Caryologia International Journal of Cytology, Cytosystematics and Cytogenetics

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Cytogenetics of Lens Esculenta Moench S. K. Bhattacharjee To cite this article: S. K. Bhattacharjee (1953) Cytogenetics of Lens Esculenta Moench, Caryologia, 5:2, 159-166, DOI: 10.1080/00087114.1953.10797436 To link to this article: http://dx.doi.org/10.1080/00087114.1953.10797436

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Date: 22 January 2017, At: 04:03

CYTOGENETICS OF LENS ESCULENT A MOENCH by

S. K. BHATT ACHARJ EE Botany Department, Presidency College, Calcutta, India

(With Plate XIV and J J figures) Rectived lllay 2i th 1953.

Lens esculenta Moench, the lentil, is one of the common pulses cuitivat~ ed in India. There are six speoies under this genus, of which Lens esculenta~ the Mediterranian one was introduced ~o India for cultivation as a winter crop in the plains. Of the two varieties macrosperma and microsperma the laMer is generally grown in West Bengal. Lens belongs to the tribe Vicieae of the sub-fami:ly Papilionaceae, the baiSic chromo~ome number of which varies from n = 5 to 8. The diploid chromosome number of L. escu~ lenta has been reported by HEITZ ( 1927), BLEIER ( 1928), MIRANDA (1931,) JANAKI AM MAL ( 1945) as 2n = 14; and the karyotype has been worked out by BHATTACHARJEE ( 1951 ). The present paper deals with the study of meiotic chromosomes in detail.

MATERIALS AND METHODS. The plants used in the study were grown in the college garden from seeds supplied by the Agriculture Department, Government of West Bengal. Mitosis was studied from root tips collected from growing seedlings. Root tips were fixed in .002 Mol aqueous Oxyquinoline solution between 10 A.M. and 1 P.M. at 15°~ 18o C for 2 I /2 to 3 hours ·and stained in ace to orcein as described by T JIO and LEVAN ( 1950). For study of meiotic chromosomes flower buds were fixed between II A.M. and I P.M. in I part of glacial acetic acid and 3 parts of 95 % alcohol for 24 hours. After washing in water, anthers were squashed and stained in aceta-carmine. For longer storage flower buds were preserved in a mixture of a I part of glacial acetic acid and 4 parts of 70 % alcohol. Camera Iucida drawings were made from temporary preparations at a 159]

[Oaryologia, vol. V, n. 2, 1953.

BHATT ACHARJEE

160

1

2

3

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\ I I 1

5

CYTOGENETICS OF LENS ESCULENT A MOENCH

161

table magnification of 1400 and 2250 times using 1.25 apochwmatic objective and compensating eye piece No. 10 and 16 respecticely. OBSERVATIONS.

The diploid chromosome number 2n= 14 corresponds with the previous reports made by other workers. During meiosis in the pollen mother cells considerable irregularities in the behaviour of the chromosomes have been observed. Seven bivalents oould be dearly seen in diakinesis (Fiigs. I & 2) and firs•t division metaphase. In early diakinesis two bivalents were observed attached to the nucleolus. In the first division anaphase, bridge-like configurations were observed in a number of pollen mother cells (Fig. 9 and Photo 3). This is possibly due to interlocking of chromosomes which starts in the prophase (Fig. 3) and persists till first division metaphase; and during its separation in anaphase stringing out of cytoplasmic strands between them results in one or two false bridge-like configurations (Photo I). Besides this, irregular separation of chromosomes in the first division anaphase have been observed (Fig. 5). Late separations of some of the bivalents we:re noted frequently (Figs. 4, 7 & 8). In the second meiotic division also irregularities in addition to normal segr.ega,tion (Fig. 6) were observed and in a number ·of cases metaphase plates could be seen with 6 and 8 chromosomes instead ·of 7 and 7 in the two nuclei (Fig. I 0). Irregular separation of chromosomes in second division anaphase (Photo 2) has been observed in a number of cases, but no chromatid bridge formation has been noticed. The tetrad formation is of simultaneous type. In the tetrad nucleus two nucleoli were observed. The pollen grains were more or less elliptical with thick but smooth exine. Considerable size variation in the pollen grains (Photo 4) and formation of abortive (Photo 5) ones noticed. This is possibly the result of irregularities in meiosis resulting in pollen grains wi~h chromosome number greater or less than seven.

Figs. 1-6 - Meiotic stages of Lens esculenta. Figs. I, 2 ~ 3. - Diplotene and diakinesis stages showing seven clear bivalents with different degr~es of terminalization of chiasmata, attachment ot two bivalcnts to the nucleolus and interlocking of bivalents respectively. Figs. 4 ~ 6. - Showing late separation during anaphase yielding fal6e bridge-like appearance. Fig. 5. - Metaphase showing non-disjunction of one bivalent.

