Intraspecific genetic diversity modulates plant–soil feedback and nutrient cycling

Abstract

Plant genetic diversity can affect ecosystem functioning by enhancing productivity, litter decomposition and resistance to natural enemies. However, the mechanisms underlying these effects remain poorly understood. We hypothesized that genetic diversity may influence ecosystem processes by eliciting functional plasticity among individuals encountering kin or genetically diverse neighbourhoods. We used soil conditioned by groups of closely related (siblings) and diverse genotypes of Deschampsia cespitosa - a species known to exhibit kin recognition via root exudation - to investigate the consequences of kin interactions for root litter decomposition and negative feedback between plants and soil biota. Genetically diverse groups produced root litter that had higher nitrogen (N) content, decomposed faster and resulted in greater N uptake by the next generation of seedlings compared with litter produced by sibling groups. However, a similar degree of negative soil feedback on plant productivity was observed in soil conditioned by siblings and genetically diverse groups. This suggests that characteristics of roots produced by sibling groups slow down N cycling but moderate the expected negative impact of soil pathogens in low-diversity stands. These findings highlight interactions between neighbouring genotypes as an overlooked mechanism by which genetic diversity can affect biotic soil feedback and nutrient cycling.

Mechanisms of plant–soil feedback: interactions among biotic and abiotic drivers

“…As such, they are commonly assumed to be the cause of negative PSF driven by soil biota (e.g. Semchenko et al ., ; Kempel et al ., ). Root herbivores, such as root‐feeding nematodes, have received less attention, but can also cause negative PSF by feeding on the roots of young plants (Dias et al ., ).…”

The genetics underlying natural variation of plant–plant interactions, a beloved but forgotten member of the family of biotic interactions

“…In addition, growing on soil previously occupied by diverse plant genotypes increased nitrogen uptake in roots of D . cespitosa compared with soil conditioned by siblings (Semchenko et al ., ) and a role of soil microbiome was suggested.…”

“…Depending on the source of phosphate available in the soil, the grass Deschampsia cespitosa produces more biomass when grown with a different grass species than with conspecifics, suggesting that nutrient availability regulates plant competition (Ahmad-Ramli et al, 2013). In addition, growing on soil previously occupied by diverse plant genotypes increased nitrogen uptake in roots of D. cespitosa compared with soil conditioned by siblings (Semchenko et al, 2017) and a role of soil microbiome was suggested.…”

Spatial heterogeneity in root litter and soil legacies differentially affect legume root traits

“…The plants also had limited access to mineralised nutrients due to litter being confined to a litterbag that excluded plant roots, even though mineralised nutrients could diffuse from the litterbag into the soil solution. Future studies should consider using litter mixed directly into the soil when estimating the effects of litter decomposition on plant-soil feedback (Semchenko et al 2017). …”