Chromosome behaviour and pollen analysis in anthurium sp

Abstract

Chromose behaviour and pollen characters had been studied in five commercially important varieties of Anthurium andreanum viz. Honeymoon Red, White (album), Lady Jane (Pink), Chillired and Pink. Some morphological characters were also recorded. The varieties show distinct differences in morphological characters. They can be identified from one another even in the absence of their typical spadices. All the varieties have a somatic chromosome number of 30+2B. The basic chromosome number is x=15. Two B chromosomes are present irrespective of the varietal type. The B chromosomes are either acentric or telocentric and round or rod shaped. Their size is always smaller than the smallest A chromosome. The karyotype of all the five varieties was analysed. On the basis of total chromosome length (TCL), average chromosome length (ACL) and arm ratio (r), the variety Pink appears to be most advanced. When the relative chromosome length (RCL) was taken in to consideration, the variety Chillired is found to be most advanced. With regard to the character, chromosome asymmetry, Lady Jane appears to be most advanced. When the karyotype asymmetry as a whole is considered, all the varieties are falling in the '3B' category which represents a high position in evolution. During meiosis, all the varieties exhibited a wide range of abnormalities like univalent formation, unequal seperation, presence of laggards, micronuclei etc. This point out the hybrid nature of the species. All the varieties are found to be protogynous with distinct interphase. This is an adaptation for natural cross pollination. However, natural crossing is occuring only to a limited extent. The pollen production capacity of the varieties varies significantly. The varieties Honeymoon Red and Pink produce the highest amount of pollen. All the varieties have round pollen with a single germ pore. The pollen size among the varieties does not vary significantly. However, the variety Lady Jane has the largest pollen. Pollen fertility is very low, when it was tested by acetocarmine staining and in vitro pollen germination methods. The latter is found to be more reliable in estimating the pollen fertility. All the varieties have paracytic type of stomata. But the varieties vary widely in their size and distribution. Morphological variations, karyotypic differences, meiotic abnormalities, high pollen sterility and the wide variability in stomatal characters point out the basic hybrid nature of the species.