2020 Volume 85 Issue 2 Pages 123-126
The genus Vateria L. (Dipterocarpaceae) with its three species namely, V. indica, V. copallifera and V. macrocarpa are distributed from India to Sri Lanka. The genus so far has not been screened for its cytological characters. In the present investigation, the mitotic chromosome number of 2n=22 and basic karyomorphology of V. indica were reported for the first time.
The family Dipterocarpaceae Blume comprises 16 genera and about 535 species worldwide (Mabberley 2017) of which five genera and 30 species are found in India (Sharma and Sanjappa 1993). The genus Vateria comprises three species namely, V. indica L., V. copallifera (Retz.) Alston and V. macrocarpa K.M.Gupta (plants of the world online.org, accessed on 2 April 2019) and all the three species occur in India (Sharma and Sanjappa 1993). V. indica and V. macrocarpa are endemic to India whereas V. copallifera is mainly found in Sri Lanka. V. indica and V. macrocarpa fall under critically endangered (CR) category and V. copallifera under endangered (EN) category of the IUCN.
Vateria indica is an economically important evergreen tree found growing in Sothern Western Ghats (Fig. 1a, b). The wood is used in plywood and veneer industry, for making tea chests, trunks, ammunition boxes, ceilings, partitions, flooring and other interior fittings; the bark and leaf juice are used in medicine; gum resin is known in the trade as Piney resin, White damar, or Dhupa in varnish industry and for making incense; the semisolid fat, known as Piney tallow, Malabar tallow or Dhupa fat obtained from the dried kernels of the seeds is used in the manufacture of candles and soap Sharma and Sanjappa (1993).
The phylogenetic assignment of Dipterocarpaceae among angiosperms has previously been problematic; however, Ashton (1982) supported their placement in the order Malvales has also done by APG IV (Chase 2016, Heckenhauer et al. 2017). The genus Vateria so far has not been studied from cytogenetic point of view. Here, we report for the first time a somatic chromosome number and karyotype of V. indica.
Seeds of V. indica were collected from Agumbe–Sringeri road of Shimoga district in Karnataka state (13°51′24.9″N and 75°11′85.4″E). The voucher specimens of the species are deposited in Herbarium of Shivaji University (SUK). Mitosis was studied from the primary root tips of germinated seeds (Fig. 1c). Seeds were germinated between two moist blotting papers in glass Petri dish. Root tips of 6–10 mm length were pre-treated with 0.002 M 8-hydroxyquinoline for 10±2°C for 3–4 h. The root tips were hydrolyzed with 1M hydrochloric acid at about 70–80°C for 1–2 min. Then the root tips were squashed in 2% propionic orcein. The well-spread chromosome plates were photographed with a LEICA DM 2000 fluorescence microscope attached with a camera. Five well spread somatic chromosomes plates were used for karyotype analysis. The nomenclature used for describing karyotype composition followed by Levan et al. (1964). The degree of karyotype asymmetry was determined using the categories of Stebbins (1971). Karyotype morphometric characters were evaluated by calculating haploid complement length together with intrachromosomal asymmetry index (A1) and interchromosomal asymmetry index (A2) as Zarco (1986).
Vateria indica showed somatic chromosome number 2n=22 (Fig. 1d). The mean chromosome length (MCL) was 6.69±1.17 µm and the total haploid genome length (TCL) was 73.59 µm. The shortest chromosome measured 2.08±1.06 µm and the longest 5.38±2.41 µm (Tables 1, 2). Figure 1e illustrates the karyogram. All the 11 pairs of chromosomes were metacentric (m) with karyotype formula: 11m. Karyotype was symmetrical and fell into the 4A category of Stebbins (1971). The A1 and A2 asymmetry indices were found to be 0.25 and 0.19, respectively.
