Ectopic expression of finger millet calmodulin confers drought and salinity tolerance in Arabidopsis thaliana

Abstract

Drought and salinity are major environmental stresses which affect crop productivity and therefore are major hindrance in feeding growing population world-wide. Calcium (Ca 2+ ) signalling plays a crucial role during the plant's response to these stress stimuli. Calmodulin (CaM), a crucial Ca 2+ sensor, is involved in transducing the signal downstream in various physiological, developmental and stress responses by modulating a plethora of target proteins. The role of CaM has been well established in the model plant Arabidopsis thaliana for regulating various developmental processes, stress signalling and ion transport. In the current study, we investigate the CaM of Eleusine coracana (common name nger millet, known especially for its drought tolerance and superior Ca 2+ content). In-silico analysis showed that Eleucine calmodulin (EcCaM) has greater similarity to rice CaM as compared to Arabidopsis CaM due to the presence of highly conserved four EF-hand domains. To decipher the in planta function of EcCaM, we have adopted the gain-of-function approach by generating the 35S::EcCaM over-expression transgenic in Arabidopsis. Overexpression of EcCaM in Arabidopsis makes the plant tolerant to polyethylene glycol (PEG) induced drought and salt stress (NaCl) as demonstrated by post-germination based phenotypic assay, ion leakage, MDA and proline estimation, ROS detection under stressed and normal conditions. Moreover, EcCaM-overexpression leads to hypersensitivity towards exogenously applied ABA at the seed germination stage. These ndings reveal that EcCaM mediates tolerance to drought and salinity stress. Also, our results indicate that EcCaM is involved in modulating ABA signalling. Summarizing our results, we report for the rst time that EcCaM is involved in modulating plants response to stress and this information can be used for the generation of future-ready crops that can tolerate a wide range of abiotic stresses.

Overexpression of a sugarcane ScCaM gene negatively regulates salinity and drought stress responses in transgenic Arabidopsis thaliana

“…Zhou et al (2016) demonstrated that the expression of AtCaM1/4 was upregulated under salt stress, and it resulted in enhanced salt tolerance in transgenic A. thaliana. Overexpression of EcCaM in A. thaliana was found to make the plant more tolerant to polyethylene glycol (PEG)-induced drought and salt stress (NaCl) (Jamra et al, 2021). Noman et al (2019) even thought that GmCaMTA12 may enhance the tolerance of Arabidopsis plants under drought stress through Ca-CaM-CAMTA-mediated stress regulatory mechanisms.…”

The integration of reactive oxygen species (ROS) and calcium signalling in abiotic stress responses

“…CaM was linked to H 2 O 2 signalling in Panax ginseng in a pathway that involved ABA-induced increases in antioxidant defence.Blocking CaM functions by the application of antagonists or the addition of ROS scavengers prevented the expression of PgCaM and abolished the increased expression of antioxidants. The expression of potato CaM2 in tobacco(Raina et al, 2021) and the Eleusine coracana CaM in Arabidopsis(Jamra et al, 2021) decreased intracellular ROS accumulation and enhanced drought tolerance. Such CaM-mediated regulation may operate in the control of plant development as well as plant responses to a wide range of abiotic and biotic stresses(Parvin…”