|Grusak, Michael - Mike|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2002
Publication Date: 7/15/2002
Citation: GRUSAK, M.A., IBRIKCI, H., KNEWTSON, S.J. QUANTITATIVE TRAIT LOCI ASSOCIATED WITH ENHANCED ROOT FE(III) REDUCTASE CAPACITY IN CHICKPEA. ABSTRACTS OF THE XI INTERNATIONAL SYMPOSIUM ON IRON NUTRITION AND INTERACTIONS IN PLANTS. 2002. p. 150. Interpretive Summary:
Technical Abstract: Chickpea is an important legume that serves as a predominant source of protein in various parts of the world. As with many food crops, chickpea can demonstrate chlorosis and impaired growth when iron is limiting in the soil. Until now, very little has been published on the root iron acquisition processes in chickpea, or on the genetic diversity of Fe-deficiency responses in this legume. Therefore, we have evaluated root Fe(III) reductase capacity in several genetically diverse lines of chickpea, in order to provide relevant knowledge in support of chickpea improvement programs, and to ultimately identify novel molecular components related to Fe-efficiency. Root Fe(III) reductase activity was measured using whole root systems excised from hydroponically grown plants. Colorimetric assays using Fe(III)EDTA and BPDS were conducted with plants up to 3 weeks of age. Several lines of common chickpea (Cicer arietinum), as well as the closely related species, Cicer reticulatum, were used in the study. Additionally, we investigated a population of individual Recombinant Inbred Lines (RILs) derived from an interspecific cross between C. arietinum and C. reticulatum. Almost all lines showed some level of enhanced reductase activity when challenged with Fe deficient conditions. For most lines, root activity was higher when plants were provided minimal Fe (0.5 uM), rather than no Fe. Reductase activities in the parental lines ranged from 0.07 to 0.59 umol Fe reduced/g FW hr when plants were grown at 0.5 uM Fe(III)EDDHA, and from 0.05 to 0.23 umol Fe reduced/g FW hr when grown with 15 uM Fe(III)EDDHA. Based on the diversity of parental responses, a unique population of RILs was chosen for further in-depth analysis. Root reductase activities at 0.5 uM growth varied 2.2-fold in the parent lines, being 0.19 and 0.42 umol Fe reduced/g FW hr, yet demonstrated a 30-fold range amongst the RILs (0.05 to 1.5 umol Fe reduced/g FW hr). Note that individual RILs exhibited reductase capacities both below, and above, the parent lines. Root reductase activities at 15 uM growth were 0.07 umol Fe reduced/g FW hr in both parents, and also demonstrated a 30-fold range amongst the RILs (0.013 to 0.39 umol Fe reduced/g FW hr). We are currently using the reductase data to identify quantitative trait loci (QTLs) with relevance to enhanced root reductase capacity; these results will be presented at the meeting, along with a discussion of their applicability in breeding programs. We also will discuss our long term plans to use the QTLs as a starting point for gene discovery in the model legume Medicago truncatula.