Root cap is an important determinant of rhizosphere microbiome assembly

Plants impact the development of their rhizosphere microbial communities. It is yet unclear to what extent the root cap and specific root zones contribute to microbial community assembly. To test the roles of root caps and root hairs in the establishment of microbiomes along maize roots (Zea mays), we compared the composition of prokaryote (archaea and bacteria) and protist (Cercozoa and Endomyxa) microbiomes of intact or decapped primary roots of maize inbred line B73 with its isogenic root hairless (rth3) mutant. In addition, we tracked gene expression along the root axis to identify molecular control points for an active microbiome assembly by roots. Absence of root caps had stronger effects on microbiome composition than the absence of root hairs and affected microbial community composition also at older root zones and at higher trophic levels (protists). Specific bacterial and cercozoan taxa correlated with root genes involved in immune response. Our results indicate a central role of root caps in microbiome assembly with ripple-on effects affecting higher trophic levels and microbiome composition on older root zones

Soil texture is a stronger driver of the maize rhizosphere microbiome and extracellular enzyme activities than soil depth or the presence of root hairs

Aims Different drivers are known to shape rhizosphere microbiome assembly. How soil texture (Texture) and presence or lack of root hairs (Root Hair) of plants affect the rhizosphere microbiome assembly and soil potential extracellular enzyme activities (EEA) at defined rooting depth (Depth) is still a knowledge gap. We investigated effects of these drivers on microbial assembly in rhizosphere and on potential EEA in root-affected soil of maize. Methods Samples were taken from three depths of root hair defective mutant rth3 and wild-type WT maize planted on loam and sand in soil columns after 22 days. Rhizosphere bacterial, archaeal, fungal and cercozoan communities were analysed by sequencing of 16S rRNA gene, ITS and 18S rRNA gene fragments. Soil potential EEA of ss-glucosidase, acid phosphatase and chitinase were estimated using fluorogenic substrates. Results The bacterial, archaeal and cercozoan alpha- and beta-diversities were significantly and strongly altered by Texture, followed by Depth and Root Hair. Texture and Depth had a small impact on fungal assembly, and only fungal beta-diversity was significantly affected. Significant impacts by Depth and Root Hair on beta-diversity and relative abundances at taxonomic levels of bacteria, archaea, fungi and cercozoa were dependent on Texture. Likewise, the patterns of potential EEA followed the trends of microbial communities, and the potential EEA correlated with the relative abundances of several taxa. Conclusions Texture was the strongest driver of rhizosphere microbiome and of soil potential EEA, followed by Depth and Root Hair, similarly to findings in maize root architecture and plant gene expression studies

Initiation and continuation of breastfeeding: theory of planned behaviour

Aims. This paper reports a study investigating new mothers' subjective norms in relation to both breast- and bottle-feeding. The influence of norms on women's infant feeding decisions and the relative influence of social referents at varying degrees of social distance were assessed.Background. Increasing breastfeeding initiation and continuation rates is a key challenge for health educators. The perceived influence of other people's views (subjective norms), including the views of women's partners and health care professionals, is an important predictor of infant feeding behaviour.Methods. Semi-structured questionnaires were administered to 203 new mothers in central and northern Scotland and followed-up by postal questionnaire at 6weeks. Infant feeding intentions, feeding behaviour at birth and follow-up, behavioural beliefs and subjective norms for both breastfeeding and bottle-feeding were assessed. The data were collected in 1998-1999.Results. Subjective norms were important determinants of initiation and continuation of breastfeeding for breast- and bottlefeeders. Breastfeeders rated close social referents as more in favour of bottle-feeding and more against breastfeeding at follow-up, whereas bottlefeeders' ratings did not change. Partner's and nurses'/midwives' views were an important influence at baseline and follow-up. Breastfeeding ‘continuers' perceived their partners as more pro-breastfeeding at 6weeks. Discontinuers perceived more overall social pressure to bottle-feed. However, sampling limitations may have led to over-representation of the views of breastfeeders at baseline and follow-up.Conclusions. Nurses and midwives have a crucial role in communicating positive views on breastfeeding to new mothers at different time points. Future interventions to promote breastfeeding could adopt a broad social approach, encouraging positive norms for existing and potential mothers and fathers, families and people in general