Figure 4. Survey of Zamia phyllosphere microbiota and metabolites
reveals potential ecological functions. a. Core members of the bacterial
endophyte community (892 ASVs) of six species (Z. elegantissima ,Z. nana , Z. pseudomonticola, Z. pseudoparasitica, Z.
skinneri, Z. stevensonii ) identified using 16S-RNA amplicon
sequencing (n = 28). The nitrogen-fixing cyanobacteriaDesmonostoc was observed in 30% of the samples with relative
abundance up to 20%. b. Leaf fungal endophyte variants (10343 ASVs) of
two species (Z. pseudoparasitica and Z. nana ) identified
using ITS1 amplicon sequencing (n = 127). The generaColletotrichum is the most prevalent fungal endophyte in
>50% of the samples studied. c. Foliar metabolome
composition of Z. nana and Z. pseudoparasitica summarized
into two dimensions with non-metric multidimensional scaling (NMDS)
based on the Bray-Curtis dissimilarity index indicating the correlation
between the metabolome and the microbiome. Solid lines correspond to
regressions with p-value = <0.05 and dashed lines with p-value
= 0.1. Modified from Sierra et al. (in review)
Cycas panzhihuaensis genome
Cycads offer a unique opportunity to uncover shared genomic traits
exclusive to seed-producing plants. The first cycad genome was recently
published and this high-quality 10.5 Gb chromosome-level assembly
immediately provided a plethora of insights (Liu et al ., 2022).
The Cycas panzhihuaensis genome contains evidence of an ancient
whole-genome duplication event in the common ancestor of living
gymnosperms and key innovations enabling seed formation are evident in
the genome, including expansions of gene families regulating embryo
development, secondary growth, and pollen tube formation. The genome
also shows remarkable expansions of genes involved in chemical defenses,
stress tolerance, and disease resistance, which may help explain the
higher extant species diversity of cycads compared to Gingko . We
elaborate further on a few particularly exciting findings from the
genome. Overall, the high-quality C. panzhihuaensis genome
assembly and annotation sheds light on the origin and evolution of
cycads and provides insights into genetic innovations underlying seed
plant success (Liu et al. , 2022).