| The ‘Rong’an kumquat’ and its actual variety,‘Huapi kumquat’,were used as materials to study the change of fruit side,color change,sugar and acid composition during the development stages.The materials in the three key stages of fruit development(90DAF,180 DAF and 210 DAF)were analyzed by transcriptome analysis.The differences of sugar and acid metabolism between the two varieties were explained at the molecular level.Through gene screening,the two varieties were selected Key genes that affect and regulate sugar and organic acid metabolism.The main results are as follows:1.Compared with ‘Rong’an kumquat’,the fruit of ‘Huapi kumquat’ is bigger,the single fruit weight is higher,and the fruit shape of is close to spherical.The content of soluble sugar was higher in peel and flesh of ‘Huapi kumquat’.Analysis of sugar components showed that sucrose was the main accumulated sugar in peel and flesh of the two varieties,and the content of sucrose and glucose was higher in peel and pulp of ‘Huapi kumquat’ during the whole fruit development period.In addition,there was higher titratable acid accumulation in the flesh of ‘Rong’an kumquat’,especially in the early stage of fruit development.It was found that citric acid,quinic acid and malic acid were the main organic acids.The three organic acids and titratable acids have the same downward trend,in 120-150 DAF and the content of them in ‘Rong’an kumquat’ is higher.Photosynthesis was carried out in the early stage of fruit development of the two kumquat varieties2.Transcriptome analysis showed that sucrose phosphate synthetase gene(sjg023350and sjg087030)was up-regulated in 90 DAF of peel and flesh respectively,while all sucrose invertase genes(sjg074620,sjg284190,sjg290780,sjg318030,sjg097240,sjg27490,sjg286780),fructokinase genes(sjg293340,sjg298920,sjg113880),hexokinase genes(sjg162090)were detected in the flesh was down-regulated at different stages of fruit development.It is suggested that sucrose phosphate synthetase,which is involved in sucrose synthesis,may have high activity in the early stage of fruit development,while sucrose invertase,fructokinase and hexokinase,which are involved in sucrose degradation,may have low activity in the whole fruit development period.In ‘Huapi kumquat’.The results showed that pyruvate kinase gene(sjg041680,sjg04220,sjg118500,sjg145340,sjg196000,sjg196980),pyruvate dehydrogenase gene(sjg156830),malic dehydrogenase gene(sjg084990,sjg039710)and malic acid synthetase gene(sjg264560)were all down regulated in 90 DAF.While ATP citrate lyase gene(sjg127500)and phosphoenolpyruvate carboxykinase gene(sjg183420)in the citric acid decomposition pathway were down regulated at 150-210 DAF.It is suggested that the pathway of ATP citrate lyase(ACL)may be the main pathway of acid degradation in the middle and later stage of ‘Rong’an kumquat’.3.Transcription factors analysis showed that in ‘Huapi kumquat’ AP2-EREBP family gene(sjg188780 and sjg290640)related to sucrose metabolism was down regulated at90-210 DAF in peel and flesh respectively,while b HLH family(sjg021870)was down regulated at 90-210 DAF in flesh.The b HLH family gene(sjg156970)and WRKY family gene(sjg084660),which are related to citric acid metabolism,were down regulated in peel90-210 DAF.The expression of AP2 EREBP family gene(sjg256130 and sjg290640)and b HLH family gene(sjg317250 and sjg021870)in 90-210 DAF of flesh was up-regulated or down regulated.In particular,b HLH family(sjg156970),which has correlation with both sucrose metabolism and citric acid metabolism,and its down-regulation times in peel and pulp are 42.81 and 18.21 times,respectively,which may be the key regulatory genes leading to the differences in sugar and organic acid metabolism between the two varieties. |
PDF Full Text Request