Effects of Mycosphaerella leaf disease on the spectral reflectance properties of juvenile Eucalyptus globulus foliage

Mycosphaerella leaf disease (MLD) can cause significant discoloration, necrosis and defoliation in commercial plantations of young Eucalyptus globulus. This study investigated the spectral reflectance changes that result in E. globulus foliage from Mycosphaerella infection. Spectral reflectance measurements were made on healthy and infected E. globulus foliage in the visible and near‐infrared wavelengths (400–1000 nm). Reflectance (R) at 760 nm produced the largest difference between the extremes of disease severity classes. The wavelength most sensitive to infection severity was R678 nm. Other sensitive wavelengths were located between 480 and 500 nm. The wavelengths near 708 and 550 nm appeared relatively insensitive to infection severity. The reflectance index best correlated to leaf infection was R678/R550 (r = 0.841, p < 0.0001). This index was used in a linear regression model for successfully predicting leaf infection levels from an independent data set (r = 0.95, p < 0.0001).     

Histopathology of loblolly pine needles infected by Mycosphaerella dearnessii,the brown-spot needle disease pathogen

The histopathology of green Pinus taeda needles infected with Mycosphaerella dearnessii was investigated. Cellular abnormalities observed were predominately the collapse of mesophyll cells within the limits of the symptom lesions. The epidermis, hypodermis, endodermis, transfusion tissue, and the vascular system within the lesions were not affected. Resin ducts exhibited cell necrosis and dissolution within and distal from the visible limits of lesions. An intercellular interface was present in non-collapsed mesophyll cells at lesion limits, and the lateral extension of the interface usually corresponded to the effects observed in resin ducts distal from the lesions. Non-stromatic hyphae were rare in and distal from lesion tissue, indicating the host tissues were affected in advance of the pathogen. The production of a toxin by M. dearnessii is suspected.     

Phomopsidone A,a novel depsidone metabolite from the mangrove endophytic fungus Phomopsis sp. A123

One novel pentacyclic depsidone containing an oxetane unit, phomopsidone A (1), together with the reported excelsione (also named as phomopsidone) (2), and four known isobenzofuranones (3–6) were isolated from the mangrove endophytic fungus Phomopsis sp. A123. Their structures were elucidated by 1D and 2D NMR spectroscopic analysis and high resolution mass spectrometry. The bioactivity assays showed that these compounds possess cytotoxic, antioxidant, and antifungal activities.     

桉树大径材培育技术研究概述

培育大径材用于实木加工是桉树人工林发展的趋势,但桉树人工林大径级原木的培育尚缺乏经验。本文综述了国内外在桉树大径材树种选择、初植密度控制、间伐、修枝和施肥管理方面的现状及其对大径材生长和材性的影响,以期为桉树资源高效利用及大径材人工林的可持续发展提供借鉴和依据。     

桉属植物叶片DNA抽提

对植物组织DNA抽提是在分子水平上对植物进行系统分析与研究的基础性工作。我们使用改良CTAB法抽提桉属植物叶片中总的DNA获得了成功，其纯度和得率完全能满足常规分子生物学操作的要求。与DNA得率有关的几个问题在此一并探讨。     

Colletotrichum siamense: A novel leaf pathogen of Sterculia nobilis Smith detected in China

Sterculia nobilis is an important tropical woody plant with high ornamental and economic value. At present, there are few reports of diseases on this plant. In August 2018, an unknown leaf spot disease was observed on S. nobilis in Nanning, China, affecting the inner leaves of the canopy and causing considerable defoliation. The pathogen was isolated, and pathogenicity tests carried out on detached leaves to verify Koch's postulates. Based on morphological observations and polygenic analyses, the pathogen causing leaf spots on S. nobilis was identified as Colletotrichum siamense.     

桉树不同地理种源木材构造性质比较研究

在海南省琼海市，中国林业科学研究院热带林业研究所按树种源试验林内，采集了巨桉，柳桉，赤桉和尾叶桉４４个种源的木材试材，对木材解剖了分子和基本密度进行了研究和评优，从中选出巨桉１４８６０、１４８４９、１４５０９，柳桉１４４２９，１４４３５、１４５２７；赤桉１２１８７、１５０５０、１５０６２和尾叶桉１５０８９为最优种源。     

尾叶桉胚状体植株诱导与增殖研究

本文报导了用尾叶桉种子下胚胎诱导体细胞胚胎发生，获得根苗齐全的胚状体再生植株，经过５～６代增殖培养，获得大量丛生苗，已完成移栽，炼苗的全套生产技术流程，是迄今世界松树组培由下胚轴产生胚状体小苗成功的第三例，在木本植物的同类组培成功研究中也是数例之一，在科学和林木良种快速选育与繁殖上有重要价值。     

