Análise citogenética em espécies de solanaceae: Investigando o número cromossômico e heterocromatina

Abstract

Among the Angiosperms, Solanaceae is one of the largest families. Composed of approximately 2,800 species distributed in more than 98 genera. Due to their diversity of use in food, solanaceous plants are also economically important. Species of Solanaceae generally present the basic chromosome number ranging from x = 7 to x = 13, other records of basic numbers are also presented x = 17, 19 and 23. However, the basic number x = 12 and the diploid chromosome number 2n = 24 are more frequent in the family. The objective of this work was (1) to determine the chromosome number and (2) to characterize the distribution patterns of constitutive heterochromatin rich in GC and AT in Solanaceae species, through double staining with CMA/DAPI. The species of the genera Athenaea, Brunfelsia, Capsicum and Solanum analyzed in this study presented chromosome number 2n = 24. Solanum hexandrum, 2n = 48, was the only polyploid species observed. Two main types of bands were identified through chromosomal banding with CMA/DAPI fluorochromes: CMA+ /DAPI bands and DAPI+ /CMA bands, rich in GC and AT, respectively. In all analyzed species, the predominance of CMA+ terminal bands was noted, varying only in number and shape, and could occur both as heterochromatic and punctiform blocks. Some species showed small terminal bands on both arms of all chromosomes. Possibly, this telomeric heterochromatin is present in all species, but sometimes it can go unnoticed due to the reduced size of the bands. Terminal punctiform CMA+ bands are common in the genus Solanum, suggesting that sharing this characteristic may represent an ancestral state in the genus, that is, a result of co-evolution.