Limits...
Cytogenetic relationships among Citrullus species in comparison with some genera of the tribe Benincaseae (Cucurbitaceae) as inferred from rDNA distribution patterns.

Li KP, Wu YX, Zhao H, Wang Y, Lü XM, Wang JM, Xu Y, Li ZY, Han YH - BMC Evol. Biol. (2016)

Bottom Line: The present study confirmed evolutionary closeness among cultivated watermelon (C. lanatus subsp. vulgaris), C. lanatus subsp. mucosospermus and C. colocynthis.Our result also supported that C. lanatus subsp. lanatus was not a wild form of the cultivated watermelon instead was a separate crop species.In addition, present cytogenetic analysis suggested that A. naudinianus was more closely related to Cucumis than to Citrullus or Acanthosicyos, but with a unique position and may be a link bridge between the Citrullus and the Cucumis.

View Article: PubMed Central - PubMed

Affiliation: Institute of Integrative Plant Biology, School of Life Sciences, Jiangsu Normal University, Xuzhou, 221116, China.

ABSTRACT

Background: Comparative mapping of 5S and 45S rDNA by fluorescent in situ hybridization (FISH) technique is an excellent tool to determine cytogenetic relationships among closely related species.

Results: In this study, the number and position of 5S and 45S rDNA loci in all Citrullus species and subspecies were determined. The cultivated watermelon (C. lanatus subsp. vulgaris), C. lanatus subsp. mucosospermus, C. colocynthis and C. naudinianus (or Acanthosicyos naudinianus) had two 45S rDNA loci and one 5S rDNA locus which was located syntenic to one of the 45S rDNA loci. C. ecirrhosus and C. lanatus subsp. lanatus had one 45S rDNA locus and two 5S rDNA loci, each located on a different chromosome. C. rehmii had one 5S and one 45S rDNA locus positioned on different chromosomes. The distribution of 5S and 45S rDNA in several species belonging to other genera in Benincaseae tribe was also investigated. The distribution pattern of rDNAs showed a great difference among these species.

Conclusions: The present study confirmed evolutionary closeness among cultivated watermelon (C. lanatus subsp. vulgaris), C. lanatus subsp. mucosospermus and C. colocynthis. Our result also supported that C. lanatus subsp. lanatus was not a wild form of the cultivated watermelon instead was a separate crop species. In addition, present cytogenetic analysis suggested that A. naudinianus was more closely related to Cucumis than to Citrullus or Acanthosicyos, but with a unique position and may be a link bridge between the Citrullus and the Cucumis.

No MeSH data available.


FISH of melon oligos probes, 5S and 45S rDNA in Cucumis metuliferus and Acanthosicyos naudinianus. a1-b1 FISH oligos probes Library 1 (green) and Library 2 (red) on metaphase chromosomes of C. metuliferus (a1) and A. naudinianus (b1). a2-b2 The same cells in a1-b1 were reprobed with 5S rDNA (red) and 45S rDNA (green) probes. a3-b3 The chromosomes with the signals of the oligos probes Library 1 (green) and Library 2 (red) in a1-b1. a4-b4 The chromosomes with the signals of 5S rDNA (red) and 45S rDNA (green) probes in a2-b2. Bars, 5 mm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4835933&req=5

Fig3: FISH of melon oligos probes, 5S and 45S rDNA in Cucumis metuliferus and Acanthosicyos naudinianus. a1-b1 FISH oligos probes Library 1 (green) and Library 2 (red) on metaphase chromosomes of C. metuliferus (a1) and A. naudinianus (b1). a2-b2 The same cells in a1-b1 were reprobed with 5S rDNA (red) and 45S rDNA (green) probes. a3-b3 The chromosomes with the signals of the oligos probes Library 1 (green) and Library 2 (red) in a1-b1. a4-b4 The chromosomes with the signals of 5S rDNA (red) and 45S rDNA (green) probes in a2-b2. Bars, 5 mm

