Ash seed orchards and implications of Chalara

Introduction to our ‘Guest Blog’ below (by Shelagh McCartan)

In Europe, ash (Fraxinus) species are under threat from an emerging disease caused by the fungus Hymenoscyphus fraxineus. Ash dieback (also known as Chalara) is characterised by leaf loss, bark lesions, and crown dieback and is often fatal particularly in young trees. In Britain, the first report of ash dieback was in 2012, but it has since been recorded at over 1000 sites. As a result, there is a ban on the movement of live ash material. Dr Jo Clark, Forestry Research Manager for Earth Trust, has been involved in breeding broadleaved trees including ash (Fraxinus excelsior) for several years. I thought it would be interesting to have a tree breeder’s perspective on the implication of this serious pathogen on ash seed orchards and future breeding programmes.

Guest Blog by Dr Jo Clark (Forestry Research Manager, Earth Trust, UK)

In the UK, The Future Trees Trust, Earth Trust and Forest Research have been working on improving the quality of ash trees for timber for over 20 years.  We started with the selection of superior phenotypes from across the UK, collected seed from them and raised them in a nursery as half sib families.  These were planted out in replicated field trials across four sites and the trees assessed over 15 years to identify which families performed best in terms of form (apical dominance, branching habit) and vigour (height and diameter increment).  Some families performed well across all sites, and others badly across all sites, and as might be expected, other families performed well to a variable degree across sites.   After thinning approximately two thirds of the poorest families, we achieved tested status under the Forest Reproductive Material Regulations (FRM regs) with genetic gains in the region of 8%.  This is the highest category of FRM and the first tested seed for a broadleaved tree available in the UK.  The first seed year after thinning was 2012, the year ash dieback officially arrived in the UK and a ban on movement of live ash material was put in place.

So what now?  The partners, along with the Sylva Foundation, have started a five year work programme called The Living Ash Project to screen the various categories of FRM to identify 400 trees that show a degree of tolerance to ash dieback from which to start a new breeding programme.  Evidence on the continent indicates that about 1% of trees show a good degree of tolerance (less than 10% crown dieback) to Chalara.  We are using the help of citizen science to screen ash trees that are in woodland in the UK and of the lowest category of FRM – source identified.  However, as tree breeders and foresters, it’s important to us that a number of trees that pass the screening process are of good timber quality so we are screening all our ash resources of which we have over 40,000 trees in trials and orchards.  We have stratified the seed that was collected from the tested orchard, and these will be planted out in field trials in winter 2015 in areas of high infection.

We would love for you to get involved.  You can help us find tolerant trees from right across the UK.  We are using Ashtag (a mobile app for your smartphone) to tag trees which are entered in to a database.  You can obtain FREE tree tags from the Sylva Foundation which includes full instructions of what you need to do to help, available from the project website.

For more information please contact or see the project website

2 BSO final thin3 Ash tag


ISSS Workshop on Seed Longevity – 1 week to go!

The ISSS Workshop on Seed Longevity to be held from 5-8 July 2015 in Wernigerode (Germany) is just around the corner – only one week to go! The program looks to be filled with some great presentations by very experienced seed biologists, and is sure to be a good event! If any of our blog followers are fortunate enough to attend, please send us some feedback after the event, and we can post it onto the blog.

For more information, the program and book of abstracts for the workshop are available here.

Fascinating Friday…

Something that I’ve been wanting to do for some time now, is to start sharing some of the interesting ‘seed biology’ journal articles that I come across from time to time. You may already be aware of these articles (via your own TOC alerts, or other searches), but nonetheless, I think it may be useful to highlight some of these on our blog! I hope they are of some interest!

New insights into how seeds are made
Paolo A. Sabelli, Brian A. Larkins
Frontiers in Plant Science

Genome-wide association mapping unravels the genetic control of seed germination and vigor in Brassica napus
Sarah V. Hatzig, Matthias Frisch, Frank Breuer, Nathalie Nesi, Sylvie Ducournau, Marie-Helene Wagner, Gunhild Leckband, Amine Abbadi, Rod J. Snowdon
Frontiers in Plant Science

Fascination of Plants Day: 18 May 2015


On 18th May 2015 the 3rd International “Fascination of Plants Day” will be celebrated worldwide. It was established in 2012 and is launched under the umbrella of the European Plant Science Organisation (EPSO). The goal of this day is to cultivate a fascination for the many ways plants sustain the environment and to highlight the importance of plant science for agriculture, in sustainably producing food, as well as for horticulture, forestry, and other non-food products such as paper, timber, pharmaceuticals, chemicals and energy.

As seeds scientists we have the opportunity of really experiencing the fascination of plants! Let’s share this fascination with those around us!

For more information click here.

