Aroma Analysis And AAT1 Gene Cloning And Expression And Enzyme Activity Detection Of Loquat (Eriobotrya Japonica (Thunb.)Lind1.) Fruit

Loquat (Eriobotrya japonica(Thunb.) Lindl.) is originated from China with about 3000 years of cultivation history in our country. People love loquat because of its flesh is soft and juicy. The researches on loquat fruit are mainly focused on sugar and acid metabolism and postharvest storage, few concerned to the aroma. In this study, we used loquat fruits as materials, and analyzed the fruit aroma of different developmental stages and different cultivars of the loquat by the biochemical and molecular biological techniques based on the basic quality index and color index determination, and then cloned AAT1 gene and studied its expression patterns. The main results were as follows:1、We determined the main fruit quality indices of loquat fruit cv.’Jinfengyihao’ and ’fengyu’ during development period. The results showed that the single weight, transverse diameter, longitudinal diameter and TSS of loquat fruit cv.’Jinfengyihao’ and ’fengyu’ showed a trend of increase from May 1st to May 22nd, but the hardness showed a trend of decrease. The single weight, transverse diameter, longitudinal diameter of ’Jinfengyihao’ were higher then ’fengyu’ during development period. TSS of ’Jinfengyihao’ and ’fengyu’ both showed a trend of increase during the time from May 15th to May 22nd, but the value of TSS of ’fengyu’ was higher than ’Jinfengyihao’ at May 22nd. There was little difference in peel color of loquat fruit cv. ’Jinfengyihao’ and ’fengyu’ during different development period, but the pulp color of ’Jinfengyihao’ were more close to red than ’fengyu’ from May 15th.2、We detected loquat fruit aroma by gas chromatography-mass spectrometry (GC-MS). The results showed that the component with the highest relative content was 2-Hexenal in the pulp of ’Jinfengyihao’ and ’fengyu’ on May 1st and May 8th, while the component with the highest relative content was (E)-3-Hexen-1-ol on May 15th and May 22nd. During development period, Hexannal was the component with the highest relative content in the peel of ’Jinfengyihao’ and ’fengyu’.Aldehydes was the highest relative content of the main aroma components in the peel and pulp among 23 varieties of loquats. The component with the highest relative content in the pulp was different. There were 7 varieties of loquats whose component with the highest relative content was 1-Nananal among 10 varieties of red flesh loquats, and there were also 7 varieties of loquats whose component with the highest relative content was 1-Nananal among 13 varieties of white flesh loquats. In addition,1-Nananal showed a large relative content in the rest of the varieties: The component with the highest relative content in the peel of 23 varieties of loquats was 2-Hexenal.3、We cloned AAT1 gene of loquat fruit, and named EjAAT1.The full length cDNA was1649 bp, and contained a 1372 bp open reading frame(ORF), encoding a protein composed of 458 amino acids and polyA tail (12bp). EjAATl was registered in GenBank with number KF704125.2. The nucleotide sequence homology with those of Malus domestica、Solanum lycopersicum and Citrus sinensis AAT1 were 95%,68%, and 67%, respectively.4、We analyzed EjAATl expression model in the peel and pulp of loquat fruit cv. ’Jinfengyihao’ and ’fengyu’ during 4 developmental stages by Real-time fluorescent quantitative PCR The results showed that the highest expression level in the pulp of ’Jinfengyihao’ was on May 15th, but the highest expression level in the peel was on May 22nd. The highest expression level in the pulp of ’fengyu’ was on May 22nd, but the highest expression level in the peel was on May 1th; We also determined the alcohol acyl transferase activity of the pulp of ’Jinfengyihao’ and ’fengyu’ during different developmental stages. Results showed that the alcohol acyltransferase activity was highest on May 8th in the pulp of ’Jinfengyihao’, and the lowest was on May 1th. In the pulp of ’fengyu’, the highest alcohol acyltransferase activity was on May 1th, and the lowest was on May 22nd.We analyzed the accumulation of ester aroma substances in the peel and pulp of loquat fruit cv.’Jinfengyihao’ and ’fengyu’ during 4 developmental stages, and compared with EjAATl expression model and the alcohol acyl transferase activity. Results showed there was no a direct relationship among them.