杂种桉无性系综合筛选试验研究

通过对23个杂种桉无性系的生长性状、形质性状和材质性状进行了差异分析和比较,结果表明:除圆满度和分枝外各性状在无性系间均差异极显著,经多重比较共有13个无性系的去皮蓄积量超过总体平均值,生长量最大的是DH32-28,其去皮蓄积量是最小无性系W5的778.91%,是总体平均值的143.55%,是对照的234.85%;无性系各性状重复力为0.15~0.85,树高和胸径的重复力最大,圆满度的重复力最小;早晚秩次相关分析表明:可对参试无性系进行早期选择;应用指数选择法,从23个参试无性系中筛选出了6个优良无性系,分别是DH32-28、DH33-27、GL9、DH32-13、DH33-9和DH32-29。     

Arambarria the pathogen involved in canker rot of Eucalyptus,native trees wood rots and grapevine diseases in the Southern Hemisphere

Arambarria (Hymenochaetales, Basidiomycota) is a monotypic genus recently described to accommodate specimens from the Patagonian forests of Argentina wrongly assigned in the past to Inocutis jamaicensis. On the basis of a wide sampling of strains and phylogenetic analysis inferred from combined sequences including the nuc rDNA ITS1‐5.8‐ITS2 region, 28S rDNA D1‐D2 domains and partial sequences of translation elongation factor 1‐a (tef1‐α), we demonstrate that this genus is associated with an important canker rot of eucalypt plantations in Uruguay, to wood rots of many native and exotic hosts, and to “hoja de malvón” and chlorotic leafroll of grapevines diseases in Central Chile, Central Argentina and Uruguay, formerly assigned to I. jamaicensis and/or Fomitiporella sp. The combined phylogenetic analysis showed the existence of three closely related clades that corresponded to (1) the Pampas of Uruguay and Argentina (“uruguay” clade), (2) the Monte, Chaco Serrano and Yungas forests of Argentina (“cognata” clade) and (3) the Patagonian Andes forests and Chilean Province (“destruens” clade). Lack of morphological differences between taxa from the three clades, their occurrence in both native and exotic hosts, previous results showing interfertility between isolates from Uruguay and Argentina, and the lack of full support in the concatenated ITS + 28S + tef1‐α analysis, prevents us to distinguish and describe three different taxa; the proper name of the taxon being Arambarria cognata comb. nov. A fourth, distinctly separated clade corresponded to South African strains isolated from vineyards representing an undescribed taxon associated with Esca grapevine disease in that country. Arambarria is shown to be unrelated to Inocutis, with which it was confused in the past and, so far, remains restricted to the Northern Hemisphere in America (Mexico, Jamaica and the USA).     

A new fungitoxic metabolite from Spiraea alpina Pall.

The fungitoxic metabolites of Spiraea alpina Pall. were identified using inhibition of Rhizoctonia solani, Gibberella zeae, Pyricularia oryzea and Exserohilum turcicum as an end-point. The major fungitoxic constituent of S. alpina was a new diacylated sugar, structurally elucidated as 6-O-(3′,4′-dihydroxy-2′-methylenbutyryl)-1-O-trans-cinnamoyl-β-D-glucopyranose. This compound could inhibit at 0.1 mg/ml Rhizoctonia solani and Exserohilum turcicum, 87.6% and 63.2%, respectively.     

Structural host responses of Acacia mangium and Eucalyptus pellita to artificial infection with the root rot pathogen,Ganoderma philippii

Structural host responses of young Acacia mangium and Eucalyptus pellita to infection with the root rot pathogen Ganoderma philippii were described. To our knowledge, this is the first report investigating the histology of root responses infected with G. philippii. The infected roots of A. mangium were characterized by the presence of a continuous multilayered mycelial sheath (~100–200 μm thick), fungal outgrowths and the production of a wound periderm. In contrast, roots of E. pellita were characterized by a mycelial sheath and fungal outgrowths and a wound periderm comprising of only one to four rows of cells.     