Mentions: The 5S rDNA locus was located syntenic to one of the 45S rDNA loci in L. siceraria (Fig. 2a), Z. mariothii (Fig. 2b), C. metuliferus (Fig. 2d), C. sessilifolia (Fig. 2f) and D. palmatus (Fig. 2g). However, only in C. metuliferus, the 5S and 45S rDNA were far apart (Fig. 2d). We found that C. metuliferus (Fig. 2d) had same number and location of 5S and 45S rDNA loci as A. naudinianus (Fig. 1g2, g4). To further confirm the close relationship between C. metuliferus and A. naudinianus, we performed FISH on the chromosomes of C. metuliferus and A. naudinianus using two melon oligos probes which were used to identify chromosomes 8, 10 and 12 with 5S and 45S rDNA loci in Cucumis species (unpublished data). Two melon probes generated distinct FISH signals on three pairs of chromosomes in C. metuliferus (Fig. 3a1, a3) and A. naudinianus (Fig. 3b1, b3). Like melon, the chromosomes with same oligo probes signals were also designated as chromosomes 8, 10 and 12 in C. metuliferus and A. naudinianus. Following the FISH analysis of using oligos probes, the slides were washed and reprobed with 5S and 45S rDNA sequences simultaneously. The FISH results showed that two 45S rDNA loci (green) were on the chromosomes 8 and 10 in C. metuliferus (Fig. 3a2, a4) and A. naudinianus (Fig. 3b2, b4). The 5S rDNA locus (red) was located syntenic to the 45S rDNA loci on chromosome 10 (Fig. 3a4, b4). We also tested melon oligos probes on chromosomes of other Citrullus species and watermelon oligos probes on chromosomes of Cucumis species and L. siceraria which was closely related to watermelon. We did not detect unambiguous signals in these species using any of the four probes (data not shown). This was consistent with our previous study that unambiguous signals weren’t detected on chromosomes of watermelon and Cucurbita pepo (2n = 4x = 40) using any of three cucumber oligo probes [31]. Therefore, cross-genus hybridization was not feasible using oligo probes.Fig. 3


Cytogenetic relationships among Citrullus species in comparison with some genera of the tribe Benincaseae (Cucurbitaceae) as inferred from rDNA distribution patterns.

Li KP, Wu YX, Zhao H, Wang Y, Lü XM, Wang JM, Xu Y, Li ZY, Han YH - BMC Evol. Biol. (2016)

FISH of melon oligos probes, 5S and 45S rDNA in Cucumis metuliferus and Acanthosicyos naudinianus. a1-b1 FISH oligos probes Library 1 (green) and Library 2 (red) on metaphase chromosomes of C. metuliferus (a1) and A. naudinianus (b1). a2-b2 The same cells in a1-b1 were reprobed with 5S rDNA (red) and 45S rDNA (green) probes. a3-b3 The chromosomes with the signals of the oligos probes Library 1 (green) and Library 2 (red) in a1-b1. a4-b4 The chromosomes with the signals of 5S rDNA (red) and 45S rDNA (green) probes in a2-b2. Bars, 5 mm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4835933&req=5

