4个核桃类树种苗木应对持续干旱的生理响应

采用自然干旱法，对引种栽培的美国黑核桃‘北加州黑核桃’和美国山核桃‘波尼’以及乡土核桃树种（漾濞大泡核桃和旺核2号）的2年生苗木进行干旱胁迫处理，测定其生理生化指标，对比分析其抗旱性。结果表明：(1) 4个树种的根系活力、叶片相对含水量、叶片水势和超氧化物歧化酶均随干旱胁迫的增强而呈下降的趋势，叶片相对电导率呈上升的趋势，叶片丙二醛含量呈先增加后下降最后上升的趋势，可溶性糖含量呈先增后减的趋势。（2）叶片可溶性糖含量在第14天时发生显著变化；根系活力在第17天时发生显著变化；叶片相对含水量和丙二醛含量以及超氧化物歧化酶活性在第19天时开始发生显著变化；叶片相对电导率、叶片水势均在第23天时发生显著变化。 (3) 4个树种的抗旱隶属值排序为：‘北加州黑核桃’>‘波尼’>‘旺核2号’>漾濞大泡核桃，说明引进种对干旱的适应性要高于乡土树种。     

干旱-低温交叉适应性对茶树抗寒性的影响

为了解干旱-低温交叉适应对茶树抗寒性的影响,以一年生无性系品种舒茶早茶苗为试验材料,用20%聚乙二醇6000(PEG-6000)模拟干旱预处理,测定低温胁迫过程中茶树半致死温度、丙二醛、抗氧化酶活性、渗透物质和内源激素等部分生理指标的变化。结果表明,经过PEG-6000预处理的茶苗半致死温度LT50明显下降。低温条件下,茶苗叶片丙二醛、抗氧化酶活性、渗透物质和激素含量整体呈上升趋势。低温胁迫第7天时,与对照相比,PEG-6000预处理的茶苗叶片丙二醛含量下降44.6%,SOD、POD酶活分别升高78%和25%,可溶性蛋白、溶性糖含量分别增加44.6%及20.0%;内源激素ABA与SA含量分别提高97.7%和122.0%。干旱可诱导茶树对低温胁迫的交叉适应性,这种交叉适应性与茶树的抗氧化酶活性、渗透物质和内源激素的调节能力有关。     

安徽省草鱼养殖群体遗传多样性及遗传结构分析

通过微卫星分子标记对来自安徽省4个草鱼养殖群体进行遗传分析。结果表明,7个微卫星位点均具有高度多态性(PIC=0.863～0.926),4个草鱼群体均显示出较高的遗传多样性(He=0.886 1～0.911 4)。AMOVA分析显示,大多数遗传变异存在于草鱼群体内(97.6%),群体间的遗传变异仅为2.4%。遗传分化和遗传距离分析显示,4个群体整体分化水平较低(Fst0.05),怀远和滁州群体遗传分化最小(Fst=0.013 7),遗传距离最近(Dn=0.269 8),池州和无为群体遗传分化最大(Fst=0.042 5),遗传距离最远(Dn=0.591 6)。系统进化树显示,怀远和滁州群体亲缘关系最近,与池州最远。此外,4个养殖场内部草鱼均存在近亲繁殖现象。建议4个养殖场及时更新亲本,增加繁殖亲本的数量,避免近交衰退带来的风险。     

含刚性沉水植物明渠水流结构的试验研究

【目的】得到含刚性沉水植物明渠的水流结构。【方法】采用粒子图像测速仪(PIV),用有机玻璃棒模拟刚性植物,在不同来水流量、植物密度条件下对明渠水流结构进行了试验研究。【结果】无植物时平均流速沿垂向呈对数分布规律,有植物时则呈现明显的分区分布特性。无植物时紊动强度值沿垂向变化不大,有植物时在植物顶端位置处紊动最剧烈。流量或植物密度越大,植物顶端位置的流速梯度就越大,植物层上方的流速最大值也越大。植物密度越大,植物顶端位置的紊动强度越大,植物密度对水流紊动强度由最大值减小到最小值的区域影响很大。【结论】刚性沉水植物的存在会改变水流结构,增强紊动掺混,增强流体质点交换和能量传递,且上述影响会随着流量或植物密度的增大而增强。     

