Melatonin Mediates Axillary Bud Outgrowth by Improving Nitrogen Assimilation and Transport in Rice

Abstract

Melatonin plays an important role in plant resistance to biotic and abiotic stresses. However, whether melatonin is involved in the regulation of plant architecture, such as the formation of axillary bud outgrowth or tillering, in rice remains unknown. Here, we found that different concentrations of melatonin influenced axillary bud outgrowth in rice, and moderate melatonin concentrations also alleviated the inhibition of axillary bud outgrowth in the presence of high concentrations of basic amino acids lysine and arginine. Furthermore, transcriptome analysis demonstrated that genes involved in nitrogen metabolism and phytohormone signal transduction pathways may affect axillary bud outgrowth, which is regulated by melatonin. We determined that the differentially expressed genes glutamine synthetase OsGS2 and amino acid transporter OsAAP14, which are involved in nitrogen metabolism and are regulated by melatonin and basic amino acids, were the key regulators of axillary bud outgrowth in rice. In addition, we validated the functions of OsGS2 and OsAAP14 using rice transgenic plants with altered axillary bud outgrowth and tillers. Taken together, these results suggest that melatonin mediates axillary bud outgrowth by improving nitrogen assimilation and transport in rice.

Physiological and transcriptomic analysis provides novel insight into growth in Kam sweet rice under different nitrogen supplies

“…Similarly, it was shown that OsAAP5 expression is up‐regulated by nitrate and ammonium concentrations (Wang et al, 2019). Additionally, it has been reported that OsAAP14 expression levels are regulated by exogenous basic amino acids (Yang et al, 2022). The expression of OsAAP15 is significantly up‐regulated under 0.5–15 mM N treatment (Yang et al, 2023).…”

“…Moreover, CRISPR of OsAAP5 significantly increases tillers by decreasing levels of basic amino acids Lys and Arg (Wang et al, 2019). OsAAP14 overexpression leads to increased tillers in rice subjected to melatonin concentrations (Yang et al, 2022). The response of OsAAP15 negatively influences panicle branching under high nitrogen conditions, affecting the levels of endogenous amino acids Tyr and Val in rice panicles (Yang et al, 2023).…”

Blocking of amino acid transporter OsAAP7 promoted tillering and yield by determining basic and neutral amino acids accumulation in rice

“…To delve deeper into amino acid transport, ZH11, OsAAP7 OE and C lines were subjected to treatment with 1 mM Fluorescent amino acid Arg, Phe or Lys for 2 h, 6 or 10 h. Subsequently, the rice seedlings were examined using a Chemiluminescence Apparatus (Qinxiang, China), and the fluorescent intensity was quantified utilizing Bandscan [ 23 , 24 ].…”

“…OsAAP6 regulates the uptake and distribution of amino acids in rice [ 22 ]. Amino acid transporter OsAAP14 determines bud outgrowth under melatonin treatment, thereby influencing rice tillering and grain yield [ 23 ]. Overexpressing of OsAAP15 in rice enhances both primary and secondary branches in the panicle, attributed to its impact on the concentrations of amino acids Tyr and Val in the rice panicle [ 24 ].…”

A Cationic Amino Acid Transporter NtCAT1 Promotes Leaf Senescence by the Accumulation of ABA in Nicotiana tabacum

“…Numerous studies have suggested that amino acid transporters play a fundamental role in the process of organic N recycling [8,11,12]. Moreover, an increasing number of reports indicate that various amino acid transporters are involved in the regulation of plant growth and development and abiotic and biotic stress tolerance [12][13][14][15][16]. In Arabidopsis, overexpressing AtCAT1 decreases the total biomass of soil-grown plants and enhances the resistance to pathogen attack (P. syringae) [12].…”