Pathways to defense metabolites and evading fruit bitterness in genus Solanum evolved through 2-oxoglutarate-dependent dioxygenases
Pathways to defense metabolites and evading fruit bitterness in genus Solanum evolved through 2-oxoglutarate-dependent dioxygenases
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DOI：
10.1038/s41467-019-13211-4
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发表时间：
2019-11-14
影响因子：
16.6
通讯作者：
Aharoni, Asaph
中科院分区：
文献类型：
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作者：
Cardenas, Pablo D.;Sonawane, Prashant D.;Aharoni, Asaph
茄属植物包括三种粮食作物（马铃薯、番茄和茄子），它们在全世界每天都被消耗，并且也是臭名昭著的抗营养甾体配糖生物碱（SGA）的生产者。羟基化的SGA（即瘦素）作为瘦素的前体，所述瘦素充当对抗科罗拉多马铃薯甲虫（马铃薯甲虫）（马铃薯甲虫是世界范围内的重要马铃薯害虫）的防御。然而，SGA羟化酶仍然未知。在这里，我们发现2-氧代戊二酸依赖性双加氧酶（2-ODD）催化不同茄属物种的SGA-羟基化。与栽培马铃薯相反，广泛分布的野生马铃薯物种Solanum chacoense已经进化出导致瘦素形成的2-ODD酶。此外，我们在番茄中发现了一种相关的2-ODD，其催化苦味α-番茄碱羟基化为羟基番茄碱，这是化学转变向下游成熟相关的非苦味SGA（例如七叶皂苷A）的第一个关键步骤。这种2-ODD酶可以防止今天食用的成熟番茄水果中的苦味，否则这些水果的味道会令人不快，毒性更大。
The genus Solanum comprises three food crops (potato, tomato, and eggplant), which are consumed on daily basis worldwide and also producers of notorious anti-nutritional steroidal glycoalkaloids (SGAs). Hydroxylated SGAs (i.e. leptinines) serve as precursors for leptines that act as defenses against Colorado Potato Beetle (Leptinotarsa decemlineata Say), an important pest of potato worldwide. However, SGA hydroxylating enzymes remain unknown. Here, we discover that 2-OXOGLUTARATE-DEPENDENT-DIOXYGENASE (2-ODD) enzymes catalyze SGA-hydroxylation across various Solanum species. In contrast to cultivated potato, Solanum chacoense, a widespread wild potato species, has evolved a 2-ODD enzyme leading to the formation of leptinines. Furthermore, we find a related 2-ODD in tomato that catalyzes the hydroxylation of the bitter a-tomatine to hydroxytomatine, the first committed step in the chemical shift towards downstream ripening-associated non-bitter SGAs (e.g. esculeoside A). This 2-ODD enzyme prevents bitterness in ripe tomato fruit consumed today which otherwise would remain unpleasant in taste and more toxic.