Proper seed storage (Liveseed Practice abstract)

What causes seed ageing? Seed ageing is caused by oxidation of the cell membranes, mitochondria, DNA, RNA and proteins in the seeds. This oxidation is stimulated by four factors: seed moisture level, temperature, oxygen and time. The main factors stimulating this ageing are moisture and oxygen. How to reduce ageing Keep sealed commercial seed packages closed until use, to avoid moisture uptake from the air. Never store an open package in a cold place like a refrigerator, were the humidity is high and the seeds will absorb moisture. If not all seeds are used, store the remainder in a dry environment. For this we developed an easy system with a ‘seed drying and storage box’ (Fig 2). The principle is an airtight transparent box. In the box is a bag with silica gel and a relative humidity (RH) meter. The optimal RH is between 20 and 40%. Home produced seeds can also be dried in the box. If the RH surpasses the 40%, the silica gel needs to be regenerated in an oven at 100 °C. The dried silica gel can be cooled down in a closed clean jam jar or alike. It is possible to store the airtight box with seeds in a cooler place, to reduce ageing further. For larger amount of seeds the box could be replaced by a large vacuum bag, as available for storage of clothes

Practical Guide for drying and storing vegetable seeds in organic small-scale and on-farm seed production

The germination rate and vigour of seeds affect how well a crop emerges and establishes. They are a crucial aspect of seed quality, as poor seed vigour will result in seedlings that are more sensitive to abiotic stress (for example soil compaction or drought) and biotic stress (pathogens, especially soil-borne ones) and might even affect the final performance of the crop! During seed storage, seeds age and their quality declines by oxidation. This is influenced by seed moisture level, presence of oxygen, and temperature, in decreasing order of importance. This guide-booklet explains and highlights the main issues to look out for when drying and storing seed. It proposes cost- and time-saving solutions for on-farm drying and storage. It namely addresses how to dry the seeds efficiently, how to ensure they stay dry during storage and how to protect them from oxygen. The fact that seeds must be properly dried after harvesting and stored in a dry, cool and dark environment is known to many seed producers. Yet, experience shows that these obvious precautions are not always taken, due to lack of time and resources or because of organisational difficulties. By providing practical examples, cases and guidance to reflect on your own context and objectives, we hope this booklet will help to lift some of the practical challenges associated with the drying and storing of vegetable seeds in small-scale seed enterprises and on-farm

Thoughts for a new seed quality strategy, incorporating seed vigour and the microbiome

Official seed tests determine seed quality, using standardised lab conditions with an early and final count of germinated seeds and counting the frequency of normal seedlings, while seed health is considered as the absence of seed borne pathogens. In the field however, the seed or seedling will encounter biotic and abiotic stresses, therefore emergence in the field is often less than germination in the lab. In the field seed vigour is important. To favour the development of more resilient cropping systems, we suggest to place more emphasis on seed vigour , because early emergence in the field has a strong effect on crop establishment and frequently also on costs for corrective measures and total yield,. The ISTA handbook lists vigour tests, including the so-called controlled deterioration (CD) test, but only for a very limited number of crops. In the frame of the European LIVESEED project1,2 we develop a new organic seed health strategy, which will also has advantages for other sustainable farming systems. The basic idea is that both seed vigour and the seed microbiome should be taken into account as elements that can aid the seed and seedling tolerance towards biotic and abiotic stresses. We showed that a CD treatment, inducing slight reduction in carrot seed vigour, increased the sensitivity to the damping-off causing pathogen Alternaria radicina. Seeds are not sterile organisms, they contain a large amount of micro-organisms, collectively called the seed microbiome, that enable transfer of the microbiota from the mother plant to the next generation. Recent research has shown that the seed microbiome contains also organisms that can aid the seedling in its tolerance, sometimes even resistance, towards pathogens and abiotic stress. An overview of this will be presented, including how this can aid in a strategy towards more resilient cropping systems

Organic seed health. An inventory of issues and a report on case studies.

