Development of Cold Tolerance in White Clover (Trifolium repens L.) in Relation to Carbohydrate and Free Amino Acid Content

Abstract

Development of cold tolerance in white clover (Trifolium repens L.) genotypes originating from various parts of Norway and grown outdoors at Tromso, latitude 69°39′N, has been studied. Stolon samples for an artificial freezing test and for chemical analysis were collected three times during the autumn. Generally, the most northern genotypes were more cold tolerant than the southern ones. Cold tolerance increased significantly from September to November in all genotypes. Content of dry matter, soluble carbohydrates, sucrose and proline in stolons increased during the hardening process. These changes were similar in both northern and southern genotypes of white clover.     

Effects of duration and combination of drought and flood conditions on leaf photosynthesis,growth and sugar content in sugarcane

Global climate change will result in extreme environments, such as droughts and floods. We investigated the individual and combined effects of droughts and floods of varying duration on sugarcane (Saccharum spp.) growth using a pot experiment under glasshouse conditions with the following six treatments: drought for 15 d, prolonged drought for 30 d, flood for 15 d, prolonged flood for 30 d, short flood followed by prolonged drought, and prolonged flood followed by prolonged drought. Plants that were subjected to drought conditions, including drought after a flood, had reduced CO₂ assimilation (through stomatal closure) and leaf areas, whereas flood conditions showed no effect. During flooding, some roots died, and adventitious roots with well-developed aerenchyma appeared from the submerged nodes. At the time of harvest, there were no significant differences in stem fresh weight, sucrose content, or sugar yield between the treatments. However, ion content analysis revealed that flood conditions caused an accumulation of sodium in the bottom of stems and adventitious roots. Therefore, under flood conditions, plants may develop adventitious roots, which may offset the negative effects of root death, helping them to maintain their growth and yield.     

外源精胺对菜用大豆贮藏冷害及蔗糖代谢的影响

【目的】探讨精胺（Spermine,Spm）处理延缓菜用大豆贮藏冷害以及调节其蔗糖代谢的作用机理,为菜用大豆的采后贮藏保鲜技术提供参考。【方法】以‘新大粒1号’菜用大豆为试验材料,分别用0.5、1 和2 mmol·L^-1外源Spm浸泡处理20 min,以清水浸泡为对照,于1℃、相对湿度为85%-90%的环境条件下贮藏10周,每周分别测定与菜用大豆抗冷性相关的生理指标,籽粒中蔗糖、果糖和葡萄糖含量,及与蔗糖代谢相关的酶活性指标。【结果】贮藏第2周即出现冷害,随着冷藏时间延长,菜用大豆冷害发生逐渐加重。与对照相比,Spm处理使冷害症状出现时间推迟到第3周,延缓了贮藏后期冷害指数的上升;也抑制了菜用大豆细胞膜透性的增加,贮藏5周后,0.5和1 mmol·L^-1 Spm处理与对照的差异均达到显著水平（P＜0.05）;此外,冷藏期间的菜用大豆籽粒中膜脂过氧化产物-丙二醛（MDA）不断积累,低浓度Spm能缓解膜脂过氧化,减少MDA积累,而高浓度Spm可能产生毒害作用;与对照相比,1 mmol·L^-1 Spm明显提高了菜用大豆冷藏期间抗氧化酶-过氧化氢酶（CAT）、过氧化物酶（POD）和超氧化物歧化酶（SOD）的活性;与此同时,Spm处理也显著减少了菜用大豆籽粒蔗糖的损失（P＜0.05）,经过Spm处理的菜用大豆籽粒中果糖与葡萄糖含量低于对照,但整个贮藏期不同浓度处理间差异不显著（P＞0.05）。进一步通过冷藏菜用大豆籽粒可溶性糖含量与酸性转化酶（AI）、中性转化酶（NI）、蔗糖合成酶（SS）和蔗糖磷酸合成酶（SPS）4种蔗糖代谢相关酶活性之间的相关性分析发现,蔗糖含量与AI活性呈极显著负相关（P＜0.01）,与SPS活性呈极显著正相关（P＜0.01）,而与NI和SS活性之间没有显著相关性,说明AI和SPS对菜用大豆冷藏期间蔗糖的降解起到了关键的调节作用,外源Spm通过对蔗糖代谢相关酶活性的调节有效抑制了冷藏菜用大豆籽粒中蔗糖含量的损失。【结论】Spm可有效延缓菜用大豆1℃贮藏期间冷害的发生,最适浓度为1 mmol·L^-1;蔗糖损失可能是导致菜用大豆冷害加剧的重要原因,Spm通过抑制AI活性增加的同时,延缓SPS活性的降低,以维持冷藏期间菜用大豆籽粒较高的蔗糖含量。     

转Susy基因对棉花农艺性状的影响

以新陆早13号为受体,对利用花粉管通道法得到的转蔗糖合成酶基因(Sucrose Synthase Gene, Susy)棉花进行研究,比较转Susy基因植株T5代株系与受体新陆早13号形态性状、产量性状和纤维品质的差异,结果表明,Susy基因的导入对棉花各农艺性状有不同程度的影响,各性状变异系数增加,其中果枝数和皮棉产量差异显著;植株叶片和茎秆的表皮茸毛密集,数量比对照显著增加5倍;纤维长度和强度略有增加,马克隆值降低,品质得到改善.有望为棉花品质育种提供优良材料.     

