Cytogenetic studies of some members of Polygonaceae of Kashmir. III Rheum L.

Abstract

Commonly called rhubarb, species of Rheum L. are important source for a number of chemical compounds like emodin, chrysophanic acid and rhaponticin, used as purgatives (Tutin and Clewer 1911). Although these chemicals are present in nearly all the species of Rheum whose chemical analysis has been done, R. emodi and Ri frazenbachii are very rich in them. The two species of this genus namely R. emodi and R. webbianum, growing wild in Kashmir Himalaya, are used as edibles and medicinals both by the people inhabiting this region and the nomads. In view of their economic importance it was decided to study these species critically. The present paper puts on record meiotic details of these two species. Materials and methodsThe material of R. emodi was collected from Mahadev (3,900m) and Baltal (2,900m) and that of R. webbianum from Kangan (1,800m). For the study of male meiosis anthers from the floral buds, fixed in modified Carnoy's 1:1:1 (acetic acid, aboslute ethanol and chloroform) fluid were squashed in I % acetocarmine. For studying pollen fertility, pollen grains from fresh, ripe but undehisced anthers were stained in acetocarmine. The shrivelled and unstained pollen grains were scored as sterile. All the observations were made from temporary mounts which were later made permanent by passing through acetic acid-n butyl alcohol series with euparol as the mounting medium. ObservationsRheum emodi: All the plants collected from Baltal and Mahadev were diploid with different anthers of a bud at different stages of development. In addition to the 22 chromosomes of this species forming eleven bivalents, in the pollen mother cells, an accessory chromosome was also observed in 96.6% of the cells scored (Fig. 1). This accessory chromosome was very small as compared to other chromo somes.At diplotene one or two bivalents remained attached to a large, round and 1 Present address:

Meiotic and Ethnobotanical Studies on <i>Rheum</i> Species from Kashmir Himalaya

“…1a, b) (Table 1), which is in accordance with the previous reports by various workers from India (Gohil andRather 1986, Saggoo andFarooq 2011). Further, the meiotic course was abnormal with the presence of chromatin transfer at M-I (Fig.…”

“…1f). Previously, the tetraploid cytotype (2n= 44) of the species has also been reported by Gohil and Rather (1986), and Saggoo and Farooq (2011) from Kashmir Himalaya (Table 1), whereas, 2n= 22 adds a new diploid cytotype for the first time on a worldwide basis and reports the presence of intraspecific polyploidy. The detailed meiotic course of the diploid cytotype shows various abnormalities as unoriented bivalents at M-I (Fig.…”

Cyto-genetic diversity with special reference to medicinal plants of the Kashmir Himalaya – a review

“…germplasm in Kashmir along with cytology of varieties Lal Farashi, Double Kesri, Hindwand Rakam, Kichhama Trail, Sabe Alif and Tursh Nawabi. Ashraf and Gohil (1986) revealed chromosome numbers of certain species of dicots, and later (Ashraf and Gohil 1989) for the first time investigated meiotic behaviour in 21 diploid species of the genus Astragalus L. Gohil and Rather (1986) carried out cytogenetic studies of members of Polygonaceae of Kashmir including buckwheats and Rheum. Hamal et al (1986) described the nucleolar organising region (NOR) of chromosomes of Apiaceae.…”