Impact of Reciprocal Translocations and Non-Synchronous Disjunction of Chromosomes on Pollen Fertility in <i>Astragalus chlorostachys</i> from the Northwest Himalayas (India)

Abstract

Summary Cytological investigations carried out on a population basis in Astragalus chlorostachys Lindl. which exists at diploid level (n=8) revealed the presence of quadrivalents, the late disjunction of 1–4 bivalents and some pollen sterility (34%) in 1 accession collected from Koksar, at 3,140 m in the Lahaul Valley (Lahaul-Spiti, Himachal Pradesh). The presence of quadrivalents in this diploid species seems to be a consequence of reciprocal translocations. The occurrence of structural heterozygosity in the species has been reported here for the first time. All of the other populations showed normal bivalent formation and regular sporad generation and 100% pollen fertility. The paper here discusses in detail the course of meiosis and the effect of multivalent formation and non-synchronous disjunction of bivalents on meiotic course and pollen fertility. Astragalus chlorostachys Lindl., known variously as Astragalus altissimus Rech. f., Astragalus nuristanicus Kitam. and Hedysarum strobiliferum Baker, belongs to the tribe Galegeae of the family Fabaceae. It is a tall woody herb with sparsely pubescent stems. Leaves are imparipinnately compound and with leaflets oblong, obtuse and glabrescent. Yellowish-white flowers are produced in axillary, peduncled racemes. The species is native to Afghanistan, Bhutan, India, Nepal and Pakistan. In India it grows in moist shady places between altitudes of 2,000–3,600 m in the states of Assam, Himachal Pradesh, Jammu-Kashmir, Sikkim and Uttarakhand (Chowdhery and Wadhwa 1984, Naithani 1984, Sharma and Jamwal 1988, Wenninger 1991, Sanjappa 1992). Local people in the Kumaon Himalayas use a whole plant infusion as a tonic and febrifuge; decoction of the root is given in tuberculosis (Trivedi 2006). During cytomorphological surveys of the species in various cold regions of the Northwest Himalayas, the authors have detected 1 population which displayed the presence of multivalents, late disjunction of some bivalents and some pollen sterility. All of the other populations showed normal bivalent formation and regular sporad generation and 100% pollen fertility. In this paper, the aim was to study in detail the male meiotic course and to investigate the effect of multivalent formation and non-synchronous disjunction of bivalents on meiotic course and pollen fertility. Materials and methods Materials for male meiotic studies were collected from the different localities falling in the