Adenosine cyclic monophosphate in potato tubers during storage at +10° and +2°

The levels of adenosine 3′: 5′ cyclic monophosphate in mature potato tubers (variety King Edward) stored at + 10°, for varying periods at + 2° and then after 28 days at + 2° transferred to + 10°, have been measured. The concentrations were very low (3–30 pmol/g fr. weight) and did not show marked changes with storage conditions.     

Genetic bottleneck in invasive species: the potato tuber moth adds to the list

The level of genetic diversity within populations of introduced species has received increasing attention as an important factor influencing their survival and adaptive potential. We examined this issue with the Guatemalan potato tuber moth Tecia solanivora, an agricultural pest which has successfully invaded South America and the Canary Islands within the last 20 years. To analyse changes in T. solanivora genetic diversity, the mitochondrial marker cytochrome b was sequenced from individuals collected across its known distribution area. High haplotypic diversity was observed in Guatemala, whereas only three haplotypes have been found in Venezuela and a single one in the remaining invaded South American countries and the Canary Islands. Invasive haplotypes were not observed in our samples from Guatemala but are closely related to Guatemalan haplotypes. These results are consistent with the hypotheses that (i) either a few individuals were introduced into Venezuela leading to a strong initial genetic bottleneck, or selection pressure may have lead to the disparition of all but a reduced number of introduced haplotypes, (ii) a second bottleneck occured between Venezuela and Colombia, and (iii) the invasion of the Canary Islands originated from South America. We further reviewed the recent literature to compare this change in genetic diversity with those reported for other invasive species. We quantified the changes in genetic diversity between native and introduced ranges for 57 biological invasions. We found that the genetic homogenization in T. solanivora was among the strongest reported and discuss factors that can explain the success of invasive populations with low genetic diversity.     

Changes in the distribution of multispecies pest assemblages affect levels of crop damage in warming tropical Andes

Climate induced species range shifts might create novel interactions among species that may outweigh direct climatic effects. In an agricultural context, climate change might alter the intensity of competition or facilitation interactions among pests with, potentially, negative consequences on the levels of damage to crop. This could threaten the productivity of agricultural systems and have negative impacts on food security, but has yet been poorly considered in studies. In this contribution, we constructed and evaluated process‐based species distribution models for three invasive potato pests in the Tropical Andean Region. These three species have been found to co‐occur and interact within the same potato tuber, causing different levels of damage to crop. Our models allowed us to predict the current and future distribution of the species and therefore, to assess how damage to crop might change in the future due to novel interactions. In general, our study revealed the main challenges related to distribution modeling of invasive pests in highly heterogeneous regions. It yielded different results for the three species, both in terms of accuracy and distribution, with one species surviving best at lower altitudes and the other two performing better at higher altitudes. As to future distributions our results suggested that the three species will show different responses to climate change, with one of them expanding to higher altitudes, another contracting its range and the other shifting its distribution to higher altitudes. These changes will result in novel areas of co‐occurrence and hence, interactions of the pests, which will cause different levels of damage to crop. Combining population dynamics and species distribution models that incorporate interspecific trade‐off relationships in different environments revealed a powerful approach to provide predictions about the response of an assemblage of interacting species to future environmental changes and their impact on process rates.     

辅色剂对紫淮山花色苷稳定性的影响及其热降解动力学研究

为探究谷胱甘肽和没食子酸对紫淮山花色苷的辅色作用,本文研究了谷胱甘肽和没食子酸对紫淮山花色苷降解率、热稳定性及色差的影响。试验表明,谷胱甘肽和没食子酸能有效抑制花色苷的降解,且最佳添加量分别为0.03%和0.2%。在此添加量条件下,紫淮山花色苷在50、70、90℃水浴中的热降解均符合一级降解反应动力学规律。添加谷胱甘肽和没食子酸的紫淮山花色苷降解速率常数(k)小于对照组,半衰期(t 1/2)和活化能(Ea)高于对照组,说明谷胱甘肽和没食子酸能够增强花色苷的热稳定性。色差测定结果表明,经谷胱甘肽和没食子酸辅色后的紫淮山花色苷,其明度指数(L*)和色品指数(a*、b*)较对照组变化缓慢,颜色的稳定性增强。     

