Expression of the Aeluropus littoralis AlSAP Gene Enhances Rice Yield under Field Drought at the Reproductive Stage

Abstract

We evaluated the yields of Oryza sativa L. ‘Nipponbare’ rice lines expressing a gene encoding an A20/AN1 domain stress-associated protein, AlSAP, from the halophyte grass Aeluropus littoralis under the control of different promoters. Three independent field trials were conducted, with drought imposed at the reproductive stage. In all trials, the two transgenic lines, RN5 and RN6, consistently out-performed non-transgenic (NT) and wild-type (WT) controls, providing 50–90% increases in grain yield (GY). Enhancement of tillering and panicle fertility contributed to this improved GY under drought. In contrast with physiological records collected during previous greenhouse dry-down experiments, where drought was imposed at the early tillering stage, we did not observe significant differences in photosynthetic parameters, leaf water potential, or accumulation of antioxidants in flag leaves of AlSAP-lines subjected to drought at flowering. However, AlSAP expression alleviated leaf rolling and leaf drying induced by drought, resulting in increased accumulation of green biomass. Therefore, the observed enhanced performance of the AlSAP-lines subjected to drought at the reproductive stage can be tentatively ascribed to a primed status of the transgenic plants, resulting from a higher accumulation of biomass during vegetative growth, allowing reserve remobilization and maintenance of productive tillering and grain filling. Under irrigated conditions, the overall performance of AlSAP-lines was comparable with, or even significantly better than, the NT and WT controls. Thus, AlSAP expression inflicted no penalty on rice yields under optimal growth conditions. Our results support the use of AlSAP transgenics to reduce rice GY losses under drought conditions.

Drought and heat stress-related proteins: an update about their functional relevance in imparting stress tolerance in agricultural crops

“…Similar findings were reported in Arabidopsis, where OsSAP1 from rice protected yields during water stress (Giri et al 2011). Upregulation of the A. littoralis, AlSAP gene in rice, also enhanced grain yield by 50-90% under drought stress in the field (Ghneim-Herrera et al 2017). The expression of Prunus persica, PpSAP1, was induced by heat and water stress and increased water retention ability in transgenic plums (Lloret et al 2017).…”

“…SAP gene products may be involved in stress signaling through stable protein-protein interactions with zinc finger motifs (Kothari et al 2016). SAPs may emerge as novel targets for improving stress tolerance, specifically with stress-responsive promoters (Ghneim-Herrera et al 2017). Functional analysis of the ShSAP1 gene from sugarcane indicated that ShSAP1 might confer drought and osmotic stress tolerance in transformed tobacco (Li et al 2014b).…”

A stress‐associated protein, AtSAP13, from Arabidopsis thaliana provides tolerance to multiple abiotic stresses

“…Overexpression of AtSAP5 in cotton also improved the tolerance to water deficit and heat stress (Hozain et al, ). Further, recently it has been shown that overexpression of A. littoralis AlSA P gene also increased 50–90% rice grain yield under field drought conditions (Ghneim‐Herrera et al, ).…”

Initial Description of the Genome of Aeluropus Littoralis, a Halophile Grass

“…Mitotic chromosomes were prepared from root tips which pretreated in ice water for 24 The Arabidopsis-type telomere probe was labelled with uorophore ATTO488 using nick translation labelling kit (Jena Bioscience). Fluorescence in situ hybridization was performed as described in [38] with pretreatment for 10 min in 45% acetic acid at room temperature, followed by 0.1% pepsine in 0.01N HCl at 37°C.…”

“…These knowledge can potentially be used for improving tolerance to abiotic stresses in economically important crops [21]. Several morphological, anatomical, ecological, and physiological traits of A. littoralis have been investigated so far [16,22,23] and also the transfer of stress related genes to other species resulted in enhanced stress resistance [24][25][26][27][28].…”