Cryptic species and population genetic structure of Plasmopara viticola in São Paulo State,Brazil

Downy mildew (Plasmopara viticola) is one of the most important diseases in grape-growing areas worldwide, including Brazil. To examine pathogen population biology and structure, P. viticola was sampled during the 2015/16 growing season from 516 lesions on nine grape cultivars in 11 locations in subtropical areas of São Paulo State, Brazil. For identification of cryptic species, a subsample of 130 isolates was subjected to cleaved amplified polymorphic sequence (CAPS) analysis, and for 91 of these isolates the ITS1 region was sequenced. These analyses suggest that the population of P. viticola in São Paulo State consists of a single cryptic species, P. viticola clade aestivalis. Seven microsatellite markers were used to determine the genetic structure of all 516 P. viticola isolates, identifying 23 alleles and 55 multilocus genotypes (MLGs). Among these MLGs, 34.5% were clonal and represented 93% of the isolates sampled. Four dominant genotypes were present in at least five different locations, corresponding to 65.7% of the isolates sampled. Genotypic diversity (Ĝ = 0.21–0.89) and clonal fraction (0.58–0.96) varied among locations (populations). Most populations showed significant deviation from Hardy–Weinberg expectations; in addition, excess of heterozygosity was verified for many loci. However, principal coordinate analysis revealed no clusters among locations and no significant isolation by distance was found, suggesting high levels of migration. The results indicate that downy mildew epidemics result from multiple clonal infections caused by a few genotypes of P. viticola, and reproduction of P. viticola in São Paulo State is predominantly asexual.     

Site‐specific management is crucial to managing Mikania micrantha

Increasingly, weeds have been taking on global distributions. With the proliferation of invasive weeds has come the challenge of managing these species over broad geographical regions, with diverse habitats and political jurisdictions. Here, we review the management of Mikania micrantha Kunth (Asteraceae; mile‐a‐minute) throughout its invaded range, extending through most of the Pacific islands and southern and south‐east Asia. Context matters when determining the best course of action for managing M. micrantha, as it has invaded a large variety of agricultural and natural systems. In Queensland, Australia and Florida, USA, M. micrantha has been targeted in relatively successful eradication campaigns, highlighting the importance of early detection and rapid response methods, while elsewhere in its invaded range, populations are either still increasing or showing limited signs of decline. An inter‐regional approach to research and management should incorporate successful management strategies employed throughout the invaded range including, but not limited to, chemical and cultural control practices, manual and mechanical control, classical biological control using the rust fungus Puccinia spegazzinii, plant–plant competition and integrated approaches utilising two or more control methods concurrently. Additional knowledge of M. micrantha genetics is required to determine if management approaches could be fine‐tuned for particular populations. Countries bordering the Mekong River formed a network in 2011 to co‐ordinate the management of invasive species such as M. micrantha. Expanding such a collaborative approach to other regions could further reduce populations of M. micrantha and limit its spread.     

基于家族基因分析的甘蓝MLPK互作PUB蛋白的筛选

MLPK(M–位点受体激酶)是芸薹属自交不亲和正向调控关键元件,其参与自交不亲和信号传导的分子机制尚不明确,同时自交不亲和下游信号元件也有待于进一步分离。为了探索分离MLPK互作蛋白的思路和方法,构建了不含核定位信号的MLPK短截蛋白(MLPK-T),并利用酵母双杂交检测到MLPK与臂重复蛋白1(ARC1)作用,通过全基因组鉴定分别获得了96个甘蓝、101个白菜、70个琴叶拟南芥和62个拟南芥PUB蛋白,其中含有臂重复序列的PUB蛋白共为127个。通过系统进化分析,筛选到8个含臂重复序列的甘蓝BoPUB蛋白,其8个基因全部在柱头内表达,且成功利用酵母双杂交检测到MLPK与3个含臂重复序列的BoPUB蛋白Bol008579、Bol016165和Bol023511相互作用。     

