ARABIDOPSIS NITRATE REGULATED 1 acts as a negative modulator of seed germination by activatingABI3expression

Abstract

Seed germination is a crucial transition point in plant life and is tightly regulated by environmental conditions through the coordination of two phytohormones, gibberellin and abscisic acid (ABA). To avoid unfavorable conditions, plants have evolved safeguard mechanisms for seed germination. Here, we report a novel function of the Arabidopsis MADS-box transcription factor ARABIDOPSIS NITRATE REGULATED 1 (ANR1) in seed germination. ANR1 knockout mutant is insensitive to ABA, salt, and osmotic stress during the seed germination and early seedling development stages, whereas ANR1-overexpressing lines are hypersensitive. ANR1 is responsive to ABA and abiotic stresses and upregulates the expression of ABI3 to suppress seed germination. ANR1 and ABI3 have similar expression pattern during seed germination. Genetically, ABI3 acts downstream of ANR1. Chromatin immunoprecipitation and yeast-one-hybrid assays showed that ANR1 could bind to the ABI3 promoter to regulate its expression. In addition, ANR1 acts synergistically with AGL21 to suppress seed germination in response to ABA as evidenced by anr1 agl21 double mutant. Taken together, our results demonstrate that the ANR1 plays an important role in regulating seed germination and early post-germination growth. ANR1 and AGL21 together constitutes a safeguard mechanism for seed germination to avoid unfavorable conditions.

Molecular Mechanism Underlying the Synergetic Effect of Jasmonate on Abscisic Acid Signaling during Seed Germination in Arabidopsis

“…Additional Arabidopsis accessions used were Wassilewskija (Ws), and Landsberg erecta (Ler). The abi3-1 (Jiang et al, 2009), abi3-8 (Lin et al, 2020), abi5-1 (Finkelstein, 1994Finkelstein and Lynch, 2000), and abi5-7 (Zhou et al, 2015) The seeds were surface-sterilized in 20% (v/v) bleach for 15 min before being sown on water agar medium supplemented with 0.7% (w/v) agar, and were then maintained at 4°C for 3 d. After 7 d, the seedlings were transferred to soil. Then, plants were grown in chambers under long-day conditions, consisting of 14-h light (120 µE m −2 s −1 at 22°C, white fluorescent bulbs, full wavelength of light) and 10-h darkness (0 µE m −2 s −1 at 19°C), or short-day conditions, consisting of 8-h light (120 µE m −2 s −1 at 22°C) and 16-h darkness (0 µE m −2 s −1 at 19°C).…”

AGL16 negatively modulates stress response to balance with growth

“…AGL16 belongs to the AGL17-like clade which includes ANR1, AGL21, and AGL17 members, having the overlapping expression pattern in MIKC-type group (Alvarez-Buylla et al, 2000; Burgeff et al, 2001). ANR1 and AGL21 both act as negative modulators of seed germination and by controlling the expression of ABI3 or ABI5 respectively (Yu et al, 2017; Lin et al, 2019). In ABA signaling pathway, ABI3, ABI4, and ABI5 act as positive regulators that are necessary for achieving growth arrest when subjected to unfavorable conditions (Giraudat et al, 1992; Finkelstein and Lynch, 2000; Yamaguchi-Shinozaki and Shinozaki, 2006).…”

“…Some members of this TF family function in seed germination and root development. For example, ANR1 regulates lateral root growth in response to change in the external NO 3 - supply, affects primary root development (Zhang and Forde, 1998; Gan et al, 2005; Gan et al, 2012), and acts as a modulator synergistically with AGL21 to regulate the expression of ABI3 in seed germination (Lin et al, 2019). XAL1/AGL12 acts as an important regulator of cell proliferation in the root (Rounsley et al, 1995; Tapia-Lopez et al, 2008; Garcia-Cruz et al, 2016).…”

Arabidopsis MADS‐box factor AGL16 is a negative regulator of plant response to salt stress by downregulating salt‐responsive genes

“…Some members of this TF family function in seed germination and root development. For example, ANR1 regulates lateral root growth in response to change in the external NO 3 À supply, affects primary root development (Zhang & Forde, 1998;Gan et al, 2005Gan et al, , 2012, and acts as a modulator synergistically with AGL21 to regulate the expression of ABI3 in seed germination (Lin et al, 2019). AGL21 also positively regulates auxin accumulation in lateral root primordia and lateral root initiation and growth (Yu et al, 2017).…”