PEAR (PYRUS)-. GENETIC DIVERSITY AND THEIR CONSERVATION

摘要

Pears (Pyrus spp.) are widely available as wild,cultivated genotypes in northern Pakistan and possess significant economic importance related to food,medicine and in breeding programs.For its differentiation and conservation,28 RAPD markers were applied on 36 pear genotypes.As a result,304 loci were amplified,fragment size ranges from 1502600 bp.The average bands per primer were 10.85 and showed high degree of polymorphism (100%).The PIC value,GD and allelic frequency range from 0.29-0.97,0.33-0.97 and 0.02-83,respectively.Among 28 RAPD markers,14 are genotype specific and produced 35 different size bands ranged from 150-2100 bp.Out of 14 genotype specific markers,8 are specific to six different genotypes with 1-2 loci 1.e primers A-11,C-09,G-07,F-17,I-16,J-20,L-08 and E-10 are specific to genotypes,Mt,Mamosay-B15,Mamosranga,Mt,Nkb,Sm,and Nashpati,respectively while other primers are specific to more than a single genotype with multiple loci.Based on the reproducible bands,UPGMA has developed phylogenetic tree and segregated 36 Pyrus genotypes into six major clusters (I-VI) based on similarity (62100%).Moreover,STRUCTURE HARVESTER has also segregated 36 Pyrus genotypes into six groups and genotype 4,27,28,29 and 31 showed highest genetic diversity.Further,most of the pears genotypes are facing serious threats due to over exploitation,habitat loss and environmental changes which seriously affect breeding programs in the future.Therefore,both ex-situ and in-situ conservation of pears and its wild relatives are needed.