Hydraulic conductance and the maintenance of water balance in flowers

Flowers face desiccating conditions, yet little is known about their ability to transport water. We quantified variability in floral hydraulic conductance (K_flower) for 20 species from 10 families and related it to traits hypothesized to be associated with liquid and vapour phase water transport. Basal angiosperm flowers had trait values associated with higher water and carbon costs than monocot and eudicot flowers. K_flower was coordinated with water supply (vein length per area, VLA) and loss (minimum epidermal conductance, g_min) traits among the magnoliids, but was insensitive to variation in these traits among the monocots and eudicots. Phylogenetic independent contrast (PIC) correlations revealed that few traits had undergone coordinated evolution. However, VLA and the desiccation time (T_des), the quotient of water content and g_min, had significant trait and PIC correlations. The near absence of stomata from monocot and eudicot flowers may have been critical in minimizing water loss rates among these clades. Early divergent, basal angiosperm flowers maintain higher K_flower because of traits associated with high rates water loss and water supply, while monocot and eudicot flowers employ a more conservative strategy of limiting water loss and may rely on stored water to maintain turgor and delay desiccation.     

Organ boundary NAC‐domain transcription factors are implicated in the evolution of petal fusion

• Research rationale: Evolution of fused petals (sympetaly) is considered to be an important innovation that has repeatedly led to increased pollination efficiency, resulting in accelerated rates of plant diversification. Although little is known about the underlying regulation of sympetaly, genetic pathways ancestrally involved in organ boundary establishment (e.g. CUP SHAPED COTYLEDON [CUC] 1–3 genes) are strong candidates. In sympetalous petunia, mutations in the CUC1/2‐like orthologue NO APICAL MERISTEM (NAM) inhibit shoot apical meristem formation. Despite this, occasional ‘escape shoots’ develop flowers with extra petals and fused inter‐floral whorl organs.
• Central methods: To To determine if petunia CUC‐like genes regulate additional floral patterning, we used virus‐induced silencing (VIGS) following establishment of healthy shoot apices to re‐examine the role of NAM in petunia petal development, and uniquely characterise the CUC3 orthologue NH16.
• Key results: Confirming previous results, we found that reduced floral NAM/NH16 expression caused increased petal–stamen and stamen–carpel fusion, and often produced extra petals. However, further to previous results, all VIGS plants infected with NAM or NH16 constructs exhibited reduced fusion in the petal whorl compared to control plants.
• Main conclusions: Together with previous data, our results demonstrate conservation of petunia CUC‐like genes in establishing inter‐floral whorl organ boundaries, as well as functional evolution to affect the fusion of petunia petals.

     

The quality of flower-based ecosystem services in field margins and road verges from human and insect pollinator perspectives

We contrasted traditionally used indicators of service provision quality, such as overall species richness and growth form composition, to three more specific functional properties: functional diversity, functional intensity, and functional stability. We defined flower colour as a functional trait perceived differently by humans and insect pollinators, and used user specific colour richness, flower size, and species richness within colour group as indicators of these three properties. We asked (1) do field margins and road verges provide flower-based ecosystem services with the quality of permanent grasslands; and (2) do traditional and detailed functional indicators of service provision quality agree on the service quality ranking of habitats?In an agricultural landscape of central and south-eastern Estonia (115 ÿ 95 km area, centroid 26°49⿲43⿳ and 58°54⿲49⿳) we sampled 87 field margins and 111 road verges as linear grassland-substitution habitats, and 84 permanent grasslands to scale their service quality.Linear habitats generally provided service of lower quality than permanent grasslands, but detailed indicators showed less evident contrast among habitat types than the overall species richness and stronger contrast than the proportion of forbs. Detailed indices, however, had strong seasonal dynamics to take into account. Vegetation in the first year field margins had greater colour richness (functional diversity) and species richness within colour groups (functional stability), but the smallest flower size (functional intensity), in contrast to road verges. By the third year of succession, field margins had become more similar to road verges. Indication of service provision quality differed between humans and pollinators, but their estimates were correlated across habitats.We showed that (1) combinations of specific service quality indicators provide more adequate information than generalized richness or growth form system, and (2) single grassland surrogate habitat type is an insufficient service providing substitute for permanent grasslands, although a mosaic of these habitats might be more efficient. Therefore, remnant fragments of semi-natural grasslands should receive top priority attention for conservation and restoration, particularly in agriculture dominated landscapes.     

Synthesis of the (9R,13R)-isomer of LDS1, a flower-inducing oxylipin isolated from Lemna paucicostata

The first synthesis of the (9R,13R)-stereoisomer of LDS1, a flower-inducing oxylipin isolated from Lemna paucicostata, has been achieved from a known allylic alcohol by a seven-step sequence that involves the Horner–Wadsworth–Emmons olefination to construct its full carbon framework and an enzymatic hydrolysis of a penultimate methyl ester intermediate to provide the target molecule.     

