Biodiversity Science ›› 2017, Vol. 25 ›› Issue (6): 627-637.doi: 10.17520/biods.2017090

• Original Papers • Previous Article     Next Article

Molecular and morphological evidence for natural hybridization between Rhododendron decorum and R. delavayi (Ericaceae)

Shuoli Zheng1, 2, Xiaoling Tian3, Chengling Huang3, Lingjun Wang4, Yuan Feng4, Jingli Zhang1, *()   

  1. 1 College of Landscape and Gardening, Yunnan Agriculture University, Kunming 650201
    2 Hunan Forest Botanical Garden, Changsha 410116
    3 College of Humanities & Science, Guizhou Minzu University, Guiyang 550025
    4 Institute of Guizhou Baili Rhododendron, Bijie, Guizhou 551518
  • Received:2017-03-22 Accepted:2017-06-28 Online:2017-07-10
  • Zhang Jingli E-mail:jl200812@yeah.net

The southwestern region of China is the center of differentiation for the genus Rhododendron. Studies on the natural hybridization of Rhododendron provide solutions for taxonomic problems and enhance the ability to breed new cultivars faster. In this paper, we compared the morphological features and sequenced nuclear internal transcribed spacer (ITS) and chloroplast trnL-trnF, rbcL, trnH-psbA for Rhododendron decorum, R. delavayi, and the putative hybrid offspring of these two species. All samples in this study were collected from Baili Rhododendron Nature Reserve in Guizhou Province, the Shibao Mountain of Yunnan Province and Kunming Botanical Garden. Results showed that all putative hybrids (natural and artificial) produced an intermediate morphology. Sequencing results revealed that all artificial hybrids and one collected from the Shibao Mountain inherited cpDNA from R. decorum, and all putative hybrids collected from Baili Rhododendron Nature Reserve and six from Shibao Mountain inherited cpDNA from R. delavayi. In this study, we have confirmed that natural hybridization between R. decorum and R. delavayi exists in the Guizhou and Yunnan sites. Hybridization was bilateral, and most of the hybrids were derived from maternal parent R. delavayi.

Key words: Rhododendron, natural hybridization, morphological traits, DNA sequences

Table 1

Sources and sample size of Rhododendron decorum, R. delavayi, and putative hybrids used in this study"

编号 Code 种类 Taxon 地点 Site 经纬度
Latitude and longitude
海拔
Altitude (m)
个体数量
Sample size
BLM (1-10) 马缨杜鹃 R. delavayi 贵州百里杜鹃自然保护区 Baili Rhododendron
Nature Reserve in Guizhou Province
27°15′ N 105°58′ E 1,700-1,800 10
BLD (1-10) 大白杜鹃 R. decorum 贵州百里杜鹃自然保护区 Baili Rhododendron
Nature Reserve in Guizhou Province
27°15′ N 105°58′ E 1,700-1,800 10
BLH (1-8) 疑似杂交后代
Putative hybrids
贵州百里杜鹃自然保护区 Baili Rhododendron
Nature Reserve in Guizhou Province
27°15′ N 105°58′ E 1,700-1,800 8
SBSM (1-5) 马缨杜鹃 R. delavayi 云南大理石宝山 Shibao Mountain of Dali, Yunnan 26°22′ N 99°50′ E 2,400-2,600 5
SBSD (1-5) 大白杜鹃 R. decorum 云南大理石宝山 Shibao Mountain of Dali, Yunnan 26°22′ N 99°50′ E 2,400-2,600 5
SBSH
(2/3/4/5/7/8/9)
疑似杂交后代
Putative hybrids
云南大理石宝山 Shibao Mountain of Dali, Yunnan 26°22′ N 99°50′ E 2,400-2,600 7
AH (1-5) 人工杂交后代
Artificial hybrids
昆明植物园 Kunming Botanical Garden 5
总计 Total 50

Table 2

Comparison of morphological characters of Rhododendron decorum, R. delavayi, artificial and putative hybrids"

