In human society, the children of a well-off family have a higher chance of getting into better school, have access to better health care and other advantages over children from less well-off families.
What about the life of a tree? Are all seeds equal and their fate depends on where we (human) and pollinators put them? These are the questions that Dr Maria Vivas thought about. It turned out that some trees are more well-off than others, all depending on where their mother grew up.
Maternal effects in Eucalyptus trees
To test this idea that the wellness of families (especially from the mother’s side) can be passed down to the next generation of trees – also called maternal effects, Dr Maria Vivas and her collaborators use eucalyptus trees (Eucalyptus grandis) planted in South Africa. When I asked her what’s so special about these trees, this is what she said:
“The Eucalyptus seed that we used are sold commercially to forestry plantations. We tapped into these resources because we can obtain seed clones (clones have the same genetic material) from mothers that were grown under different environmental condition.”
If a eucalyptus seed comes from a mother plant that grew up in a better environment (i.e. a temperate climate zone), the seed has a higher chance of germination (i.e. sprouting of a seedling from seed), compared to seeds that come from a mother plant growing in worse conditions.
Better immune system if mum has already encountered the pest and pathogen
In addition to the early start in germination, Maria Vivas also measured seedling responses to pest and pathogen infestation to see whether maternal effects have anything to do with how resistance their seeds are.
The pest that they tested is gall forming wasp (Leptocybe invasa) – a devastating pest that attacks the Eucalyptus trees and causes the trees to form galls. L. invasa’s infection stunted the tree growth and if heavily infested can cause tree death.
They also tested the Eucalyptus canker pathogen (Chrysoporte austroafricana) – an important fungal pathogen that grown inside Eucalyptus trees in the tropical and subtropical regions worldwide and causes substantial deaths, especially in young trees.
What they found is that seedlings from mother plants that were more affected by the pest (the gall forming wasp) and pathogen (the Eucalyptus canker) have a better resistance and can withstand the same pest and diseases that the mother plants experienced.
Maternal effects influenced the fungal communities of the seedlings
Most surprisingly, the maternal effects extend to the whole fungal communities of their offsprings. Seedlings from different maternal conditions gave rise to different composition and diversity of fungal communities even when the seedlings were raised together. These fungal communities, which are equivalent to human’s gut communities, are vital for tree resistance to getting pests and diseases and overall growth performance.
“In the current changing climatic environment, this study on the maternal effects will be essential to maximise plant growth while minimising the stressors in seedlings. Moreover, if one uses this knowledge wisely, one can improve the efficiency of tree breeding programs!” – says Maria Vivas when asked about the perspective of her work.
Conclusion: The maternal effects (mothers’ growth environmental conditions) not only give their offspring an advantage in growth and resistance to pests and diseases, they also influenced a whole suite of fungal communities of their offspring – ALL to give their babies a head-start in life!
Source: Vivas M, Kemler M, Mphahlele MM, Wingfield MJ & Slippers B (2017) Maternal effects on phenotype, resistance and the structuring of fungal communities in Eucalyptus grandis. Environmental and Experimental Botany 140: 120-127.
Picture credit: Maria Vivas provides all the images for this blog post.