OsRLCK160 contributes to flavonoid accumulation and UV-B tolerance by regulating OsbZIP48 in rice

Science China Life Sciences - Plants produce specialized metabolites to adapt to the ever-changing environments. Flavonoids are antioxidants essential for growth, development, and breeding with...     

Elevated CO2 levels enhance the uptake and metabolism of organic nitrogen

The effects of elevated CO₂ (eCO₂) on the relative uptake of inorganic and organic nitrogen (N) are unclear. The uptake of different N sources by pak choi (Brassica chinensis L.) seedlings supplied with a mixture of nitrate, glycine and ammonium was studied using ¹⁵N‐labelling under ambient CO₂ (aCO₂) (350 ppm) or eCO₂ (650 ppm) conditions. ¹⁵N‐labelled short‐term uptake and ¹⁵N‐gas chromatography mass spectrometry (GC–MS) were applied to measure the effects of eCO₂ on glycine uptake and metabolism. Elevated CO₂ increased the shoot biomass by 36% over 15 days, but had little effect on root growth. Over the same period, the N concentrations of shoots and roots were decreased by 30 and 2%, respectively. Elevated CO₂ enhanced the uptake and N contribution of glycine, which accounted for 38–44% and 21–40% of total N uptake in roots and shoots, respectively, while the uptake of nitrate and ammonium was reduced. The increased glycine uptake resulted from the enhanced active uptake and enhanced metabolism in the roots. We conclude that eCO₂ may increase the uptake and contribution of organic N forms to total plant N nutrition. Our findings provide new insights into plant N regulation under eCO₂ conditions.     

不同生态稻区覆膜旱作稻氮营养生理及抗逆生理特性探讨

不同生态稻区生态环境和栽培管理方式不同,覆膜旱作稻氮营养生理和抗逆生理与常规水作稻有些异同,尤其是体内NO₃^--N和NH₄⁺-N含量及分布差异很大.杭嘉湖平原区覆膜旱作稻生长前期受干热天气影响,其分蘖期、拔节期、孕穗期体内NO₃^--N含量较水作稻有不同程度的降低,而NH₄⁺-N含量则极显著提高;金衢盆地覆膜旱作稻孕穗期体内NO₃^--N含量比常规水作稻高,根部NH₄⁺-N含量则显著降低,茎基部和叶片NH₄⁺-N含量有一定增加.正常气候条件下两生态稻区覆膜旱作稻孕穗期叶片硝酸还原酶(NR)活性和谷氨酰胺合成酶(GS)活性较水作稻均有不同程度的提高;丙二醛(MDA)、可溶性糖及脯氨酸(Pro)含量与水作稻相差不大,表明不同生态稻区的覆膜旱作稻可以通过不同的栽培管理模式,促进生长发育,达到高产目的.     

Mixed-nitrogen nutrition-mediated enhancement of drought tolerance of rice seedlings associated with photosynthesis,hormone balance and carbohydrate partitioning

To investigate whether mixed-N (NO₃ ^??+?NH₄ ⁺) nutrition can enhance rice growth under water-deficit condition, a hydroponic experiment in which rice plants were supplied with different N forms (NO₃ ^?, NH₄ ⁺ and mixed-N) was conducted, and the intrinsic mechanisms involved in photosynthesis, root-shoot carbon partitioning, and hormone signalling were investigated. Water stress was found to decrease rice biomass, leaf area, chlorophyll and Rubisco contents. However, mixed-N nutrition substantially alleviated these inhibitions compared with NO₃ ^? nutrition alone. Mixed-N nutrition also maintained a higher electron transport rate, actual photochemical efficiency of PSII, and non-photochemical quenching, causing higher photosynthesis and photochemical efficiency. Water stress up-regulated leaf sucrose-phosphate synthase (SPS), but down-regulated acid invertase (InvA). However, leaf InvA and root sucrose synthase in the cleavage direction (SSc) in NO₃ ^? nutrition was higher than that in mixed-N nutrition. Water stress decreased indole acetic acid (IAA) content in leaves and cytokinins content in roots, but their contents in mixed-N nutrition were higher than those in NO₃ ^? nutrition. In mixed-N nutrition, the up-regulation of SPS and IAA in leaves and the reduction of sucrose metabolism (SSc and InvA) in roots jointly resulted in the accumulation of sucrose in leaves and the inhibition of its transportation to roots, finally reducing the root:shoot ratio (R/S). The reduced R/S provides more photosynthates for shoots and increases the utilisation efficiency, thereby strengthening the water-deficit tolerance of plants. We concluded that the strengthened water-deficit tolerance in mixed-N-supplied rice was closely associated with higher accumulation of dry matter mainly via improvement of photosynthesis and photochemical efficiency, hormone balance, and coupling with root-shoot carbon partitioning.     

Gompertz曲线与logistic增长曲线之比较

本文给出了生物增长模型中常用的logistic曲线与Gompertz曲线之间的主要差异与相似处．     

Branched-chain amino acids regulate plant growth by affecting the homeostasis of mineral elements in rice

<正>Dear Editor,Branched-chain amino acids (BCAAs) are essential amino acids that must be obtained from the diet for humans and animals. Branched-chain amino acid transaminases (BCATs)catalyze a key step in the BCAA synthesis pathway, however, little is known about their biological roles in planta. In this study, we functionally characterized two BCATs, OsBCAT4 and OsBCAT5, in rice and showed that they regulate     

供氮水平对爬山虎（Parthenocissus tricuspidata Planch）生物量及养分分配的影响

爬山虎是典型的亚热带木本攀援植物,在垂直绿化、植被恢复和水土保持等方面的应用日益普遍,而营养元素对爬山虎生长的影响还缺乏研究,这不利于爬山虎的生长调控与合理应用。通过水培试验,对不同氮素水平（0、0.15、0.3、0.45、0.6、0.75 g•L-1）条件下爬山虎幼苗生长、氮磷钾营养分配和利用状况作了研究。结果表明：供氮水平的提高能显著促进植株的生物量增加,并影响茎叶的生物量分配比例,供氮处理的叶生物量占总生物量的50%以上;供氮水平的提高能增加植株根、茎、叶的氮含量,对磷含量影响不显著,对茎叶中的钾含量有一定的稀释作用;叶片是主要的氮养分贮存器官,叶片氮累积量达到整个植株总氮累积量的60%以上;供氮水平的增加,降低了爬山虎的氮利用率,提高了磷钾的利用率。