"彩色马铃薯"块茎花色苷分子结构研究进展

“彩色马铃薯”是指块茎的“皮”和／或“肉”为红、紫、蓝或橙色的马铃薯,其块茎“皮”和“肉”变化多端的着色模式源于花色苷的积累,块茎各种颜色在根本上由花色素决定。在“彩色马铃薯”块茎中已发现6种花色素,即矮牵牛色素、花葵素、锦葵色素、芍药色素、花青素和花翠素;不同颜色块茎所含的花色素种类不同,同一颜色块茎所含花色素种类也可能不同;紫色块茎所含的花色素种类最为多样化。“彩色马铃薯”块茎的各种花色素一般在C3位经过氧一糖苷键实现1个芸香糖基取代,在苷元的C5位,要么以氧．糖苷键实现单葡萄糖基取代,要么不发生取代。“彩色马铃薯”块茎花色苷常在花色素C3位二糖取代基上或在C5位的单糖取代基上进一步发生反式单酰基取代,实现酰基取代的酚酸多为对香豆酸,其次为阿魏酸和咖啡酸。“彩色马铃薯”块茎矮牵牛素、锦葵色素、花葵素和芍药色素的对香豆酸酰化衍生物的惯用名分别为“petanin”,“malvanin”,“pelanin”和“peonanin”。本文可以为“彩色马铃薯”块茎颜色呈现的机理探索及其花色苷的分子结构鉴定提供参考。     

太子参试管微块根形成及其应用初探

太子参组培苗单茎节段插入含45g·L^-1蔗糖的MS培养基中,于60μmol·m^-2·s^-1光照强度下培养120d后,其节部位长出不定根膨大形成与太子参体内块根相似、重量约为块根1/20的微块根,平均每株可形成1.54个微块根。微块根移植入大田后,其生长特性和物候期与大田块根相似,都有低温萌芽、高温休眠的特性;开花结果、不定根膨大、块根成熟等也相似。同时,组培中的微块根还具有易培养、耐贮存、体积小、易移栽和繁殖系数高等优点,在生产中具有很大的应用潜力。     

Transgenerational maintenance of transgene body CG but not CHG and CHH methylation

In plants, RNA-directed DNA methylation (RdDM) can target both transgene promoters and coding regions/gene bodies. RdDM leads to methylation of cytosines in all sequence contexts: CG, CHG and CHH. Upon segregation of the RdDM trigger, at least CG methylation can be maintained at promoter regions in the progeny. So far, it is not clear whether coding region methylation can be also maintained. We showed that the body of Potato spindle tuber viroid (PSTVd) transgene constructs became densely de novo methylated at CG, CHG and CHH sites upon PSTVd infection. In this study, we demonstrate that in viroid-free progeny plants, asymmetric CHH and CHG methylation was completely lost. However, symmetric CG methylation was stably maintained for at least two generations. Importantly, the presence of transgene body methylation did not lead to an increase of dimethylation of histone H3 lysine 9 or a decrease of acetylation of H3. Our data supports the view that CG methylation can be maintained not only in promoters but also in the body of transgenes. They further suggest that maintenance of methylation may occur independently of tested chromatin modifications.     

影响茎用芥菜愈伤组织诱导和植株再生的因素

茎用芥菜子叶培养在MS 0.25 mg·L-1NAA 0.5 mg·L-16-BA 0.25 mg·L-12,4-D培养基上,可获得较高质量的愈伤组织.愈伤组织培养在MS 1～1 mg·L-16-BA 0.2 mg·L-1NAA培养基上分化频率为8.3%,而在加有羧苄青霉素和头孢霉素的培养基上,最高分化频率可达52.4%.将获得的再生植株转移到1/2MS 0.1 mg·L-1 NAA的生根培养基中,可获得完整植株.     

Serological detection of yam viruses in farmers' fields in Ogun State,Nigeria

A field survey was conducted in eight local government areas (LGA) of Ogun state, Nigeria to assess the incidence of viral diseases of yams in the areas. Leaf samples were collected from 90 yam plants which were either symptomatic or asymptomatic. These were bulked into 45 during serological tests and the viruses indexed include yam mosaic virus (YMV); Dioscorea alata bacilliform virus (DaBV) and cucumber mosaic virus (CMV). DaBV was the most prevalent virus on the field with incidence of 48.9% (22/45) followed by YMV which occurred in 42.2% (19/45). CMV had the lowest percentage of incidence; 2.2% (1/45). Of all the LGAs visited, Abeokuta north and Abeokuta south had the highest incidence of YMV and DaBV, respectively. Mixed virus infections were also detected.