© 2010 The Japan Mendel Society Cytologia 75(3): 313–318, 2010 Meiotic Studies in Poa annua L. from Different Altitudinal Ranges of North India Harpreet Kaur*, Akshita Gupta, Santosh Kumari and Raghbir Chand Gupta Department of Botany, Punjabi University, Patiala 147 002, India Received May 26, 2010; accepted July 28, 2010 Summary Poa annua L. (family Poaceae) is a cosmopolitan, cytologically variable and apomictic species. At present, cytomorphological studies have been carried out for North-Indian materials on 29 populations from Haryana (North Indian plains), Shiwalik hills and Kangra (H.P.) covering different altitudinal ranges (216–1489 m) of relatively unexplored areas. All the 29 populations are found to be tetraploid with nϭ14. Morphologically, plants of all the populations looked similar without any significant variation but cytologically speaking, among these, 24 populations show normal meiotic course whereas 4 populations show abnormal meiosis in the form of bridges, laggards, etc. The phenomenon of cytomixis has also been studied in 1 population. The variable number of B-chromosomes (1–3B) has been reported in some of the populations. Key words Altitudinal change, B-chromosomes, Kangra (H.P.), Haryana, Meiotic abnormalities, Shiwalik hills. The genus Poa L. includes 300 species on the world-wide basis embracing 45 species from India (Santapau and Henry 1973). Poa annua, belonging to the tribe Festuceae of family Poaceae, occurs in most of the natural habitats as well as in cultivated fields. The cosmopolitan distribution is attributed to various types of reproductive systems from outbreeding to inbreeding to apomictic nature (Ellis 1973, Johnson et al. 1993), habit from annual to biennial to perennial (Grime 1979, Warwick 1979, Lush 1989) and high colonizing ability (Frenot et al. 1997). Though the species is listed as fodder plant (Farooq et al. 2009), lawn grass (Warwick and Briggs 1978) and as an important food plant for the caterpillars of many species of butterfly (Carter 1982), it grows mainly as a crop weed (Frenot et al. 1999). Material and methods Materials for the meiotic studies were collected from 29 populations growing at various places from Haryana, Shiwalik hills and Kangra (Table 1). Voucher specimens were deposited in the Herbarium, Department of Botany, Punjabi University, Patiala (PUN). Meiotic studies were carried out through standard smearing technique from young panicles fixed in Carnoy’s fixative. For the analysis of meiotic abnormalities, large numbers of PMCs were counted for each type of anomaly. Pollen fertility was estimated through glyceroacetocarmine stainability. Well-filled pollen grains with stained nuclei were taken as apparently viable/fertile while shrivelled and unstained pollen grains were counted as sterile. Pollen grain size was measured using occulomicrometre. Photomicrographs of chromosome counts were made from freshly prepared slides using Nikon 80i eclipse Digital Imaging System. * Corresponding author, e-mail: [email protected] Table 1. Information about Herbarium Accession number, locality with altitude, meiotic details, occurance of B-chromosomes and pollen details in different populations of 314 Poa annua collected from selected areas of North India PMCs showing PMCs with PMCs with Pollen grains Population Locality with altitude Bridges at Laggards at Hypo- and (Acc. No.) (m) A-I, T-I, A-I, T-I, Cytomixis Hyperploid B-Chromosomes (%) Fertility Size A-II, T-II A-II, T-II (%) PMCs 1B 2B 3B (%) (mm) (%) (%) (%) District Kangra (H.P.), higher Western Himalaya P-1(52584) Dharamsala (1345) — 23.97 —— 0.96 13.46 — 70.50 28.30ϫ26.88 (171) (104) (104) P-2 (52585) Tal-mata (1103) —— —— ——— 95.20 30.19ϫ26.39 P-3 (52592) Rehlu (850) 20.40 — —— 4.2 10.6 — 75.84 29.66ϫ27.66 (98) (47) (47) P-4 (52586) Bandla (1266) 22.34 — — — 18.10 14.6 10.34 68.80 25.54ϫ24.75 (94) (116) (116) (116) H. Kaur P-5 (52588) Chhota Bhangal (1489) —— —— 6.00 3.02 3.00 74.20 29.68ϫ21.63 (100) (100) (100) ϫ P-6 (52587) Bhagsunaag (1456) —— —— ——— 96.50 27.25 26.28 et al. P-7 (52583) Bada Gran (1480) —— 21.30 3.00 ——— 90.80 29.54ϫ28.68 (187) Haryana, North Indian plains P-8 (50168) Mullana, Ambala (272) —— —— ——— 99.90 16.90ϫ15.00 P-9 (50169) Indri, Karnal (252) —— —— ——— 92.70 16.90ϫ15.00 P-10 (50171) Guhla, Kaithal (219) —— —— ——— 85.20 19.80ϫ18.80 P-11 (50173) CCS Univ., Hissar (216) —— —— ——— 98.00 17.80ϫ16.90 P-12 (50174) Mirpur, Rewari (242) —— —— ——— 95.45 16.90ϫ16.90 P-13 (50175) KUK, Kurukshetra (350) —— —— ——— 92.60 17.80ϫ17.80 P-14 (50176) Jyotisar, Kurukshetra (350) — — —— ——— 88.90 16.90ϫ16.90 P-15 (50177) Agroha, Hissar (216) —— —— ——— 99.98 16.90ϫ15.00 P-16 (50178) Gharaunda, Karnal (252) —— —— ——— 93.40 17.90ϫ16.90 P-17 (50179) Narnaul, Mahendragarh (261) — — —— ——— 82.66 17.80ϫ16.90 P-18 (50180) Sanauli, Panipat (218) —— —— ——— 96.10 16.90ϫ15.00 P-19 (50181) Devsar, Bhiwani (224) —— —— ——— 95.70 16.90ϫ16.90 75(3) Cytologia P-20 (50182) Radaur, Yamunanagar (255) — — —— ——— 99.98 17.80ϫ16.90 P-21 (50184) Kala amb, Ambala (272) —— —— ——— 99.90 19.60ϫ17.80 P-22 (50186) Mohri, Ambala (272) —— —— ——— 85.70 17.80ϫ16.90 Table 1. (Continued) 2010 PMCs showing PMCs with PMCs with Pollen grains Population Locality with altitude Bridges at Laggards at Hypo- and (Acc. No.) (m) A-I, T-I, A-I, T-I, Cytomixis Hyperploid B-Chromosomes (%) Fertility Size A-II, T-II A-II, T-II (%) PMCs 1B 2B 3B (%) (mm) (%) (%) (%) Shiwalik hills, lower western Himlaya P-23 (50165) Dharampur, Solan (1250) —— —— ——— 87.60 16.90ϫ16.90 P-24 (50166) Jabli, Shiwaliks (900) —— —— ——— 99.60 17.80ϫ16.90 P-25 (50167) Kalka, Shiwaliks (624) —— —— ——— 92.90 17.80ϫ17.80 meioticstudiesin Population-based P-26 (50170) Chambaghat, Solan (1350) — — —— 2.8 6.4 — 83.90 17.80ϫ15.00 (60) (60) P-27 (50172) Barog, Solan (1250) —— —— ——— 91.70 17.80ϫ16.90 P-28 (50183) Trilokpur, Shiwaliks (932) — — —— ——— 99.20 17.80ϫ17.80 P-29 (50185) Nahan, Sirmaur (932) — — —— ——— 96.20 17.80ϫ17.80 The figures in the perenthesis indicate the number of PMCs observed. Poa annua Poa Table 2. Chiasma frequency recorded in PMCs at Diakinesis stage in populations collected from higher altudinal areas of district Kangra (H.P.) in Poa annua Total number of Number of PMCs with Number of chiasmata Population Course of PMCs observed meiosis at Diakinesis 26xta 27xta 28xta 29xta Total per PMC per bivalent P-1 abnormal 28 8 6 12 2 764 27.2 1.94 P-2 normal 20 5 3 11 1 548 27.4 1.95 P-3 abnormal 35 4 20 8 3 955 27.28 1.94 P-4 abnormal 32 18 8 6 — 852 25.62 1.90 P-5 normal 42 14 10 11 7 1145 27.26 1.94 P-6 normal 40 12 8 15 5 1093 27.32 1.95 P-7 abnormal 28 12 7 6 3 756 27.0 1.92 315 316 H. Kaur et al. Cytologia 75(3) Fig. 1–11. PMCs showing nϭ14: 1) PMC at Diakinesis. 2) PMC at Anaphase-I. 3) PMC at Diakinesis Showing bivalent with 3 chiasmata. 4) PMC at Metaphase-I showing 2B chromosomes. 5) PMC at Metaphase-I showing 3B chromosomes. 6) PMC and Metaphase-II with lagging chromosomes. 7) PMC at Anaphase-I showing multiple bridges. 8) PMC at Metaphase-I showing unoriented bivalent. 9) PMC at Metaphase-I showing cytomixis with transfer of chromatin. 10) Heterogenous sized pollen grains. 11) Fertile and sterile pollen grains. Scaleϭ10 mm. Results and discussion Populations from different altitudinal ranges do not show any significant differences in morphological features. However, much morphological diversity which leads to many infraspecific categories has been reported in species from different countries (Web 1). Keeping in view the 2010 Population-based meiotic studies in Poa annua 317 existence of cytomorphological diversity, the present study has been undertaken to evaluate the genetic diversity from less explored areas of North India. Detailed meiotic analysis made on all the populations revealed the same chromosome number nϭ14 with normal bivalent formation during M-I (Fig. 1) and mostly equal distribution (14 : 14) during A-I (Fig. 2) and thus, all the populations are at tetraploid level. However, the species in India, is already known to have 2nϭ14 (Mehra and Sunder 1969) from North India, 2nϭ28 from South India (Christopher and Abraham 1971) and from Central and Eastern Himalaya (Mehra and Sharma 1975, 1977), 2nϭ52 from Western Himalaya (Mehra and Remanandan 1973) whereas from outside India, a few more cytotypes (2nϭ14, 21, 24–26, 28, 42, 52) have been reported. Thus, the species has well developed intraspecific polyploid races on xϭ7, besides some aneuploid cytotypes at polyploid level. The high intraspecific morphological diversity in the species might be due to the presence of these cytological races which can originate easily and survive in nature due to the facultative apomictic nature of the taxa (Johnson et al. 1993). Out of the 14 bivalents, 2 are quite large and can accommodate up to 3 chiasmata (Fig. 3), whereas the remaining ones are small to medium-sized with mostly 2 chiasmata and 1–2 having single chiasma. There is no significant difference in the chiasma frequency in the different populations (Table 2). Koshy (1968), on the basis of karyotypic study, reported the presence of pairs of large sized chromosomes, one small-sized and the remaining ones as the medium-sized chromosomes in the species. Among these, 5 populations are found to have a variable number (1–3B) of B-chromosomes (Figs. 4, 5). Similarly, 0–1B chromosome per PMC has been reported by Mehra and Kohli (1966) from North-East India and Mehra et al. (1968) from North India.