Teasing out elevational trends in infraspecific Prunus taxa: A vein analysis approach.

Using 33 specimens collected from across their range in Turkey, we demonstrate that the subspecies of Prunus microcarpa C.A.Mey react very differently to altitude. We first outline a simplified, flexible protocol for sectioning and removing the epidermis of small, difficult-to-image leaves for leaf vein studies. We then used venation analysis software to evaluate the two subspecies of this wild cherry in relation to altitude. We also found key differences in venation features between short-shoot and long-shoot leaves for each taxon. Differences include statistically significant negative correlation between vein density, and positive correlation between areole area and altitude in long-shoot leaves of Prunus microcarpa subsp. microcarpa, while its short-shoot leaves had a positive relationship between maximum areole area, and negative relationship between vein density, numbers of veins and endpoints. Meanwhile, P. microcarpa subsp. tortuosa (Boiss. & Hausskn.) Browicz recorded trends that were largely opposite of this, but beside vein thickness and areole area, were not statistically significant. This difference may be part of each taxon's overarching syndrome of anatomical and morphological adaptations to its external environment. RESEARCH HIGHLIGHTS: Features of vein density and thickness fell, while areole area and vein length rose with altitude in P. microcarpa. P. microcarpa subsp. tortuosa showed opposite trends, but reacted less strongly to altitude. Short-shoot and long-shoot have significantly different venation parameters. Using sections proportionate to leaf size is useful to compare venation of leaves that vary due to dimorphism. We discuss protocol strategies for imaging of difficult leaves for venation analyses.

Genome skimming approach reveals the gene arrangements in the chloroplast genomes of the highly endangered Crocus L. species: Crocus istanbulensis (B.Mathew) Ruksans.

Crocus istanbulensis (B.Mathew) Ruksans is one of the most endangered Crocus species in the world and has an extremely limited distribution range in Istanbul. Our recent field work indicates that no more than one hundred individuals remain in the wild. In the present study, we used genome skimming to determine the complete chloroplast (cp) genome sequences of six C. istanbulensis individuals collected from the locus classicus. The cp genome of C. istanbulensis has 151,199 base pairs (bp), with a large single-copy (LSC) (81,197 bp), small single copy (SSC) (17,524 bp) and two inverted repeat (IR) regions of 26,236 bp each. The cp genome contains 132 genes, of which 86 are protein-coding (PCGs), 8 are rRNA and 38 are tRNA genes. Most of the repeats are found in intergenic spacers of Crocus species. Mononucleotide repeats were most abundant, accounting for over 80% of total repeats. The cp genome contained four palindrome repeats and one forward repeat. Comparative analyses among other Iridaceae species identified one inversion in the terminal positions of LSC region and three different gene (psbA, rps3 and rpl22) arrangements in C. istanbulensis that were not reported previously. To measure selective pressure in the exons of chloroplast coding sequences, we performed a sequence analysis of plastome-encoded genes. A total of seven genes (accD, rpoC2, psbK, rps12, ccsA, clpP and ycf2) were detected under positive selection in the cp genome. Alignment-free sequence comparison showed an extremely low sequence diversity across naturally occurring C. istanbulensis specimens. All six sequenced individuals shared the same cp haplotype. In summary, this study will aid further research on the molecular evolution and development of ex situ conservation strategies of C. istanbulensis.

Phylogeny of the saffron-crocus species group, Crocus series Crocus (Iridaceae).

Phylogenetic relationships among the taxa of Crocus series Crocus are still unclear, preventing the understanding of species diversity and the evolution of the important spice saffron (Crocus sativus). Therefore, we analyzed sequences of two chloroplast (trnL-trnF, matK-trnK) and three nuclear (TOPO6, ribosomal DNA ETS and ITS) marker regions to infer phylogenetic relationships among all species belonging to series Crocus. Our phylogenetic analyses resolved the relationships among all taxa of the series. Crocus hadriaticus and the former C. pallasii subspecies appeared polyphyletic. The latter deserve elevating the subspecies to species rank, while for C. hadriaticus a detailed study of species boundaries is necessary. Multi-locus and also genome-wide single nucleotide polymorphism data obtained through genotyping-by-sequencing placed C. sativus within C. cartwrightianus with no indication that other Crocus species contributed to the evolution of the triploid. Our analyses thus made an autotriploid origin of C. sativus from C. cartwrightianus very likely.