Extremely long-distance seed dispersal by an overfished Amazonian frugivore

Throughout Amazonia, overfishing has decimated populations of fruit-eating fishes, especially the large-bodied characid, Colossoma macropomum. During lengthy annual floods, frugivorous fishes enter vast Amazonian floodplains, consume massive quantities of fallen fruits and egest viable seeds. Many tree and liana species are clearly specialized for icthyochory, and seed dispersal by fish may be crucial for the maintenance of Amazonian wetland forests. Unlike frugivorous mammals and birds, little is known about seed dispersal effectiveness of fishes. Extensive mobility of frugivorous fish could result in extremely effective, multi-directional, long-distance seed dispersal. Over three annual flood seasons, we tracked fine-scale movement patterns and habitat use of wild Colossoma, and seed retention in the digestive tracts of captive individuals. Our mechanistic model predicts that Colossoma disperses seeds extremely long distances to favourable habitats. Modelled mean dispersal distances of 337-552 m and maximum of 5495 m are among the longest ever reported. At least 5 per cent of seeds are predicted to disperse 1700-2110 m, farther than dispersal by almost all other frugivores reported in the literature. Additionally, seed dispersal distances increased with fish size, but overfishing has biased Colossoma populations to smaller individuals. Thus, overexploitation probably disrupts an ancient coevolutionary relationship between Colossoma and Amazonian plants.     

外源ALA、SNP和Spd对NaCl胁迫下桔梗种子萌发特性的影响

以药用植物桔梗为研究对象,通过测定不同浓度的ALA、SNP和Spd对NaCl胁迫下桔梗种子发芽势、发芽率、萌发指数和平均根长等萌发指标的影响,寻找提高桔梗种子及幼苗在盐胁迫条件下抗性能力的途径.实验结果表明,75 mmol·L-1 NaCl胁迫下的桔梗种子萌发受到显著抑制,但是用不同浓度的ALA、SNP和Spd对桔梗种...     

乌拉山种子植物属的地理成分分析

运用植物区系地理学基本原理,对内蒙古阴山山脉乌拉山段种子植物属的组成及地理成分进行了统计分析.结果表明:乌拉山种子植物区系包含227属,约占内蒙古全区总属数的34.8%;属的分布区类型中,以温带成分为主,占非世界分布总属数的80.9%,其中,北温带分布占到了54.2%,旧大陆温带分布占18.0%,体现出乌拉山种子植物的分布与所处自然地理位置及其气候带相适应的结果.从生活型看,草本植物占绝对优势.     

基于景观指数的九寨沟旅游区旅游干扰评价

旅游活动对景观格局的影响是旅游干扰的重要体现,景观指数则是反映景观格局变化的定量指标.为评价旅游干扰,本文选取景观指数,综合旅游利用幅度和旅游利用强度两方面,构建旅游干扰度指标,并将该指标用于九寨沟旅游区旅游干扰的评价.评价过程中,首先选取旅游区QuickBird遥感影像,并运用3S技术实施影像解译和分区(1～5区),5个分区海拔递增且垂直距离相等,然后计算各分区的旅游干扰度.结果表明:从1区到5区,旅游利用幅度相同,旅游利用强度总体呈递减趋势,因此,旅游干扰度总体呈递减趋势.具体来说,2区最大,其次为1区和3区,4区和5区较小.各分区旅游干扰度和平均斑块分维数之间无显著相关性,说明旅游干扰在改变土地利用形态方面作用不显著.     

棉花根醇提物与水提物的止咳祛痰抗炎作用研究

制备棉花根醇提物和水提物,止咳实验采用小鼠浓氨水引咳法,祛痰实验采用气管酚红排泌法,抗炎实验采用二甲苯致耳肿胀法,观察棉花根醇提物和水提物的止咳祛痰抗炎作用。实验小鼠分正常对照组,醇提物与水提物高低剂量组及阳性药物对照组。结果发现棉花根醇提物、水提物均能延长小鼠的咳嗽潜伏期,减少咳嗽次数,均能增加气管内的酚红排泌量,对二甲苯所致的耳肿胀均有显著的抑制作用。     

秸秆还田条件下灌水模式对冬小麦产量和水肥利用效率的影响

于2008-2010年,在山西省临汾市尧都区半干旱、半湿润季风气候区,通过大田试验研究了玉米秸秆连续还田条件下灌水模式对冬小麦籽粒产量、干物质转移及水肥利用效率的影响.结果表明:浇越冬水可促进小麦分蘖;浇拔节水可提高分蘖成穗率,增加成穗数;浇孕穗水可促进穗部干物质积累,提高千粒重.浇2水时,推迟第2次浇水时期使叶片干物质转移量和穗粒数增加;浇2水比浇l水的肥料表观利用率高,可促进穗部干物质积累.越冬水灌水量和总灌水量对分蘖、穗部干物质积累的影响较小;拔节期或孕穗期增加灌水量则更有利于养分吸收及干物质积累与转移,提高籽粒水分利用效率,产量构成因素协调,增产效果明显.因此,确保越冬水可实现稳产,在越冬水基础上,拔节期增量灌水(900 m3·hm-2)可满足冬小麦中后期生长发育的需要,提高籽粒水分利用效率,实现节水高产栽培.     