Chromosome pairs | Long arm l (µm) | Short arm s (µm) | Total length c=l+s (µm) | ‘d’ value l−s (µm) | ‘r’ value l/s | i=s/c×100 | Centromeric position |
---|---|---|---|---|---|---|---|
1 | 5.38±2.41 | 3.62±1.81 | 9.00±4.06 | 1.76 | 1.54 | 40.10 | m |
2 | 4.69±2.21 | 3.42±1.18 | 8.11±3.33 | 1.27 | 1.34 | 42.93 | m |
3 | 4.22±1.74 | 3.22±1.17 | 7.44±2.83 | 1.00 | 1.34 | 43.13 | m |
4 | 3.96±1.29 | 3.05±1.35 | 7.01±2.62 | 0.91 | 1.41 | 42.11 | m |
5 | 3.75±1.60 | 2.93±1.00 | 6.68±2.60 | 0.82 | 1.24 | 44.75 | m |
6 | 3.59±1.46 | 3.02±1.19 | 6.61±2.60 | 0.57 | 1.19 | 46.06 | m |
7 | 3.53±1.46 | 2.66±0.93 | 6.18±2.39 | 0.87 | 1.30 | 43.47 | m |
8 | 3.63±1.78 | 2.43±0.81 | 6.06±2.47 | 1.20 | 1.48 | 41.03 | m |
9 | 3.51±1.34 | 2.55±1.20 | 6.06±2.47 | 0.96 | 1.44 | 41.54 | m |
10 | 3.20±1.48 | 2.40±1.00 | 5.60±2.47 | 0.80 | 1.32 | 43.10 | m |
11 | 2.74±1.06 | 2.08±1.06 | 4.82±2.11 | 0.66 | 1.45 | 41.40 | m |
Species name | Chromosome number (2n) | The range of chromosome length | TCL | References |
---|---|---|---|---|
Hopea odorata | 14 | 2.4–3.6 µm | 46.4 µm | Roy and Jha 1965 |
Shorea robusta | 14 | 1.4–2.8 µm | 27.9 µm | Roy and Jha 1965 |
S. talura | 14 | 1.75–2.5 µm | 29.8 µm | Roy and Jha 1965 |
Dipterocarpus alatus | 22 | 2.1–4.7 µm | 66.8 µm | Roy and Jha 1965 |
Vatica grandiflora | 22 | 1.6–3.4 µm | 57.0 µm | Roy and Jha 1965 |
Vateria indica | 22 | 1.16–2.21 µm | 35.92 µm | Present study |
Roy and Jha (1965) reported the chromosome number for five species belonging to four genera of Dipterocarpaceae. They reported chromosome numbers 2n=14 in Hopea odorata, Shorea robusta, and S. talura while chromosome number 2n=22 was reported in Dipterocarpus alatus and Vatica grandiflora. Their chromosome range and TCL of all studied species were summarized in Table 2.
On the basis of chromosome number, members of family Dipterocarpaceae can be divided into two groups viz. 2n=22 (Dipterocarpus, Vatica and Vateria) and 2n=14 (Hopea and Shorea). The V. indica showed 2n=22 and it comes under Dipterocarpus and Vatica group. There are two base chromosome number in Dipterocarpaceae i.e., x=7 and x=11. The group with x=11 has only diploid species but the group with x=7 base number possesses triploid and tetraploid species viz. Hopea jucunda 2n=21 and Shorea ovalis 2n=28 (Table 3). This polyploid nature of Hopea and Shorea also showed their derived nature as compared to Dipterocarpus, Vatica and Vateria.
Taxon | n, 2n | Authors | Geographical distribution |
---|---|---|---|
Dipterocarpus alatus Roxb. ex G.Don | 20, 22 | Tixier (1953), Roy and Jha (1965) | Andaman and Nicobar Islands. |
D. costatus C.F.Gaertn. | 20 | Tixier (1960) | Andaman & Nicobar Islands and Tripura. |
D. turbinatus C.F.Gaertn. | 20 | Tixier (1960) | Assam, Manipur, Meghalaya, Mizoram and Tripura. |
Hopea odorata Roxb. | 20–22, n=7, 14, 20 | Tixier (1960), Roy and Jha (1965), Jong and Lethbridge (1967), Sarkar et al. (1982), Kaur et al. (1986) | Andaman and Nicobar Islands. |
Shorea robusta Gaertn. | 14 | Roy and Jha (1965), Pal et al. (1993) | Andhra Pradesh, Assam, Bengal, Bihar, Himachal Pradesh, Madhya Pradesh, Orissa, Tripura, West Bengal. |
S. roxburghii G.Don | 14 | Roy and Jha (1965) | Andhra Pradesh, Karnataka and Tamil Nadu. |
Vateria indica L.* | n=10 22 | Mehra (1976), Present communication | Karnataka, Kerala and Tamil Nadu. |
Vatica chinensis L. | 22 | Mane et al. (2018) | Karnataka, Kerala and Tamil Nadu. |
*Represents endemic taxa.
We are grateful to the Head, Department of Botany, Shivaji University, Kolhapur for providing laboratory facilities. Rohit N. Mane is grateful to Rajiv Gandhi Science and Technology Commission (RGSTC), Government of Maharashtra for financial assistance (RGSTC/File-2007/DPP-054/CR-028). Avinash R. Gholave is thankful to principal K.V.N. Naik Arts, Commerce and Science College, Nashik.