Short Communication |
Corresponding author: Jipei Yue ( yuejipei@mail.kib.ac.cn ) Corresponding author: Hang Sun ( hsun@mail.kib.ac.cn ) Academic editor: Peter de Lange
© 2019 Hongliang Chen, Ihsan A. Al-Shehbaz, Jipei Yue, Hang Sun.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Chen H, Al-Shehbaz IA, Yue J, Sun H (2019) Sisymbrium linifolium and Sisymbriopsis schugnana (Brassicaceae), two new records from Xinjiang, China. PhytoKeys 119: 39-52. https://doi.org/10.3897/phytokeys.119.32985
|
Sisymbrium linifolium and Sisymbriopsis schugnana, previously confined to western North America and Tajikistan, respectively, were discovered in Xinjiang during a recent field trip to this autonomous region of China. The identity of these two species was subsequently confirmed by extensive morphological and molecular studies. The biogeographical significance of these new floristic records is briefly addressed.
Brassicaceae (Cruciferae), China, new records, North America, Sisymbriopsis, Sisymbrium, Tajikistan
Although mainly distributed in the temperate regions, species of the mustard family (Brassicaceae / Cruciferae; authorised alternative names, Art. 18.5 and 18.6 of the ICN:
Two of the authors (H.L.C and J.P.Y) have conducted a botanical expedition to Xinjiang and Xizang from 15 June to 22 July 2017, during which we collected about 130 species of 25 genera of Brassicaceae. Subsequent molecular and morphological studies supported the addition of two species as new records to China. Sisymbrium linifolium (Nutt.) Nutt. (Figure
Collected specimens were deposited in KUN, and species identification was based on the floras of China (
The nrITS sequence of Sisymbriopsis schugnana was included in our previous study on the phylogeny of the tribe Euclidieae (
Total genomic DNA was extracted from silica gel-dried leaf materials using the Plant Genomic DNA Kit (Tiangen Biotech, Beijing, China) following the manufacturer’s protocol. The ITS region was amplified with the primers ITS-18F as modified by
Original chromatograms were evaluated with Sequencher 4.1.4 (Gene Codes Corporation, 2002) for base confirmation and contiguous sequences editing, and sequences were aligned with MAFFT v7.311 (
Parsimony analysis was performed with heuristic searches of 1000 replicates with random stepwise addition using tree bisection reconnection (TBR) branch swapping as implemented in PAUP* 4.0a161 (
The aligned ITS dataset comprised 24 species (59 accessions) with 584 characters, of which 192 were variable and 152 (26.03%) were parsimony-informative. Four individuals of the newly collected Sisymbrium from Xinjiang have exact sequences, and sequence divergence between them and S. linifolium ranged from 0–0.2%, which was lower than that of 1.5% compared with S. polymorphum (Murray) Roth.
The generated MP trees had a very similar topology to the Bayesian tree, thus only the BI topology, which is almost as same as the result of
The generic placement of Sisymbrium linifolium has long been in dispute. It was originally placed in Nasturtium W.T.Aiton (Nuttall, 1834), and then transferred to Sisymbrium (Nuttall in Torrey and Gray, 1838) and Schoenocrambe Greene (Greene, 1896). Though several authors claimed that, on aspects of habit, leaves and flowers morphology, this species is very similar to the Eurasian S. polymorphum and retained it in Sisymbrium (
Based on morphology, the Xinjiang Sisymbrium material we collected could be identified as S. polymorphum, but both phylogenetic analyses and sequence alignments supported its placement in S. linifolium (Figure
Another possible explanation is that Sisymbrium linifolium actually has both North American and Central Asian distribution, and most, if not all, of its Asian populations were misidentified as the very similar species, S. polymorphum. Further molecular phylogenetic studies and crossing experiments on more populations from both continents are needed to determine whether a single species or two are in fact involved. If it turned out that the species grows on both continents, then the name for the combined species should be the earlier-published one, S. polymorphum.
Sisymbriopsis Botsch. & Tzvelev was originally recognised as a monospecific genus including S. schugnana as its type (
The material studied here was collected from alluvium of the Muztagata (also Mugtag Ata) Glacial Public Park in Tashkurgan County, Xinjiang, an area close to the borders of Tajikistan. The plant has decumbent stems, dentate and palmately veined leaves, linear and latiseptate secund fruit, and white to pink flowers (Figure
Sisymbriopsis schugnana is narrowly distributed in the eastern Pamir (Figure
We are grateful to Dunyan Tan, Yutao Wang, and Amet Kurbanjan for their help in field-work, and to Minshu Song for assistance on molecular studies. This study was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA 20050203 to H.S.), the National Key R&D Program of China (2017YFC0505200), the Major Program of the NSFC (31590823 to H.S.), and the NSFC grant (31170181 to J.Y.).
Taxa and GenBank accession numbers for the nrITS sequences downloaded from GenBank and used in the phylogenetic analyses; an asterisk (*) indicates the new species record.
Capsella bursa-pastoris (L.) Medik. (AF531561), Erucastrum supinum (L.) Al-Shehbaz & S.I.Warwick (AF531604, AF531605), Neotorularia torulosa (Desf.) Hedge & J.Léonard (AF137571), Neuontobotrys lanata (Walp.) Al-Shehbaz (AF531651, AF531652), Polypsecadium solidagineum (Triana & Planch.) Al-Shehbaz (AF531602); Sisymbrium altissimum L. (AF531559, AF531569, AF531571), S. austriacum Jacq. (AF531576, AF531577, AF531578), S. brassiciforme C.A.Mey. (AF531579, AF531580), S. burchellii DC. (AF531581), S. capense Thunb. (AF531582), S. erysimoides Desf. (AF531584, AF531585), S. heteromallum C.A.Mey. (AF531586), S. irio L. (AF531558, AF531567, AF531568), S. linifolium Nutt. (AF183088, AF183089, AF531613, KX646463), S. loeselii L. (AF531573, AF531574, AF531575, AF531587), S. luteum (Maxim.) O.E.Schulz (AF531588), S. malatyanum Mutlu & Karakuş (KJ557138, KJ557140, KJ557142), S. officinale (L.) Scop. (AF531557, AF531564, KJ557136), S. orientale L. (AF531590, AF531591, AF531592, KJ557139, KJ557143), S. polyceratium L. (AF531594), S. polymorphum (Murray) Roth (AF531595, AF531596), S. septulatum DC. (AF531600, AF531601, KJ557137), S. strictissimum L. (AF531603, AF531653), S. volgense M.Bieb. ex E.Fourn. (AF531608, AF531609, AF531610),*S. linifolium (Nutt.) Nutt. (MK419926, MK419927, MK419928, MK419929).