The bitter side of the nightshades: Genomics drives discovery in Solanaceae steroidal alkaloid metabolism

Cárdenas, Pablo D.; Sonawane, Prashant; Heinig, Uwe; Bocobza, Samuel; Burdman, Saul; Aharoni, Aspah

doi:10.1016/j.phytochem.2014.12.010

Cited by 115 publications

(89 citation statements)

References 72 publications

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“…PGA2 gene is in a gene cluster on chromosome 7 (Itkin et al, 2013;Cárdenas et al, 2015), but the PGA1 genes are tandemly located on chromosome 6 of S. tuberosum Group Phureja DM1-3 (Xu et al, 2011), not in a specialized gene cluster for metabolism as described (Nützmann and Osbourn, 2014). As the SSR2 gene is also located on chromosome 2 (Sawai et al, 2014), specialized gene clusters for the SGA biosynthesis are though not to be complete.…”

Section: Discussion Pga1 and Pga2 Catalyze Hydroxylation Steps From Chrmentioning

confidence: 98%

Two Cytochrome P450 Monooxygenases Catalyze Early Hydroxylation Steps in the Potato Steroid Glycoalkaloid Biosynthetic Pathway

et al. 2016

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Solanine and a-chaconine, steroidal glycoalkaloids (SGAs) found in potato (Solanum tuberosum), are among the best-known secondary metabolites in food crops. At low concentrations in potato tubers, SGAs are distasteful; however, at high concentrations, SGAs are harmful to humans and animals. Here, we show that POTATO GLYCOALKALOID BIOSYNTHESIS1 (PGA1) and PGA2, two genes that encode cytochrome P450 monooxygenases (CYP72A208 and CYP72A188), are involved in the SGA biosynthetic pathway, respectively. The knockdown plants of either PGA1 or PGA2 contained very little SGA, yet vegetative growth and tuber production were not affected. Analyzing metabolites that accumulated in the plants and produced by in vitro enzyme assays revealed that PGA1 and PGA2 catalyzed the 26-and 22-hydroxylation steps, respectively, in the SGA biosynthetic pathway. The PGA-knockdown plants had two unique phenotypic characteristics: The plants were sterile and tubers of these knockdown plants did not sprout during storage. Functional analyses of PGA1 and PGA2 have provided clues for controlling both potato glycoalkaloid biosynthesis and tuber sprouting, two traits that can significantly impact potato breeding and the industry.

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Section: Discussion Pga1 and Pga2 Catalyze Hydroxylation Steps From Chrmentioning

confidence: 98%

Two Cytochrome P450 Monooxygenases Catalyze Early Hydroxylation Steps in the Potato Steroid Glycoalkaloid Biosynthetic Pathway

et al. 2016

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“…Based on coexpression analyses of two genes relevant for biosynthesis of α-tomatine, the major SGA in tomato, a number of additional genes (denoted GAME1 to GAME18 ) in α-tomatine biosynthesis were identified and functionally characterized21. Orthologous genes in potato were also described, leading to a model for SGA biosynthesis in potato and tomato22. Recently, the transcription factor GAME9 (also called JRE4) was shown to regulate the expression in tomato and potato of genes in the isoprenoid and SGA biosynthesis pathways2324.…”

mentioning

confidence: 99%

Transcript profiling of two potato cultivars during glycoalkaloid-inducing treatments shows differential expression of genes in sterol and glycoalkaloid metabolism

Nahar

Westerberg

Arif

et al. 2017

Sci Rep

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Steroidal glycoalkaloids (SGA) are sterol-derived neurotoxic defence substances present in several members of the Solanaceae. In the potato (Solanum tuberosum), high SGA levels may render tubers harmful for consumption. Tuber SGA levels depend on genetic factors, and can increase as a response to certain stresses and environmental conditions. To identify genes underlying the cultivar variation in tuber SGA levels, we investigated two potato cultivars differing in their SGA accumulation during wounding or light exposure; two known SGA-inducing treatments. Using microarray analysis coupled to sterol and SGA quantifications, we identified a small number of differentially expressed genes that were associated with increased SGA levels. Two of these genes, encoding distinct types of sterol Δ24-reductases, were by sense/antisense expression in transgenic potato plants shown to have differing roles in sterol and SGA metabolism. The results show that an increased SGA level in potato tubers during both wounding and light exposure is mediated by coordinated expression of a set of key genes in isoprenoid and steroid metabolism, and suggest that differences in this expression underlie cultivar variations in SGA levels. These results may find use within potato breeding and quality assessment.

