KIYOTA, E.

KOCH, K. E.

SOUSA, S. M. de

YUNES, J. A.

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P48Maize aldose reductase: A role in sugar-handling?(submitted by Sylvia Morais de Sousa <smsousa(à),cnpms.embrapa.br»Full Author List: de Sousa, Sylvia M1 23; Kiyota, Eduardo"; Yunes, Jose A3 4; Koch, Karen E2I Embrapa Maize and Sorghum, Sete Lagoas, MG, Brazil, 35701-970.2 Department ofHorticultural Sciences, University ofFlorida, Gainesville, FL, USA, 32611-0690.3 Genetics.and Molecular Biology Program, Biology Institute, State University ofCampinas, Campinas, SP, Brazil,13083 - 970.4 Molecular Biology Laboratory, Boldrini Children's Cente., Campinas, SP, Brazil, 13083-210.Our initial interest in aidose reductase (AR) rose from its possible role in sorbitol metabolism by maize kemels.This is the only known enzyme in maize, other than sorbitol dehydrogenase, with capacity to synthesize or usethe sorbitol so prominent in developing kemels. The reaction is reversible(sorbitoI+NADP<=>glucose+NADP[H]) and could allow sorbitol use by embryos. However, ARs can catalyzediverse reactions and may have multiple roles in sugar- and redox-handling. Aldo-keto reductases (AKRs) arewidely distributed in nature and play numerous roles in metabolismo In this study, we present eight maizeputative AKRs and characterize one ofthem, AKR4CI3, due to its embryo specificity. To analyze in detail theexpression of maize AKRs at the protein leveI we raised polyclonal antisera against the recombinant maize ARand used it in westem blot assays. We also designed specific primers for each of the eight putative maize ARs toanalyze their gene expression in different tissues and development times ..The analysis of different maize tissuesshowed reaction with several polypeptides. The amount of each polypeptide also appeared to vary among tissues,consistent with potentially different roles for the AR-like polypeptides. Data on westem blots were consistentwith predicted molecular weights ofthe AR family members as well as their expression patterns. The AKR4CI3was embryo-specific, with a MW of 35,659 Da and was temporally correlated with seed maturation. Analysis ofthe recombinant AKR4C 13 enzyme indicated that, in addition to DL-glyceraldehyde, reactions favored use ofNADPH to reduce pentoses, but not D-glucose. Maize AKR4CI3 was also able to oxidize sorbitol in thepresence ofNADP. One possibility is that the maize sorbitol pathway, and AR in vivo, has similarities to roles inhurnans, where their primary effect is that of balancing sugar pools and redox levels under high-sugar conditions.Funding acknowledgement: United States Department of Agriculture (USDA), Conselho Nacional deDesenvolvimento Científico e Tecnógico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de NívelSuperior (CAPES)P49Monitoring Ds Transposition in Soybean Genome(submitted by Manmeet Singh <manmeet.agri@2gmai1.com»Full Author List: Singh, Manmeet': Nguyen, Hanhl; Bihmidine, Saadia'; Sato, Shirley'; Razvi, Fareha'; Shaver, Scott';Clemente, ThomaslIUniversity ofNebraska, 1901 Vine Street, N322, Lincoln, NE - 68588The maize two-component transposon system Ac/Ds has been used in many plant speeies as a means to generateinsertional and activation tagged mutants. The long-term goal ofthis program is to develop a repository oftransgenic soybean events harboring mapped Ds elements positioned approximately every eM, thereby creating acollection of Ds soybean events that will have utility for local mutagenesis. The usefulness of the system will beinfluenced by the ability of Ds to transpose when stacked with Ac. To investigate the transposition of Ds in thesoybean genome we seleeted a set of five soybean events harboring gene or enhancer trap elements delineated byDs termini. These events carry either one or two transgenic loci. To induce transposition we stacked therespective Ds events with an Ac cassette under control of either the constitutive 35S CaMV promoter or thereported meiosis specific promoter, DMCI, from Arabidopsis and generated 351 crosses. We found somatietranspositions in 144 FI plants and 14 germinal transpositions in the progeny of 23 FI plants analyzed so far.One specific transposition has a Ds delineated enhancer trap element re-inserted into the third intron of the ligandgated potassium ion channel (glyma 06g081I O). In addition we have generated 461 events carrying an activationtag construct delineated by Ds termini and crossed selected events with the Ac carrying events to generateanother 121 crosses. The data gathered from this study will allow us to test the influence ofboth levei, and tissuespecificity of Ac expression on transposition of Ds in the soybean genome.Funding acknowledgement: National Science Foundation (NSF), United States Department of Agriculture(USDA), United Soybean Board70

Maize aldose reductase: a role in sugar-handling?

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