The complete plastid genome sequence and the photosynthetic activity of the putative mycoheterotrophic orchid Limodorum abortivum: Supplementary material

<p>The sparsely distributed <i>Limodorum abortivum</i> is a European-Mediterranean orchid species, which grows on decomposing plant material. Although some chlorophyll-pigmentation is observed in the degenerated scales-shaped leaf and stems regions of the plant, its photosynthetic capacity is assumed to be insufficient to support the full energy requirements of an adult plant. In Israel, <i>L. abortivum</i> shows a patchy distribution patterns in the Galilee, Golan, Carmel and Judean regions. To gain more insights into the physiology and photosynthetic activity of <i>L. abortivum</i>, we analyzed the organellar morphologies, photosynthetic activities the chloroplast-DNA sequence by Illumina-HTS. Microscopic analyses indicated to the presence of mature chloroplasts with well-organized grana-thylakoids in the leaves and stems of <i>L. abortivum</i>. However, the numbers of chloroplasts per cell and the grana ultrastructure density within the organelles were notably lower than those of model plant species and fully photosynthetically-active orchids. The cpDNA of <i>L. abortivum</i> (154,954 bp) encodes 60 proteins, 34 tRNAs and 4 rRNAs. The coding-regions of 24 genes are interrupted by 26 group-II intron-sequences. While many genes related to photosynthesis (RuBisCo, PSI, PSII and cytochrome <i>b<sub>6</sub>/f</i> subunits) have remained intact in the cpDNA, the majority of the NADH-dehydrogenase (<i>ndh</i>) subunits were either lost or became nonfunctional (i.e. pseudogenized). In agreement with previous reports, the photosynthetic-rates of adult <i>Limodorum</i> plants were found to be very low, further indicating that carbon-assimilation activity is insufficient to support the energy requirements of an adult plant, and may suggest that <i>L. abortivum</i> have adopted nutritional strategies similar to that of mycoheterotrophic orchid species. </p>