UTILIZATION OF MORPHOLOGICAL AND MOLECULAR MARKERS TO STUDY COLOUR DETERIORATION OF THE COTTON GIZA 70 IN THE COMMERCIAL SCALE

Abstract

Gene frequencies and genotypes frequencies are constant from generation to generation in the absence of migration, mutation and selection in a large random mating population. Although, Egyptian cotton programme depends on elaborate maintenance system but some varieties have shown some changes in their homogeneity or uniformity of some traits such as lint colour, lint quality and seed characters (Naked and Fuzzy). Traditionally, breeder’s seed companies and certification agencies determine genetic purity using physical traits expressed by the seed, seedling and mature plant. Recently, continuing advancements in molecular biology techniques provide even greater promise for enhancing the sensitivity of genetic purity determinations (McDonald, 1998). Very scent studies were conducted to determined genetic changes Abdel-Bary and Bisher (1969) and Lewis (1970) reported that the main causes of genetic changes of a variety were due to mechanical mixing, outcrossing and mutations. El-Kilany and Youssef (1985) found that lint characteristics started to degenerate in the fifth year of the general use of cotton varieties. Al-Didi (1984) suggested that the various degrees of brown colour existed in the Egyptian cotton variety “Giza 70” was probably raised from either the accumulation of some plus modifiers or as a result of segregation of some minor and major genes. El-Okkia et al. (1990) pointed out that the brown lint off type, isolated from the cultivar Giza 70 showed lower lint percent and having shorter, coarser and weaker lint. Tatinei et al. (1996) examined the genetic diversity of 16 near-homozygous elite cotton genotypes derived from interspecific hybridization using RAPD procedure and their morphological characters performances. Iqbal et al. (1997) investigated varieties belonging to G. hirsutum L. and to G. arboretum L., using RAPD analysis. Cluster analysis by unweight pair group method of arithmetic means (UPGMA) showed that seventeen genotypes were placed in two-groups with similarity coefficient ranging from 81% to 93%. Therefore, the present investigation was aimed to study the genetic relationships between some off types in the Egyptian cotton variety Giza 70 using some markers i.e. morphological and molecular marker (RAPD).