Maize Carbohydrate Partitioning Defective33 Encodes an MCTP Protein and Functions in Sucrose Export from Leaves  

作　　者：Thu M.Tran Tyler J.McCubbin Saadia Bihmidine Benjamin T.Julius R.Frank Baker Martin Schauflinger Clifford Weil Nathan Springer Paul Chomet Ruth Wagner Jeff Woessner Karen Grote Jeanette Peevers Thomas L.Slewinski David M.Braun 

机构地区：[1]Division of Biological Sciences’Interdisciplinary Plant Group,Missouri Maize Center,University of Missouri,Columbia,MO 65211,USA [2]Division of Plant Sciences,University of Missouri,Columbia,MO 65211,USA [3]Electron Microscopy Core Facility,University of Missouri,Columbia,MO 65211,USA [4]Department of Agronomy,Purdue University,West Lafayette,IN 47907,USA [5]Department of Plant and Microbial Biology,University of Minnesota,Saint Paul,MN 55108,USA [6]NRGene Inc.,8910 University Center Lane,\r\n S u ite 400,San Diego,CA 92122,USA [7]Bayer Crop Science,Chesterfield,MO 63017,USA [8]National Key Laboratory for Plant Cell Technology,Agricultural Genetics Institute,Hanoi,Vietnam

出　　处：《Molecular Plant》2019年第9期1278-1293,共16页分子植物（英文版）

摘　　要：To sustain plant growth,development,and crop yield,sucrose must be transported from leaves to distant parts of the plant,such as seeds and roots.To identify genes that regulate sucrose accumulation and transport in maize(Zea mays),we isolated carbo/iydrafe part/f/ofi/ngf defecf/Ve33(cpd33),a recessive mutant that accumulated excess starch and soluble sugars in mature leaves.The cpd33 mutants also exhibited chlorosis in the leaf blades,greatly diminished plant growth,and reduced fertility.Cpd33 encodes a protein containing multiple C2 domains and transmembrane regions.Subcellular localization experiments showed the CPD33 protein localized to plasmodesmata(PD),the plasma membrane,and the endoplasmic reticulum.We also found that a loss-of-function mutant of the CPD33 homolog in Arabidopsis,QUIRKY,had a similar carbohydrate hyperaccumulation phenotype.Radioactively labeled sucrose transport assays showed that sucrose export was significantly lower in cpd33 mutant leaves relative to wild-type leaves.However,PD transport in the adaxial-abaxial direction was unaffected in cpd33 mutant leaves.Intriguingly,transmission electron microscopy revealed fewer PD at the companion cell-sieve element interface in mutant phloem tissue,providing a possible explanation for the reduced sucrose export in mutant leaves.Collectively,our results suggest that CPD33 functions to promote symplastic transport into sieve elements.

关 键 词：carbohydrate accumulation COMPANION cells phloem  PLASMODESMATA SIEVE elements symplastictransport 

分 类 号：S51[农业科学—作物学]