Characterization of Pigeonpea Genotypes for Waterlogging Tolerance Based on Morpho-physiological and Molecular Traits

Aim: To screen and characterize pigeonpea genotypes using morpho-physiological, biochemical and molecular traits.

Study Design: The field trial was conducted using the Randomized Block Design (RBD) while Completely Randomized Design was used for laboratory and pot screening experiments.

Place and Duration of Study: The research trial was conducted at Laboratory and Pulse Research Farm, Model Bhitti, BAU, Sabour, which lies between 25°15’40” N latitude to 87°2’42” E longitude and 46 meters above sea level. Study was undertaken between July, 2018 to March, 2019.

Methodology: Sixty pigeonpea genotypes were screened for submergence tolerance at seed stage in the laboratory. Based on results of laboratory screening, 40 genotypes with sufficient genotypic variability for waterlogging tolerance were further taken for seedling stage screening at field, finally 20 genotypes were taken to pots for waterlogging tolerance evaluation and characterization on the basis of morpho-physiological, biochemical and molecular traits. According to pot results, six contrasting genotypes were considered for RAPD primers amplification.

Results: The three levels of sieving of genotypes fetched results directing the opportunity of particular genotypes to be sown inlow land areas. Character like seed colour varied from brown, dark brown to black, which showed significant relationship with level of tolerance. Significant (p=0.01) higher germination with less reduction due to waterlogging stress was observed in genotypes such as ICP-11809, ICPL-20098, NDA-1 and ICP-5028. Maximum survival percent was found in ICP-5028 (62.28%) while least survival percent was observed in ICP-7035 (10.98%). At the field stage, genotypes such as ICP-5028, ICPL-990985, ICPL-20238 were best performing genotypes. SPAD Chlorophyll Content results exhibited significant reduction among the susceptible genotypes. However, there was least reduction among tolerant genotypes such as LRG-30, Mal-9, Pusa-992 and ICP-5028.Genotypes namely: Manak, Pusa-991 and Pusa-992 faced hastened senescence under waterlogging condition as compared to ICP-5028, Mal-15, Mal-9, LRG-30. Molecular evaluation results of six genotypes chosen across screening showed that ICP-7035 and Manak were clubed together in one cluster. Nevertheless, ICP-5028 and Mal-9 were grouped in another cluster of Dendrogram, constructed using Jaccard similarity coefficient. In the present investigation two unique amplicons were amplified by primers OPA-13 and OPC-01. OPA-13 amplified unique band was linked with susceptible genotypes of size ~1240 bp while the unique amplicon given by OPC-01 was of ~980 bp size linked with tolerant genotypes.

Conclusion: Available waterlogging tolerance in pigeonpea gene pool to some extent can provide source for breeding waterlogging tolerant cultivars. Physiological and genetic approach involving efficient screening techniques and evaluation of breeding material/lines under targeted environment for the traits linked to tolerance is likely to lead to the identification of specific component traits and high yielding varieties with improved stress tolerance.