In mammals, cadmium is widely considered as a non-genotoxic carcinogen acting through a methylation-dependent epigenetic mechanism. Here, the effects of Cd treatment on the DNA methylation patten are examined together with its effect on chromatin reconfiguration in Posidonia oceanica. DNA methylation level and pattern were analysed in actively growing organs, under short- (6 h) and long- (2 d or 4 d) term and low (10 mM) and high (50 mM) doses of Cd, through a Methylation-Sensitive Amplification Polymorphism technique and an immunocytological approach, respectively. The expression of one member of the CHROMOMETHYLASE (CMT) family, a DNA methyltransferase, was also assessed by qRT-PCR. Nuclear chromatin ultrastructure was investigated by transmission electron microscopy. Cd treatment induced a DNA hypermethylation, as well as an up-regulation of CMT, indicating that de novo methylation did indeed occur. Moreover, a high dose of Cd led to a progressive heterochromatinization of interphase nuclei and apoptotic figures were also observed after long-term treatment. The data demonstrate that Cd perturbs the DNA methylation status through the involvement of a specific methyltransferase. Such changes are linked to nuclear chromatin reconfiguration likely to establish a new balance of expressed/repressed chromatin. Overall, the data show an epigenetic basis to the mechanism underlying Cd toxicity in plants.

/pdf/in-posidonia-oceanica-cadmium-induces-changes-in-dna-3cu7uj83mr.pdf

In Posidonia oceanica cadmium induces changes in DNA methylation and chromatin patterning

The transition from the juvenile to adult phase in plants is controlled by diverse exogenous and endogenous cues such as age, day length, light, nutrients, and temperature. Previous studies have shown that the gradual decline in microRNA156 (miR156) with age promotes the expression of adult traits. However, how age temporally regulates the abundance of miR156 is poorly understood. We show here that the expression of miR156 responds to sugar. Sugar represses miR156 expression at both the transcriptional level and post-transcriptional level through the degradation of miR156 primary transcripts. Defoliation and photosynthetic mutant assays further demonstrate that sugar from the pre-existing leaves acts as a mobile signal to repress miR156, and subsequently triggers the juvenile-to-adult phase transition in young leaf primordia. We propose that the gradual increase in sugar after seed germination serves as an endogenous cue for developmental timing in plants.

https://cdn.elifesciences.org/articles/00269/elife-00269-v1.pdf

Sugar is an endogenous cue for juvenile-to-adult phase transition in plants

The CCAAT box is one of the most common cis-elements present in eukaryotic promoters and is bound by the transcription factor NUCLEAR FACTOR Y (NF-Y). NF-Y is composed of three subunits, NF-YA, NF-YB, and NF-YC. Unlike animals and fungi, plants have significantly expanded the number of genes encoding NF-Y subunits. We provide a comprehensive classification of NF-Y genes, with a separation of closely related, but distinct, histone fold domain proteins. We additionally review recent experiments that have placed NF-Y at the center of many developmental stress-responsive processes in the plant lineage.

/pdf/the-promiscuous-life-of-plant-nuclear-factor-y-transcription-37631hbm6y.pdf

The Promiscuous Life of Plant NUCLEAR FACTOR Y Transcription Factors

https://www.cell.com/trends/plant-science/pdf/S1360-1385(12)00169-0.pdf

CCAAT-box binding transcription factors in plants: Y so many?

Seeds develop differently in dicots and monocots, especially with respect to the major storage organs. High-resolution transcriptome data have provided the first insights into the molecular networks and pathway interactions that function during the development of individual seed compartments. Here, we review mainly recent data obtained by systems biology–based approaches, which have allowed researchers to construct and model complex metabolic networks and fluxes and identify key limiting steps in seed development. Comparative coexpression network analyses define evolutionarily conservative (FUS3/ABI3/LEC1) and divergent (LEC2) networks in dicots and monocots. Finally, we discuss the determination of seed size—an important yield-related characteristic—as mediated by a number of processes (maternal and epigenetic factors, fine-tuned regulation of cell death in distinct seed compartments, and endosperm growth) and underlying genes defined through mutant analyses. Altogether, systems approaches can make impor...

