Regulation of the ascorbate-glutathione cycle in wild almond during drought stress

Abstract

In wild species of almond (Prunus spp.), the activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR), as well as the levels of ascorbate/glutathione pools and H2O2 were subjected to water deficit and shade conditions. After 60 days of water shortage, the species were subjected to a rewatering treatment. During water recovery, leaves exposed to sunlight and leaves under shade conditions of about 20–35% of environmental irradiance were sampled. After 70 days without irrigation, mean predawn leaf water potential of all the species fell from −0.32 to −2.30 MPa and marked decreases in CO2 uptake and transpiration occurred. The activities of APX, MDHAR, DHAR, and GR increased in relation to the severity of drought stress in all the wild species studied. Generally, APX, MDHAR, DHAR, and GR were down-regulated during the rewatering phase and their activities decreased faster in shaded leaves than in sun-exposed leaves. The levels in total ascorbate, glutathione, and H2O2 were directly related to the increase in drought stress and subsequently decreased during rewatering. The antioxidant response of wild almond species to drought stress limits cellular damage caused by reactive oxygen species during periods of water deficit and may be of key importance for the selection of drought-resistant rootstocks for cultivated almond

Induction of antioxidant system in niger (Guizotia abyssinica Cass.) under drought stress

“…ASC levels in stressed seedlings of niger showed a 0.48-fold increase over 72 h of exposure time. These results are in conformity with drought stressed almond (Sorkheh et al, 2011). Parallel increase in ASC and GSH levels suggested efficient operation of ASC-GSH cycle during early period of drought stress.…”

Sustainable Fruit Production in Mediterranean Orchards Subjected to Drought Stress

“…Almond ( Prunus dulcis L.) is the most important tree nut produced on a global basis, and its limited gene pool limits the cultivation to specifi c areas with Mediterranean climate (Sorkheh et al 2011 ) . This species is one of the oldest tree nut crops, and today represents the largest production of any commercial tree nut product.…”

“…Among the different wild almond varieties, Rouhi et al ( 2007 ) studied the intrinsic water use effi ciency, defi ned as the ratio of assimilation rate over stomatal conductance, in cultivated and wild almond species, fi nding that P. dulcis is the species most tolerant to drought, P. scoparia tries to avoid drought, and P. lycioides has an intermediate behavior and this latter can have potential for use as rootstock for commercial almond production. As wild almond species can be very important for rootstock selection, in a recent paper, Sorkheh et al ( 2011 ) examined the changes of antioxidant enzyme activities and the level of some antioxidant compounds involved in the ascorbate-glutathione cycle in droughtstressed plants of eight wild almond species from different geographical points of Iran. The authors found that after 70 days without irrigation, mean pre-dawn LWP in all the species fell from 0.32 to −2.30 MPa and marked decreases in CO 2 uptake and transpiration occurred.…”

“…The decrease of soil humidity, together with high values of vapour pressure deficit (VPD), causes reduction in leaf water potential (LWP), carbon assimilation and transpiration in different species of Prunus (Rieger and Duemmel 1992 ;Rieger 1995 ;Berman and DeJong 1996 ;Alar on et al 2000 ;Besset et al 2001 ;Esparza et al 2001 ;Klein et al 2001 ;Rieger et al 2003 ;Matos et al 2004 ;Romero et al 2004c ;Gomes-Laranjo et al 2006 ;Intrigliolo and Castel 2006 ;Dichio et al 2007 ;Godini et al 2008 ;Egea et al 2010 ) . Some studies also highlighted the activation of antioxidant defenses as a strategy to face drought-dependent oxidative stress in this genus (Scebba et al 2001 ;Sofo et al 2005 ;Sorkheh et al 2011 ) .…”

Cold-induced changes in antioxidant defenses and reactive oxygen species in eight wild almond species

“…demonstrate a greater resistance to abiotic and biotic stresses, including low temperatures, and so represent valuable germplasm sources for rootstock breeding. 1,2 Low temperatures induce a number of alterations in cellular components, leading to the loss of compartmentalization, reduction and impairing of photosynthesis, protein assembly and general metabolic processes. 3,4 Particularly, reactive oxygen species (ROS) produced by plants in response to cold contribute to membrane damage.…”