This report describes the state of the art and research results on the production of heathy organic seeds, as performed in the frame of the LIVESEED project, with support from the European Horizon 2020 program. Organic seed health is based on a multitude of factors and cannot simply be managed through one-size-fits-all solutions such as curative seed treatments. Use of seeds produced under organic conditions can also have benefits, as organic soils may have a richer and more diverse microbiome and part of this microbiome enters the seed during development. Although much more research is needed, there are indications that certain microorganisms in this seed microbiome play a role in tolerance of the emerging seedling toward biotic and abiotic stress in the field. In the frame of the LIVESEED project, case studies have been performed on some of these issues, with the aim of providing background information and tools to tackle them

Exploring the Involvement of the Alternative Respiratory Pathway in Pisum sativum L. Seed Germination

Proceeding PaperOrganic agriculture, recognized as a more sustainable agricultural system, strongly de-pends on the use of highly resilient genotypes. Resilient seeds, with increased tolerance to germinate and provide vigorous seedlings under environmental stresses, currently represent one of the most important agronomical traits. Seed germination involves the activation of several metabolic path-ways, including cellular respiration. Alternative oxidase (AOX), a key enzyme in the alternative respiratory pathway, plays a crucial role in regulating cell reprogramming by controlling metabolic transitions related to the cellular redox state and the variable carbon balance. The involvement of the alternative respiratory pathway during germination was explored by analysis of PsAOX gene/protein expression. Seeds of four Pisum sativum L. cultivars (‘Respect-1′, ‘S134′, ‘G78′ and ‘S91′) were imbibed in sterile tap water for 16 h and metabolic parameters measured by calorespirometry (heat and CO2 emission rates) in a Multi-Cell Differential Scanning Calorimeter in isothermal mode at 25 °C. The involvement of PsAOX was evaluated by transcript quantification (PsAOX1, PsAOX2a, and PsAOX2b) through RT-qPCR, and by of analysing the PsAOX expression through Western blot. The results demonstrate that the cv. ‘S91′, characterized by a low germination rate, exhibited the lowest metabolic heat and CO2 emission rate. However, contrary to expectations, PsAOX transcript accumulation and PsAOX protein expression were significantly higher for ‘S91′ than for the other cultivars. These results indicate that higher levels of AOX (transcript and protein) could be linked to lower metabolic rates for embryo growth when seed germination is compromisedinfo:eu-repo/semantics/publishedVersio

Alternative Oxidase (AOX) Senses Stress Levels to Coordinate Auxin-Induced Reprogramming From Seed Germination to Somatic Embryogenesis—A Role Relevant for Seed Vigor Prediction and Plant Robustness

Somatic embryogenesis (SE) is the most striking and prominent example of plant plasticity upon severe stress. Inducing immature carrot seeds perform SE as substitute to germination by auxin treatment can be seen as switch between stress levels associated to morphophysiological plasticity. This experimental system is highly powerful to explore stress response factors that mediate the metabolic switch between cell and tissue identities. Developmental plasticity per se is an emerging trait for in vitro systems and crop improvement. It is supposed to underlie multi-stress tolerance. High plasticity can protect plants throughout life cycles against variable abiotic and biotic conditions. We provide proof of concepts for the existing hypothesis that alternative oxidase (AOX) can be relevant for developmental plasticity and be associated to yield stability. Our perspective on AOX as relevant coordinator of cell reprogramming is supported by real-time polymerase chain reaction (PCR) analyses and gross metabolism data from calorespirometry complemented by SHAM-inhibitor studies on primed, elevated partial pressure of oxygen (EPPO)–stressed, and endophyte-treated seeds. In silico studies on public experimental data from diverse species strengthen generality of our insights. Finally, we highlight readyto- use concepts for plant selection and optimizing in vivo and in vitro propagation that do not require further details on molecular physiology and metabolism. This is demonstrated by applying our research & technology concepts to pea genotypes with differential yield performance in multilocation fields and chickpea types known for differential robustness in the field. By using these concepts and tools appropriately, also other marker candidates than AOX and complex genomics data can be efficiently validated for prebreeding and seed vigor prediction

Alternative Oxidase (AOX) Senses Stress Levels to Coordinate Auxin-Induced Reprogramming From Seed Germination to Somatic Embryogenesis—A Role Relevant for Seed Vigor Prediction and Plant Robustness

