Research Article |
Corresponding author: Qi Gao ( qigao_qg@aliyun.com ) Academic editor: Luiz Gustavo Souza
© 2017 Jian-she Chen, Qi Gao, Hao Zhou, Yu-song Huang, Mikinori Ogisu, Ming Cao.
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 J-s, Gao Q, Zhou H, Huang Y-s, Ogisu M, Cao M (2017) Distribution, karyomorphology, and morphology of Aspidistra subrotata (Asparagaceae) at different ploidy levels in limestone areas of Asia. Comparative Cytogenetics 11(1): 1-13. https://doi.org/10.3897/CompCytogen.v11i1.9803
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Aspidistra subrotata Y. Wan & C.C. Huang, 1987 is considered for the first time as a widespread polyploidy complex in the genus Aspidistra Ker Gawler, 1823 from limestone areas of Asia. The chromosome number of the tetraploid is 2n = 76 and the karyotype is formulated as 2n = 44 m + 8 sm + 24 st, while the chromosome number of the diploid is 2n = 38 and the karyotype formula 2n = 22 m + 4 sm + 12 st. In our studies, diploids occupy broader geographical and environmental niche spaces than tetraploids. Although the leaf-shape of A. subrotata varies quantitatively between and within diploid and/or tetraploid population(s), no obvious discontinuity in the width of leaf has been observed. The tetraploid plants may be distinguished from the diploid plants by their rigid petioles as well as thick deep green lamina. A. subrotata is therefore an interesting material to explore the formation and the evolutionary dynamics of a natural polyploid complex from limestone areas of the tropical regions.
Aspidistra , chromosome number, karst plants, karyotype asymmetry, polyploid complex
Aspidistra Ker Gawler, 1823 is a large genus including more than 140 species from Asia, belonging to the Asparagacae (
Aspidistra subrotata Y. Wan & C.C. Huang, 1987 was originally found in Guangxi Botanical Garden of Medicinal Plants, Nanning City, Guangxi Province, China. After that,
The plants were collected from field work in Guangxi Province, China and Hanoi, Vietnam (Table
Sample | Voucher | Location | Latitude Longitude | Altitude | Figure |
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JL | Huang Y.S. QG375 | China: Jinlong Town, Longzhou County, Chongzuo City, Guangxi Province | 22°26.04'N 107°01.65'E | ca. 300m | |
5M | Huang Y.S. QG378 | China: 5th boundary marker, Nonggang National Nature Reserve, Longzhou County, Chongzuo City, Guangxi Province | 22°27.82'N 106°58.03'E | ca. 300m | |
NG | Wu W.H. QG526 | China: Nonggang National Nature Reserve, Longzhou County, Chongzuo City, Guangxi Province† | 22°28'N 106°58'E | ~ | 5a |
NN | Gao Q. QG735 | China: cultivated in Guangxi Botanical Garden of Medicinal Plants, Nanning City, Guangxi Province | ~ | 5b | |
SK | Anonymous QG766 | China: Shuikou Town, Longzhou County, Chongzuo City, Guangxi Province† | 22°28'N 106°35'E | ~ | |
4M1 | Gao Q. QG807 | China: 4th boundary marker, Nonggang National Nature Reserve, Longzhou County, Chongzuo City, Guangxi Province | 22°27.61'N 106°57.95'E | ca. 400m | 6a |
4M2 | Gao Q. QG809 | China: 4th boundary marker, Nonggang National Nature Reserve, Longzhou County, Chongzuo City, Guangxi Province | 22°27.58'N 106°57.93'E | ca. 370m | 6c |
4M3 | Gao Q. QG810 | China: 4th boundary marker, Nonggang National Nature Reserve, Longzhou County, Chongzuo City, Guangxi Province | 22°27.57'N 106°57.93'E | ca. 370m | 6e |
4M4 | Gao Q. QG811 | China: 4th boundary marker, Nonggang National Nature Reserve, Longzhou County, Chongzuo City, Guangxi Province | 22°27.53'N 106°57.93'E | ca. 380m | 5c, 6h |
PM | Liu Y. QG281 | China: Mt. Poman, Napo Town, Baise City, Guangxi Province† | 22°57'N 160°00'E | ~ | |
DQ1 | Liao Y.B. QG662 | China: Mt. Daqing, Pingxiang County-level City, Guangxi Province | 22°18.27'N 106°41.93'E | ca. 950m | 5f, 7f |
DQ2 | Gao Q. QG823 | China: Mt. Daqing, Pingxiang County-level City, Guangxi Province | 22°18.06'N 106°42.15'E | ca. 900m | 7a |
BV | Ogisu M. QG365 | Vietnam: Mt. Bavi, Hanoi† | 21°05'N 105°22'E | ca. 540m | 5d, e |
Karyomorphological features were observed in 13 samples of Aspidistra subrotata (Table
Eight samples of five tetrapoloid populations of Aspidistra subrotata were all from Longzhou and were located not far away from each other (Map
Distribution of Aspidistra subrotata. Black circle represents the tetraploid population; gray circle represents the diploid population; empty triangle represents typical A. subrotata var. crassinervis; empty square represents typical A. subrotata var. angustifolia.
