Analysis of drought tolerance and genetic and epigenetic variations in a somatic hybrid between Ipomoea batatas (L.) Lam. and I. triloba L.

The somatic hybrid KT1 was previously obtained from protoplast fusion between sweetpotato （Ipomoea batatas （L.） Lam.） cv. Kokei No. 14 and its wild relative I. triloba L. However, its genetic and epigenetic variations have not been investigated. This study showed that KT1 exhibited significantly higher drought tolerance compared to the cultivated parent Kokei No. 14. The content of proline and activities of superoxide dismutase （SOD） and photosynthesis were significantly increased, while malonaldehyde （MDA） content was significantly decreased compared to Kokei No. 14 under drought stress. KT1 also showed higher expression level of well-known drought stress-responsive genes compared to Kokei No. 14 under drought stress. Amplified fragment length polymorphism （AFLP） and methylation-sensitive amplified polymorphism （MSAP） analyses indicated that KT1 had AFLP and MSAP band patterns consisting of both parent specific bands and changed bands. Fur- ther analysis demonstrated that in KT1. the proportions of Kokei No. 14 specific genome components and methylation sites were much greater than those of I. triloba. KT1 had the same chloroplast and mitochondrial genomes as Kokei No. 14. These results will aid in developing the useful genes ofI. triloba and understanding the evolution and phylogeny of the cultivated sweetpotato.

Temperature is a cryptic factor shaping the geographical pattern of genetic variation in Ceratophyllum demersum across a subtropical freshwater lake

Macrophyte habitats exhibit remarkable heterogeneity,encompassing the spatial variation of abiotic and biotic components such as changes in water conditions and weather as well as anthropogenic stressors.Environmental factors are thought to be important drivers shaping the genetic and epigenetic variation of aquatic plants.However,the links among genetic diversity,epigenetic variation,and environmental variables remain largely unclear,especially for clonal aquatic plants.Here,we performed population genetic and epigenetic analyses in conjunction with habitat discrimination to elucidate the environmental factors driving intraspecies genetic and epigenetic variation in hornwort(Ceratophyllum demersum)in a subtropical lake.Environmental factors were highly correlated with the genetic and epigenetic variation of C.demersum,with temperature being a key driver of the genetic variation.Lower temperature was detected to be correlated with greater genetic and epigenetic variation.Genetic and epigenetic variation were positively driven by water temperature,but were negatively affected by ambient air temperature.These findings indicate that the genetic and epigenetic variation of this clonal aquatic herb is not related to the geographic feature but is instead driven by environmental conditions,and demonstrate the effects of temperature on local genetic and epigenetic variation in aquatic systems.

Novel hepatocellular carcinoma molecules with prognostic and therapeutic potentials

Hepatocellular carcinoma(HCC), the predominant form of primary liver cancer, is the sixth most common cancer worldwide and the third leading cause of cancerrelated death. The difficulty to diagnose early cancer stages, the aggressive behaviors of HCC, and the poor effectiveness of therapeutic treatments, represent the reasons for the quite similar deaths per year and incidence number. Considering the fact that the diagnosis of HCC typically occurs in the advanced stages of the disease when the therapeutic options have only modest efficacy, the possibility to identify early diagnostic markers could be of significant benefit. So far, a large number of biomarkers have been associated to HCC progression and aggressiveness, but many of them turned out not to be of practical utility. This is the reason why active investigations are ongoing in this field. Given the huge amount of published works aimed at the identification of HCC biomarkers, in this review we mainly focused on the data published in the last year, with particular attention to the role of(1) molecular and biochemical cellular markers;(2) micro-interfering RNAs;(3) epigenetic variations; and(4) tumor stroma. It is worth mentioning that a significant number of the HCC markers described in the present review may be utilized also as targets for novel therapeutic approaches, indicating the tight relation between diagnosis and therapy. In conclusion, we believe that integrated researches among the different lines of investigation indicated above should represent the winning strategies to identify effective HCC markers and therapeutic targets.

Trans-generational effects in the clonal invader Alternanthera philoxeroides

Aims Recent studies have revealed heritable phenotypic plasticity through vegetative generations.In this sense,changes in gene regulation induced by the environment,such as DNA methylation(i.e.epigenetic changes),can result in reversible plastic responses being transferred to the offspring generations.This trans-generational plasticity is expected to be especially relevant in clonal plants,since reduction of sexual reproduction can decrease the potential for adaptation through genetic variation.Many of the most aggressive plant invaders are clonal,and clonality has been suggested as key to explain plant invasiveness.Here we aim to determine whether trans-generational effects occur in the clonal invader Alternanthera philoxeroides,and whether such effects differ between populations from native and non-native ranges.Methods In a common garden experiment,parent plants of A.philoxeroides from populations collected in Brazil(native range)and Iberian Peninsula(non-native range)were grown in high and low soil nutrient conditions,and offspring plants were transplanted to control conditions with high nutrients.To test the potential role of DNA methylation on trans-generational plasticity,half of the parent plants were treated with the demethylating agent,5-azacytidine.Important Findings Trans-generational effects were observed both in populations from the native and the non-native ranges.Interestingly,trans-generational effects occurred on growth variables(number of ramets,stem mass,root mass and total mass)in the population from the native range,but on biomass partitioning in the population from the non-native range.Trans-generational effects of the population from the native range may be explained by a‘silver-spoon’effect,whereas those of the population from the non-native range could be explained by epigenetic transmission due to DNA methylation.Our study highlights the importance of trans-generational effects on the growth of a clonal plant,which could help to understand the mechanisms underlying expansion success of many clonal plants.

MSH1 Is a Plant Organellar DNA Binding and Thylakoid Protein under Precise Spatial Regulation to Alter Development

As metabolic centers, plant organelles participate in maintenance, defense, and signaling. MSH1 is a plant- specific protein involved in organeUar genome stability in mitochondria and plastids. Plastid depletion of MSH1 causes heritable, non-genetic changes in development and DNA methylation. We investigated the rash I phenotype using hemi-complementation mutants and transgene-null segregants from RNAi suppres- sion lines to sub-compartmentalize MSH1 effects. We show that MSH1 expression is spatially regulated, specifically localizing to plastids within the epidermis and vascular parenchyma. The protein binds DNA and localizes to plastid and mitochondrial nucleoids, but fractionation and protein-protein interactions data indicate that MSH1 also associates with the thylakoid membrane. Plastid MSH1 depletion results in variegation, abiotic stress tolerance, variable growth rate, and delayed maturity. Depletion from mitochon- dria results in 7%-10% of plants altered in leaf morphology, heat tolerance, and mitochondrlal genome sta- bility. MSH1 does not localize within the nucleus directly, but plastid depletion produces non-genetic changes in flowering time, maturation, and growth rate that are heritable independent of MSH 1. MSH1 deple- tion alters non-photoactive redox behavior in plastids and a sub-set of mitochondrially altered lines. Ectopic expression produces deleterious effects, underlining its strict expression control. Unraveling the complexity of the MSH1 effect offers insight into triggers of plant-specific, transgenerational adaptation behaviors.