Characterization and genetic relatedness among 37 yardlong bean and cowpea accessions based on morphological characters and RAPD analysis

Abstract

Twenty four yardlong bean and 13 cowpea accessions were planted in the field to characterize their morphology and genetic relatedness. A randomized complete block design (RCBD) with two replicationswas used. Growth habit, days to flowering, pod color, pod length, number of pods/plant, yield/plant and consumption quality were recorded. The results showed that pod length, number of pods/plant and podyield/plant among 37 accessions were highly significant differerence. Mean pod yield and pod length of 24 yardlong bean accessions were 212.1 g/plant and 48.7 cm, respectively, while mean pod yield and pod lengthof 13 cowpea accessions were 117.4 g/plant and 21.3 cm, respectively. Twenty two yardlong bean accessions exhibited indeterminate growth habit while 10 of 13 cowpea had determinate growth habit and the restsexhibited semi-determinate growth. Genetic variation and relationships among accessions were investigated based on RAPD technique. Total DNA was extracted from young leaf samples of all accessions using CTAB buffer. One hundred and twenty decamer oligonucleotide primers were screened and 5 primers (OPC-06,OPR-12, OPZ-03, OPZ-08, OPZ-13) were chosen for further evaluation. A dendrogram of genetic similarity was constructed based on 23 polymorphic bands obtained from 5 primers using UPGMA in SPSS program,which revealed separate groups between yardlong bean and cowpea. The similarity coefficient among yardlong bean and cowpea accessions ranged from 0.515 to 1.000 and 0.548 to 1.000, respectively.

Keywords

• yardlong bean
• cowpea
• genetic polymorphism
• RAPD