Effects of progeny in the modulation of the response to water stress in isohydric and anisohydric varieties

Abstract

Each grapevine variety has a specific water use regulation response under drought, and it is still unclear whether this regulation results from innate genotypic behavior (iso- and anisohydric), or is a response to environmental factors, namely recurrent water stress priming effects. In the present work, we explored the influence of the field-grown genotypes’ drought memory in the drought-response phenotype of their vegetative progenies, in Trincadeira (isohydric) and Castelão (anisohydric) varieties under a drought event followed by recovery in a glasshouse. Cuttings from both cultivars subjected to full irrigation (FI) and non-irrigation (NI) treatments for 5 consecutive years were used. Progenies were subjected to two irrigation treatments, well-watered (WW), where the soil was kept at field capacity, and water-stress (WS), where irrigation was withheld for 7 days. WS plants were then re-watered and kept at field capacity for 72h. Measurements and sampling were done in both progenies of both treatments, at 0h, 72h and 168h after the beginning of the treatment and after 24h and 72h of recovery. NI progenies from both cultivars had improved gas exchange parameters, better total plant hydraulic conductance under drought, and faster recovery than FI progenies. Nocturnal and diurnal transpiration were affected both by progeny and treatment. Leaf wax content was significantly enhanced by WS in both progenies, but it was higher in NI progenies. Stomatal conductance kinetic showed differences in the timing of stomatal aperture between progenies, in particular after water recovery. Leaf temperature (T_c) was similar in both varieties and progenies, but higher temperatures were measured under WS. Leaf temperature only recovered 72h after re-watering. Although isohydric and anisohydric genotypes exhibited different drought acclimation responses due to their inner genetic behavior, their underlying hydraulic, stomatal and photosynthetic regulatory mechanisms were also affected by historical origin. In this presentation, fundamental insights about potential priming mechanisms in grapevine will be further discussed.