Methane yield and species diversity dynamics of perennial wild plant mixtures established alone,under cover crop maize (Zea mays L.), and after spring barley (Hordeum vulgare L.)

The cultivation of perennial wild plant mixtures (WPMs) in biogas cropping systems dominated by maize (Zea mays L.) restores numerous ecosystem functions and improves both spatial and temporal agrobiodiversity. In addition, the colorful appearance of WPM can help enhance landscape beauty. However, their methane yield per hectare (MYH) varies greatly and amounts to only about 50% that of maize. This study aimed at decreasing MYH variability and increasing accumulated MYH of WPM by optimizing the establishment method. A field trial was established in southwest Germany in 2014, and is still running. It tested the effects of three WPM establishment procedures (E1: alone [without maize, in May], E2: undersown in cover crop maize [in May], E3: WPM sown after whole‐crop harvest of spring barley [Hordeum vulgare L.] in June) on both MYH and species diversity of two WPMs [S1, S2]). Mono‐cropped maize and cup plant (Silphium perfoliatum L.) were used as reference crops. Of the WPM treatments tested, S2E2 achieved the highest (19,296 , 60.5% of maize) and S1E1 the lowest accumulated MYH (8,156 , 25.6% of maize) in the years 2014–2018. Cup plant yielded slightly higher than S2E2 (19,968 , 62.6% of maize). In 2014, the WPM sown under maize did not significantly affect the cover crop performance. From 2015 onward, E1 and E2 had comparable average annual MYH and average annual number of WPM species. With a similar accumulated MYH but significantly higher number of species (3.5–10.2), WPM S2E2 outperformed cup plant. Overall, the long‐term MYH performance of WPM cultivation for biogas production can be significantly improved by undersowing with maize as cover crop. This improved establishment method could help facilitate the implementation of WPM cultivation for biogas production and thus reduce the trade‐off between bioenergy and biodiversity.     

Informing native plant sourcing for ecological restoration: cold‐hardiness dynamics,flowering phenology,and survival of Eriogonum umbellatum

Despite advances in restoration of degraded lands around the world, native plants are still underutilized. Selection of appropriate plant materials is a critical factor in determining plant establishment and persistence. To better inform decision‐making, we examined cold‐hardiness dynamics, flowering phenology, and survival among five geographically distinct sulfur‐flower buckwheat (Polygonaceae: Eriogonum umbellatum Torr.) populations in a common garden. LT₅₀ (a measure of freezing injury) was determined every 6 weeks across a complete year; one population was also evaluated at the source. Cold‐hardiness dynamics were similar across populations, with annual fluctuations in mean LT₅₀ exceeding 40°C. Rate of deacclimation (i.e. loss of cold tolerance) in spring varied across populations and was not related to the elevation from which a population came. Plants were less cold hardy in October 2014 compared to October 2013, likely reflecting a response to colder local conditions in 2013. Although the range of LT₅₀ was similar for a single comparison of common garden versus wild‐grown plants, wild‐grown plants acclimated and deacclimated earlier than common garden‐grown plants. Plants derived from a low‐elevation population showed delayed flowering phenology, while high‐elevation populations showed earlier flowering phenology, with one high‐elevation population having the lowest survival rate in the common garden. These results suggest that while considerable plasticity in seasonal cold‐hardiness dynamics occur, population variability in deacclimation and flowering phenology have implications for selection and movement of sulfur‐flower buckwheat for ecological restoration.     

二态混合交配系统的适合度优势及其维持机制研究进展

由开花受精花(chasmogamous, CH)和闭花受精花(cleistogamous, CL)构成的二态混合交配系统植物有着特殊的繁殖策略, 对其进行深入研究有助于理解植物交配系统的维持机制、进化趋势以及植物对环境变化的应对策略。本文综述了国内外关于CH-CL系统两型花研究的文献资料, 包括非生物因素和生物因素对该繁育系统两型花的生长、发育及相对比例的影响, 两型花的维持机制及进化意义, 阐明了CH-CL系统的研究现状及科学问题, 重点评述了基于近年来对CH-CL系统研究成果的新认识。作者提出, 精确地检测两种花型的后代在异质生境下以及在生活史的不同阶段的适合度差异是十分必要的; 微环境(种子的散布模式及位置效应)对两型花种子萌发和子代生长发育的影响非常重要; 两型花表达的时空差异(即开花模式及对异质生境的敏感性差异)的表达机制可能与内源激素的水平变化相关; 对于多年生具CL系统植物来说, 不同性质、不同来源的后代在居群中的分布式样及对居群遗传结构的影响很可能是该系统维持的重要机制。因此, 深入研究和科学认识二态混合交配系统对认识整个植物界繁育系统的进化有十分重要的意义。     