,.,.,. ,

BHATT ACHARJEE

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CLass value Len_gth of fer>tile pollen grain i.n A 11

CYTOGENETICS OF LENS ESCULENTA MOENCH

163

TABLE I. Lenght of abortive pollen grains in microns Percentage of abortive pollen grains

n

X

25

2.5 6

75

17

s

Sx

+ 0.188

+ 0.038

+ 6.8

+ 0.08

TABLE 11. Length of fertile pollen grains in microns and their occurrence in a population of one hundred

Class value in p.

Frequency of occurrence per I 00

2.5

2.7

2.9

3.1

3.3

3.5

3.7

to

to

to

to

to

to

to

to

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

14

24

19

31

5

6

0

3.9

DISCUSSION

The karyotype analysis with oxyquinoline method has been found to confirm the previous observations of the author. The number of nucleoli has been found to correspond with the number of secondary constrictions, the maximum number of which has been found to be 4 in the somatic chromo-somes. The two pairs of bivalents attached to two nucleoli of different size observed in a .number of cases in diakinesis also confirm the theory of corre· lation of secondary constrictions and nucleoli (BHADURI, 1942, 1944; BHA· DURI and SHARMA, 1946; 8HADURI and BosE, 1947; SHARMA, 1947; 8HADURI and KAR, 1948). The tetrad nuclei too, as expected, show two nucleoli in each of them.

Figs. 7-10. -Meiotic stages of Lens esculenta (contd.) Figs. 7 f!S 8. - First anaphase showing regular and irregular separation of bivalents. Figs. 9 f!S 10. - Second meiotic anaphase showing regular ( 7 f!S 7) and irregular number ( 6 f!S 8) respectively. Fig. 11. - Showing length of fertile pollen grains in relation to their frequency of occurrence.

164

BHATT ACHARJEE

As has been pointed out in the text, bridge-like configurations were noted during meiotic cycle. The absence of acentric fragment associated with clear dicentric bridge leads one to infer that the configuration is the Tesult of interlocking noted during the previous stage. The interlocking results in irregular disjunction in first and second division anaphase forming pollen grains with greater or less number of chromosomes than the normal. Unequal distribution of chromosomes results in abortion and variation in the size of pollen grains. There ar'e about 17 % of abortive pollen grains. The graph (Fig. 11) shows that of the ferbiile poillen grains 14% are small being about 2.5-2.6 (-L in length, 12% are large being 3.3-4.0 (-L in length and 7 4% are medium being 2.7-3.2 P· in lenght. Of the total population 17% are abortive (2.56 (-L in length), 61.42% are normal (2.7-3.2 p.), 11.62% small (2.5-2.6!L) and 9.91% large (3.2-4.0 p.). So it seems likely that 39% of pollen grains are product of abnormal disjunction. This high percentage of irregularity in meiosis and occurrence ·of abnormal grains is indeed unexpected in a stable crop like that of L. esculenta. These features reveal that possibly the species under consideration is not a true diploid one. However, as no trisomic, tetrasomic or such other form:s have uptil now been noted to occur 'it may be !inferred that !Such abnorma:.I gamete11 are not effective in the production of viable seeds. The possibility of this inference finds support in the stable nature of the species which by continued cultivation and selection has acquired the capability of eliminating such abnormal forms in nature. SUMMARY

Cytological investigations of Lens esculenta has been made. Mitosis has been studied with oxyquinoline method and the diploid chromosome 2n = 14 has been found to correspond with the observations of previous workers. The number of secondary constrictions has been found to correspond with the number of nucleoli which has been found to be 4 in the somatic cells. The observation is in conformity with the theory of numerical correspondence between the maximum number of nucleoli and the total number of secondary constrictions in a species. Meiotic study shows considerable irregularities in the behaviour of the chromosomes. Bridge-like configurations formed due to interlochink of chromosomes have been observed in the first division anaphase in a number of pollen mother cells. Besides this, irregular disjunctions have been observed in the first and the second division anaphase resulting in the formation of

