Association and path-coefficient studies on vegetatively propagating and sexually reproducing parts in ramie (Boehmeria nivea L. Gaud.)

Summary In 30 genotypes of ramie (Boehmeria nivea L. Gaud.) there were significant genotypic differences in the weight of reproductive parts (male + female flowers), vegetatively propagating parts (clump and rhizome) and non-propagating vegetative parts (leaf and root). The weight of reproductive parts was significantly and positively associated with the weight of vegetatively propagating parts. Path-coefficient analysis revealed that the selection of genotypes with a high weight of reproductive parts should be based on genotypes with a high weight of vegetatively propagating parts.     

First Report of Black Leaf Spot Caused by Alternaria alternata on Ramie in China

In 2012 and 2013, black leaf spot disease was observed on ramie plants in Hunan and Hubei Provinces, China. In the field, the symptoms of this disease included dark green to black big spots on leaves, often resulting in upwardly curled leaf margins. The pathogen isolates were identified as Alternaria alternata (Fr.) Keissler on the basis of morphology and sequence similarity of 99–100% to the published data for internal transcribed spacer (ITS), and glyceraldehyde‐3‐phosphate dehydrogenase (gdp). To our knowledge, this is the first report of Alternaria leaf spot of ramie in China.     

基于SRAP分析苎麻及近缘种的系统学关系

苎麻与近缘种的系统学关系一直存在争议。利用26对多态性好的随机引物,对中国苎麻属的17种9变种的共27份材料进行SRAP分子标记分析。扩增结果是26对引物共扩出368条带,其中363条为多态性带,占98.64%。聚类分析表明:(1)腋球苎麻组的腋球苎麻和苎麻组的苎麻、贴毛苎麻聚在一支并靠近系统树的根部,支持王文采苎麻组起源于原始的腋球苎麻组观点。(2)苎麻和贴毛苎麻聚在一支,支持郭安平苎麻直接起源于贴毛苎麻的观点。(3)苎麻组的青叶苎麻、微绿苎麻和大叶苎麻组的多倍体类群聚在一支,可能是由于在种间杂交导致。     

Differences in photosynthetic characteristics and accumulation of osmoprotectants in saplings of evergreen plants grown inside and outside a glasshouse during the winter season

Photochemical efficiency, photosynthetic capacity, osmoprotectants, and relative water content (RWC) were recorded in saplings of two evergreen plants (Boehmeria rugulosa Wedd. and Olea glandulifera Wall. ex G. Don) grown inside (GL) and outside (OP) a glasshouse during the winter season. The OP plants experienced 2.0–2.5 °C lower air temperature and dew formation in comparison to GL plants. Diurnal observations indicated no change in RWC in the leaves of GL and OP plants, while significant reduction in both transpiration and net photosynthetic (P _N) rates was observed in OP plants: the reduction in P _N was much more prominent as was also reflected by poor water use efficiency of these plants. Similarly, OP plants also showed decrease in the apparent quantum yield and irradiance-saturated CO₂ assimilation rate. The decrease in P _N was not associated with decreased stomatal conductance. However, a significant reduction in the ratio of variable to maximum chlorophyll (Chl) fluorescence (F_v/F_m) and Chl content was recorded in the OP plants which also contained more total soluble saccharides but less proline contents. The greater enhancement of P _N at 15 °C in comparison to measurements taken at 10 °C in OP plants over GL plants probably indicated an increase in mesophyll capacity of the OP plants’ growth at increased temperature. Hence the enhanced growth and productivity of plants grown in sheltered environments could be associated to their higher photosynthetic activity that may have important bearing on their field establishment and productivity in the long run. The response varied with plant species; reduction in P _N was greater in B. rugulosa than in O. glandulifera. However, the recovery of OP plants in terms of F_v/F_m in the subsequent months revealed that photosynthetic system of these plants is revocable.     