新疆昆仑雪菊水提物对 小鼠肠道菌群的调节作用

目的 研究新疆昆仑雪菊水提物对小鼠肠道菌群的影响。方法 C57BL/6小鼠,雄性,8周龄,40只,分为4个组(每组10只):高、中、低三个剂量组和空白对照组,给药14 d,收集给药前后小鼠粪样,16S rDNA实时荧光定量PCR法测定粪样中肠杆菌、肠球菌、乳杆菌和产气荚膜梭菌水平。结果 与空白对照组比较,中剂量组小鼠肠道粪样中乳杆菌显著增多(t=-2.503,P0.05),低剂量组与高剂量组变化不显著;与空白对照组比较,其他组小鼠肠道中肠杆菌属、肠球菌属和产气荚膜梭菌水平均无显著变化。结论 参照《保健食品检验与评价技术规范—2003版》之"调节肠道菌群作用检验方法",新疆昆仑雪菊水提物对小鼠肠道菌群具有一定的调节作用。     

叶面喷施PP_(333)和6-BA对甜荞花芽分化及内源激素的影响

以甜荞品种‘北早生’和‘赤甜荞1号’为材料,利用多效唑(PP_(333))和6-苄基腺嘌呤(6-BA)在不同幼苗时期进行叶片喷施处理,并采用扫描电镜观察花芽分化过程,记录开花时间,调查开花和结实数,通过液质联用方法检测3种内源激素生长素(IAA)、赤霉素(GA_3)、脱落酸(ABA)及人工合成细胞分裂素(6-BA)含量,探究两种植物生长调节剂对甜荞的花芽分化及内源激素含量的影响,为甜荞花期调控提供依据。结果显示:(1)第二片真叶期喷施100mg·L~(-1)PP_(333)和150mg·L~(-1)6-BA能显著提高甜荞结实率和单株产量,两种处理的结实率分别较对照提高49.5%、39.4%,单株产量分别提高41.8%、23.0%。(2)观察甜荞花芽分化过程并将其划分5个时期,分别为生长锥分化前期、生长锥分化期、小花原基分化期、雌雄蕊分化期和雌雄蕊形成期,在第二片真叶期喷施PP_(333)和6-BA均加快了甜荞花芽分化进程,使其开花时间提前。(3)喷施PP_(333)在幼苗期和现蕾期降低了内源IAA、6-BA含量,增加GA_3、ABA含量,而在盛花期增加内源IAA、6-BA含量,降低ABA、GA_3含量;喷施6-BA在幼苗期和现蕾期增加了内源GA_3、IAA含量,在盛花期降低了内源GA_3、IAA含量,3个时期均降低了内源ABA含量,增加了6-BA含量。研究发现,第二片真叶期是调控甜荞小花发育的关键时期,在此时叶面喷施100mg·L~(-1)PP_(333)和150mg·L~(-1)6-BA的调控效果最佳,可加快甜荞花芽分化进程,使开花时间提前,增加单株结实粒数,提高甜荞品种的结实率和单株产量;PP_(333)主要是通过减少甜荞开花数,增强弱势小花活力来提高结实粒数,而6-BA主要是利用增加开花数,提高有效可孕小花数来增加结实粒数。     

秦岭石蝴蝶人工种群花器变异现象研究

以人工栽培的秦岭石蝴蝶为实验材料,通过观察并记录花器官形态和数目的变化,初步探讨秦岭石蝴蝶花器变异规律,并分析了导致其变异的诱因。结果显示:(1)在观察的1 996朵秦岭石蝴蝶花朵中,发现了17种花冠变异类型、5种萼片变异类型和7种可育雄蕊变异类型,总变异率分别为34.57%、38.38%和32.67%。(2)秦岭石蝴蝶花梗或可分支,花梗苞片数目2～3枚。(3)相关性分析结果表明,下唇数目与可育雄蕊数目呈正相关,相关系数为0.927 4,而上唇数目与可育雄蕊数目呈负相关,相关系数为-0.481 1,结合花型图示分析这可能与秦岭石蝴蝶雄蕊着生于花冠下唇内侧近基部有关。该研究统计的秦岭石蝴蝶变异类型丰富,可能对于今后秦岭石蝴蝶的系统进化、花器官发育、生殖生态以及分子遗传方面研究奠定了基础,也为培育不同观赏价值的品种提供思路。