Microsporogenesis in Somaclones of Cereusperuvianus Mill. (Cactaceae)

摘要

Current study investigates the microsporogenesis in three somaclones of Cereus peruvianus since information on the meiotic characteristics of somaclones is important to indicate somaclones and/or their descendents for the species's genetic breeding programs. Whereas meiotic irregularities were recorded in the two meiotic divisions, in pachytene, small asynaptic regions were observed in some bivalents. One terminal chiasma predominated in bivalents in diakinesis and one to three pairs of univalent were recorded in this phase. Precocious chromosome migration to the poles, laggards and micronuclei were also observed, mainly in the first division. Partial or total chromosome transfer between microsporocytes (cytomixis) was recorded in the first division. Two types of spindle arrangement were observed in the second division, generating isobilateral and tetrahedral tetrads. Since abnormalities recorded in the S3, S9 and S71 somaclones were also detected in control, pollen of somaclones or progenies of somaclones may contribute towards the broadening of the species's genetic basis.