SGAs Level,Distribution And Cloning,Expression Of SGTs In Potato(Solanum Tuberosum L.)

The steroidal glycoalkaloids(SGAs)is one of the toxicant secondary metabolities in Solanaceae and some Liliaceae,that has a strong physiological and drug activity andenhance plant resistance stresses,It also can play a role in disease prevention and insect-resistant in potato plants.The content of steroidal glycoalklaloids was accumulated due to genetic and environmental factors.SGTs are the key enzymes in biosynthesis of SGAs,including three genes:Sgtl,Sgt2 and Sgt3.Research on gene structure and the nature of the encoded protein,and its expression difFerences in different parts of the potato plants,would help us to further analysis of the molecular mechanisms of anabolic pathways of SGAs in potato,provided a theoretical basis for the molecular level to regulate the accumulating on SGAs in potato.Main results of the experiment are displayde as follows:1.Measured the dynamic changes of the potato tuber during the sprouting in each part of the content of SGAs,the results show:among varieties the difference of SGAs content was significant,in different parts and periods of the same species,the differences in the content of SGAs were extremely significant;the content of SGAs in buds was the highest and followed by potato skin,the content of SGAs in meat was the lowest.In terms of the overall level,the content of SGAs in N9-49 was higher than qinyu30's during the sprouting,and it was showed that the content of SGAs of potato tubers related with genetic factors of the potato varietes during the sprouting.2.Measured the dynamic changes of the plant during the growth in each part of the content of SGAs,the results show:different variety,different parts,different period,the differences of content of SGAs were highly significant,the content of SGAs in stem tip was the highest,the content of SGAs had little difference between leaves and stem segments.In terms of the overall level,the content of SGAs in N9-49 was higher than qinyu30's during the growth,and it was showed that the content of SGAs of potato plant related with genetic factors of the potato varietes during the growth.3.Through two test materials SGTs cloning analysis,The results show:the three genes shared a high level of similarity with the reported Sgtl,Sgt2 and Sgt3 in Genbank more than 99%,and consistency of encoded amnio acid sequence with the reported sequence reached more than 98.5%.Tertiary structure prediction indicated:there was little difference between cloned genes in the experiment and reported genes.4.Measured the dynamic changes of the plant during the growth in each part of the content of the expression of Sgt3,the results show:different variety,different parts,different period,the differences of the expression of Sgt3 were highly significant.The expression of Sgt3 in stem tip was the highest,and followed by leaves,The expression of Sgt3 in Stem segments was the lowest.In terms of the overall level,The expression of Sgt3 in N9-49 was higher than qinyu30's during the growth;Combined SGAs content and Sgt3 expression analysis can be drawn that,during the plant growth,in the synthesis of SGAs,Sgt3 plays an important role,and SGAs content and Sgt3 expression levels related to genetic factors.5.From 1 and 2 shows,SGAs content in N9-49 during tuber sprouting and plant growth,which is higher than Qinyu30,for breeding potato tubers with low SGAs and plant with high SGAs of potato varieties are not the ideal material.Breeding is a very complex task,we need combine conventional breeding,mutation breeding and biotechnology breeding,use a variety of breeding methods,select material widely,this experiment laid the foundation for the potato SGAs breeding work.6.From 3 and 4 shows,the experiment cloned the SGTs of the tested varieties,the three genes shared a high level of similarity with the reported genes in Genbank,tertiary structure prediction indicated:there was little difference between cloned genes in the experiment and reported genes.In the growth process,the expression of Sgt3 and the content of SGAs in different varieties are different,they are related to genetic composition of potato varieties.The correlation between the expression levels of Sgt3 and the content of SGAs was not significant,it shows that the accumulation aontent not only related with expression Sgt3,also associated with the expression Sgtl and Sgt2,the three genes jointly regulate and control the synthesis of SGAs.