成花光敏感的雌雄性不育苎麻活性氧代谢研究

为研究成花光敏感雌雄不育苎麻(Floral initiation photo-sensitive male and female sertile ramie,SMSFS)的败育与活性氧代谢的关系,对SMSFS及其回复突变株SMSFS(R)花器官的活性氧(ROS)清除酶活性和丙二醛(MDA)含量测定．结果表明：SMSFS蕾的过氧化物酶(POD)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性明显高于可育株SMSFS(R),而膜脂过氧化产物MDA的含量低于SMSFS(R);与蕾期相比,败育期SMSFS雌雄花除POD活性有所上升,而SOD和CAT活性则显著下降,MDA含量升高并高于开花期可育株．可见活性氧代谢的失衡引起了的膜脂过氧化,与SMSFS雌雄性败育明显相关．     

苎麻属野生种的研究与利用

把从我国长江流域及以南14个省(市、自治区)搜集到的苎麻属野生种进行建圃保存,通过对其生长环境条件的控制,观察和研究野生种的植物学特征、主要经济性状、抗逆性、无融合生殖特性等,并对其有效利用进行了进一步的探索。     

苎麻雄性不育系生化代谢和育性遗传研究

用不同温度和日长处理盆栽材料,测试苎麻雄性不育系的温光反应;于雌雄性器官发育期取盆栽植株顶部展开叶往下数第7叶,分析不育系的生化代谢;根据杂交及自交后代育性分离情况,鉴定不育系的不育性遗传方式.结果如下高温加速营养生长,而短日促进生殖生长,短日高温明显加快不育系的发育进度,但高温的促进作用随日长增加而减弱,以至消失.不育系的叶片粗蛋白质、氨基酸含量比可育系减少,尤其是天门冬氨酸、谷氨酸、甘氨酸、胱氨酸、缬氨酸、苯丙氨酸和精氨酸减少明显,但游离脯氨酸含量增加.这些物质代谢的变化,可能是导致苎麻雄性不育的原因.不育系GS14-1、SS370、GSA-2、GS15-8和SS387等的不育性遗传与1对相对性状的遗传方式相符,已找到不育系的保持系和恢复系.     

荨麻科新分类群

一新种,曼耗楼梯草Elatostema manhaoense,和一新变种,洞头水麻Boehmeria macrophylla var.dongtouensis。     

赤苎无融合生殖细胞胚胎学研究

对赤苎(Boehmeria silvestrii (Pamp.)W.T.Wang)细胞胚胎学研究表明,其生殖模式属无融合生殖的二倍体孢子生殖(diplospory),但其未减数胚囊的发育途径不同于已报道的类型。大孢子母细胞的减数分裂I在到达终变期时停滞,染色体呈单价体状态并维持较长的时间。在尚未到达以核膜、核仁消失,纺锤体出现为特征的中期I前,大孢子母细胞由终变期直接“跳”入间期,从而始终保持了二倍体水平。减数分裂Ⅱ正常进行并产生二倍体二分孢子。珠孔端孢子退化,合点端孢子经3次分裂形成包括1个卵细胞、2个助细胞、2个极核和3个反足细胞的八核胚囊。胚和胚乳分别起源于卵和次生核未受精的自发分裂。胚乳属核型,其发育早于胚。     

苎麻小分子G蛋白Racl基因的克隆及表达分析

植物Rac是植物中特有的小分子G蛋白,我们从苎麻转录组中获得一个小分子G蛋白基因eDNA,．5部分序列,设计引物后采用RT-PCR结合RACE技术克隆了该基因的cDNA。序列分析表明,所克隆的RaclcDNA全长为l043bp,包括594bp开放阅读框、214bp的3’端非编码区和235bp的5’端非编码区,能编码一个197氨基酸的推导蛋白。该蛋白包含G蛋白典型的效应因子结合位点、GTP／GDP结合位点和碱性氨基酸区,c末端具有保守的异戊烯基化位,CSIL。采用半定量RT-PCR分析了该基因在5个苎麻品种及不同组织器官中的表达情况,结果表明Racl基因在苎麻根、茎、叶中均有表达,其中在叶中的表达量最高。纤维木质素含量不同的品种中,Racl基因的表达量存在明显差异。木质素含量高的品种具有较高的Racl基因表达,表明该基因可能在苎麻木质素合成过程中发挥作用。