Genetic memory of stress in plants

In the world, plants belong to a group with a relatively long life cycle, reproduce slowly and have to withstand many harsh conditions of the environment even though they are unable to move. Therefore, nature has given plants the ability to respond very flexibly to stress conditions such as hot, cold, drought, inundation, all kinds of attack microorganisms .

Recent studies have shown that under the influence of stress, plants not only physiologically change but also changes in genomes have initially been recorded. Whether or not plant material is able to pass those responses back to children is still unclear.

A new study in the journal Nature confirms this, an initial study to determine the stress state of plants increases the variability in genomes and this property can be inherited for future generations. . The trait of increasing the frequency of homologous recombination is an inherited trait and can be transmitted from both parents in crosses (conventional trait is dominant trait). The research results show that adverse factors in the environment are not only inherited through generations, but also can increase genetic diversity at the individual level, making the species more adaptable to any condition. profit.

An experiment of the resistance of leaves when temperature increases (Photo: ugent.be)

Plants often have to resist different environmental conditions by stress responses. It is not only physiological changes but also changes in genomic variability, such as the activation of transposition factors, mutation induction, or increased frequency of homologous recombination. UV-B effect. Especially when attacked by pathogens, plants also respond by increasing genomic variation. All responses on the genome are accumulated to some extent which may affect phenotypic expression. Although their role has a very high value in evolution and adaptation in plants, it is not yet well-understood in terms of mechanism and has not yet assessed the popularity in the world in general and in particular plants. .

Most studies of stress response on genom in recent years have only recorded the existence of this phenomenon at the specific phenotype level of the individual. This study demonstrates that biotic stress responses (fgl 22) and abiotic (UV-C) on plant genomes (A.thaliana) can be transmitted over many generations.

Genomic variation was assessed through the frequency of homologous recombinant HRF (Homologous Recombinant Frequency).

To be able to quantify recombinant frequencies, people rely on the pre-designed GUS fusion system. In it, the transformed sample of GUS fusion system was kept in an anti-recombinant condition on media containing Hygromycin; when there is no selective, recombinant antibiotic, if it occurs, it will form GUS intact and become active enzyme. The higher the color score, the greater the frequency of recombination.

Research shows that Arabidopsis responds to UV-C as well
pathogens by increasing recombination frequency.

After recording the frequency of homologous recombination in the first generation, the treated tree is brought to the soil and performs cross-breeding to check the genetic trait and the role of the parents. It was found that although it was not treated for stressors, there were no changes in some sequences, but high HRF traits remained stable for at least 4 generations. At the same time in cross-breeding with wild individuals, the inheritance of high HFR traits is very different when changing the role of a parent.

(Photo: Nature)

However, another unexpected result is that this trait is still transmitted to the next generations almost completely, even if their parents are wild (untreated, without directive genes). ).

This proves that when unfavorable conditions occur, plants have a mechanism that allows it to improve the level of fluctuation of the genom (but not change the sequence) and the following generations can also be redundant. enjoy this property if their parents respond to stress. Research shows more clearly the evolutionary nature of plants in relation to stressors, if compared to a slightly lame way, it is similar to the gene concept for gene (Flor), plants are always available. transform to evolve.

Appendix:

Planting conditions : Planting in soil: Arabidopsis seeds are planted in soil at 4oC and placed in the dark for 3 days, then placed in phytotron with 70% moisture content, photosynthesis 16/8 at 16 ^° C.

In vitro cultivation : Seeds are sown on MS broth (Duchefa) 1% sucrose, 0.8% agar, pH 5.8, and 16/8 phototropic.3-week-old plants are brought to the soil to collect seeds by self-pollination or cross-breeding.

UV-C and flagelin treatment : Two representative stressors used in the experiment were UV-C and flagelin (representing biotic and abiotic).In all experiments, plants were grown in the sowing environment for 13 days before being treated.UV-C-illuminated plants (254nm) or embedded in flagelin-containing media (flg22 conservation zone from bacteria and flg22Atum specific regions from Argobacterium tumefacient)

References : Jean Molinier, Gerhard Ries, Cyril Zipfel & Barbara Hohn, 2006. Transgeneration memory of stress in plants.Nature letters.442 (31): 1046 -1049

Nguyen Huu Hoang