钙对镉胁迫下花生生理特性、产量和品质的影响

通过盆栽试验,选用高油品种豫花15和高蛋白品种XB023,研究了不同浓度钙对镉胁迫下不同类型花生品种营养生长、叶片叶绿素含量、光合速率、保护酶活性等生理特性及产量和品质的影响.结果表明： 施钙可以缓解镉胁迫对花生植株主茎高和侧枝长的抑制作用,增加花生植株干物质量,提高叶片叶绿素含量和光合速率,提高叶片超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）活性和可溶性蛋白质含量,降低丙二醛（MDA）的积累量,减轻镉胁迫对花生叶片的伤害;施钙可以缓解镉胁迫对花生的减产作用,增加花生荚果和籽仁产量,其增产的主要原因是增加了单株结荚数和出仁率;施钙可以促使籽仁中可溶性糖向粗脂肪和蛋白质转化,增加籽仁中脂肪和蛋白质含量,改善镉胁迫下花生籽仁品质.施钙可以降低两花生品种籽仁中镉含量,对豫花15的降低效果好于XB023.     

Identification of QTLs for seed germination capability after various storage periods using two RIL populations in rice

Seed germination capability of rice is one of the important traits in the production and storage of seeds. Quantitative trait loci (QTL) associated with seed germination capability in various storage periods was identified using two sets of recombinant inbred lines (RILs) which derived from crosses between Milyang 23 and Tong 88-7 (MT-RILs) and between Dasanbyeo and TR22183 (DT-RILs). A total of five and three main additive effects (QTLs) associated with seed germination capability were identified in MT-RILs and DT-RILs, respectively. Among them, six QTLs were identified repeatedly in various seed storage periods designated as qMT-SGC5.1, qMT-SGC7.2, and qMT-SGC9.1 on chromosomes 5, 7, and 9 in MT-RILs, and qDT-SGC2.1, qDT-SGC3.1, and qDT-SGC9.1 on chromosomes 2, 3, and 9 in DT-RILs, respectively. The QTL on chromosome 9 was identified in both RIL populations under all three storage periods, explaining up to 40% of the phenotypic variation. Eight and eighteen pairs additive × additive epistatic effect (epistatic QTL) were identified in MT-RILs and DT-RILs, respectively. In addition, several near isogenic lines (NILs) were developed to confirm six repeatable QTL effects using controlled deterioration test (CDT). The identified QTLs will be further studied to elucidate the mechanisms controlling seed germination capability, which have important implications for long-term seed storage.     

秸秆浸提液漂浮栽培对不结球白菜产量及相关品质特性的影响

以1/4园试营养液为对照,以腐熟发酵的农业秸秆(苋菜和番茄植株残体)浸提液模拟富含N、P的水体进行不结球白菜(Brassica campestris ssp.chinensis Makino)的漂浮栽培,对茎叶的单株鲜质量和干质量及叶片的VC、可溶性蛋白质、蔗糖、果糖、葡萄糖含量及可溶性糖总含量进行了比较分析。结果表明:在24 d的栽培周期内,随生长时间的延长,处理组和对照组茎叶的单株鲜质量和干质量均呈增加趋势,但从第10天开始,处理组茎叶的单株鲜质量和干质量均显著低于对照组。栽培初期叶片VC含量均最高且处理组叶片VC含量显著低于对照组;从第10天开始,叶片VC含量降低,但处理组叶片VC含量与对照组无显著差异。处理组与对照组叶片可溶性蛋白质含量均呈波动的变化趋势,但总体差异不显著。处理组叶片蔗糖含量总体上与对照组差异不显著,仅在第24天显著低于对照组。处理组叶片的果糖含量均高于对照组,特别是在第24天为对照组的1.81倍,差异显著。叶片葡萄糖含量均呈先升高后降低的趋势,可溶性糖总含量则呈波动的变化趋势,对照组叶片葡萄糖含量和可溶性糖总含量总体上高于处理组,但差异不显著。研究结果显示:用秸秆浸提液漂浮栽培,虽然不结球白菜的生长量(即产量)有所减少,但相关的品质指标变化不大,对果糖合成和积累还有一定的促进作用,因而,此种秸秆浸提液可用于栽培商品不结球白菜。     

Metabolically engineered soybean seed with enhanced threonine levels: biochemical characterization and seed‐specific expression of lysine‐insensitive variants of aspartate kinases from the enteric bacterium Xenorhabdus bovienii

Threonine (Thr) is one of a few limiting essential amino acids (EAAs) in the animal feed industry, and its level in feed rations can impact production of important meat sources, such as swine and poultry. Threonine as well as EAAs lysine (Lys) and methionine (Met) are all synthesized via the aspartate family pathway. Here, we report a successful strategy to produce high free threonine soybean seed via identification of a feedback‐resistant aspartate kinase (AK) enzyme that can be over‐expressed in developing soybean seed. Towards this goal, we have purified and biochemically characterized AK from the enteric bacterium Xenorhabdus bovienii (Xb). Site‐directed mutagenesis of XbAK identified two key regulatory residues Glu‐257 and Thr‐359 involved in lysine inhibition. Three feedback‐resistant alleles, XbAK_T359I, XbAK_E257K and XbAK_E257K/T359I, have been generated. This study is the first to kinetically characterize the XbAK enzyme and provide biochemical and transgenic evidence that Glu‐257 near the catalytic site is a critical residue for the allosteric regulation of AK. Furthermore, seed‐specific expression of the feedback‐resistant XbAK_T359I or XbAK_E257K allele results in increases of free Thr levels of up to 100‐fold in R₁ soybean seed when compared to wild‐type. Expression of feedback‐sensitive wild‐type AK did not substantially impact seed Thr content. In addition to high Thr, transgenic seed also showed substantial increases in other major free amino acid (FAA) levels, resulting in an up to 3.5‐fold increase in the total FAA content. The transgenic seed was normal in appearance and germinated well under greenhouse conditions.