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“…Выявлена корреляция между высоким содержанием СГА и высоким уровнем транскриптов генов этих двух ферментов (Krits et al, 2007). Фермент скваленэпоксидаза превращает сква лен в 2,3оксидосквален (Heftmann, 1983;Cárdenas et al, 2015). Циклоартенолсинтаза преобразует 2,3оксидосква-лен в наиболее элементарный стерол -циклоартенол.…”

Section: регуляция биосинтеза сгаunclassified

“…Два послед-них шага являются точкой ветвления путей синтеза СГА и безазотистых сапонинов картофеля. Последующие нуклео фильные замены посредством промежуточного соедине-ния тенеимина могут объяснить образование со ланидина (Cárdenas et al, 2015). В гликозилировании соланидина участвуют три фермента: SGT1 (гомолог GAME1), SGT2 и SGT3 (GAME2).…”

Section: регуляция биосинтеза сгаunclassified

“…СГА локализованы непо-средственно в цитоплазме -главным образом в вакуолях, а также в апопласте растений томата и картофеля (Cárdenas et al, 2015). Они найдены во всех органах и тканях рас-тений картофеля, кроме сердцевины клубня.…”

Section: метаболизм сга и распределение в растительных тканяхunclassified

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The Biosynthesis Regulation of Potato Steroidal Glycoalkaloids

Ivanova¹,

Gerasimova²,

Хлесткина³

2018

Vestn. VOGiS

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Potato steroidal glycoalkaloids (SGAs) compose a part of plant immunity. Some of their modified variants are toxic to humans. In the course of potato domestication, plants with a lower SGA level were selected. The advent of approaches for manipulation with the regulation of metabolic pathways provides an opportunity to overcome the undesirable direct relationship between the potato resistance to pests and the toxicity of its tubers. However, for such a fine regulation, a deep knowledge of the regulatory network of potato SGA biosynthesis is required. The purpose of this review is to summarize the information on the known SGA biosynthesis genes in plants and the results of the investigation of these genes in potato, as well as to consider the mechanisms of the SGA protective toxic action against pathogens and pests. The SGA biosynthesis is realized via the cytosolic mevalonate pathway and consists of three stages. The first two stages are required for the synthesis of primary metabolites, and lead to cycloartanol and cholesterol, respectively. Twelve enzymes are involved in the biosynthesis, and the half of them are involved in the biosynthesis of phytosterols, which is a branch of the first stage of this metabolic pathway. In the potato leaves with an excess of phytosterols, the synthesis switches to SGAs, increasing the content of the latter. In tubers, with an excess of SGA precursors, they are involved in the synthesis of lanosterol, supporting in this way the stable level of SGA. The importance of structural genes encoding the enzymes of the first two stages of biosynthesis does not allow us to consider them as a target for knockout in order to reduce the level of SGAs. However, information about the tissue-specific mechanisms of switching between the pathways of synthesis of SGA and other compounds having common precursors with SGAs can be used to manipulate the tissue-specific level of steroidal glycoalkaloids. At the third stage (the synthesis of glycoalkaloids from cholesterol), about 20 enzymes participate. In the potato genome, 14 corresponding genes were identified, 8 of which were studied in detail using reverse genetics approaches. As a promising target for reducing SGA levels in tubers, the genes encoding PGA enzymes (belonging to the CYP72 subfamily cytochrome-P450-dependent monooxygenases catalyzing the conversion of hydrocholesterol to trihydrocholesterol) and SGT (SGA glycosyltransferases that catalyze the conversion of solanidine to its toxic glycosylated derivatives α-solanine and α-chaconine) are considered. Cis-regulatory elements in the promoter regions of some glycoalkaloid biosynthesis genes, including elements responsible for tissue-specific expression, Стероидные гликоалкалоиды (СГА) картофеля составляют часть иммунитета растений. Некоторые их модифицированные фор-мы токсичны для человека. В ходе доместикации картофеля происходил отбор растений с пониженным уровнем СГА. В на-стоящее время с появлением методов, при помощи которых возможно специфично влиять на регуляцию метаболических пу...

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The bitter side of the nightshades: Genomics drives discovery in Solanaceae steroidal alkaloid metabolism

Cited by 115 publications

References 72 publications

Two Cytochrome P450 Monooxygenases Catalyze Early Hydroxylation Steps in the Potato Steroid Glycoalkaloid Biosynthetic Pathway

Two Cytochrome P450 Monooxygenases Catalyze Early Hydroxylation Steps in the Potato Steroid Glycoalkaloid Biosynthetic Pathway

Transcript profiling of two potato cultivars during glycoalkaloid-inducing treatments shows differential expression of genes in sterol and glycoalkaloid metabolism

The Biosynthesis Regulation of Potato Steroidal Glycoalkaloids

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