生物炭对酸化茶园土壤性状和真菌群落结构的影响

为探讨生物炭长期施用对酸化茶园土壤改良和真菌群落结构的影响,分析了按生物炭用量0、2.5、5、10、20、40 t·hm^-2施用5年后的茶园土壤性状和真菌群落结构变化。结果表明,施用生物炭5年后的茶园土壤pH提高了0.16~1.11,可溶性有机碳含量提高了52.6%~92.3%,而铵态氮和硝态氮含量以10 t·hm^-2处理最高。施用生物炭5年后的土壤性质变化,进一步影响了真菌群落结构,表现为Chao指数、ACE指数和Shannon指数随生物炭用量增加呈先增加后降低的趋势;提高生物炭施用量对茶园土壤次要作用的真菌（LDA值<3.50）丰度的增加效果高于优势真菌（LDA值>3.50）的效果,其中被孢霉属、木霉属、毛壳菌属的相对丰度增加,黑盘孢属的相对丰度降低。     

Hormonal changes play important roles in the key period of superior and inferior earshoot differentiation in maize

The upper earshoots with higher superiority usually have higher yield potential and higher efficiency. To determine the key period for the asynchronous differentiation of superior and inferior earshoots and how hormones are involved in this process, a two-year experiment was designed using two maize hybrids: Suyu 41 (S41, single-ear hybrid) and AN 101 (A101, double-ear hybrid). The results showed that the lag of lower earshoot differentiation was not only caused by the delay of the differentiation starting time but also related to extension of the duration in spikelet differentiation (stage II) and sexual organ formation stage (stage IV). From 12 days before silking (DBS), the contents of indole-3-acetic acid (IAA), zeatin riboside (ZR)+zeatin (ZT), and gibberellic acid (GA₃) in both upper and lower earshoots of the two hybrids increased dramatically and then decreased quickly. ABA slightly increased in the two hybrids and then decreased slowly in S41, while it was maintained at a high level in A101. At 8 DBS, i.e., the transition period from floret differentiation to sexual organ formation stage, not only the growth of upper-to-lower earshoot difference (ULED), but also the values for ULED of IAA, ZR+ZT and GA₃ were all significantly higher in S41 than in A101. Furthermore, the upper-to-lower hormone ratios IAA_U//AA_L and (ZR+ZT)_U/(ZR+ZT)_L were also much higher in the single-ear hybrid than in the double-ear hybrid, while the GA_3U/GA_3L and ABA_U/ABA_L had no significant differences. In addition, the time course of ULED_hormone/ULED_{earshoot growth rate} also suggested that the hormones work in different ways in earshoot superiority/inferiority formation. The delayed differentiation of lower ear shoots was conclusively related to the later initiation of differentiation and the longer durations of specific differentiation stages. Compared with the regulating roles of IAA and ZR+ZT in the key period (8 DBS) of superiority/inferiority differentiation, GA₃ seems to be affected earlier, while ABA contributes little to this process.     

不同基质对闭鞘姜生长发育和光合作用的影响

采用随机区组设计,研究不同配比的红壤、泥炭、椰糠和珍珠岩6种基质配方对闭鞘姜生长的影响。测定6种基质的物理和化学性质,观测萌芽率、叶片数、茎粗、株高、株幅、光合日变化、根茎鲜重和根茎干重。结果显示,基质S4（泥炭+椰糠+珍珠岩=1∶2∶2）的植株净光合速率（P_n）显著高于其他基质处理。在6种基质生长的植株叶片净光合速率曲线呈单峰或双峰变化,而蒸腾速率曲线呈单峰变化。最大株高、最大根茎鲜重和根茎干重也出现在基质S4种植的植株。从以上结果可知,基质S4比较适合闭鞘姜的生长和根状茎干物质积累。