Understanding the role of DNA polymerase λ gene in different growth and developmental stages of Oryza sativa L. indica rice cultivars

DNA polymerase lambda (Pol lambda) is the only member of DNA polymerase family X present in plants. The enzyme is ddNTP sensitive as it contains the conserved C-terminal Pol domain. The 1.1 kb partial coding sequence isolated spanned the whole 3' regions of the gene containing functionally important domains of the Pol lambda gene. Comparative in silico studies from both indica and japonica cultivars involving homology modelling showed that the model for the partial Pol A gene was stable and acceptable. The alignment of both the protein models showed a RMS value of 0.783. Apart from this, expression of Pol lambda and its relative activity is studied during different development stages of three different indica rice cultivars (IR29, Nonabokra and N22). Enhanced accumulation and higher activity of Pol lambda during the early seedling stage was detected. Higher expression and activity were observed in the anthers, which was probably necessary for DNA repair during microspore formation. However, during the maturation stage of seed development and plant growth, expression and the activity of Pol lambda decreased due to slow metabolic activity and a reduced rate of cell division respectively. Furthermore, the expression and activity of Pol lambda were found to be higher in IR29 in comparison to Nonabokra and N22. IR29 is a rice cultivar susceptible to environmental stresses and hence it encounters higher DNA damages. The enhanced presence and activity of the Pol lambda enzyme in IR29 with respect to the other two cultivars, which are more tolerant to the environmental stresses during various developmental stages, is therefore explainable. (C) 2017 Elsevier Masson SAS. All rights reserved.