Cytological elucidation of somaclonal variation in grasspea (Lathyrus sativus L.)

Abstract

Three mutagenised populations each of gamma rays, sodium azide (SA) and ethyl methane sulphonate (EMS) showed local was carried out for elucidation of the origin of tissue culture instability and somaclonal variation. Wide range of euploids, aneuploids and structural variations of chromosomes including stickiness, multipolar spindle, asymmetric chromatid separation, binucleate cells with micronuclei and chromosome bridges and fragments could be the cause for tissue culture instability. Frequency of chromosomal anomalies in calli increased with the age of subculrure and the increase was more in B5 medium supplemented with 2, 4-D than NAA. Majority of the abnormalities happens to be sieved off owing to morphogenetic selectivity. While, a few of these were carried on to regenerants as evidenced from mitotic (euploid, aneuploid and structural variation) and meiotic (interchanges and/or loss of chromosome segments following breakage events, lack of pairing resulting univalents, precocious and late separation of bivalents, anaphase laggards, conspicuous anaphase bridges with or without acentric fragments, chromosome rings, tetrad with multinucleoli) abnormalities in regenerants. Such carryover events have been substantiated as the origin of somaclonal variation in regenerants.