ER-Anchored Transcription Factors bZIP17 and bZIP60 Regulate Triterpene Saponin Biosynthesis inMedicago truncatula^1[OPEN]

Abstract

One sentence summaryER stress bZIP transcription factors can interfere with the activity of jasmonateinducible bHLH transcription factors to modulate the elicitation of plant specialized metabolism in stress conditions. Footnotes:

Saponin Biosynthesis in Pulses

“…Compared to the positive regulators, fewer negative regulators have been identified for saponin biosynthesis. The basic leucine zipper (bZIP) TFs, bZIP17 and bZIP60, downregulate JA-dependent triterpenoid saponin synthesis in M. truncatula by suppressing the activities of TSAR1 and TSAR2 [70].…”

Bridging the Gaps between Plant and Human Health: A Systematic Review of Soyasaponins

“…In addition to investigating positive regulators that mediate soyasaponin synthesis, negative regulators in soyasaponin synthesis also have been explored to a lesser extent. For example, the basic leucine zipper (bZIP) transcription factors bZIP17 and bZIP60, indicative of endoplasmic reticulum stress, have suspected roles in downregulating MeJA-induced triterpene saponin synthesis in barrel medic by impeding the activity of TSAR1 and TSAR2 . Furthermore, phytohormones such as gibberellins may act as negative regulators by downregulating enzymes such as β-amyrin in licorice and therefore decreasing soyasaponin synthesis .…”

“…For example, the basic leucine zipper (bZIP) transcription factors bZIP17 and bZIP60, indicative of endoplasmic reticulum stress, have suspected roles in downregulating MeJA-induced triterpene saponin synthesis in barrel medic by impeding the activity of TSAR1 and TSAR2. 66 Furthermore, phytohormones such as gibberellins may act as negative regulators by downregulating enzymes such as βamyrin in licorice and therefore decreasing soyasaponin synthesis. 61 Although transcriptional regulation plays the most prominent role in soyasaponin gene expression, recent work suggests that post-transcriptional modifications may also play a significant role in modulating soyasaponin production.…”