李果实有机酸组成特征及其与苹果酸转运体基因PsALMT9和PstDT的相关性

Organic Acid Composition Characteristics and Its Correlation with Malate Transporter Genes PsALMT9 and PstDT in Plum Fruit

为了阐明李果实有机酸组成特征及其与苹果酸转运体基因PsALMT9、PstDT的相关性,该研究以‘皇冠李’(Prunus salicina‘Huangguan’)和‘黑琥珀李’(Prunus salicina‘Black Amber’)为试材,测定了不同发育阶段果实有机酸组分与含量、可滴定酸含量、pH、单果重,采用实时荧光定量PCR(qPCR)分析了苹果酸转运体基因PsALMT9和PstDT在果实生长发育过程中的表达变化规律,并通过Pearson相关系数探讨PsALMT9和PstDT基因与果实有机酸的相关性。结果显示:(1)‘皇冠李’和‘黑琥珀李’果实各发育阶段主要有机酸组分为苹果酸(占73.83%~92.10%),其次为酒石酸(占4.59%~14.26%),柠檬酸、草酸、乙酸和琥珀酸含量较低(0.47%~7.21%),富马酸仅以微量存在。(2)果实苹果酸含量与可滴定酸含量呈极显著正相关关系,与pH呈极显著负相关关系;PsALMT9表达量与酒石酸含量呈显著正相关关系,与乙酸和草酸含量呈极显著正相关关系;PstDT表达量与柠檬酸、可滴定酸含量呈显著正相关关系,但PsALMT9和PstDT均与苹果酸含量的相关性较低。研究发现,‘皇冠李’和‘黑琥珀李’属于苹果酸型果实,果实酸度主要由苹果酸决定;PsALMT9基因可能同时参与酒石酸、乙酸和草酸的跨液泡膜转运,PstDT基因可能参与柠檬酸的跨液泡膜转运,而苹果酸跨液泡膜转运过程可能与PsALMT9、PstDT等多种膜蛋白基因的协同调控有关。

Organic acids play an important role in fruit quality of plum,and malate transporters are involved in trans-tonoplast transportation and accumulation of organic acids in fruit.In order to reveal the organic acid composition and its correlation with malate transporter genes(PsALMT9 and PstDT)in plum fruit,this study used two plum cultivars(Prunus salicina‘Huangguan’and Prunus salicina‘Black Amber’)as samples to determine the organic acid composition and content,single fruit weight,titratable acid(TA)and pH of fruits at different stages of fruit development,and using quantitative real-time PCR(PCR)to analyze the relative expression levels of PsALMT9 and PstDT.We also carried out the pearson correlation coefficient to determine the correlation of PsALMT9,PstDT and fruit acids.The results showed that:(1)malic acid is the main organic acid component at all developmental stages of‘Huangguan’and‘Black Amber’(proportion for 73.83%~92.10%),followed by tartaric acid(4.59%~14.26%),the contents of citric acid,oxalic acid,acetic acid and succinic acid are low(0.47%~7.21%),and the content of fumaric acid is trace.(2)The pearson correlation coefficient showed that malic acid was significantly positively correlated with TA,and significantly negatively correlated with pH;PsALMT9 was significantly positively correlated with tartaric acid,and significantly positively correlated with acetic acid and oxalic acid;PstDT was significantly positively correlated with citric acid and TA,but both PsALMT9 and PstDT were less correlated with malic acid.Our research indicated that‘Huangguan’and‘Black Amber’belong to malate-type fruits,and fruit acidity is mainly determined by malic acid.PsALMT9 may be involved in the trans-tonoplast transport of tartaric acid,acetic acid and oxalic acid simultaneously,and PstDT may be involved in the trans-tonoplast transport of citric acid,while the trans-tonoplast transport process of malate may be related to the synergistic regulation of varied membrane protein genes such as PsALMT9 and PstDT.