NUCLEAR TRANSPORT FACTOR 2‐LIKE improves drought tolerance by modulating leaf water loss in alfalfa (Medicago sativa L.)

Abstract

Drought is a major environmental factor that limits the production of alfalfa (Medicago sativa). In the present study, M. sativa NUCLEAR TRANSPORT FACTOR 2-LIKE (MsNTF2L) was identified as a nucleus-, cytoplasm-, and plasma membrane-localized protein. Its transcriptional expression was highly induced by ABA and drought stress. Overexpression of MsNTF2L in Arabidopsis resulted in hypersensitivity to ABA during both the seed germination and seedling growth stages. However, transgenic Arabidopsis plants exhibited enhanced tolerance to drought stress by reducing the levels of reactive oxygen species (ROS) and increasing the expression of stress/ABA-inducible genes. Consistently, analysis of MsNTF2L overexpression (OE) and RNA interference (RNAi) alfalfa plants revealed that MsNTF2L confers drought tolerance through promoting ROS scavenging, a decrease in stomatal density, ABA-induced stomatal closure, and epicuticular wax crystal accumulation. MsNTF2L highly affected epicuticular wax deposition, as a large group of wax biosynthesis and transport genes were influenced in the alfalfa OE and RNAi lines. Furthermore, transcript profiling of drought-treated alfalfa WT, OE, and RNAi plants showed a differential drought response for genes related to stress/ABA signaling, antioxidant defense, and photosynthesis. Taken together, these results reveal that MsNTF2L confers drought tolerance in alfalfa via modulation of leaf water loss (by regulating both stomata and wax deposition), antioxidant defense, and photosynthesis.

A 3-Ketoacyl-CoA Synthase 10 (KCS10) Homologue from Alfalfa Enhances Drought Tolerance by Regulating Cuticular Wax Biosynthesis

“…Leaf epidermal permeability affected the water loss rate and plant response to drought stress. 37 The detached leaves of tobacco OE lines showed higher RWC than WT in the dark, implying that overexpression of MsKCS10 decreased nonstomatal water evaporation. The OE lines were more drought tolerant than the WT, with less wilting and higher RWC under drought stress for 10 days.…”

“…The OE lines also showed enhanced drought tolerance with decreased oxidative damage, improved osmotic regulation capacity, and greater photosynthesis. Leaf epidermal permeability affected the water loss rate and plant response to drought stress . The detached leaves of tobacco OE lines showed higher RWC than WT in the dark, implying that overexpression of MsKCS10 decreased nonstomatal water evaporation.…”

“…It has been reported that an increase in the leaf wax content in alfalfa can improve abiotic stress tolerance. 37 Overexpression of the WXP1 gene from M. truncatula increased the wax content by 30% in alfalfa leaves and improved drought and cold tolerance by decreasing the reduction in chlorophyll and water loss. 38 The wax components in alfalfa leaves were mainly composed of primary alcohols, followed by n-alkanes and aldehydes.…”

Genome-Wide Identification of ERF Transcription Factor Family and Functional Analysis of the Drought Stress-Responsive Genes in Melilotus albus

“…The guaranteed incubation conditions were as follows: 16 h light/8 h dark cycle, 80% relative humidity, and 22 °C. Previous studies have indicated that H 2 O 2 , proline, malondialdehyde (MDA) and soluble sugar can be used as indicators to evaluate drought resistance in plants [ 60 ]. Our previous study found that under drought stress, the content of H 2 O 2 peaked up to 24 h and the content of malondialdehyde (MDA), proline, and soluble sugar increased continuously up to 48 h, while the soluble protein content remained basically unchanged for 24 h and then decreased significantly [ 24 ].…”

How Does Stomatal Density and Residual Transpiration Contribute to Osmotic Stress Tolerance?

“…The transcriptional expression of MsNTF2L is highly induced by ABA and drought stress. The overexpression of MsNTF2L increased drought tolerance in alfalfa via the modulation of leaf water loss by regulating both stomatal density and wax deposition [ 84 ].…”