Abstract
Understanding the mechanism of abiotic-tolerance and producing germplasm of abiotic tolerance are important in plant research. Wild species often show more tolerance of environmental stress factors than their cultivated counterparts. Genes from wild species show potential abilities to improve abiotic resistance in cultivated species. Here, a tomato proline-, lysine-, and glutamic-rich type gene SpPKE1 was isolated from abiotic-resistant species (Solanum pennellii LA0716) for over-expression in tomato and tobacco for salt tolerance. The protein encoded by SpPKE1 was predominantly localized in the cytoplasm in tobacco. SpPKE1 and SlPKE1 (from cultivated species S. lycopersicum cv. M82) shared 89.7% similarity in amino acid sequences and their transcripts abundance in flowers and fruits was reduced by the imposition of drought or oxidative stress and the exogenous supply of abscisic acid. The DNA of the PKE1 promoter was highly methylated in fruit and leaf, and the methylation of the coding sequence in leaf was significantly higher than that in fruit at different development stages. The over-expression of SpPKE1 under the control of a CaMV (Cauliflower Mosaic Virus) 35S promoter in transgenic tomato and tobacco plants enhanced their tolerance to salt stress. PKE1 was downregulated by abiotic stresses but enhanced the plant’s salt stress tolerance. Therefore, this gene may be involved in post-transcriptional regulation and may be an important candidate for molecular breeding of salt-tolerant plants.
Highlights
Plant growth and development are continuously influenced by environmental factors, including water content, salinity, and temperature, which may disrupt plant homeostasis
In a previous study of drought stress in tomato introgression lines [15], a differential expression profile of the PKE1 gene was observed between the drought-tolerant introgression line (IL) and M82
Proline in SlPKE1 and SpPKE1 accounted for 18.7% and 18.5% of the total amino acid residues respectively, followed by lysine (17.2% and 16.3%) and glutamate (12.3% and 11.2%)
Summary
Plant growth and development are continuously influenced by environmental factors, including water content, salinity, and temperature, which may disrupt plant homeostasis. The tomato plant belongs to the Solanaceae family. It is mainly cultivated as edible fruit and is a kind of vegetable crop which can be commercially grown worldwide (FAOSTAT 2013). Production and consumption of tomato has been increasing continuously [1]. Some available tomato germplasms possess tolerance for various abiotic stresses, crop losses will become severe under extreme climatic conditions. Domestication, selection, and different breeding methods have narrowed down the genetic diversity of cultivated tomato. Developing new high-yielding cultivars, that are tolerant to various abiotic stresses, will substantially influence tomato production [2]
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