Fine root turnover of irrigated hedgerow intercropping in Northern Kenya

Fine root turnover (<2 mm) was determined from repeated measurements of root distribution up to 120 cm soil depth by core sampling in four month intervals. Sole cropped Sorghum bicolor and Acacia saligna were compared with the agroforestry combination in an alley cropping system in semiarid Northern Kenya. Three methods for the calculation of root production were used: the max-min, balancing-transfer and compartment-flow method. The highest root biomass was found in the topsoil for all cropping systems, though trees had a deeper root system. Trees and crops had a similar amount of below-ground biomass during the vegetation period (0.3 and 0.4 Mg DM ha^-1 120 cm^-1), but in the agroforestry combination root biomass was more than the sum of the sole cropped systems (1.1 Mg DM ha^-1 120 cm^-1). The tree system showed a very static root development with little fluctuation between seasons, whereas root biomasses were very dynamic in the crop and tree + crop systems. Root production was highest in the tree + crop combination with 2.1 Mg DM ha^-1 a^-1, with about 50% less in sole cropped trees and crops. Root N input to soil decreased in the order tree + crop>tree>crop system with 13.5, 11.0 and 3.2 kg N ha^-1 a^-1, and cannot be estimated from total below-ground biomass or carbon turnover, as N is accumulated in senescing roots. Such low N input to soil stresses the need for investigating other processes of nutrient input from roots to soil. Areas of highest N input were identified in the topsoil under the tree row in the tree system. Resource utilisation and C and N input to soil were highest with a combination of annual and perennial crops.     

二色补血草LbGRP基因的克隆及抗逆能力分析

富含甘氨酸RNA结合蛋白(Glycine-rich RNA-binding proteins, GRP)是植物中重要的转录后调控蛋白, 在植物的生长发育及对胁迫的抗性调控等过程中起重要作用。文章从二色补血草(Limonium bicolor (Bunge) O.) cDNA文库中克隆出了富含甘氨酸RNA结合蛋白基因(LbGRP)的全长cDNA序列(GenBank登录号: GQ398238)。为了研究LbGRP的抗逆功能, 将其构建到酵母表达载体pYES2中, 转化到酿酒酵母INVSc1菌株中, 获得重组酵母INVSc1(pYES2-LbGRP), 同时将转空pYES2质粒的酵母INVSc1(pYES2)作为对照。对重组酵母INVSc1 (pYES2-LbGRP)和对照INVSc1(pYES2)进行NaCl、KCl、NaHCO₃、Na₂CO₃、干旱和冷冻胁迫, 比较它们在不同胁迫下的存活率。结果表明, INVSc1(pYES2-LbGRP)在各种胁迫下的存活率明显高于对照INVSc1(pYES2), 证明LbGRP基因具有抗NaCl、KCl、NaHCO₃、Na₂CO₃、干旱和冷冻等胁迫的能力, 推测该基因参与了二色补血草的抗逆调控过程。     

二色补血草液泡膜H^＋-ATP酶C亚基（LbVHA-C）基因克隆和表达分析

从二色补血草cDNA文库中分离出一个V-H^＋-ATP酶C亚基（LbVHA-C）基因全长cDNA序列。该基因全长为729bp。其中,开放读码框（ORF）为498bp,编码165个氨基酸,预测编码蛋白的分子量为16.6kDa,理论等电点为8.62。用实时定量RT-PCR方法进一步研究二色补血草在NaCl、NaHCO3和NaCO3胁迫下的不同时间内该基因表达模式的结果表明,NaCl强烈诱导二色补血草叶组织中LbVHA-C基因的表达,但其根部的表达变化不明显。NaHCO3胁迫下LbVHA-C基因在根部组织的表达受抑制。Na2CO3胁迫24h时的LbVHA-C基因在根和叶部组织中的表达都强烈受抑制,随后在根和叶组织的表达量逐步升高。     

