Secondary associations in ‘Himalayan pink’ (Dianthus angulatus Royle ex Benth., Caryophyllaceae) from cold deserts of Lahaul-Spiti

Abstract

In current investigation we studied the male meiosis and details of secondary chromosomal associations or pairing recorded for the first time in Dianthus angulatus Royle ex Benth., from the cold deserts of Lahaul-Spiti (Himachal Pradesh, India). All the presently studied individuals of the species existed at 2x level (x = 15). The present chromosome count of n = 15 in the species is in conformity with the previous counts from India and outside of India. Secondary associations are defined as the affinity of bivalents to be positioned in pairs having gentle connections. The secondary chromosomal associations in the species existed among bivalents/chromosomes were observed in the meiocytes at metaphase-I and continued till the metaphase-II. The bivalents positioned side by side and end to end to form secondary pairing. The difference in the number of bivalents/chromosomes involved in the secondary associations has also been witnessed. A secondary association between bivalents is considered to be of immense importance as it is being taken as a gauge of ploidy in plants. The incidence of such secondary associations of bivalents/chromosomes in D. angulatus which existed at 2x level indicated the secondary polyploid nature of the species.

Milium effusum (Poaceae: Poeae: Miliinae): species of systematic and cytological interest with notes on polymorphic nature and cytogeography

“…The formation of distal interbivalent connections bet ween 2-5 bivalents in 1-5 groups in diakinesis meiocytes seen as loose connections between homoeologs bivalents re sulted due to fusion of heterochromatic regions (Thomas &Revell1946,Bennett&Thomas1991).Duringlatermeio tic stages these structures get demolished through directed restriction to paring by diploidizing genes (Jenkins & Rees 1991).Chromatinstickinessandnonsynchronousdis junc tion in meiocytes depicts some sort of associated ge no mic changes with spindle apparatus (Kumar & Singhal 2013, Kumar et al 2017. Chiasma frequency values in meio cytes of analyzed plants depicted variation over pairing to chromosomes having chiasma per bivalent 1.28-1.31 (Table 1).…”