S-Like Ribonuclease T2 Genes Are Induced during Mobilisation of Nutrients in Cotyledons from Common Bean

Germination and seedling development are crucial phases in a plant’s life cycle with economical and agronomical implications. The RNA quality in seeds is linked to seed viability, being an important agronomic trait since this leads to a loss in germination efficiency. In addition, RNA can be an important phosphorous reservoir in seeds, affecting the efficiency of the mobilisation of nutrients towards the seedlings. However, knowledge about the physiological function of ribonucleases during germination and seedling development is scarce. We analysed the ribonuclease activities of cotyledons during these processes and the expression of S-like ribonucleases T2. Ribonuclease activity was detected in cotyledons at 1 day after imbibition and the specific activity increased during germination and seedling development, reaching a maximal value at 10 days after imbibition. At this stage, the levels of proteins and RNA in cotyledons were very low. Using in-gel assays, three ribonucleases were detected with apparent molecular masses of 16, 17 and 19 kDa along cotyledon ontogeny. The S-like ribonucleases T2 family consists of four genes in common bean (PvRNS1 to PvRNS4). The expression of PvRNS1, PvRNS2 and PvRNS4 increased in the phase of nutrient mobilisation in cotyledons. The expression of PvRNS1 increased 1000 fold in cotyledons, from 1 to 6 days after imbibition. The suppression of the induction of ribonuclease activity and gene expression in decapitated seedlings suggests that the regulatory signal comes from the developing axes. These results clearly state that S-like ribonucleases T2 are involved in RNA turnover in cotyledons during seedling development.

Review article: Nutritional effects on fetal development during gestation in ruminants

Intrauterine growth retardation is a massive problem in animal production as it influencesthe body composition, carcass quality, and impairs health. This condition can lead to areduction in neonatal survival, growth, feed efficiency utilisation, and future production bythe animals. Pregnancy may negatively influence maternal nutritional status because ofincreased uteroplacental blood flow, nutrient mobilisation, and transfer of nutrients from thedam to the fetus. The critical factor for fetal survival and health is an adequate nutrient andoxygen supply to the dam during gestation. This ability is dependent on her nutritionalsupply, body size, body composition, and metabolism during pregnancy. The placenta is aunique organ of reproduction that helps in the exchange of nutrients, respiratory gases andexcretory waste between the mother and offspring. Maternal nutrition restriction inembryonic, placenta and fetal stages of pregnancy can result in metabolic compromise,cardiovascular, renal and adipose tissue dysfunction. The major effects of nutritionalchallenges on fetoplacental growth and development appear to occur when the placenta israpidly developing. Poor nutrition caused by inadequate, excess or imbalanced nutrientintake has been shown to adversely affect subsequent reproductive performance (delayedpuberty, luteal inadequacy, reduced follicular reserve, reduced ovulation, and conceptionrates). Proteins, carbohydrates, fats, minerals and vitamins are key components in animalfeeds that are required for a daily maintenance diet. Amino acids serve as building blocks forproteins and essential precursors for the synthesis of different physiologicalmolecules–hormones, neurotransmitters, nitric oxide, creatine, glutathione, carnitine, andpolyamines.

Proteomics reveals commitment to germination in barley seeds is marked by loss of stress response proteins and mobilisation of nutrient reservoirs

