Shikimate pathway modulates the elicitor-stimulated accumulation of fragrant 2-hydroxy-4-methoxybenzaldehyde in Hemidesmus indicus roots

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• 作者：Anish Kundu^a ; Narendra Jawali^b ; Adinpunya Mitra^a ; ^{adin@iitkgp.ac.in}
• 关键词：Glyphosate ; Hemidesmus indicus ; 2-Hydroxy-4-methoxybenzaldehyde ; Phenylalanine ammonia-lyase ; Shikimic acid ; Shikimate dehydrogenase
• 刊名：Plant Physiology and Biochemistry
• 出版年：2012
• 期刊代码：87_09819428
• 类别：abs
• 出版时间：July, 2012
• 卷：56
• 期：Complete
• 页码：104-108
• 文件大小：292 K

摘要

Enzymatic route to fragrant 2-hydroxy-4-methoxybenzaldehyde (MBALD) formation in Hemidesmus indicus roots is not known. Earlier studies with H.聽indicus excised roots suggested a possible origin of MBALD via central phenylpropanoid pathway. Different elicitors (e.g., chitosan, methyl jasmonate, yeast extract) were tested for their relative efficiency in uplifting MBALD accumulation in roots, amongst which, treatment with yeast extract for 18聽h showed maximum accumulation in excised roots. As benzoate pathways originate either directly from shikimate or via phenylpropanoid pathway, this study aimed at finding the roles of shikimate pathway in uplifting/enhancing MBALD accumulation in H.聽indicus roots upon elicitation. In fact, a sharp increase in shikimate dehydrogenase (SKDH; E.C. 1.1.1.25) along with phenylalanine ammonia-lyase (PAL; E.C. 4.3.1.24) activities was noted on a time-course basis in yeast extract-treated roots as compared to the untreated ones. PAL as well as phenylpropanoid C₂ side-chain cleavage activities (leading to p-hydroxybenzaldehyde, the first benzoate product formed in the MBALD pathway) were compared in elicited roots, non-elicited roots and glyphosate-treated elicited roots at different concentrations of glyphosate. It was observed that glyphosate treatment, in addition to 25%suppressions of phenylalanine ammonia-lyase and C₂ chain-cleavage enzyme activities as compared to elicited one, also resulted in around 40%suppression of MBALD accumulation, when used in conjunction with yeast extract treatment; in contrast, shikimic acid content was increased as compared to glyphosate untreated ones. These findings suggest that shikimate pathway plays an important role in modulating MBALD biosynthesis in H.聽indicus roots.