Ammonium (NH4 +) serves as a nitrogen source, but its elevated levels can hinder plant growth and production. Excess NH4 + with α-ketoglutarate is assimilated into glutamate, a precursor of proline and glutathione (GSH). This study aimed to investigate the effects of excessive NH4 + on the regulation of proline and GSH synthesis. Detached leaves from oilseed rape (Brassica napus L.) were fed with 0, 50, 100, 500, and 1000 mM NH4Cl for 16 h. As the NH4 + concentrations increased, the leaves exhibited progressive wilting and yellowing. Furthermore, total carotenoid and chlorophyll concentrations declined in response to all NH4 + treatments, with the lowest levels observed in 1000 mM NH4 + treatment. Hydrogen peroxide (H2O2) concentration showed a minor increase at low NH4 + concentration (50 and 100 mM) treatments but a significant increase at high NH4 + (500 and 1000 mM), which was consistent with the localization of H2O2. Amino acid concentrations increased with increasing in NH4 + concentration, while the protein concentration displayed the opposite trend. Proline and cysteine concentrations exhibited a gradual increase in response to increasing NH4 + concentrations. However, GSH concentrations rose only in the 50 mM NH4 + treatment and decreased in the 500 and 1000 mM NH4 + treatments. These results indicate that excessive NH4 + is primarily assimilated into proline, while GSH synthesis is adversely affected.

Sulfur is an essential element in plants, including amino acids, vitamin synthesis, and acting as an antioxidant. However, the interaction between endogenous sulfur and proline synthesis has not been yet fully documented. White clover (Trifolium repens L.) is known as a species highly sensitive to sulfate supply. Therefore, this study aimed to elucidate the role of sulfur in regulating proline metabolism in relation to ammonia detoxification and hydrogen peroxide (H2O2) accumulation in white clover. The detached leaves of white clover were immersed in solution containing different concentration of sulfate (0, 10, 100, and 1000 mM MgSO4). As MgSO4 concentrations were increased, the concentration of H2O2 increased up to 2.5-fold compared to control, accompanied with H2O2 detection in leaves. Amino acid concentrations significantly increased only at higher levels (100 and 1000 mM MgSO4). No significant difference was observed in protein concentration. Proline and Δ1-pyrroline-5-carboxylate (P5C) concentrations slightly decreased at 10 and 100 mM MgSO4 treatments, whereas it rapidly increased over 1.9-fold at 1000 mM MgSO4 treatment. Ammonia concentrations gradually increased up to 8.6-fold. These results indicate that exogenous sulfur levels are closely related to H2O2 and ammonia synthesis but affect proline biosynthesis only at a higher level.

기니아그라스의 유성생식 계통과 아포믹시스 계통을 이용하여 최적의 조직배양 조건을 검토하기 위하여 절편체 부위의 조직배양 능력 및 배양배지의 조건을 검토하였다. 그 결과 미성 숙배를 분리한 후 L-proline 2 g/L가 첨가된 캘러스 유도 배지에 치상하였을 때 높은 캘러스 유도율 및 활발한 증식을 관찰할 수 있었다. 또한 유도된 캘러스를 대상으로 재분화 효율을 조사한 결과, 성숙종자 유래의 캘러스는 재분화 능력을 가지고 있지 않은 반면에, 미성숙배 유

This study conducted to elucidate the change of the cation content (Na+ , K+ , and Ca2+ ), the L-proline content, and the sugar and starch content in the stems, roots, and leaves of three cultivars of the 30 days old seedling soybeans (Glycine max L. cv. Danwonkong, Hwang-keumkong, and Kwangankong) after 100 mM NaCl stress containing 1/2 Hoaglands nutrient solution in the sand culture. The reduction of the dry matter weight after 100 mM NaCl treatment among cultivars was higher in the order of Kwangankong, Danwonkong, and Hwang-keumkong. The highest reduction of the dry matter weight was occurred at the roots among three parts of plant. The Na+ content increased with NaCl treatment in overall and specially greatly increased in roots and stems. The K+ and Ca2+ content decreased with NaCl treatment at the roots and stems. The K+ content, however, at the leaves increased in all three cultivars with the NaCl treatment. The L-proline content with NaCl stress increased greatly. The increment of the L-proline content at the stems and roots of Hwangkeumkong was lower than that of other two cultivars, K wangankong and Danwonkong. The sugar content decreased with NaCl treatment at the stems and leaves. The starch content also decreased at the stems and leaves with NaCl treatment.aCl treatment.