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The Scientific World Journal
Volume 2012, Article ID 691545, 9 pages
http://dx.doi.org/10.1100/2012/691545
Research Article

Erratic Male Meiosis Resulting in 2𝑛 Pollen Grain Formation in a 4x Cytotype (2𝑛=28) of Ranunculus laetus Wall. ex Royle

Department of Botany, Punjabi University, Patiala 147 002, Punjab, India

Received 13 October 2011; Accepted 7 December 2011

Academic Editors: A. Kulharya and B. Vyskot

Copyright © 2012 Puneet Kumar and Vijay Kumar Singhal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Two accessions were studied for male meiosis in Ranunculus laetus from the cold regions of Northwest Himalayas. One accession showed the presence of 14 bivalents at diakinesis and regular segregation of bivalents at anaphase I which lead to normal tetrad formation with four 𝑛 microspores and consequently 𝑛 pollen grains and 100% pollen fertility. Second accession from the same locality revealed the erratic meiosis characterized by the presence of all the 28 chromosomes as univalents in meiocytes at metaphase I. Univalent chromosomes failed to segregate during anaphases and produced restitution nuclei at meiosis I and II. These restitution nuclei resulted into dyads and triads which subsequently produced two types of apparently fertile pollen grains. On the basis of size, the two types of pollen grains were categorized as 𝑛 (normal reduced) and 2𝑛 (unreduced, 1.5-times larger than the 𝑛 pollen grains). The estimated frequency of 2𝑛 pollen grains from dyads and triads (61.59%) was almost the same as that of the observed one (59.90%), which indicated that 2𝑛 pollen grains in R. laetus were the result of dyads and triads. The present paper herein may provide an insight into the mechanisms of the formation of various intraspecific polyploids through sexual polyploidization in R. laetus.