SENSITIVE TO FREEZING2 Aids in Resilience to Salt and Drought in Freezing-Sensitive Tomato

Abstract

SENSITIVE TO FREEZING2 (SFR2) is crucial for protecting chloroplast membranes following freezing in Arabidopsis (Arabidopsis thaliana). It has been shown that SFR2 homologs are present in all land plants, including freezing-sensitive species, raising the question of SFR2 function beyond freezing tolerance. Similar to freezing, salt and drought can cause dehydration. Thus, it is hypothesized that in freezing-sensitive plants SFR2 may play roles in their resilience to salt or drought. To test this hypothesis, SlSFR2 RNAi lines were generated in the cold/freezing-sensitive species tomato (Solanum lycopersicum [M82 cv]). Hypersensitivity to salt and drought of SlSFR2-RNAi lines was observed. Higher tolerance of wild-type tomatoes was correlated with the production of trigalactosyldiacylglycerol, a product of SFR2 activity. Tomato SFR2 in vitro activity is Mg 2+ -dependent and its optimal pH is 7.5, similar to that of Arabidopsis SFR2, but the specific activity of tomato SFR2 in vitro is almost double that of Arabidopsis SFR2. When salt and drought stress were applied to Arabidopsis, no conditions could be identified at which SFR2 was induced prior to irreversibly impacting plant growth, suggesting that SFR2 protects Arabidopsis primarily against freezing. Discovery of tomato SFR2 function in drought and salt resilience provides further insights into general membrane lipid remodeling-based stress tolerance mechanisms and together with protection against freezing in freezing-resistant plants such as Arabidopsis, it adds lipid remodeling as a possible target for the engineering of abiotic stress-resilient crops.

Differential Chloroplast Proteomics of Temperature Adaptation in Apple (Malus x domestica Borkh.) Microshoots

“…[29] We observed two beta-glucosidase 13-like proteins, one of which may be an analog of the arabidobsis SFR2, which is a beta glucosidase, responsible for chloroplast membrane integrity in exposure to low temperature. [9] Apple Dehydrins 2 and 4 were highly abundant in low temperature grown plantlets, consistent with our previous results. [30] While the localization of these proteins is not known, the high abundance of these proteins in our preparates may suggest association with chloroplast.…”

“…A chloroplastic aquaporin has been previously reported in N. tabacum . We observed two beta‐glucosidase 13‐like proteins, one of which may be an analog of the arabidobsis SFR2, which is a beta glucosidase, responsible for chloroplast membrane integrity in exposure to low temperature …”

“…Recent study of Arabidosis mutants with different sensitivity to chilling highlighted the importance of chloroplasts in the adaptation process. [9] Plant productivity highly depends on chloroplasts functioning. These organelles are responsible for sensing the signal and triggering response.…”

Coevolution of Domain Interactions in the Chloroplast TGD1, 2, 3 Lipid Transfer Complex Specific to Brassicaceae and Poaceae Plants

“…The Pro35S:BdTGD1 RNAi construct was built by first amplifying the 695-bp (359-1053 bp) cDNA of BdTGD1 using primers as shown in Supplemental Table 6. PCR products were purified and recombined into the pHELLSGATE12 vector as described (Wang et al, 2016). The plant expression cassette Pro35S -BdTGD1 hairpin-NOS terminator was digested with EcoRI and ScaI followed by blunting and was then inserted into the SfoI-digested pJJ247 vector.…”

“…For TGD1 complementation and chimeric TGD1 lines, AtTGD1 and BdTGD1 full-length cDNAs were first amplified from 4-week-old Arabidopsis and Brachypodium wild-type leaf tissues, respectively. PCR products were purified and inserted into the pENTR/D-TOPO vector as described (Wang et al, 2016). AtTGD1-pENTR and BdTGD1-pENTR were then used as the templates to generate TGD1-A to TGD1-E DNA fragments by site-directed mutagenesis PCR as described (Reikofski and Tao, 1992).…”