PdEPF1 regulates water‐use efficiency and drought tolerance by modulating stomatal density in poplar

Abstract

SummaryWater deficiency is a critical environmental condition that is seriously reducing global plant production. Improved water-use efficiency (WUE) and drought tolerance are effective strategies to address this problem. In this study, PdEPF1, a member of the EPIDERMAL PATTERNING FACTOR (EPF) family, was isolated from the fast-growing poplar clone NE-19 [Populus nigra 9 (Populus deltoides 9 Populus nigra)]. Significantly, higher PdEPF1 levels were detected after induction by dehydration and abscisic acid. To explore the biological functions of PdEPF1, transgenic triploid white poplars (Populus tomentosa 'YiXianCiZhu B385') overexpressing PdEPF1 were constructed. PdEPF1 overexpression resulted in increased water deficit tolerance and greater WUE. We confirmed that the transgenic lines with greater instantaneous WUE had approximately 30% lower transpiration but equivalent CO 2 assimilation. Lower transpiration was associated with a 28% reduction in abaxial stomatal density. PdEPF1 overexpression not only strongly enhanced WUE, but also greatly improved drought tolerance, as measured by the leaf relative water content and water potential, under limited water conditions. In addition, the growth of these oxPdEPF1 plants was less adversely affected by reduced water availability than plants with a higher stomatal density, indicating that plants with a low stomatal density may be well suited to grow in water-scarce environments. Taken together, our data suggest that PdEPF1 improves WUE and confers drought tolerance in poplar; thus, it could be used to breed droughttolerant plants with increased production under conditions of water deficiency.

PeCHYR1, a ubiquitin E3 ligase from Populus euphratica, enhances drought tolerance via ABA‐induced stomatal closure by ROS production in Populus

“…Accordingly, the instantaneous WUE in the transgenic plants was elevated (Figure d), consistent with the normal‐temperature water loss rate of 35S: PeCHYR1 plants, which showed less water loss than WT plants did (Figure d). Previous studies have indicated that the decreased stomatal conductance in 35S: PdEPF1 plants would not necessarily lead to decreased photosynthesis under well‐watered conditions (Wang et al ., ). Rubisco and ribulose‐1,5‐bisphosphate are nonstomatal factors that play roles in modulating photosynthetic rate (Pearcy and Seemann, ; Qin et al ., ), and thus, stomatal conductance does not solely control changes in foliar photosynthetic rate (Niinemets, ).…”

“…One‐year‐old seedlings of P. euphratica were transplanted in individual pots (10 L) containing sandy soil (approximately 70% sand) and placed in a seed plot [light cycle: 16.0 h of light (06:00 am–10:00 pm); temperature (20–24 °C)] at Haidian, Beijing, China (40°000N, 116°200E; 49 m above sea level). Potted P. euphratica were watered on the basis of evaporation demand and irrigated with 1 L of Hoagland nutrient solution every 2 weeks for 2 months before treatment (Li et al ., ; Wang et al ., ).…”

“…Meanwhile, the control was treated with 1 g TWEEN® 40 in ultrapure water. Dehydration treatment was applied to seedlings that had been removed from the soil and exposed to air with 70% RH at 23 °C under dim light for 12 h (Ma et al ., ; Wang et al ., ). To obtain complete plants, we gently pulled out each seedling and carefully washed the roots to remove the soil.…”

Understanding physiological and morphological traits contributing to drought tolerance in barley

“…Stomatal development is regulated by the epidermal patterning factors ( EPF1 , EPF2 ) in the epidermis and STOMAGEN or EPFL9 in the mesophyll. It has been documented that overexpression of EPF1 and EPF2 in Arabidopsis (Hara et al., ), poplar (Wang et al., ) and tobacco (Yu et al., ) mutants reduced stomatal density resulting in an improved WUE. Our previous study demonstrated that drought‐tolerant barley genotypes contained lower SD than the sensitive genotypes under optimum growth conditions (irrigated) and showed a negative correlation with drought tolerance index (Hasanuzzaman, Shabala, Brodribb, Zhou, & Shabala, ).…”

Modulating AtDREB1C Expression Improves Drought Tolerance in Salvia miltiorrhiza

“…Drought is one of the primary abiotic stresses limiting global agricultural production (Zeppel et al, 2014; Shavrukov et al, 2015; Wang et al, 2016). Plant genetic engineering provides an important approach for improving drought resistance in crops via the introduction of transgene(s) to mitigate physiological and agronomic penalties associated with drought (Bihmidine et al, 2013; Patel et al, 2015; Mendiondo et al, 2016).…”