形态特征
Morphological characters
大白杜鹃
R. decorum
疑似自然杂交与人工杂交后代
Putative and artificial hybrids
马缨杜鹃
R. delavayi
花冠颜色 Corolla color 白色 White 粉红 Pink 红色 Red
花冠裂片数 No. of corolla lobes 6-8, 通常7 6-8, usually 7 5-6, 无规律 5-6, irregular 5
叶片形状 Leaf shape 长圆形 Oblong 长圆形至披针形 Oblong to lanceolate 披针形 Lanceolate
叶片毛被 Ventral leaf suraface indumentum 无毛 Glabrous 稀疏毛被 Thin indumentum 浓密海绵状毛被
Woolly indumentum
果实表面特征 Fruit surface
character
有腺体 Glands 有腺体或毛被或两者均有
Glands or/and indumentum
密被棕红色毛被 Continuous brownish red indumentum
花期 Flowering period 5-6月 May to June 4月中旬-5月中旬 Mid-April to mid-May 3月-5月 March to May

Table 3

The location of variable sites based on ITS and clone sequences of Rhododendron decorum, R. delavayi and putative hybrids"

编号
Code
克隆数量
Clone numbers
类型
Type
差异位点 Variable sites (bp) 类型 Type
94 101 114 203 494 505 A1 A2 A4
大白杜鹃 R. decorum 0 A1 T G G T T C 15 0 0
马缨杜鹃 R. delavayi 0 A2 C C T G C T 0 15 0
AH、BLH、SBSH A3 Y S K K Y Y
克隆测序 Clone sequences
BLH1 2 1 1 0
BLH2 4 1 2 1
BLH3 3 2 1 0
BLH4 3 2 1 0
BLH5 3 1 1 1
BLH6 5 1 1 3
BLH7 4 2 1 1
BLH8 4 2 1 1
AH1 3 1 2 1
AH2 3 1 2 0
AH3 4 2 2 0
AH4 3 2 1 0
AH5 4 2 2 1
SBSH2 6 4 2 0
SBSH3 8 5 3 0
SBSH4 5 4 1 0
SBSH5 5 4 1 0
SBSH7 7 5 2 0
SBSH8 7 6 1 0
SBSH9 5 3 2 0
克隆数量总计
Total clone numbers
53 31 10

Table 4

The location of variable sites based on trnL-trnF sequences of Rhododendron decorum, R. delavayi and putative hybrids"

编号
Code
类型
Type
差异位点 Variable sites (bp)
147 622 623 624 626 627 629 646 831
大白杜鹃 Rhododendron decorum B1 G T T T T T T C T
马缨杜鹃 R. delavayi B2 T A A A A A A A C
AH、SBSH5 B1 G T T T T T T C T
BLH、SHSH2/3/4/7/8/9 B2 T A A A A A A A C

Table 5

The location of variable sites based on rbcL sequences of Rhododendron decorum, R. delavayi and putative hybrids"

编号
Code
类型
Type
差异位点 Variable sites (bp)
8 30 263 398 407
BLD C1 C G T C C
BLM C2 C T A T T
SBSD C3 G G T C C
SBSM C4 G T A T T
AH C1 C G T C C
BLH C2 C T A T T
SBSH5 C3 G G T C C
SBSH2/3/4/7/8/9 C4 G T A T T

Table 6

The location of variable sites based on trnH-psbA sequences of Rhododendron decorum, R. delavayi and putative hybrids"

编号
Code
类型
Type
差异位点 Variable sites (bp)
1 2 128 135 211 214 245 254 254 299 313 333 337 340 344 348 351 358 365-369
BLD D1 G A T C G C G A C A A G T G G T T T AATTC
SBSD D2 - G * * * * * * * * * A A A A A G G *****
BLM D3 * * A G A C T T T T G * * * * * * * G----
SBSM D4 * * A G A A T T T T G * * * * * * * G----
AH D1 G A T C G C G A C A A G T G G T T T AATTC
SBSH5 D2 * G * * * * * * * * * A A A A A G G *****
BLH D3 * * A G A C T T T T G * * * * * * * G----
SBSH2/3/4/7/8/9 D4 * * A G A A T T T T G * * * * * * · G----

Fig. 1

Clustering chart of combined ITS, trnL-trnF, rbcL, psbA-trnH sequence of Rhododendron decorum, R. delavayi and putative hybrids. The means of AH, BLH, SBSH, BLM, BLD, SBSM, and SBSD see Table 1."

Fig. 2

Flowers and leaves of Rhododendron decorum, R. delavayi, putative and artificial hybrids"

Fig. 3

Part of quantitative characters of Rhododendron decorum, R. delavayi, putative and artificial hybrid. The means of AH, BLH, and SBSH see Table 1."

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