CYTOGENETIC OF LENS ESCULENTA MOENCH

165

-----------

pollen grains with chromosome number greater or less than seven. Irregular distribution of chromosomes results in the size variation and abortion of pollen grains. About 17 % of the pollen grains are abortive being 2.5 ~l in lenght, 61,42% are normal being about 2.7 to 3.2 p. in length, 11.62% are small being 2.5 to 2.6p. in length and 9.91% large being 3,2 to 4.0 p. in length. It seems that about 39% of the pollen grains are the product ·of abnormal disjunction. The irregularity in meiosis, occurrence of abortive pollen grains and size variation in fertile pollen grains suggests that the plant is not a true diploid. The author wishes to express his thanks to Dr. J. C. Sen Gupta, Principal, Presidency College, Calcutta, for his encouragement and to Mr. A. K. Sharma, Lecturer in Botany, Calcutta University, for his helpful suggestions. The 15th May, 1953. LITERATURE CITED BHADURI P. N., -

Chromosome nucleolus relationship and its bearing on cytofogical inter-

pretation. Jour. Roy. Micros. Soc 63: 19-120, 1944.

BHADURI

~

BOSE P. C., -

Cytogenetical investigations in some Common Cuwrbits with

special reference to fragmentation of chromosomes as a .physical basis of speciation. Jour.

Genet., 48: 237-256, 1947. ~

BHADURI

KAR A. K., -·Study of chromosome nucleolus relationship and its bearing

on the interpretation of Oenothera cytogenetics. Bull. Bot. Soc., Soc., Bengal. 2: l-14,

1948. BHADURI

~

SHARMA A. K. -

Cytogenetics of Datura fastLtosa L. Bull. Torr. Bot. Club.

73: 438-450, 1946. BHATTACHARJEE S. K., -

Karyotype analysis of Lens escufenta Moench var. microsperma.

Sci. Cult., 16: 426-427, 1951. BLEIER H., -

Karyologische

Untersuchungen an Winsenwi.chen-Bastarden.

Genetica 2:

111-118, 1928. HEITZ E . - Der Nachweis der Chromosomen. Z. Bot. 18: 625-81, 1926. JANAK! AMMAL E . - Chromosome Atlas of cultivated plants. George Allen and Unwin Ltd.,

1945. MIRANDA F. SAKAMURA T. -

Bot. oc. esp. Hist. nat. 31: 403, 1931. Experime-nte-l!e Studie uber .die Zell und Kerteilung mit besonderer Ruck-

sicht auf Form, Gross and Zahl der Chromosomen. J. Coli. Sci. Imp. Univ. Tokyo, 39:

11, 1-219, 1920.

BHATT ACHARJEE

166 SHARMA A. K. -

A cytological investigation of inccxmpatibility between Cosmos bipinnatus

Cav. and C. sulphureus Cav. Bull. Bot. Soc. Bengal. I, 19-26, 1947. T JIO J. H. ~ LEVAN A. -

Use of oxyquinoline in chromosome analysis. Annal. De La

Estac. Expt. De Aula Dei 2 (I): 21-64, 1950.

Explanation of Plate XIV Microphotographs showing: (I) double bridge like appearance in anaphase, ( 2) non-disjunction in second division metaphase, ( 3) single bridge like appearance in first anaphase. ( 4) Pollen grains empty and full ones, and ( 5) size variation in pollen grains.

RIASSUNTO L'A. ha compiuto ricerche citologiche su Lens esculenta Moench, analizzando le mitosi col metodo dell'ossichinolina. E' stato confermato il numero diploide dei cromosomi 2n= 14. Nelle cellule somatiche il numero dei nucleoli

e stato

riscontrato in numero di 4, corrispon-

dente a! numero delle costrizioni secondarie dei cromosomi. Lo studio della meiosi ha dimostrato notevoli irregolarita, per Ia presenza di ponti e per disgiunzioni irregolari, per cut il numero dei cromosomi dei granelli pollinici puo esserr maggiore o minore di 7. La irregolare distribuzione dei cromosomi determina variazioni nella grandezza del granello di polline e puo determinare l'aborto dei granelli di polline. Circa il 17 % dei granelli di polline sono abortiti avendo una lunghezza di 2,5 6

P··

il 61,42 % sono normali avendo una lun-

ghezza fra 2,7 e 3,2 flo• il 11.62 % sono piccoli avendo una lunghezza di 2,5-2,61-'-, e il 9, 91 % sono grandi avendo una lunghezza da 3, 2 a 4,0

ll .

Circa il 3 9 Jlo dei granelli di

polline sono formati in seguito a disgiunzioni anormali. Le irregolarita nella meiosi, l'aborto di alcuni granuli pollinici e le variazioni in grandezza dei granelli di polline fertili depongono in favore dell'ipotesi che Ia pianta non sia un vero diploide.

CARYOLOGIA

S. K.

BHATIACHARJEE. -

Vol. V, Plate XIV.

Cytogenetics of Lens esculenta Moench.