| Cassava(Manihot esculenta Crantz)is mainly planted with seed stem in production.At present,the quality of seed stem has become one of the main obstacles to increase yield of cassava.In order to find the efficient and rapid evaluation indices of cassava seed stem vigor,the proteomic mechanism of aging of cassava seed stem was explored,and the key proteins related to the aging of cassava seed stem or anti-aging was looked for,and the correlation between cassava seed stem vigor and its physiological and biochemical indices was analyzed.Its rusults can provides a theoretical basis for efficient screening for storage technology and chemical treatment measures of cassava seed stem,for improving quality of seed stem by biotechnology measures,and for maintaining or improving the seed stem vigor.In this paper,the seed stem of SC8 and NZ199 were chose as material,which planted in the field,collected during the six different growth stages and the harvest period,and the stem at the harvest period were artificially aged to different stages.In order to find the vitality evaluation indices,the germination and seedling growth experiments were carried out,and the comprehensive score of seed stem vigor of different growth stages and different aging days was obtained by the principal component analysis method.The relationship between the comprehensive score of seed stem vigor and the physiological and biochemical indices of seed stem at the natural growth stage and artificial aging stage was carried out by the related analysis.In addition,the proteomic difference of aging cassava seed stem in different days were analyzed.The main results are as follows:(1)With the cassava seed stem aged degree deepen,the comprehensive score of seed stem vigor decreased from slow to fast during storage.To the 6 days aged,the vigor of all the SC8 cassava seed stem were lost,and the vigor of NZ199 cassava seed stem was quickly reduced to a minimum.From the mutative trend of cassava seed stem vigor,we could conclude that the cassava seed stem vigor would decrease rapidly and even disappeared when cassava seed stem were aged 4 to 6 days.(2)48 differentially expressed proteins were obtained by comparative proteomic analysis and mass spectrometry identification of cassava seed stem in different aging days,and functional classification analysis showed that the differentially expressed proteins were energy metabolism and carbon metabolism related proteins,transfer proteins,detoxification and antioxidant related proteins,defense proteins,and chaperone proteins.Most of the energy metabolism and carbon metabolism related proteins and detoxification and anti-oxidation related proteins down-regulated,while the expression levels of transfer proteins,defense proteins,and chaperone proteins were up-regulated.At aged 6 days,the NZ199 cassava seed stem still had vigor should be related to its unique enolase,isoflavone reductase and nuclear redox protein,dehydrin,CPN60 chaperone protein.(3)For the two varieties of cassava,the comprehensive scores of the seed stem vigor were significantly positively correlated with the starch content during storage,but they were significant negative correlation with soluble protein content.It indicated that soluble protein content and starch content of stem could be used as indices for measuring cassava seed stem vigor during storage.Therefore,measures should be taken to reduce the consumption of starch when the seed stem was stored.(4)With the growth period of cassava prolong,the seed stem vigor of SC8 and NZ199 increased,and reached the peak at 300th day after planted.The seed stem vigor had an increasing trend after planted,however,there were two rapid ascent stages,from 180th day to 210th day after planted and 270th day to 300th day after planted.It showed that the cassava seed stem vigor was not evenly changed during the formation process,there was a period of rapid change,so it was crucial for the formation of seed stem vigor during this stage,and must be pay attention to manage in production.(5)For the two varieties of cassava,there was a significant positive correlation between the seed stem vigor and starch content,but there was a significant negative correlation with the MDA content during the natural growth stage.Therefore,the starch content and MDA content of the seed stem were recommended as the cassava seed stem vigor evaluation indices during the growth stage.In summary,the cassava seed stem vigor evaluation indices are different in different states.During the natural growth stage,the starch content and the MDA content were recommended as the evaluation indices of the seed stem vigor,but during storage,the soluble protein content and starch content were recommended as the evaluation indices of seed stem vigor.The seed stem degeneration is closely related to the down-regulation of energy metabolism proteins and detoxification and anti-oxidation proteins,while the anti-aging ability is closely related to transfer proteins,defense proteins and chaperone proteins. |
PDF Full Text Request