Low-temperature pretreatment of the root system of Brassica rapa L. plants: effects on the xylem sap exudation and on the nitrate absorption rate

1994 ◽  
Vol 17 (6) ◽  
pp. 721-729 ◽  
Author(s):  
J. BIGOT ◽  
J. BOUCAUD
2013 ◽  
Vol 275-277 ◽  
pp. 1662-1665 ◽  
Author(s):  
Qiang Li ◽  
Juan Juan Fei ◽  
Xu Ding Gu ◽  
Geng Sheng Ji ◽  
Yang Liu ◽  
...  

This study aims to establish a natural cellulosic biomass pretreatment process using ionic liquid (IL) for efficient enzymatic hydrolysis and second generation bioethanol. The IL 1-Butyl-3-methylimidazolium Chloride/FeCl3 ([Bmim]Cl/FeCl3) was selected in view of its low temperature pretreatment ability and the potential of accelerating enzymatic hydrolysis, and it could be recyclable. The yield of reducing sugars from sugarcane residue pretreated with this IL at 80 oC for 1 h reached 46.8% after being enzymatically hydrolyzed for 24 h. Sugarcane residue regenerated were hydrolyzed more easily than that treated with water. The fermentability of the hydrolyzates, obtained after enzymatic saccharification of the regenerated sugarcane residue, was transformed into bioethanol using Candida shehatae. This microbe could absorb glucose and xylose efficiently, and the ethanol production was 0.38 g/g glucose within 30 h fermentation. In conclusion, the metal ionic liquid pretreatment in low temperature shows promise as pretreatment solvent for natural biomass.


1990 ◽  
Vol 68 (9) ◽  
pp. 1942-1947 ◽  
Author(s):  
Philippe Brunet ◽  
Bruno Sarrobert ◽  
Nicole Paris-Pireyre ◽  
Ange-Marie Risterucci

Two species of tomato, Lycopersicon esculentum Mill. var. EGE12P1 and Lycopersicon hirsutum Humb. & Bonpl. ecotype LA 1777, were submitted to two temperature treatments, 20 or 10 °C. After a short study of plant growth, we analysed the chemical composition (cations, anions, and amino acids) of xylem sap by high performance liquid chromatography. A comparison of fresh weight increase at 20 and 10 °C of both plant species showed that L. hirsutum was the least affected by low temperature. The volumes of secreted sap and the quantities of ions transported showed great disturbances in the sensitive species (L. esculentum), especially in the case of potassium. In xylem sap of both species studied, but only at 10 °C, we noticed the appearance of ammonium. The possibility of contamination during analytical processing was eliminated. Moreover, determinations of amino acids levels showed that ammonium did not arise from degradation of amides present in xylem sap. In any event, the proportion of nitrate absorbed and reduced in roots increased at low temperature; it is much more important in L. hirsutum and could constitute a tolerance factor to low temperatures. Key words: ammonium, low temperature, Lycopersicon, xylem sap.


1996 ◽  
Vol 76 (2) ◽  
pp. 367-377 ◽  
Author(s):  
Liangxue Liu ◽  
Barry J. Shelp

In the present study, we tested the hypothesis that continuous chloride treatment decreases nitrate absorption and accumulation by broccoli (Brassica oleracea var. italica) plants. In a field experiment, both fresh and dry weights of shoot and inflorescence increased linearly with increasing nitrogen applied (70–130 kg ha−1). Chloride application (0–450 kg ha−1) did not significantly affect the final yield. In a greenhouse experiment in which the plants were grown in soilless culture and supplied with 10–18 mmol L−1 nitrate, only the fresh weights of shoot and inflorescence decreased linearly with increasing chloride application (0–45 mmol L−1). In both experiments, increasing chloride application slightly decreased the concentrations of nitrate nitrogen and total nitrogen in xylem sap, and increased the chloride concentrations of both xylem sap and phloem exudate and the total-nitrogen concentration of phloem exudate. The shoot-nitrate contents increased with increasing nitrogen application and decreased with increasing chloride application, whereas the shoot-chloride contents increased with increasing chloride application and decreased with increasing nitrate application. The total-nitrogen contents of the shoot were not affected by chloride application. These data are interpreted to suggest that nitrate absorption was not inhibited by the presence of chloride in the growing medium and that the decrease in nitrate accumulation of the shoot resulted from the stimulation of organic-nitrogen formation from absorbed nitrate. Key words: Antagonism, broccoli, chloride, interaction, nitrate


2021 ◽  
Author(s):  
Li Ma ◽  
Jing Bai ◽  
Jia Xu ◽  
Weiliang Qi ◽  
Haiyun Li ◽  
...  

Abstract Winter Brassica rapa is an important oilseed crop in northern China, but the mechanism of its cold resistance remains unclear. APX plays important roles in response of this plant to abiotic stress and in scavenging free radicals. In this study, 59 DEPs were isolated and identified from winter B. rapa and B. napus using bidirectional electrophoresis, and APX was found to be differentially expressed in these two species. Therefore, the roles of APX proteins in the cold response and superoxide metabolism pathways in both rapeseed species were further investigated. And comprehensive analysis of phylogeny, chromosome distribution, motif identification, sequence structure, gene duplication, and RNA-seq expression profile in APX gene family. Most of the BrAPX genes were specifically expressed under low temperature stress and behaved significantly differently in cold-tolerant and cold-sensitive varieties. qPCR was also used to verify the differences in expression between these two varieties under cold, freezing, drought and heat stress, and these candidate genes and proteins may play important roles in the response of B. rapa to low temperature stress and provide new information for the elucidation of the cold resistance mechanism in B. rapa.


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