The Architectural Unit Setting up and Architectural Characteristics of Néré, <i>Parkia biglobosa</i>, Jack, R. Br. (Fabaceae)

Parkia biglobosa is a much-loved and over-exploited African savannah species for its socio-economic importance. Knowing and taking into account its architectural unit, which is the basis for diagnosing phenology, productivity and tree health, could provide a new perspective on its sustainable management. The aim of this study is to establish the architectural development in Parkia biglobosa by retrospective analysis. To achieve this objective, 390 individuals of all sizes ranging from seedlings to senescent trees were observed and analysed under various soil and climatic conditions in Côte d’Ivoire. The results showed that Parkia biglobosa is a light plant but shading tolerant. It is a mixed vegetative axis plant, the stem is orthotropic* in its proximal part and plagiotropic* (collapsing) in its distal part in young stage. The tree then transitions to an adult and old stage into a tree with a plagiotropic* axis in the proximal and distal parts, the trunk is built up by superimposing collapsed relay axes that gradually straighten, branching is sympodial*, growth is defined and sexuality is terminal and lateral. The ontogeny takes place in three phases: initiation of development and establishment of the crown (young), then flowering and establishment of the architectural unity (adult) and finally the death of secondary axes in the crown, duplication of the architecture by a series of partial and total reiterations (old). The level of organisation is 5: the phytomere, the module or growth unit, the axis, the architectural unit and the reiterated complex. Retrospective analysis of the modules showed that the dimensions of the growth units are indicators of morphological variation and species adaptation to a changing climate (P < 0.05). However, the equations generated by the morphological and habitat dimension linkage models are not significant (R2 and r < 0.7) to be used as a guide for field data collection. This study represents an initiation into the architectural study of this species and the information provided will serve as a basis for further research into the architecture in relation to the sustainable use of this species.

CNGC20 plays dual roles in regulating plant growth and immunity in Brassica napus

Inflorescence architecture is determined by inflorescence length,branch angles and the density of siliques,which affects planting density,lodging resistance and mechanical operation in rapeseed.However,the molecular mechanisms controlling inflorescence architecture are poorly understood,restricting the progress of breeding varieties with ideal plant architecture in oilseed rape.In this study,we have identified and characterized a rapeseed inflorescence development mutant,reduced inflorescence length(ril),which exhibits determinate and shortened inflorescences,reduced plant height,compact branches,and increased silique density.Through BSA-seq and map-based cloning,we find that RIL encodes a cyclic nucleotide-gated channel 20(BnaA01.CNGC20).A substitution of proline at the 304th position to leucine(P304L)was identified in the conserved transmembrane domain of BnaA01.CNGC20.This P304L substitution neither affects the subcellular localization and self-assembly of BnaA01.CNGC20,nor disrupts the interactions with BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1(BAK1),which interacts with CNGC20 and phosphorylates it to regulate Ca^(2+)channel stability.However,the P304L substitution increases channel activity and Ca^(2+)influx,which in turn induces immune responses such as cell death,H2O2 accumulation,upregulation of pathogenesis-related genes,and pattern-triggered immunity.The enhanced immunity improves the resistance to Leptosphaeria biglobosa and Sclerotinia sclerotiorum.Transcriptome analysis further revealed that CNGC20 plays dual roles in regulating plant growth and immunity via the brassinosteroid and auxin signaling pathways.The findings in this study provide deeper insights into the intricate relationship between cytosolic Ca^(2+)level and plant development and immunity,as well as the trade-off between immunity and the performance of yield-related traits in the heterozygous plants(+/ril),which may serve as a guide for balancing yield and disease resistance in oilseed rape breeding.