Somatic Chromosome at mitotic metaphase in Aspidistra subrotata of 2n = 76. a Jilong population b 5th boundary marker population c Nonggang National Nature Reserve population, and the arrow shows the secondary constriction of the chromosome d 4th boundary marker population. Bar = 10 μm.
Karyomorphological characters in Aspidistra subrotata. ALC = average length of chromosome, NCC = number of cells calculated, A1 = karyotype intrachromosomal asymmetry index and A2 = karyotype interchromosomal asymmetry index.
Sample | Literature | Karyotype formula | ALC(μm) | NCC | A1 | A2 | Figure |
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JL | this study | 2n = 76 = 44 m + 8 sm + 24 st | 4.87 ± 0.03 | 2 | 0.38 ± 0.01 | 0.58 ± 0.01 | 1a, 3a |
5M | this study | 2n = 76 = 44 m + 8sm + 24 st | 4.94 ± 0.51 | 3 | 0.35 ± 0.01 | 0.56 ± 0.01 | 1b, 3b |
NG | this study | 2n = 76 = 44m + 8 sm + 24 st | 5.7 ± 0.30 | 3 | 0.38 ± 0.01 | 0.55 ± 0.01 | 1c, 3c |
NN | this study | 2n = 76 = 44 m + 8 sm + 24 st | 5.56 | 1 | 0.36 | 0.60 | |
SK | this study | 2n = 76 = 44 m + 8 sm + 24 st | 5.06 ± 0.20 | 2 | 0.35 ± 0.00 | 0.58 ± 0.02 | |
4M1 | this study | 2n = 76 = 44 m + 8 sm + 24 st | 4.88 ± 0.47 | 5 | 0.35 ± 0.02 | 0.60 ± 0.01 | 1d, 3d |
4M2 | this study | 2n = 76 = 44 m + 8 sm + 24 st | 4.98 | 1 | 0.37 | 0.64 | |
4M3 | this study | 2n = 76 = 44 m + 8 sm + 24 st | 4.71 ± 0.19 | 5 | 0.36 ± 0.01 | 0.62 ± 0.00 | |
4M4 | this study | 2n = 76 = 44 m + 8 sm + 24 st | 4.88 ± 0.09 | 2 | 0.37 ± 0.01 | 0.64 ± 0.02 | |
PM | this study | 2n = 38 = 22 m + 4 sm + 12 st | 5.71 ± 0.28 | 4 | 0.38 ± 0.01 | 0.60 ± 0.02 | 2a, 4a |
DQ1 | this study | 2n = 38 = 22 m + 4 sm + 12 st | 5.26 ± 0.32 | 4 | 0.37 ± 0.01 | 0.60 ± 0.03 | 2b, 4b |
DQ2 | this study | 2n = 38 = 22 m + 4 sm + 12 st | 4.47 ± 0.17 | 2 | 0.33 ± 0.01 | 0.56 ± 0.00 | 2c, 4c |
BV | this study | 2n = 38 = 22 m + 4 sm + 12 st | 5.44 ± 0.17 | 2 | 0.37 ± 0.01 | 0.59 ± 0.00 | 2d, 4d |
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2n = 38 = 22 m + 2 sm + 14 st (2sat) | 5.26 | 1 | 0.41 | 0.60 | ||
~ |
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2n = 38 = 22 m + 6 sm (2sat) + 10 st | 5.29 | 1 | 0.35 | 0.59 |
Four samples of three populations from Mt. Poman, Mt. Daqing, and Mt. Bavi of Aspidistra subrotata have a chromosome number of 2n = 38, uniformly formulated as 2n = 22 m + 4 sm + 12 st (Figures
Somatic Chromosome at mitotic metaphase in Aspidistra subrotata of 2n = 38. a Mt. Poman population b, c Mt. Daqing population d Mt. Bavi population. Bar = 10 μm.
