian Congress of Plant Physiology. I Brazilian-Israeli Plant Science Conference.; 2015

Sociedad Brasilera de Fisiología Vegetal

Ilex paraguariensis St. Hil. (erva-mate) is a shade-tolerant tree that is cultivated either via agroforestry systems or monoculture in northeastern Argentina, southeastern Brazil, and Paraguay. The primary production has several drawbacks that require attention in order to preserve the economic and social sustainability of the producing region. Among them, drought is the most important limiting factor for crop production in Argentina, since plants are frequently exposed to water deficit during the summer season, which leads to leaf abscission and yield reduction.Initially, two cultivars growing in the field with contrasting behavior respect to gas exchange were selected. Subsequently, to determine the physiological basis of drought tolerance and identify drought long-term responsive genes, a 35-day experiment under controlled environmental conditions was developed by inducing a gradual decrease of soil moisture.The physiological analysis indicated that tolerant genotype strongly reduces stomatal conductance, as a strategic tool to avoid wilting at an early stage of dehydration. Subsequently, as the leaf water potential decreases due to the intensification of stress, plant reacts making osmotic adjustment to sustain metabolic activity and enable rapid recovery of photosynthetic activity after re-watering. Sequence analysis revealed that activated genes were mostly involved in signal transduction, transcription, photosynthesis, and respiration while down-regulated genes were involved in metabolism, protection, and plant defense against microorganisms.