Seed-Development Programs: A Systems Biology–Based Comparison Between Dicots and Monocots

The seed oil content in oilseed crops is a major selection trait to breeders. In Arabidopsis (Arabidopsis thaliana), LEAFY COTYLEDON1 (LEC1) and LEC1-LIKE (L1L) are key regulators of fatty acid biosynthesis. Overexpression of AtLEC1 and its orthologs in canola (Brassica napus), BnLEC1 and BnL1L, causes an increased fatty acid level in transgenic Arabidopsis plants, which, however, also show severe developmental abnormalities. Here, we use truncated napin A promoters, which retain the seed-specific expression pattern but with a reduced expression level, to drive the expression of BnLEC1 and BnL1L in transgenic canola. Conditional expression of BnLEC1 and BnL1L increases the seed oil content by 2% to 20% and has no detrimental effects on major agronomic traits. In the transgenic canola, expression of a subset of genes involved in fatty acid biosynthesis and glycolysis is up-regulated in developing seeds. Moreover, the BnLEC1 transgene enhances the expression of several genes involved in Suc synthesis and transport in developing seeds and the silique wall. Consistently, the accumulation of Suc and Fru is increased in developing seeds of the transgenic rapeseed, suggesting the increased carbon flux to fatty acid biosynthesis. These results demonstrate that BnLEC1 and BnL1L are reliable targets for genetic improvement of rapeseed in seed oil production.

Enhanced Seed Oil Production in Canola by Conditional Expression of Brassica napus LEAFY COTYLEDON1 and LEC1-LIKE in Developing Seeds

The invention discloses a diacylglycerol acytransferase gene and protein coded by the same, belonging to the field of gene engineering. The descurainia sophia diacylglycerol acytransferase DsDGAT has a cDNA sequence SEQ ID NO.1, and the amino acid sequence SEQ ID NO.2 is coded by the DsDGAT. The gene is the first report for dicotyledon descurainia sophia, participates in biosynthesis of descurainia sophia storing grease, and mRNA expression analysis indicates that the gene is induced by injury and low temperature. Transgenosis experiments prove that the over-expression of the gene can obviously improve the oil content and the grain weight of rapeseeds. DsDGAT can be used as a target gene to be introduced into plants so as to improve the yield and oil production of plant seeds.

Diacylglycerol acyltransferase gene and protein coded by same

The invention discloses a creating method and characteristics of male sterile cytoplasm NAU10A of Brassica napus, belonging to the fields of genetic engineering and plant breeding. The protoplast technology of Brassica napus is employed to obtain a blending progeny, and a sterile plant is found in the blending progeny. An NAU10B maintainer line is crossed and backcrossed with the sterile plant toobtain a stable sterile line NAU10A. Mitochondrial DNA of the sterile line NAU10A is extracted and the PCR technology is employed to clone and identify the sterile cytoplasm to obtain a characteristicsequence SEQ ID NO.1 and an amino acid sequence SEQ ID NO.2 of the mitochondrial DNA of the sterile line NAU10A. The cytoplasm and the characteristic gene sequence of the invention are reported for the first time. The NAU10A cytoplasm can be widely applied to heterosis utilization of cruciferae and has good application prospect.

Breeding method of male sterile cytoplasm NAU10A of rapeseed

The invention discloses an oleic acid dehydrogenase gene and a protein coded by the same, and belongs to the field of genetic engineering. The invention particularly discloses a cDNA sequence SEQ ID NO.1 of a descurainia sophia oleic acid dehydrogenase gene Ds FAD2 and an amino acid sequence SEQ ID NO.2 coded by the same. The gene is the first report of a dicotyledonous plant descurainia sophia, and takes part in the biological synthesis of linoleic acid stored in descurainia sophia seeds; and the mRNA expression analysis shows that the gene is induced by harm, and is insusceptible to the temperature. Transgenic tests prove that when rape is converted by the DsFAD2 gene, the contents of the linoleic acid and linolenic acid in the rape are increased; and an antisense segment of the transgenic gene can inhibit the synthesis of the linoleic acid, so that the content of the oleic acid in rapeseeds is obviously increased.

Xiu Zheng

Papers

Enhanced Seed Oil Production in Canola by Conditional Expression of Brassica napus LEAFY COTYLEDON1 and LEC1-LIKE in Developing Seeds

Diacylglycerol acyltransferase gene and protein coded by same

Breeding method of male sterile cytoplasm NAU10A of rapeseed

Oleic acid dehydrogenase gene and protein coded by same