Karyotype of Aspidistra subrotata of 2n = 76, formulated as 2n = 44 m + 8 sm + 24 st. a Jilong population b 5th boundary marker population c Nonggang National Nature Reserve population, and the empty ellipse shows the presence of the secondary constriction on the chromosome 12 d 4th boundary marker population. Bar = 10 μm.
Based on the observation in the field, flowers of Aspidistra subrotata were commonly found with the perigone lobes red–purple and the stigma white with more or less small red dots on the upper surface (Figure
Flower morphology Aspidistra subrotata. a–c flowers of diploid plants from a Nonggang population b Nanning population c 4th boundary marker population d–f flowers of tetraploid plants from d, e Mt. Bavi population f Mt. Daqing population. Bar = 1 cm.
Leaf morphology of tetraploid plants of Aspidistra subrotata. from 4th boundary marker population. a–c sublinear leaves with a. smooth face b blotches c blotches and raised secondary veins d–e narrowly lanceolate leaves with d smooth face e blotches f–h ovate–lanceolate leaves with f smooth face g blotches h blotches and raised secondary veins i plants with ovate–lanceolate leaves and ones with sublinear leaves grow together.
Leaf morphology of diploid plants of Aspidistra subrotata from Mt. Daqing population. a–c leaves with smooth face. a. sublinear leaves b lanceolate leaves c ovate–lanceolate leaves d, e ovate–lanceolate leaves with inconspicuously raised secondary veins f lanceolate leaves with blotches and raised secondary veins.
The karyotypes of nine samples of six populations of Aspidistra subrotata are described here as tetraploid for the first time, with a chromosome number of 2n = 76 and the karyotype formulated as 2n = 44 m + 8 sm + 24 st. Among them, eight samples of five populations are all from Longzhou and are located not far away from each other (Table
There is a long-standing debate on the ecological success of polyploids relative to diploids. Although some studies suggest that polyploids generally have larger ranges (
Our studies show that leaves of Aspidistra subrotata varied in leaf shape, color pattern, and venation in either the tetraploid population of the fourth boundary marker (Figure
Although the leaf-shape of Aspidistra subrotata varies quantitatively between and within diploid or tetraploid population(s), no obvious discontinuity has been observed. It seems unreasonable to divide it into three varieties on the basis of leaf-shape. According to the independent distribution and external morphology in relation to the ploidal levels of chromosome of A. subrotata, two subspecies may be recognized; however, the taxonomic treatment of A. subrotata has not been properly dealt with until the types of all three varieties are checked and confirmed, with additional samples, geographical locations of collections, and molecular data analysis together. We hope this study will be helpful not only to better understand the origin and evolution of the species and the genus but also shed some light on the formation and the evolutionary dynamics of a new natural polyploidy complex in the limestone areas of the tropical regions.
This study was supported by the National Natural Science Foundation of China under Grant 31560056; National Basic Research Development Program of the Ministry of Science and Technology of China under Grant 2013FY112100; and Western Light Talent Culture Project under Grant 2013-165.