Germination is a critical process in the reproduction and propagation of flowering plants, and is also the key stage of industrial grain malting. Germination commences when seeds are steeped in water, followed by degradation of the endosperm cell walls, enzymatic digestion of starch and proteins to provide nutrients for the growing plant, and emergence of the radicle from the seed. Dormancy is a state where seeds fail to germinate upon steeping, but which prevents inappropriate premature germination of the seeds before harvest from the field. This can result in inefficiencies in industrial malting. We used DIA/SWATH-MS proteomics to measure changes in the barley seed proteome throughout germination. We found a large number of proteins involved in desiccation tolerance and germination inhibition rapidly decreased in abundance after imbibition. This was followed by a decrease in proteins involved in lipid, protein and nutrient reservoir storage, consistent with induction and activation of systems for nutrient mobilisation to provide nutrients to the growing embryo. Dormant seeds that failed to germinate showed substantial biochemical activity distinct from that of seeds undergoing germination, with differences in sulfur metabolic enzymes, endogenous alpha-amylase/trypsin inhibitors, and histone proteins. We validated our findings with analysis of germinating barley seeds from two commercial malting facilities, demonstrating that key features of the dynamic proteome of germinating barley seeds were conserved between laboratory and industrial scales. The results provide a more detailed understanding of the changes in the barley proteome during germination and give possible target proteins for testing or breeding to enhance germination or control dormancy.

Reviews and syntheses: Biological weathering and its consequences at different spatial levels – from nanoscale to global scale

Plant nutrients can be recycled through microbial decomposition of organic matter but replacement of base cations and phosphorus, lost through harvesting of biomass/biofuels or leaching, requires de novo supply of fresh nutrients released through weathering of soil parent material (minerals and rocks). Weathering involves physical and chemical processes that are modified by biological activity of plants, microorganisms and animals. This article reviews recent progress made in understanding biological processes contributing to weathering. A perspective of increasing spatial scale is adopted, examining the consequences of biological activity for weathering from nanoscale interactions, through in vitro and in planta microcosm and mesocosm studies, to field experiments, and finally ecosystem and global level effects. The topics discussed include the physical alteration of minerals and mineral surfaces; the composition, amounts, chemical properties, and effects of plant and microbial secretions; and the role of carbon flow (including stabilisation and sequestration of C in organic and inorganic forms). Although the predominant focus is on the effects of fungi in forest ecosystems, the properties of biofilms, including bacterial interactions, are also discussed. The implications of these biological processes for modelling are discussed, and we attempt to identify some key questions and knowledge gaps, as well as experimental approaches and areas of research in which future studies are likely to yield useful results. A particular focus of this article is to improve the representation of the ways in which biological processes complement physical and chemical processes that mobilise mineral elements, making them available for plant uptake. This is necessary to produce better estimates of weathering that are required for sustainable management of forests in a post-fossil-fuel economy. While there are abundant examples of nanometre- and micrometre-scale physical interactions between microorganisms and different minerals, opinion appears to be divided with respect to the quantitative significance of these observations for overall weathering. Numerous in vitro experiments and microcosm studies involving plants and their associated microorganisms suggest that the allocation of plant-derived carbon, mineral dissolution and plant nutrient status are tightly coupled, but there is still disagreement about the extent to which these processes contribute to field-scale observations. Apart from providing dynamically responsive pathways for the allocation of plant-derived carbon to power dissolution of minerals, mycorrhizal mycelia provide conduits for the long-distance transportation of weathering products back to plants that are also quantitatively significant sinks for released nutrients. These mycelial pathways bridge heterogeneous substrates, reducing the influence of local variation in C:N ratios. The production of polysaccharide matrices by biofilms of interacting bacteria and/or fungi at interfaces with mineral surfaces and roots influences patterns of production of antibiotics and quorum sensing molecules, with concomitant effects on microbial community structure, and the qualitative and quantitative composition of mineral-solubilising compounds and weathering products. Patterns of carbon allocation and nutrient mobilisation from both organic and inorganic substrates have been studied at larger spatial and temporal scales, including both ecosystem and global levels, and there is a generally wider degree of acceptance of the “systemic” effects of microorganisms on patterns of nutrient mobilisation. Theories about the evolutionary development of weathering processes have been advanced but there is still a lack of information connecting processes at different spatial scales. Detailed studies of the liquid chemistry of local weathering sites at the micrometre scale, together with upscaling to soil-scale dissolution rates, are advocated, as well as new approaches involving stable isotopes.