caa a22 4500 606208143 CHVBK 20210128101021.0 cr unu---uuuuu 210128e20151001xx s 000 0 eng 10.1007/s00425-015-2342-0 doi (NATIONALLICENCE)springer-10.1007/s00425-015-2342-0 Transgenic alfalfa ( Medicago sativa ) with increased sucrose phosphate synthase activity shows enhanced growth when grown under N2-fixing conditions [Elektronische Daten] [Sayed Gebril, Mark Seger, Fabiola Villanueva, Jose Luis Ortega, Suman Bagga, Champa Sengupta-Gopalan] Main conclusion : Overexpression of SPS in alfalfa is accompanied by early flowering, increased plant growth and an increase in elemental N and protein content when grown under N 2 -fixing conditions. Sucrose phosphate synthase (SPS; EC 2.3.1.14) is the key enzyme in the synthesis of sucrose in plants. The outcome of overexpression of SPS in different plants using transgenic approaches has been quite varied, but the general consensus is that increased SPS activity is associated with the production of new sinks and increased sink strength. In legumes, the root nodule is a strong C sink and in this study our objective was to see how increasing SPS activity in a legume would affect nodule number and function. Here we have transformed alfalfa (Medicago sativa, cv. Regen SY), with a maize SPS gene driven by the constitutive CaMV35S promoter. Our results showed that overexpression of SPS in alfalfa, is accompanied by an increase in nodule number and mass and an overall increase in nitrogenase activity at the whole plant level. The nodules exhibited an increase in the level of key enzymes contributing to N assimilation including glutamine synthetase and asparagine synthetase. Moreover, the stems of the transformants showed higher level of the transport amino acids, Asx, indicating increased export of N from the nodules. The transformants exhibited a dramatic increase in growth both of the shoots and roots, and earlier flowering time, leading to increased yields. Moreover, the transformants showed an increase in elemental N and protein content. The overall conclusion is that increased SPS activity improves the N status and plant performance, suggesting that the availability of more C in the form of sucrose enhances N acquisition and assimilation in the nodules. Springer-Verlag Berlin Heidelberg, 2015 Carbon metabolism nationallicence Nitrogen assimilation nationallicence Sucrose phosphate synthase nationallicence SPS transgenic alfalfa nationallicence Plant growth nationallicence Nodule number nationallicence Flowering time nationallicence SPS : Sucrose phosphate synthase nationallicence GS1 : Cytosolic glutamine synthetase nationallicence Suc : Sucrose nationallicence Glc : Glucose nationallicence Gln : Glutamine nationallicence NT : Non-transformed nationallicence SPS : Transformants alfalfa expressing MzSPS nationallicence 3PG : Glyceride 3-phosphate nationallicence G6P : Glucose 6-phosphate nationallicence UDPGlc : Uridine diphosphate glucose nationallicence SucSy : Sucrose synthase nationallicence PEP : Phosphoenol pyruvate nationallicence α-ΚG : α Ketoglutarate nationallicence Asx : Asn/Asp nationallicence F6P : Fructose 6-phosphate nationallicence MDH : Malate dehydrogenase nationallicence Gebril Sayed Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut Seger Mark Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut Villanueva Fabiola Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut Ortega Jose Luis Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut Bagga Suman Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut Sengupta-Gopalan Champa Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut Planta Springer Berlin Heidelberg 242/4(2015-10-01), 1009-1024 0032-0935 242:4<1009 2015 242 425 https://doi.org/10.1007/s00425-015-2342-0 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00425-015-2342-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Gebril Sayed Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut NATIONALLICENCE 700 1- Seger Mark Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut NATIONALLICENCE 700 1- Villanueva Fabiola Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut NATIONALLICENCE 700 1- Ortega Jose Luis Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut NATIONALLICENCE 700 1- Bagga Suman Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut NATIONALLICENCE 700 1- Sengupta-Gopalan Champa Department of Plant and Environmental Sciences, New Mexico State University, 88003, Las Cruces, NM, USA aut NATIONALLICENCE 773 0- Planta Springer Berlin Heidelberg 242/4(2015-10-01), 1009-1024 0032-0935 242:4<1009 2015 242 425