海南桉树引种种植成功经验

海南种植桉树对国家、集体、个人、企业都有利益,有许多功绩。海南引种种植桉树88年历史,海南生态环境仍然保持良好生态环境,仍然成为世界人居好环境。海南种植桉树为海南经济发展,保护好天然林,保护好环境,保护好橡胶林,促进平原绿化,增加海南森林覆盖率,丰富森林资源,在短时间内为社会提供大量的木材和薪炭材,保持林业可持续发展,起到非常重要作用。海南种植桉树具有生态效益,社会效益,经济效益。但我们发展桉树同时必须讲究科学规划,适地适树,选用良种,讲究科学种植、合理密度、科学管理,科学施肥,桉树一定能获得高产,又有良好的生态效益。但不能盲目经营,绝不能砍伐天然林,次生林来种植桉树,海南人民有能力把桉树产业这篇文章做得更好。     

Variations in the secondary metabolite camptothecin in relation to tissue age and season in Camptotheca acuminata

We investigated variation in concentration of the secondary metabolite, camptothecin (CPT), in relation to leaf, branch and tree age, season, and leaf drying method in Camptotheca acuminata Decaisne saplings. Younger leaves contained higher CPT concentrations than older leaves. Within a branch, there was a linear decline in CPT concentration from leaves at the apex of the branch down to Leaf 7. Comparing leaves of similar age, those from younger trees had higher CPT concentrations than those from older trees. Over the course of the growing season, there was a steady decline of 11% per month in leaf CPT concentration. Branches showed a similar seasonal decline in CPT concentration to leaves; however, the rate of decline was threefold greater in leaves than in branches. Freeze-dried tissues had a 27% higher CPT concentration than oven- or air-dried tissues, suggesting that oven- and air-drying caused degradation of CPT. The decline in CPT concentration with tissue aging may reflect a genetically determined mechanism whereby, in young trees, chemicals serve as a first line of defense against attacks by herbivores and pathogenic microorganisms until other mechanisms are developed and deployed. We hypothesize that chemical defense mechanisms are programmed for early ontogenic stages, whereas they are induced by biotic and abiotic factors during later ontogenic stages.     

A novel isoflavone from the stems of Ageratum conyzoides

A novel isoflavone glycoside, 5,7,2′,4′-tetrahydroxy-6,3′-di-(3,3-dimethylallyl)-isoflavone 5-O-α-l-rhamnopyranosyl-(1→4)-α-l-rhamnopyranoside (1), was isolated from the stems of Ageratum conyzoides.     

刚果12号W5桉枝、叶凋落物产生的相关因素研究

通过全年收集2～6林龄桉树(刚果12号W5无性系)枝、叶凋落物量和测定树冠冠幅,研究了枝、叶凋落物产生的相关规律.结果表明低温和较低的降雨量以及树冠竞争促使枝、叶凋落物产生,叶凋落物占主要部分;2月和10月以及桉树2林龄和5林龄是枝、叶凋落物产生的月高峰期和林龄高峰期;树冠的竞争促进了枝叶凋落物的产生,树冠扩展时凋落物量最小.认为掌握凋落物月高峰期和林龄高峰期对确定桉树人工林采伐时期和季节以及维护林地养分平衡具有理论和实践意义.     

近三十年我国桉树专题文献计量分析

为了解我国桉树相关行业的发展动态,本文以中国知网数据库(www.cnki.net)的文献为数据源,以文献计量学方法,对我国1987—2016年共30 a的桉树专题相关文献进行阶段性(以10 a为界)统计,从文献数量、学科分布、研究层次、文献作者、发文机构、资助基金、文献来源和关键词等8个方面进行了分析.结果表明:随着年份增长,桉树专题文献数量总体呈现上升趋势,1987—1996、1997—2006及2007—2016年的文献数量分别为965、2115及4631篇,以第3阶段(2007—2016年)增幅最大.30 a间3个阶段桉树研究的学科领域均以林业学科最多,所占比例为70%左右,研究层次均以工程技术(自科)和基础与应用基础研究(自科)为主.不同阶段文献作者的最高发文数量分别为11、30和75篇,发文机构均主要集中在广东、广西、云南、湖南、福建等地.3个阶段的文献主要以国家科技攻关计划和国家自然科学基金资助为主,文献来源主要出自期刊,整个30 a间,均以《桉树科技》所刊登的文章数量为最多,是其他期刊的2~6倍.关键词均以"桉树"出现的频次最高,其他主要关键词主要为品种与人工林.     

耐寒桉树的纤维形态特征的变异

对湖南郴州地区引种的4种桉树的木材纤维长度和纤维宽度进行试验和研究.结果表明,4种桉树木材的纤维长度均值变幅在743～948μm之间,巨尾桉的纤维长度最长.纤维长度、纤维宽度在幼龄期最小,并随年轮增加而增大,直至达到最大长度而成近似稳定状态.纤维长度是树种的属性之一,受生态环境的影响较小,纤维宽度则随不同的立地条件和施肥管理而发生改变.