ABSTRACT
Sweet potato is an important food crop that can also be used as an industrial raw material. Sucrose is the main form of long-distance carbohydrate transport in plants, and sucrose transporter (SUT) regulates the transmembrane transport and distribution of sucrose during plant growth and metabolism. Moreover, SUT plays a key role in phloem mediated source-to-sink sucrose transport and physiological activities, supplying sucrose for the sink tissues. In this study, the full-length cDNA sequences of IbSUT62788 and IbSUT81616 were obtained by rapid amplification of cDNA ends (RACE) cloning according to the transcripts of the two SUT coding genes which were differentially expressed in sweet potato storage roots with different starch properties. Phylogenetic analysis was performed to clarify the classification of IbSUT62788 and IbSUT81616. The subcellular localization of IbSUT62788 and IbSUT81616 was determined by transient expression in Nicotiana benthamiana. The function of IbSUT62788 and IbSUT81616 in sucrose and hexose absorption and transport was identified using yeast functional complementarity system. The expression pattern of IbSUT62788 and IbSUT81616 in sweet potato organs were analyzed by real-time fluorescence quantitative PCR (RT-qPCR). Arabidopsis plants heterologous expressing IbSUT62788 and IbSUT81616 genes were obtained using floral dip method. The differences in starch and sugar contents between transgenic and wild-type Arabidopsis were compared. The results showed IbSUT62788 and IbSUT81616 encoded SUT proteins with a length of 505 and 521 amino acids, respectively, and both proteins belonged to the SUT1 subfamily. IbSUT62788 and IbSUT81616 were located in the cell membrane and were able to transport sucrose, glucose and fructose in the yeast system. In addition, IbSUT62788 was also able to transport mannose. The expression of IbSUT62788 was higher in leaves, lateral branches and main stems, and the expression of IbSUT81616 was higher in lateral branches, stems and storage roots. After IbSUT62788 and IbSUT81616 were heterologously expressed in Arabidopsis, the plants grew normally, but the biomass increased. The heterologous expression of IbSUT62788 increased the soluble sugar content, leaf size and 1 000-seed weight of Arabidopsis plants. Heterologous expression of IbSUT81616 increased starch accumulation in leaves and root tips and 1 000-seed weight of seeds, but decreased soluble sugar content. The results obtained in this study showed that IbSUT62788 and IbSUT81616 might be important genes regulating sucrose and sugar content traits in sweet potato. They might carry out physiological functions on cell membrane, such as transmembrane transport of sucrose, sucrose into and out of sink tissue, as well as transport and unloading of sucrose into phloem. The changes in traits result from their heterologous expression in Arabidopsis indicates their potential in improving the yield of other plants or crops. The results obtained in this study provide important information for revealing the functions of IbSUT62788 and IbSUT81616 in starch and glucose metabolism and formation mechanism of important quality traits in sweet potato.
Subject(s)
Ipomoea batatas/metabolism , Arabidopsis/metabolism , Sucrose/metabolism , Saccharomyces cerevisiae/metabolism , DNA, Complementary , Phylogeny , Plants, Genetically Modified/genetics , Membrane Transport Proteins/metabolism , Starch/metabolism , Plant Proteins/metabolism , Gene Expression Regulation, PlantABSTRACT
El cultivo del boniato presenta una gran importancia, ya que se puede emplear en la alimentación humana y animal, así como en la industria; el mismo produce raíces reservantes de gran valor calórico y nutritivo con alto contenido de carbohidratos. Entre las raíces y tubérculos cultivados es el segundo en importancia y representa más del 80% de la producción mundial. El empleo de las técnicas in vitro constituye una poderosa herramienta en la explotación comercial, propiciando el empleo de la micropropagación en diferentes especies. Para desarrollar el presente trabajo se recolectaron raíces tuberosas pertenecientes al clon Inivit B 93-1. Se procedió a la formación de callos potencialmente embriogénicos, para lo cual se emplearon explantes de limbos foliares, desinfectados con hipoclorito de sodio (1%) y sembrados en el medio de cultivo propuesto por Murashige y Skoog (1962), vitaminas MS (10,0 ml/l-1), mioinositol (100 mg/l-1), sacarosa (3%), gelrite (0,2%), 2,4-D (0,25-2,5 mg/l-1) y 6-BAP (0,25-1,0 mg/l-1), el pH fue ajustado a 5,8 ± 0,01 mantenidos en la oscuridad durante treinta días, lográndose los mejores resultados con el uso del 2,4-D (0,50 mg/l-1) y 6-BAP (0,25 mg/l-1), y en los mismos se evaluó la dinámica del crecimiento y se lograron los mejores resultados entre los 28 y 32 días después de la siembra, para lo cual los resultados obtenidos servirán de base a otros estudios y permitirán evaluar, controlar y desarrollar estrategias para la conservación y el uso de los recursos naturales, dando cumplimiento al objetivo referente a estudiar la dinámica del crecimiento en la formación de callos potencialmente embriogénicos en el cultivo del boniato.
The cultivation of the sweet potato presents a great importance, since you can use in the human feeding, animal as well as in the industry, the same one produces roots reservantes of great caloric and nutritious value with high content of carbohydrates. Between the roots and cultivated tubers it is the second in importance and it represents more than 80% of the world production. The employment of the techniques in vitro constitutes a powerful tool in the commercial, propitiated exploitation the employment of the micropropagación in different species. It is for it that you/they were gathered to develop the present work tuberous roots of the clon INIVIT B 93-1. Was realized the formation of callus with embryogenic structures, explantes of leaves were used, disinfected with hipoclorito of sodium (1%) and inoculated in the tissue culture medium proposed by Murashige and Skoog (1962), vitamins MS (10.0 ml/l-1), myoinositol (100 mg/l-1), sucrose (3%), gelryte (0.2%), 2,4-D (0.25-2.5 mg/l-1) and 6-BAP (0.25-1.0 mg/l-1), the pH was adjusted 5.8 ± 0.01 maintained in the darkness during thirty days, being achieved the best results with the use of the 2,4-D (0.50 mg/l-1) and 6-BAP (0,25 mg/l-1) and was evaluated the grow dynamic and obtained the better resulted between 28 and 32 days after culture, for that which the obtained results will serve from base to other studies and they will allow to evaluate, to control and to develop strategies for the conservation and use of the natural resources, giving execution to the objective with respect to studying the dynamics of the growth potentially in the formation of tripes embriogénicos in the cultivation of the sweet potato.