a metabolomics approach to elucidate apple fruit responses to static
ａnd dynamic controlled atmosphere storage
代谢组学方法阐明苹果果实对静态和动态受控气氛存储的反应
stefano brizzolaraa,*, claudio santuccib, leonardo tenoric, maarten hertogd,
bart nicolaid,e, stefan stürzf, angelo zanellaf, pietro tonuttia
a istituto di scienze della vita, scuola superiore sant’anna, pisa, italy
b cerm, university of firenze, firenze, italy
c fondazione fiorgen onlus, firenze, italy
d division of mechatronics, biostatistics and sensors (mebios), department of biosystems (biosyst), ku leuven, leuven, belgium
e flanders centre of postharvest technology (vcbt), leuven, belgium
f laimburg research centre for agriculture and forestry, ora, bolzano, italy
abstract
the response of apple fruit to storage conditions based on low oxygen protocols depends on their genetic background. in order to elucidate common and divergent processes characterizing the metabolic changes under hypoxia, fruit of two apple (malus domestica) varieties (‘granny smith’, gs, and ‘red delicious’, rd) were stored under two different low oxygen protocols (ultra low oxygen, ulo, at 0.9 kpa oxygen, and dynamic controlled atmosphere based on chlorophyll fluorescence, dca-cf, between 0.2 and 0.55 kpa oxygen) for up to 200 and 214 days of storage for gs and rd samples, respectively. through an integrated metabolomics approach (1h nmr, gc–ms, hs-spme-gc–ms analyses) a total of 130 metabolites (volatiles and non-volatiles) were identified. most of them (117) were common to both c*rs; 95 were significantly different between both c*rs when comparing the whole set of data (ulo + dca-cf), whereas 13 volatile compounds, identified via hs-spme-gc–ms, were specific for either gs or rd. m*riate analyses (pca and pls) of the whole dataset allowed to clearly discriminate between gs and rd samples. when storage condition was used as a categorical response variable, a lower percentage explained variance was obtained as this effect was overshadowed by the large effect of storage time. after 4 months of storage, rd underwent more pronounced metabolic compositional changes of the cortex, possibly associated with the evolution of ripening. based on the accumulation pattern of pyruvate- derived metabolites (ethanol, acetaldehyde, lactate, alanine) it can be hypothesized that there are two main metabolic reconfiguration strategies in gs and rd to regenerate nad+ and cope with energy crisis under hypoxia. gs showed more pronounced responses through changes in the nitrogen metabolism and limited induction of the ethanol fermentation while the latter was highly induced in rd under both ulo and dca-cf. marked differences were detected between the voc profiles of the two c*rs regardless storage conditions. ethyl esters and 2-methylbutyl derivatives appeared finely modulated by the oxygen level in gs and rd apples, respectively.
苹果果实对低氧贮藏条件的反应取决于其遗传背景。为了阐明在缺氧条件下代谢变化的共同和不同过程，两个苹果品种（granny smith，gs和red delicious，rd）的果实在两种不同的低氧条件下贮藏（超低氧，ulo，0.9kpa氧气，以叶绿素荧光为基础的动态控制大气，dca-cf，0.2-0.55kpa氧气），分别对gs和rd样品进行长达200天和214天的储存。通过综合代谢组学方法（1hnmr、gc-ms、hs-spme-gc-ms分析），共鉴定出130种代谢物（挥发物和非挥发物）。其中大多数（117个）是两个品种共有的；在比较整个数据集（ulo+dca-cf）时，两个品种之间的95个显著不同，而通过hs-spme-gc-ms鉴定的13个挥发性化合物，对gs或rd都有特异性。整个数据集的多变量分析（pca和pls）可以清楚区分gs和rd样本。当存储条件被用作分类响应变量时，由于存储时间的巨大影响掩盖了这一影响，因此得到的解释方差百分比较低。贮藏4个月后，rd的皮层代谢成分发生了更明显的变化，可能与成熟的进化有关。根据丙酮酸代谢产物（乙醇、乙醛、乳酸、）的积累模式，可以推测gs和rd有两种主要的代谢重构策略来再生nad+，应对缺氧下的能量危机。gs通过氮代谢的变化和乙醇发酵的有限诱导而表现出更明显的响应，后者在ulo和dca-cf两种条件下均在rd中被高度诱导，两个品种的voc谱在不同贮藏条件下存在显著差异。在gs和rd苹果中，乙酯和2-甲基丁基衍生物分别受到氧含量的精细调节。
keywords:hypoxic metabolism，ultra low oxygen (ulo)，dynamic controlled atmosphere (dca)，malus domestica，postharvest，metabolic profiling
关键词：低氧代谢、超低氧（ulo）、动态控制气氛（dca）、苹果、采后、代谢谱