Effects of light deficiency on genome methylation in Posidonia oceanica

Abstract

Growth and distribution of seagrasses is closely related to undersea light quality and intensity. Currently, several factors linked to anthropogenic pressure, such as increased sediment runoff, resuspension of bottom sediments, and algae accumulations, reduce sub-surface light availability in most Mediterranean coastal areas, and are causing a general regression of Posidonia oceanica (L.) Delile meadows. We investigated whether plant capacity to adapt to light deficiency could be related to a repatterning of genome methylation in a natural population of P. oceanica subjected to low-light conditions. DNA methylation status was analyzed in shoot apical meristems and leaves of plants growing in a disturbed meadow, characterized by reduced light availability, versus plants growing in a preserved meadow. Two complementary approaches were applied, viz. the methylation-sensitive amplification polymorphism (MSAP) technique and im muno cytological detection of methylated sites on interphase nuclei. Genome hypermethylation was detected in the organs of plants growing at the disturbed site, indicating that de novo methylation occurred under light-related stress conditions. MSAP analysis revealed that changes in methylation status involved specific classes of genes with various functions, including light perception and harvesting genes such as PoPHYB and LHCB5. It is likely that epigenetic regulation of these 2 genes through methylation plays a role in the resistance and resilience of P. oceanica plants to critical light conditions. We propose that the status of genome methylation is a promising diagnostic tool for early detection of stress factors affecting P. oceanica meadows.

Epigenetic variation reflects dynamic habitat conditions in a rare floodplain herb

“…) and also the few studies specifically addressing the effects of light availability are equivocal: whereas reduction of light led to genome hypermethylation in seagrass (Greco et al . ), low R/FR ratios as a signal of foliage shade resulted in genome hypomethylation in Stellaria longipes (Tatra et al . ).…”

“…; Greco et al . ). Moreover, as light is a strong environmental cue, influencing an array of other biotic and abiotic parameters (e.g.…”

Tissue-Specific Response to Experimental Demethylation at Seed Germination in the Non-Model Herb Erodium cicutarium

“…Nevertheless, different investigations have used different compounds and protocols (see e.g., [21][22][23][24]), and, occasionally, variations in the magnitude of the observed response are reported when different genetic lines or source populations are used (e.g., [21][22][23]). In addition to such a genotype-specific response, we should note that the magnitude of methylation changes in response to DNMTi treatment and/or experimental stress is usually analyzed in a single tissue, yet global methylation is known to differ between tissues and developmental stages [1], and changes in DNA methylation in response to stress can differ between tissues of treated individuals (see e.g., [3,[25][26][27][28]). Above and below-ground plant organs are highly differentiated, and experience distinctive environments, thus, exploring variation in methylation between them might be particularly useful when trying to interpret plant responses to certain soil stress factors such as drought or salinity (see e.g., [25,26]).…”

The Genome of a Southern Hemisphere Seagrass Species (Zostera muelleri)

“…Seagrasses also are adapted to the slow diffusion rate of CO 2 in seawater; some have evolved to utilize HCO 3 2 as a carbon source (Beer et al, 2002;Borum et al, 2016), and they also have adapted to variable and low levels of light that attenuates quickly in seawater into blue or green wavelengths of the spectrum (Larkum et al, 2006). Studies of gene (Dattolo et al, 2013(Dattolo et al, , 2014Salo et al, 2015) and protein (Mazzuca et al, 2009) expression, together with genome methylation signatures (Greco et al, 2013) of seagrasses in response to differing light conditions, revealed the differential expression of genes for protein turnover and enzymes related to cellular stress and photosynthesis. Salt tolerance mechanisms in seagrass are of particular interest due to their potential to be applied to improve salinity tolerance in crop plants, such as the use of a Zostera marina salt tolerance gene in transgenic Oryza sativa research (Zhao et al, 2013).…”