Chromosome numbers, characterization of chromosomal pairing during meiosis, origin and natural propagation in polyploid cytotypes (4x, 5x and 6x) of Agrimonia eupatoria L. (Rosaceae) in northwest Himalayas (India)

Abstract

Despite the presence of intraspecific polyploidy (2x, 4x, 5x and 6x) in Agrimonia eupatoria, origin of these cytotypes has never been addressed adequately. The aim of the present study was to record the original chromosome counts and characterize chromosomal pairing during meiosis and microsporogenesis in the 5x cytotype, and discussing the hypothesis regarding the possible origin of polyploid cytotypes (4x, 5x and 6x) in the species. The geographical distribution pattern of cytotypes in the Indian Himalayas and elsewhere has also been analyzed. The present meiotic analysis revealed three chromosomes counts, the tetraploid (2n = 4x = 56), the pentaploid (2n = 5x = 70) and the hexaploid (2n = 6x = 84) cytotypes based on x = 14. Meiotic course was perfectly normal in the 4x and 6x cytotypes resulting into high pollen fertility (94-100 %). Meiotic course in the imbalanced 5x cytotype has been found to be irregular characterized by the presence of high frequency of univalents at diakinesis and metaphase-I. Abnormal meiotic course contributed towards high pollen sterility (74-88 %). Even the apparently fertile/stained pollen grains were of irregular shape and of heterogeneous sizes. Meiotic behaviour of the 5x cytotype is like typical of allopolyploid. Individuals of 5x cytotype did not produce seeds and propagate vegetatively (root suckers) while 4x and 6x cytotypes exploited sexual (seeds) as well as vegetative means for propagation. Chromosomal pairing in pentaploid cytotype is like typical of an allopolyploid and we assume that it might have originated owing to natural inter-cytotype hybridization between 4x and 6x cytotypes in a mixed population. Analysis of geographical distribution pattern of cytotypes shows that Indian Himalayas represent the most cytotype-diverse region for A. eupatoria with the existence of all the four cytotypes (2x, 4x, 5x, 6x). This shows the dynamic nature of the species at chromosomal level in this part of the world.

Cytomixis and Intraspecific Polyploidy (2<i>x</i>, 4<i>x</i>) in <i>Inula grandiflora</i> Willd. from Malana Valley, Kullu District, Himachal Pradesh

“…The 4x plants also possessed larger sized stomata and pollen grains. It is thus apparent that increase in plant height and size of leaves and capitula including micro-characters in 4x individuals is directly correlated with the increase in ploidy level as has been reported earlier in Terminalia chebula (Gill et al 1982), Syzigium cumini (Gill et al 1991), Centaurea phrygia (Kouteckỳ 2007), Centaurea stoebe (Spaniel et al 2008, Mraz et al 2011, Galinsoga parviflora (Bala et al 2011), Parasenecio auriculata (Nakagawa 2006), Ranunculus hirtellus (Kumar and Singhal 2011), Spergularia diandra (Kaur and Singhal 2012), Agrimonia eupatoria , Kumar et al 2014a, Silene vulgaris (Kumar et al 2014b) and Tordyliopsis brunonis (Kumar et al 2014c).…”

First Report of Intraspecific Polyploidy (2<i>x</i>, 4<i>x</i>) in <i>Physochlaina praealta</i> (Decne.) Miers. (Family: Solanaceae)

“…All these factors could enable polyploids to be more competitive and potentially more invasive in a new environment (Pandit et al 2011(Pandit et al , 2014. Such an increase in the size of various vegetative and reproductive parts including micro-characters like stomata, trichome and pollen grains in the 4x individuals seems to be directly correlated with polyploidy and has been reported in a number of species, such as Terminalia chebula (Gill et al 1982), Syzygium cumini (Gill et al 1991), Centaurea stoebe (Spaniel et al 2008, Mráz et al 2011, Ranunculus hirtellus (Kumar and Singhal 2011), Galinsoga parviflora , Plantago depressa , Spergularia diandra (Kaur and Singhal 2012), Agrimonia eupatoria (Kumar et al , 2014a, Silene vulgaris (Kumar et al 2014b), and Tordyliopsis brunonis (Kumar et al 2014c).…”

The phytochemical investigation of Agrimonia eupatoria L. and Agrimonia procera Wallr. as valid sources of Agrimoniae herba—The pharmacopoeial plant material

“…These two species can be distinguished by the morphological features of hypanthium, fruits, and leaves but the higher intraspecific variation of A. eupatoria has to be borne in mind. Throughout its distribution range, A. eupatoria plants have several ploidy levels with polyploid cytotypes present mainly in Asia, whereas in Europe the diploid cytotype (2n = 2x = 28) predominates [2].…”