American Society of Plant Physiologists
F
N
PROG
BALTIMORE, MARYLAND USA
Saturday, July 24 through Wednesday, July 28, 1999
Pos ter Sess io ns (Pi) in the cytosol con trols many me tabolic pathways within a plant W ore a constant level (homoeos tasis) must be maintai.ned in this .e nt, tha t is not affected by phosphate nutrition . The homoeostasis oJ Pi is maintained by either mobilization of vacuolar Pi or by carbon ..m , e.g. when sucrose is synthesized, four molecules Pi are released ~"synthe tic intermediates. The vacuole serves as a s tore for Pi, and its dependent on the nutrition conditions. To date it is not w1derstood dis tribution of Pi throughout the plant and within the indiv idual ce ll 'd. Transgenic plants can be llsed to study regul ation processes and ~r insights into ph osphate metabolism. By ex pression of ba cterial diHeren·t subcellula r co mpartments we produ ced novel p hosphate olecu les, that are normally not present in plants. These new phosph a te used to manipul ate the vario us Pi pools within the cells and thereby he utilization effici ency lor p hosphate in pla nts. The polyphosphate l'il1g gene polyphosphate kinase (PPK) fro m E. coli was introduced in .nl a nd plas tid s of potato plants. Although tuber yield was increased in pressing potato plants unde r phosphate deficient conditions, only the 'TI}'la te content w as increased significantly jn correlat ion to the tuber .ato p la nts with plastidic loca liz.a tion of the PPK were reduced in shoot \' root growth, which made it impossible to grow these p lants in soil.
lecular Plant Pathology Laboratory, USOA-AR S Presenter: Andrianov, Vy ach eslav
[email protected] .gov Vege ta tively propagated Gladiolus crops are constantly threa tened by the desease ea used by cucumber mosaic virus (CMV) infection. Beca use the method of propagation is amendable to spread of the virus from genera tion to genera tion, the in troduction of CMV resistance into important valu able cultivars is highly d esirable. Comme rcial eultivars of Gladiolus w ere transform ed with plasmid co nstructs for expression of subgroup 1 coat protein (CP-l ), s ubgroup 2 coa l protein (CP-2), and defective s ubgroup 1 repli case genes eitl, er al one or in combination to achieve CMV resistance. Stable transformation of Gladiolus using particle gun bombardmen t of s uspensi on cells w as previo usly rep orted (Kamo e t.al. 1995, j. Amer. Soc. Hort. Sci. 120, 347-352). Plant cells w ere cotransformed with the phosphinotricin acetyltransfe rase gene and selected on e ither 1 or 2 mg / l for cu lti va r Pe ter Pea rs, and eithe r 3 or 6 mg/ l bialaphos lor jenny Lee. Transgenjc plants w e re then regenera ted from microcalli, and trans genes were d etected usin g PCR analysis of th eir genomic DNA. Independen tly transformed lines have been established lor each plasmid combination and confirmed by Southern hybridiza tion. Analysis of express ion 01 transgenes and cha llenging 01 transgenic plan ts with CMV are in prog ress .
369 Session 41, Transgenics and Biotechnology ''lnding and influencing starch synthesis. Kossmann, jens Lloyd, Scheidig, Andreas Ma x-Planck-/llstitute of Molecu lar Plant Physiology uetze, Volker Ri esrneier, jocrg W. Plauttec Biotechnology Ltd. l~ , Lothar Presenter: Kossmann, jens kossmann@mpimp ;. de constitutes most of the dry matter acc umulating in the harvested f crop plants and is, therefore, not only the prima ry source 01 ca lories man di et, but it can also be regarded as renewable resource which is m many industria l a pp lications. The am ount of starch synthesised in age organs harves ted from wheat, rice, moize, and potato exceeds a ns per year. About 20 million tons are isola ted pe r year worldwide for ap plications, mainly derived from corn, however, jn Eu rope a signif p ortion Df starch is a lso isolated from potato. Small bu t increaSing mS of the worldwide nla rke t for starch are d erived from cassava, ri ce '.at. The ADP-gl ucose pothway, involving ADPglucose pyrophosphory h synthases and bronchin g enzymes, is almost the sole route through rbon gets incorporated into sta rch. Starch less, Or reduced starch con m u tants in a range 01 pla nt", have been shown to contain reduced levels DPglucose pyrophosphory lase . ADPglu cose is used by the sta rch syn , manufacture «-lA-glucans. The third step in the comitted pa thway of ,synthesis, the introduction of a -l,6-glycosidic linkages, is catalyzed by I i.soforms of bra nching enzyme. Other en zymes, which are able to act ""glucans, and wh ich are mainly tho ught to be responsible lor starch tion, play an impo rtant role in d etermining the fin e structure and the .-chem.ical properties oi starch. All the differen t steps in starch biosyn 11.1 be discussed with respect to the potential for genetic modification, as , other steps, especia lly the phosph orylation of s tarch. FinaUy we wilJ ·r a lso the bioche mi stry of starch mobilisation.
Session 41, Transgenics and Biotechnology olic engineering of the glyerne betaine synthesis pathway in tobacco: is of flux control by choline monooxygenase. N uccio, Michael L Mc tt D. Ziemak,Michael Hanson, Andrew D. UniversilyojFlorida Pre '
