Biochemical Changes: Their Potential Role against Fungal Disease Resistance Development in Mustard

Rape-seed mustard is an imperative edible oilseed crop which is adversely affected by different biotic stresses causing import of edible oils from abroad. The experiment was carried out for screening mustard genotypes based on disease indexing and putative role of diverse biochemical parameters in development of resistant against three major fungal diseases. A modified 0-9 scale was used for rating of disease indicators to calculate disease incident (DI). In disease indexing, mustard genotypes L-4, GSC-7 and PC-6 were considered as immune against Alternaria brassicae, Maya, L-4, China, GSL-1, GSC-7, PC-5, PC-6 and RP-9 were classified as immune against Albugo candida while L-4 and PC-5 were found immune against Erysiphe cruciferarum. The study of biochemical constituents demonstrated that these immune genotypes accumulated higher osmolytes content including free proline content and total phenol under diseased condition showing their tolerance ability against these pathogens. The tolerant genotypes also had lesser lipid peroxidation rate as indicated by malondialdehyde content analysis to induce lesser effect on total chlorophyll, amino acids, proteins and soluble sugars including reducing and non-reducing sugars. These identified genotypes have wider scope for further phyto-pathological studies and utilization in development of fungal resistance breeding.