If you go down to the woods…

While those of us in the southern hemisphere head towards winter, those in the northern hemisphere are beginning to experience the joys of spring! Shelagh has already begun to see signs of spring, with the longer, warmer days triggering flowering in many trees species, such as hazel, mistletoe and yew. Whilst the male cones and catkins are usually easy to see, particularly when releasing vast clouds of pollen (which unfortunately causes seasonal hay fever in many people), the female flowers and cones are often small, but nonetheless, very striking!

 cupressus glabraalder female cone

The quest for sterile seed in black wattle

Introduction to our ‘Guest Blog’ below (by Marnie Light)

Shelagh and I thought that an article by Dr Sascha Beck-Pay would be an interesting addition to the blog. Sascha, one of my colleagues, worked on a project for several years with the aim of developing a sterile black wattle tree in order to reduce the seed load of this commercially important, yet invasive species, in South Africa. So, in one sense this research does fly in the face of seed scientists (we love to see seeds germinate!), but it does highlight some interesting research…

Guest Blog by Sascha Beck-Pay (Senior Research Scientist at the Institute for Commercial Forestry Research, South Africa)

In South Africa, black wattle (Acacia mearnsii) is a leading commercially grown forestry tree species. However, it is also considered to be an exotic invader of indigenous vegetation. This ‘alien invader’ status adds pressure on the forestry industry, making future afforestation to black wattle difficult, particularly for small-scale growers. Thus, the production of a sterile or seedless variety of black wattle was considered a favourable solution to help reduce the contribution of seed to the existing seedbank, thereby potentially removing the invasive status of black wattle whilst allowing the forestry industry to continue as a thriving contributor to the South African economy.

A project was conducted within the Acacia Breeding Programme at the Institute for Commercial Forestry Research (ICFR) in South Africa to try and produce a sterile or seedless tree using the following two approaches:

  • The production of a triploid variety; and
  • The use of gamma irradiation techniques to produce sterile trees.

With the first approach, tetraploids were successfully induced and controlled-crosses were made with diploids. Due to the fact that no triploids were produced from the controlled-crosses, reproductive biology studies were conducted to investigate possible barriers that could be preventing this. Fluorescent microscopy revealed that, in the cross between diploids and tetraploids, the pollen tubes were reaching the ovary and ovules indicating that fertilisation was possible and that the barrier preventing seed maturation was located within the ovary. Embryo rescue, using tissue culture techniques, was then attempted at varying stages of pod development post-fertilisation. Due to the small size of the pods, however, it was impossible to identify and isolate a clean embryo, devoid of maternal tissue, until 11 months post-fertilisation, at which stage embryo abortion would have occurred.

The second approach tested the use of gamma irradiation to induce sterility in seeds. Samples of seed were irradiated, the seedlings raised in a nursery, and then established in a field trial. It was apparent that reductions in flowering and seed production occurred at doses of 350, 400, 450 and 520 Gy. Although seed production was not completely eliminated, reductions of up to 50 % were recorded. Where seed was produced, the seed was determined to be viable, leading to the conclusion that, although seed production can be reduced, the viability of the seed is not affected and thus gamma irradiation does not affect the female reproductive structures of the plant. This suggested that reduced flowering and resultant lower seed production could be as a result of male sterility, although this still needs further investigation. At the doses tested, there was no detrimental effect on the growth of the trees, which makes this approach to reducing seed production quite promising.

The project was conducted over a period of 12 years from 2000 to 2012 and, although a number of advancements were achieved in trying to produce a sterile or seedless variety of black wattle, the project was closed due to funding constraints. For more information contact Sascha Beck-Pay, or for click here for further reading.

Black wattle inflorescences Diploid and tetraloid polyadsStigma with multiple polyads attached

In memory of Prof. Berjak (South Africa)

It is with much sadness that we recently learned of the death of Prof. Patricia Berjak on the 21st January 2015. Prof. Berjak was a world-renowned seed scientist, with a particular interest and expertise in recalcitrant seed biology. She served as the President of the International Society for Seed Science from 2008 until 2011, and has presented many interesting research papers around the world. Indeed, Prof. Berjak made a remarkable contribution to botanical research, especially concerning our understanding of seed physiology and technology. She will be missed.

Click here for an obituary on Prof. Patricia Berjak.

Small spores, but potentially big impact!

Introduction to our ‘Guest Blog’ below (by Shelagh McCartan)

During December, I was routinely assessing seeds that had failed to germinate during a germination test. Sometimes, ungerminated seeds can be overwhelmed by various moulds, particularly when incubated at warm temperatures for a few weeks.  On this occasion, I spotted an unusual-looking mould, which I passed onto Caroline Gorton for identification. She identified it as an Aspergillus mould – from which a person can develop health problems. It is, therefore, important to be aware of this, and take the necessary precautions. The bottom line is to ‘work smart and stay safe’!

Guest Blog by Caroline Gorton (Diagnostician in the Tree Health Advisory and Diagnostic Service, Forest Research, Britain)

Aspergillus is a ubiquitous mould found in air and soil.  Aspergillus, like other moulds, thrives in humid environments and spores can reach high levels in damp housing and compost.  Most people are immune to infection; however, people with damaged lungs, allergies or a compromised immune system may develop aspergillosis.  The type of disease can vary from an ‘allergy’ type response to life threatening invasive infections.

These images were taken of Aspergillus which had grown in a germination box containing seeds of European silver fir (Abies alba).  As Aspergillus is a common member of the microbial flora, it may well be present on seeds which are incubated and the moist conditions are perfect for its growth.  It is, therefore, worth being aware of when assessing seeds as the spores can cause significant health problems.  It is advisable to work in a well-ventilated environment or to wear a HEPA filter face mask if moulds are present.  Further information is available here.

Aspergillus 3 Aspergillus

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