Analysis of genetic diversity in oilseed brassica germplasm through ISSR markers and isozyme profiling

Eleven Brassica germplasm were characterized through the application of 12 oligonucleotide Inter Simple Sequence Repeat (ISSR) primers. A total 1248 bands were amplified through polymorphic chain reaction and were visualized by agarose gel electrophoresis. Among the amplified marker bands 71.47% were polymorphic in nature and 352 bands were found to be monomorphic. The polymorphic bands of the amplified DNAs mostly ranged between 110 bp and 3 kb. Genetic distance among the germplasm ranged between 0.0468 and 0.7189. Moreover, three isozyme systems such as esterase, acid phosphatase and peroxidase were analyzed for allozyme variability that detected distinct 93 isozyme loci of which nearly 61.9% were polymorphic. Two dendrograms were constructed based on the ISSR profiling and isozyme data obtained through electrophoresis to find out the relatedness and phylogenetic relationship among the investigating Brassica germplasm. The clusters of the phylogenetic tree revealed 4 distinct groups of Brassica based upon their ISSR banding patterns and isozyme analysis. Nei’s genetic distance analysis provided strong information about the existence of variability among the germplasm of Brassica. All the germplasm was found to be clustered according to their respective species. Brassica carinata (Ethiopian mustard) showed individuality from all the germplasm studied and made a different branch in the phylogenetic tree suggesting its diverse origin. From the clustering pattern and genetic relationship obtained with ISSR markers and isozyme analysis, breeders can successfully identify the diverse germplasm from different cluster and use them in their future breeding program. Introduction Brassica is one of the major crop genera in the family Brassicaceae (syn. Cruciferae). The genus is remarkable for containing a large number of important vegetables to oilseed and condiment crops than any other genus. Brassica is the second largest oilseed crop after soybean in the world (Raymer 2002, FAO 2010). Brassica oil contains many monoand polyunsaturated fatty acids and a few harmful saturated fatty acids which make it nutritionally superior to most other edible oils (Agnihotri et al. 2007). Oilseed Brassica collectively contribute about 15% of the world’s total supply of vegetable oils and became the third-leading source of edible oil in the world after soybean and palm (McVetty et al. 2016). Indian mustard (Brassica juncea L.), rapeseed (Brassica campestris L. syn Brassica rapa L.), Brassica napus L. are important oil yielding crops in Bangladesh. Bangladesh Agricultural Research Institute (BARI) and Bangladesh Institute of Nuclear Agriculture (BINA) have already developed several varieties of Brassica in Bangladesh using efficient breeding techniques. But there are some problems associated with this crop such as unsynchronized maturity, pest and disease invasions, effect of abiotic stress like salinity and drought, etc. It may be pointed here that Brassica carinata constitutes an interesting alternative to diesel fuel in less-favored regions of the world (Dorado et al. 2004). It has been introduced into and field-tested for biofuel production in Canada (Marillia et al. 2014), India *Author for correspondence: <rhsarker2000@yahoo.co.uk>. Department of Botany, Jagannath University, Dhaka-1100, Bangladesh.