Somatic embryogenesis (SE) is the most striking and prominent example of plant plasticity upon severe stress. Inducing immature carrot seeds perform SE as substitute to germination by auxin treatment can be seen as switch between stress levels associated to morphophysiological plasticity. This experimental system is highly powerful to explore stress response factors that mediate the metabolic switch between cell and tissue identities. Developmental plasticity per se is an emerging trait for in vitro systems and crop improvement. It is supposed to underlie multi-stress tolerance. High plasticity can protect plants throughout life cycles against variable abiotic and biotic conditions. We provide proof of concepts for the existing hypothesis that alternative oxidase (AOX) can be relevant for developmental plasticity and be associated to yield stability. Our perspective on AOX as relevant coordinator of cell reprogramming is supported by real-time polymerase chain reaction (PCR) analyses and gross metabolism data from calorespirometry complemented by SHAM-inhibitor studies on primed, elevated partial pressure of oxygen (EPPO)–stressed, and endophyte-treated seeds. In silico studies on public experimental data from diverse species strengthen generality of our insights. Finally, we highlight ready-to-use concepts for plant selection and optimizing in vivo and in vitro propagation that do not require further details on molecular physiology and metabolism. This is demonstrated by applying our research & technology concepts to pea genotypes with differential yield performance in multilocation fields and chickpea types known for differential robustness in the field. By using these concepts and tools appropriately, also other marker candidates than AOX and complex genomics data can be efficiently validated for prebreeding and seed vigor prediction.</p

Chronic Q fever diagnosis—consensus guideline versus expert opinion

Chronic Q fever, caused by Coxiella burnetii, has high mortality and morbidity rates if left untreated. Controversy about the diagnosis of this complex disease has emerged recently. We applied the guideline from the Dutch Q Fe­ver Consensus Group and a set of diagnostic criteria pro­posed by Didier Raoult to all 284 chronic Q fever patients included in the Dutch National Chronic Q Fever Database during 2006–2012. Of the patients who had proven cas­es of chronic Q fever by the Dutch guideline, 46 (30.5%) would not have received a diagnosis by the alternative cri­teria designed by Raoult, and 14 (4.9%) would have been considered to have possible chronic Q fever. Six patients with proven chronic Q fever died of related causes. Until results from future studies are available, by which current guidelines can be modified, we believe that the Dutch lit­erature-based consensus guideline is more sensitive and easier to use in clinical practice

Thoughts for a new seed quality strategy, incorporating seed vigour and the microbiome

Official seed tests determine seed quality, using standardised lab conditions with an early and final count of germinated seeds and counting the frequency of normal seedlings, while seed health is considered as the absence of seed borne pathogens. In the field however, the seed or seedling will encounter biotic and abiotic stresses, therefore emergence in the field is often less than germination in the lab. In the field seed vigour is important. To favour the development of more resilient cropping systems, we suggest to place more emphasis on seed vigour , because early emergence in the field has a strong effect on crop establishment and frequently also on costs for corrective measures and total yield,. The ISTA handbook lists vigour tests, including the so-called controlled deterioration (CD) test, but only for a very limited number of crops. In the frame of the European LIVESEED project we develop a new organic seed health strategy, which will also has advantages for other sustainable farming systems. The basic idea is that both seed vigour and the seed microbiome should be taken into account as elements that can aid the seed and seedling tolerance towards biotic and abiotic stresses. We showed that a CD treatment, inducing slight reduction in carrot seed vigour, increased the sensitivity to the damping-off causing pathogen Alternaria radicina. Seeds are not sterile organisms, they contain a large amount of micro-organisms, collectively called the seed microbiome, that enable transfer of the microbiota from the mother plant to the next generation. Recent research has shown that the seed microbiome contains also organisms that can aid the seedling in its tolerance, sometimes even resistance, towards pathogens and abiotic stress. An overview of this will be presented, including how this can aid in a strategy towards more resilient cropping systems

Evaluating the EPPO method for seed longevity analyses in Arabidopsis

Seed longevity (storability) is an important seed quality trait. High seed quality is important in agriculture, for the industry, and for safeguarding biodiversity as many species are stored as seeds in genebanks. To ensure ex-situ seed survival, seeds are mostly stored at low relative humidity and low temperature. Oxidation is the main cause of seed deterioration in these dry storage conditions. The molecular mechanisms underlying dry seed survival remain poorly understood. Research on seed longevity is hampered by the lack of an experimental ageing method that mimics dry ageing well. Here, we propose the Elevated Partial Pressure of Oxygen (EPPO) method as the best available method to mimic and accelerate dry seed ageing. We have tested seed germination in Arabidopsis thaliana after EPPO storage at two different relative humidity (RH) conditions and confirm the large effect of oxygen and the seed moisture content on ageing during dry storage. Comparative Quantitative trait locus (QTL) analysis shows that EPPO at 55 % RH mimics dry ageing better than the commonly used Artificial Ageing and Controlled Deterioration tests at higher moisture levels.</p