Stressed mothers, tolerant daughters: a case studyabout the physiological responses and growth of sugarcane plants under water deficit

Abstract

24Drought stress can imprint marks in plants after a previous exposure, leading to a 25 permissive state that facilitates a more effective response to subsequent stress events. 26 Such stress imprints would benefit plants obtained from progenitors previously exposed 27 to drought. Herein, our hypothesis was that daughter plants obtained from mother 28 plants previously exposed to water deficit will perform better under water deficit as 29 compared to those obtained from mothers that did not face stressful conditions. 30 Sugarcane mother plants were grown under well-hydrated conditions or subjected to 31 three cycles of water deficit by water withholding. Then, daughter plants produced 32 through vegetative propagation were subjected to water deficit. Leaf gas exchange was 33 reduced under water deficit and daughters from mothers that experienced water deficit 34 presented a faster recovery of CO 2 assimilation and higher instantaneous carboxylation 35 efficiency after rehydration as compared to daughters from mothers that did not face 36 water deficit. Plants obtained from mother plants that faced water deficit showed the 37 highest leaf proline concentration under water deficit as well as higher leaf H 2 O 2 38 concentration and leaf ascorbate peroxidase activity regardless of water regime. Under 39 well-watered conditions, daughters from mothers that faced stressful conditions 40 presented higher root H 2 O 2 concentration and root catalase activity than ones from 41 mothers that did not experience water shortage. Such physiological changes were 42 associated with improvements in leaf area and shoot and root dry matter accumulation 43 in daughters from stressed mothers. Our results suggest that root H 2 O 2 concentration is 44 a chemical signal associated with stress memory and improved sugarcane growth. Such 3 45 findings bring a new perspective to sugarcane production systems, in which stress 46 memory can be explored for improving drought tolerance in rainfed areas. 47 48