Under climate change, plants experience many biotic and abiotic stresses which make them evolve different strategies to cope with it. Plants have developed diverse morphological, physiological, biochemical and molecular mechanisms in their response. One of those mechanisms is “Transgenerational memory”, which is defined as the ability of an organism to ‘remember’ the environmental conditions at the molecular level with the subsequent alteration of progeny phenotype. This memory can be fixed in the chromatin conformation and at the differential level of smRNAs in the cytoplasm of gametes and the developing embryo, thereby priming an organism to perform better with future conditions of stress1.

DNA methylations, Histone modifications and smRNAs comprise the three major components of transgenerational memory modules5. All three are interconnected and can form a self-reinforcing loop of gene expression regulation. DNA methylation is the covalent transfer of a methyl group to the C-5 position of the cytosine ring of DNA by DNA methyltransferases (DNMTs) which induces an epigenetic mark which is heritable. Histone modifications are also covalent modifications that occur post translationally to the histone proteins, these modifications can be in the form of methylation, phosphorylation, acetylation, ubiquitylation, and sumoylation. The regulation of gene expression through smRNAs can occur either at the level of transcription through transcriptional gene silencing (TGS) or post-transcriptionally (PTGS). These modifications are inherited through Replicative transmission or Reconstructive transmission which are widely accepted models of inheritance2.

A study on the performance of four common European perennial plant species for transgenerational memory of drought and water logging, reflected the fact that drought exposed offspring experienced lower oxidative stress by reducing levels of H2O2 and malondialdehyde concentrations when their mothers were also exposed to drought and the same results were observed for water logging, where in the offspring which had a mother previously exposed to water logging, performed better by increasing phenolic compounds concentration. These results support the fact that plants with drought and waterlogging memory will have less oxidative stress and tolerate stress conditions more effectively4. The results of numerous studies in plants demonstrated the stability of epialleles across generations along with the amenability of epigenetic related traits to artificial selection have led to the inclusion of epigenetic components in the plant breeding process3, 6.

Considering the importance of transgenerational memory many researchers are showing keen interest in understanding the mechanism involved and it has emerged as a blooming area of research in recent times. It requires a multidisciplinary effort of researchers involved in different areas of plant science and crop breeding with better integration of epigenomic data obtained in different crops. And the recent advances like genome editing technologies can assist with multiple applications that have to be tapped to evolve climate ready cultivars that are tolerant to stress.

References 

1. BILICHAK, A. AND KOVALCHUK, I., 2016. Transgenerational response to stress in plants and its application for breeding. J. Exp. Bot., 67(7):2081-2092.

 2. FITZ-JAMES, M.H. AND CAVALLI, G., 2022. Molecular mechanisms of transgenerational epigenetic inheritance. Nat. Rev. Genet., 23(6):325-341.

 3. HAUBEN, M., HAESENDONCKX, B., STANDAERT, E., VAN DER KELEN, K., AZMI, A., AKPO, H., VAN BREUSEGEM, F., GUISEZ, Y., BOTS, M., LAMBERT, B. AND LAGA, B., 2009. Energy use efficiency is characterized by an epigenetic component that can be directed through artificial selection to increase yield. Proc. Natl. Acad. Sci., 106(47):20109-20114. 

4. LUKIĆ, N., SCHURR, F.M., TRIFKOVIĆ, T., KUKAVICA, B. AND WALTER, J., 2023. Transgenerational stress memory in plants is mediated by upregulation of the antioxidative system. Environ. Exp. Bot., 205:105-129. 

5. SHANKER, A.K., BHANU, D. AND MAHESWARI, M., 2020. Epigenetics and transgenerational memory in plants under heat stress. Plant Physiol. Rep., 25(4):583-593. 

6. VERKEST, A., BYZOVA, M., MARTENS, C., WILLEMS, P., VERWULGEN, T., SLABBINCK, B., ROMBAUT, D., VAN DE VELDE, J., VANDEPOELE, K., STANDAERT, E. AND PEETERS, M., 2015. Selection for improved energy use efficiency and drought tolerance in canola results in distinct transcriptome and epigenome changes. Plant physiol., 168(4):1338-1350.