Aftab Hussain, I.S.NISARGA, K.N.2020-10-052020-10-052018-12-24https://krishikosh.egranth.ac.in/handle/1/5810152344Iron is an indispensable plant micronutrient and its deficiency severely impairs crop growth. Although iron is abundant in soil, it is not readily available to plants due its low solubility, especially under high pH condition. In crops, like rice even aerobic soil conditions affects iron acquisition and further accentuated with increase in soil pH. However, genotypes differ in iron acquisition under these conditions. In view of this, the emphasis is to identify rice accessions differing in iron acquisition and aim is to characterize and identify the relevant mechanisms associated with iron acquisition. Among 200 genotypes grown under aerobic condition, few contrasting lines were identified varying in shoot and grain iron content. These selected genotypes showed considerable variation in shoot and grain Fe content under aerobic condition. Further, characterisation of selected rice genotypes showed reduced root, shoot and active iron content under high pH condition. The tolerant genotypes JBT37/128 and PS-369 showed higher chlorophyll content, root and shoot iron content, translocation index, Ferric chelate reductase activity and phytosiderophore release at high pH condition compared to relatively susceptible genotypes like CTH-1 and JBT-3/60. In JBT37/128 and CTH-1 genotypes under iron deficiency conditions we have examined the expression profile of reported iron deficiency responsive genes (OsIRO2, OsIRT1, OsNAS1, OsTOM1, OsNRAMP1, OsYSL15) and 10 putative Fe deficiency responsive genes, shown to be expressed in microarray analysis of other studies. JBT37/128 showed higher expression level compared to CTH-1. The differential expression could also be due to altered expression of microRNA’s regulating these genes. In CTH-1 the expression of microRNA’s (Osa-miR531b, miR1848 and miR2104) was high and target genes was low. The differentially expressed genes in tolerant type could be potential candidate genes to improve iron acquisition in rice under iron deficiency condition.EnglishThesis