The HD-ZIP IV transcription factor GLABRA2 acts as an activator for proanthocyanidin biosynthesis in Medicago truncatula seed coat.

Publisher: Blackwell Scientific Publishers and BIOS Scientific Publishers in association with the Society for Experimental Biology Country of Publication: England NLM ID: 9207397 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1365-313X (Electronic) Linking ISSN: 09607412 NLM ISO Abbreviation: Plant J Subsets: MEDLINE

Original Publication: Oxford : Blackwell Scientific Publishers and BIOS Scientific Publishers in association with the Society for Experimental Biology, c1991-

Medicago truncatula*/genetics ; Medicago truncatula*/metabolism ; Proanthocyanidins*/metabolism ; Proanthocyanidins*/biosynthesis ; Seeds*/genetics ; Seeds*/metabolism ; Seeds*/growth & development ; Plant Proteins*/genetics ; Plant Proteins*/metabolism ; Transcription Factors*/metabolism ; Transcription Factors*/genetics ; Gene Expression Regulation, Plant*; Plants, Genetically Modified ; Homeodomain Proteins/genetics ; Homeodomain Proteins/metabolism

Proanthocyanidins (PAs), a group of flavonoids, are found in leaves, flowers, fruits, and seed coats of many plant species. PAs are primarily composed of epicatechin units in the seed coats of the model legume species, Medicago truncatula. It can be synthesized from two separate pathways, the leucoanthocyanidin reductase (MtLAR) pathway and the anthocyanidin synthase (MtANS) pathway, which produce epicatechin through anthocyanidin reductase (MtANR). These pathways are mainly controlled by the MYB-bHLH-WD40 (MBW) ternary complex. Here, we characterize a class IV homeodomain-leucine zipper (HD-ZIP IV) transcription factor, GLABRA2 (MtGL2), which contributes to PA biosynthesis in the seed coat of M. truncatula. Null mutation of MtGL2 results in dark brown seed coat, which is accompanied by reduced PAs accumulation and increased anthocyanins content. The MtGL2 gene is predominantly expressed in the seed coat during the early stages of seed development. Genetic and molecular analyses indicate that MtGL2 positively regulates PA biosynthesis by directly activating the expression of MtANR. Additionally, our results show that MtGL2 is strongly induced by the MBW activator complexes that are involved in PA biosynthesis. Taken together, our results suggest that MtGL2 acts as a novel positive regulator in PA biosynthesis, expanding the regulatory network and providing insights for genetic engineering of PA production.
(© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.)

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2023YFF1001400 National Key Research and Development Program of China; 32170833 National Natural Science Foundation of China; 32201446 National Natural Science Foundation of China; 32370881 National Natural Science Foundation of China; ZR2020KC018 Natural Science Foundation of Shandong Province; Tianfu Outstanding Scientist Program

Keywords: Medicago truncatula; GLABRA2; HD‐ZIP IV transcription factor; anthocyanidin reductase; proanthocyanidin; seed coat

0 (Proanthocyanidins)
0 (Plant Proteins)
0 (Transcription Factors)
18206-61-6 (proanthocyanidin)
0 (Homeodomain Proteins)

Date Created: 20240711 Date Completed: 20240827 Latest Revision: 20240904

20240904

10.1111/tpj.16918

38990552