Fig3: FISH of melon oligos probes, 5S and 45S rDNA in Cucumis metuliferus and Acanthosicyos naudinianus. a1-b1 FISH oligos probes Library 1 (green) and Library 2 (red) on metaphase chromosomes of C. metuliferus (a1) and A. naudinianus (b1). a2-b2 The same cells in a1-b1 were reprobed with 5S rDNA (red) and 45S rDNA (green) probes. a3-b3 The chromosomes with the signals of the oligos probes Library 1 (green) and Library 2 (red) in a1-b1. a4-b4 The chromosomes with the signals of 5S rDNA (red) and 45S rDNA (green) probes in a2-b2. Bars, 5 mm
Mentions: The 5S rDNA locus was located syntenic to one of the 45S rDNA loci in L. siceraria (Fig. 2a), Z. mariothii (Fig. 2b), C. metuliferus (Fig. 2d), C. sessilifolia (Fig. 2f) and D. palmatus (Fig. 2g). However, only in C. metuliferus, the 5S and 45S rDNA were far apart (Fig. 2d). We found that C. metuliferus (Fig. 2d) had same number and location of 5S and 45S rDNA loci as A. naudinianus (Fig. 1g2, g4). To further confirm the close relationship between C. metuliferus and A. naudinianus, we performed FISH on the chromosomes of C. metuliferus and A. naudinianus using two melon oligos probes which were used to identify chromosomes 8, 10 and 12 with 5S and 45S rDNA loci in Cucumis species (unpublished data). Two melon probes generated distinct FISH signals on three pairs of chromosomes in C. metuliferus (Fig. 3a1, a3) and A. naudinianus (Fig. 3b1, b3). Like melon, the chromosomes with same oligo probes signals were also designated as chromosomes 8, 10 and 12 in C. metuliferus and A. naudinianus. Following the FISH analysis of using oligos probes, the slides were washed and reprobed with 5S and 45S rDNA sequences simultaneously. The FISH results showed that two 45S rDNA loci (green) were on the chromosomes 8 and 10 in C. metuliferus (Fig. 3a2, a4) and A. naudinianus (Fig. 3b2, b4). The 5S rDNA locus (red) was located syntenic to the 45S rDNA loci on chromosome 10 (Fig. 3a4, b4). We also tested melon oligos probes on chromosomes of other Citrullus species and watermelon oligos probes on chromosomes of Cucumis species and L. siceraria which was closely related to watermelon. We did not detect unambiguous signals in these species using any of the four probes (data not shown). This was consistent with our previous study that unambiguous signals weren’t detected on chromosomes of watermelon and Cucurbita pepo (2n = 4x = 40) using any of three cucumber oligo probes [31]. Therefore, cross-genus hybridization was not feasible using oligo probes.Fig. 3

Bottom Line: The present study confirmed evolutionary closeness among cultivated watermelon (C. lanatus subsp. vulgaris), C. lanatus subsp. mucosospermus and C. colocynthis.Our result also supported that C. lanatus subsp. lanatus was not a wild form of the cultivated watermelon instead was a separate crop species.In addition, present cytogenetic analysis suggested that A. naudinianus was more closely related to Cucumis than to Citrullus or Acanthosicyos, but with a unique position and may be a link bridge between the Citrullus and the Cucumis.

View Article: PubMed Central - PubMed

Affiliation: Institute of Integrative Plant Biology, School of Life Sciences, Jiangsu Normal University, Xuzhou, 221116, China.

ABSTRACT

Background: Comparative mapping of 5S and 45S rDNA by fluorescent in situ hybridization (FISH) technique is an excellent tool to determine cytogenetic relationships among closely related species.

Results: In this study, the number and position of 5S and 45S rDNA loci in all Citrullus species and subspecies were determined. The cultivated watermelon (C. lanatus subsp. vulgaris), C. lanatus subsp. mucosospermus, C. colocynthis and C. naudinianus (or Acanthosicyos naudinianus) had two 45S rDNA loci and one 5S rDNA locus which was located syntenic to one of the 45S rDNA loci. C. ecirrhosus and C. lanatus subsp. lanatus had one 45S rDNA locus and two 5S rDNA loci, each located on a different chromosome. C. rehmii had one 5S and one 45S rDNA locus positioned on different chromosomes. The distribution of 5S and 45S rDNA in several species belonging to other genera in Benincaseae tribe was also investigated. The distribution pattern of rDNAs showed a great difference among these species.

Conclusions: The present study confirmed evolutionary closeness among cultivated watermelon (C. lanatus subsp. vulgaris), C. lanatus subsp. mucosospermus and C. colocynthis. Our result also supported that C. lanatus subsp. lanatus was not a wild form of the cultivated watermelon instead was a separate crop species. In addition, present cytogenetic analysis suggested that A. naudinianus was more closely related to Cucumis than to Citrullus or Acanthosicyos, but with a unique position and may be a link bridge between the Citrullus and the Cucumis.

No MeSH data available.