Molecular characterization of shisham dieback-associated fungal isolates across the Punjab Province, Pakistan

Abstract

The Shisham (Dalbergia sissoo) population is threatened by the fungal pathogens causing dieback disease.
Research over the past decade has shown the involvement of multiple fungal pathogens in causing the dieback
disease. Here we reported the RAPD-PCR-based genetic diversity in three potential fungal pathogens including
Botrydiplodia theobromae, Fusarium solani, and F. oxysporum isolated from diseased plants across the Punjab
province in Pakistan. Twenty fungal isolates of three major fungal species were isolated from dieback-infected
trees from eight districts in Punjab Pakistan to investigate the genetic diversity with a set of fifteen RAPD markers
of OPB, OPK, and OPL series. Consequently, fifteen markers produced 166 loci with an average of 55.33 loci
per population. Of these, 76.31% loci were polymorphic highlighting the presence of abundant genetic diversity
in pathogens. Moreover, OPK-06 primer showed a higher PIC value of 0.416 along with higher heterozygosity
contents of 0.49. However, population structure analysis of each fungal strain grouped similar and dissimilar ones
based on their amplification into the same and different clusters respectively. The isolates of B. theobromae of the
Ayub Agriculture Research Institute (AARI) and Attock district showed higher genetic distance (0.6812) and were
found in different clusters. Similarly, isolates of F. solani from UAF formed a different group which further
highlighted its degree of polymorphism. Moreover, the UAF isolate displayed a maximum of 0.6432 genetic
distance from the AARI isolate. Conversely, the isolates of F. oxysporum were grouped into two main groups
highlighting the limited genetic diversity. Further, isolates from UAF also exhibited a maximum of 0.7372 genetic
distance from AARI. Consistent results of UAF and AARI isolates of F. oxysporum and F. solani are suitable
grounds for further genetic studies.