异型花柱植物喀什补血草的传粉者功能群与花粉转移效率

异型花柱是受遗传控制的花柱多态现象, 被达尔文认为是植物通过在传粉者体表不同部位滞落花粉以促进型间花粉准确传递的一种适应。该现象虽已受到广泛关注, 但在一些花型变异较大且不稳定的传粉系统中, 不同传粉者对各花型繁殖所产生的影响仍知之甚少。该研究以分布于新疆天山南坡的一个有同长花柱共存的异型花柱植物喀什补血草(Limonium kaschgaricum)种群为研究对象, 对其花型构成及频率、传粉者及花粉转移效率等进行了调查分析。结果表明: 1)种群中除了存在雌/雄蕊长度交互对应的长(L)/短(S)花柱型花外, 还有雌/雄蕊同长的花(H型), 且各花型花的花冠口直径、花冠筒长及花粉量等参数间无差异, 但花粉纹饰和柱头乳突细胞形态具二型性。其中, H型花的花粉和柱头形态与L型花(或S型花)的一致。2)花型内和自花授粉均不亲和; 型间授粉时, 花粉和柱头形态不同的花型间亲和, 反之不亲和。3)种群内存在长/短吻两类传粉昆虫。在以短吻传粉者为主的盛花初、中期, L和H型花柱头上的异型花粉数均显著高于S型花的, 且L和S型花高位性器官间的异型花粉传递效率高于低位性器官间的; 而在以长吻传粉者为主的盛花后期, L和S型花的柱头间异型花粉数无显著差异, 且高/低位性器官间具有相同的异型花粉转移效率; 与传粉者出现时期相对应的、在花期不同阶段开放花的结实率也明显不同。4)长/短吻昆虫具明显不同的传粉功能, 短吻昆虫只能对L和H型花进行有效传粉, 且访花频率和型间花粉转移效率较低, 为低效传粉者; 而长吻昆虫对各花型均能有效传粉, 具高的访花频率和型间花粉转移效率, 为高效传粉者。因为长吻昆虫的阶段性出现所形成的不稳定传粉系统, 使低效的短吻昆虫可能会成为种群中花型变异的驱动力, 并使S型花受到更大的选择压力。H型花克服了柱头缩入的弊端, 可能会成为不稳定传粉系统下的一个替代花型而持续存在。     

Individuation in Sorghum bicolor: a self-organized process involved in physiological adaptation to salinity

In Sorghum bicolor, salt-adaptation was defined as the capacity of plants to grow at 300 m M NaCl (a lethal concentration) following a 3-week pre-treatment with 150 m M NaCl (a sublethal concentration). Large populations induced for salt-adaptation were analysed. Two modes of osmotic regulation (Na-includer and Na-excluder) were differentiated during induction of salt-adaptation, in spite of the genetic and environmental homogeneity. This variability was not related to any incapacity of the Na-includers to control accumulation of Na ⁺ ions in the shoot, because most of the pre-treated plants displayed a similar capacity of growth and control of Na ⁺ uptake after transfer to 300 m M NaCl. This unsuspected complexity of initially homogeneous populations points on the inadequacy of physiological studies focused on the ‘average individual’. Further analyses showed that variability was not directly related to micro-environmental variations. It is concluded that a process of individuation is caused by a third source of variability, which is the expression of a self-organizing process normally occurring during the transition phases in development. In constraining environments, this phenomenon of individuation includes adaptive modifications.     

两色绿刺蛾生物学特性及发生规律

两色绿刺蛾在福建闽西北1a发生2代，以老熟幼虫在土壤中结茧越冬。该虫1a有2次发生高峰期，分别在6月上、中旬和9月下旬至10月上旬。以第1代发生量大，危害严重。该虫发生与竹林结构、竹立量、坡向、坡位均有关系。林间调查表明：该虫第2代的天敌寄生率高。天敌是抑制种群数量增长的重要因素之一。     

SNFL3: A Protein Kinase Homologue of Sorghum bicolor with a High Similarity to the Yeast SNF1 Protein Kinase

We have identified several protein kinases that are differentially expressed in mesophyll and bundle sheath cells of the C4 plant Sorghum bicolor. Here we describe the characterization of a protein kinase homologue that shows a high amino acid sequence similarity to the SNF1/AMPK family of protein serine/threonine kinases. The mRNA of this gene accumulates to much higher levels in mesophyll cells than in the bundle sheath and can also be detected in root tissue.     

不同类型双色百合的花色形成分析

以3个花朵双色的亚洲百合品种('Black Eye'、'Pieton,和'Twosome')为试验材料,通过对不同部位(花被片上部和下部)的花色表型、色素成分和含量进行综合分析,解析不同类型双色百合的形成机理.结果表明:(1)于紫色花被片下部检测到矢车菊素3-O-β-芸香糖苷一种花青苷,且在花被片下部深紫色的'Blac...