菜用大豆籽粒中蔗糖的遗传与调控机制研究进展

甜味是菜用大豆食味品质的重要方面,是菜用大豆区别于普通粒用型大豆的显著特征之一。菜用大豆的甜味主要归因于可溶性糖含量,其中蔗糖含量约占可溶性总糖的71%,是决定菜用大豆甜度的关键因素,同时也与菜用大豆食味品质评分高度相关。理解蔗糖在菜用大豆籽粒中的遗传与调控机制,对于加速菜用大豆食味品质的遗传改良,提升我国菜用大豆的国际市场竞争力具有重要意义。本文主要对菜用大豆籽粒中蔗糖积累的遗传基础、蔗糖代谢过程中关键酶及同源基因的克隆与调控机制研究进行了归纳总结,并展望了今后菜用大豆蔗糖含量遗传改良发展趋势,以期为菜用大豆食味品质的提升提供参考依据。     

辛酸蔗糖酯的合成与杀虫活性研究

该文以无水碳酸钾为催化剂,低毒的二甲基亚砜为溶剂,采用酯交换法在减压条件下高效合成了一类新型绿色杀虫剂——辛酸蔗糖酯,并针对其合成条件进行了初步的优化.通过单因子实验得到合成辛酸蔗糖酯最佳条件为:蔗糖与辛酸乙酯的投料摩尔比2∶1,反应温度95～100℃,反应时间5 h,催化剂用量（占辛酸乙酯质量分数）16%,反应绝对压力11 kPa,产率为79.11%.所得产物经柱色谱分离、质谱表征,以及傅立叶红外光谱分析,确定分离得到的为辛酸蔗糖单酯、二酯和三酯.合成的辛酸蔗糖酯、分离得到的单酯、二酯和三酯分别对舞毒蛾1龄幼虫进行杀虫实验,单酯的杀虫活性为最高;对农业害虫大豆蚜虫的室内防治实验,在施药5 d后,高浓度处理的校正虫口减退率在80%左右,证明了产物具有一定的杀虫活性.      

中国双低油菜饼粕与加拿大卡诺拉粕品质特性的化学评价

系统地评价了 3个中国双低油菜与加拿大卡诺拉的商品饼粕与脱脂种籽的蛋白质、氨基酸、蔗糖、寡聚糖、饲粮总纤维和灰分等化学特性 ,并对饲粮总纤维的构成成分及加工的影响进行了研究。饲粮总纤维由非淀粉多糖、木质素和多酚、细胞壁蛋白质和矿物质组成。 3个中国双低菜粕的粗蛋白、蔗糖及必需氨基酸含量均接近或高于卡诺拉帕 ,但饲粮总纤维含量显著不同 ,尤其是蛋白质含量由于加工方式不同变异极大。在试验室条件下加工的脱脂种籽样品与相应的饼粕样品相比 ,蔗糖、赖氨酸和饲粮纤维含量变化显著。因此 ,改进双低油菜的加工技术是提高饼粕质量的关键     

Comparison of methods for protein extraction from pine needles

Extraction of proteins from pine needles for proteomic analysis has long been a challenge for scientists. We compared three different protein extraction methods including sucrose, Tris-HCl and trichloroacetic acid （TCA）/acetone （TCA method） to determine their efficiency in separating pine needle proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS-PAGE） and two-dimensional PAGE （2D-PAGE）. Proteins were then separated by SDS-PAGE. Among three methods the method using sucrose extraction buffer showed the highest efficiency and highest quality in separating proteins. In addition, clearer and more stable strips were detected by SDS-PAGE using sucrose extraction buffer. When the proteins extracted using sucrose extraction buffer were separated by 2D-PAGE, more than 300 protein spots, with isoelectric points （PI） ranging from 4.0 to 7,0 and molecular weights （MW） from 6.5 to 97.4 kD, were observed. This confirmed that the method with sucrose extraction buffer was an efficient and reliable method for extracting proteins from pine needles.     

蔗糖酯的特性及在食品中的应用

蔗糖酯是一种安全的食品乳化剂,有宽范围的HLB值,具有优良的物理化学性质,在食品中应用广泛。