Rootstock control of scion transpiration and its acclimation to water deficit are controlled by different genes

Abstract

• The stomatal control of transpiration is one of the major strategies by which plants cope with water stress. Here, we investigated the genetic architecture of the rootstock control of scion transpiration-related traits over a period of 3yr. • The rootstocks studied were full sibs from a controlled interspecific cross (Vitis vinifera cv. Cabernet Sauvignon×Vitis riparia cv. Gloire de Montpellier), onto which we grafted a single scion genotype. After 10d without stress, the water supply was progressively limited over a period of 10d, and a stable water deficit was then applied for 15d. Transpiration rate was estimated daily and a mathematical curve was fitted to its response to water deficit intensity. We also determined δ 13C values in leaves, transpiration efficiency and water extraction capacity. These traits were then analysed in a multienvironment (year and water status) quantitative trait locus (QTL) analysis. • Quantitative trait loci, independent of year and water status, were detected for each trait. One genomic region was specifically implicated in the acclimation of scion transpiration induced by the rootstock. The QTLs identified colocalized with genes involved in water deficit responses, such as those relating to ABA and hydraulic regulation. • Scion transpiration rate and its acclimation to water deficit are thus controlled genetically by the rootstock, through different genetic architectures. © 2012 INRA. New Phytologist © 2012 New Phytologist Trust.