沙棘种子高积累碳十八不饱和脂肪酸的多基因协同调控机制

为探讨沙棘种子油高积累碳十八不饱和脂肪酸的多基因协同作用机制,以近缘低油沙棘品系‘绥棘1号’和高油品系‘新俄3号’6个不同发育期的种子为材料,利用气相色谱飞行时间质谱法测定种子油脂肪酸组份,采用qRT-PCR方法分析不饱和脂肪酸合成积累相关基因KAR、FATB、Δ9 D、KASⅡ、SAD、FAD2、FAD3、FAD7和FAD8的表达模式,验证多基因表达对碳十八不饱和脂肪酸积累的影响。结果表明:(1)‘绥棘1号’和‘新俄3号’种子油均高积累碳十八不饱和脂肪酸,分别占总脂肪酸的87.71%和88.68%;种子发育期间,油酸相对含量一直呈上升趋势,亚油酸相对含量短时下降后上升趋稳,而亚麻酸相对含量则呈先上升后下降趋稳。(2)FATB基因下调表达协同Δ9 D基因低表达,使C16∶0-ACP转化为棕榈酸和棕榈油酸的代谢减弱,而KAR和KASⅡ基因的相对上调表达,促进了硬脂酸合成,为碳十八不饱和脂肪酸的合成积累了较多前体。(3)SAD基因的持续高表达催化硬脂酸去饱和为油酸,且持续上升的SAD/FATB基因表达比直接提高了脂肪酸的去饱和速率;FAD2、FAD3、FAD7和FAD8基因在亚油酸和亚麻酸快速合成期间同时出现明显的表达量峰值,进而促进油酸逐步去饱和为亚油酸和亚麻酸。研究认为,沙棘种子油高积累碳十八不饱和脂肪酸源于FATB和Δ9 D基因的低表达及KAR、KASⅡ、SAD、FAD2、FAD3、FAD7和FAD8基因的协同高表达,本研究结果为进一步理解种子油中碳十八不饱和脂肪酸的合成积累提供了理论依据,对改良植物油脂的不同脂肪酸比具有重要意义。     

油茶种子发育期油脂合成积累的源汇基因协同表达

为探讨油茶种子油脂的合成积累与源汇基因表达间的关系,以高油品系‘MY003’和低油品系‘MY008’的不同发育时期(6月2日、7月4日、8月5日、9月3日)种子为材料,利用氯仿甲醇法测定含油率,采用qRT-PCR技术分析油脂合成源基因(GPD1)和汇基因(DGAT1和DGAT2)在高低油种子间的表达差异及其对油脂合成积累的影响,为进一步研究油茶种子油脂合成积累的分子机制提供理论依据。结果显示:(1)油茶种子含油率均处于逐渐上升趋势(0.16%~24.1%),并在7月4日以后开始迅速上升,且‘MY003’种子含油率一直高于‘MY008’。(2)在‘MY003’种子中GPD1、DGAT1和DGAT2基因表达量均明显高于‘MY008’,DGAT1和DGAT2在源基因GPD1高水平表达后仍出现表达高峰;源基因GPD1在种子发育初期高表达,促进了TAG前体G3P的高效合成,而汇基因DGAT1和DGAT2在种子发育后期高表达,则促进了TAG的高效积累,GPD1与DGAT1、DGAT2之间呈正相关关系。研究表明,油茶种子油脂的合成积累来源于源基因GPD1和汇基因DGAT1与DGAT2的协同高表达。     

紫苏油脂合成相关基因家族鉴定及表达分析

该研究从转录组数据库中筛选鉴定紫苏溶血磷脂酸酰基转移酶(LPAT)家族基因,采用生物信息学方法分析了该家族基因的序列特征及蛋白结构,利用qRT PCR技术对该基因时空表达特性进行了研究,为进一步了解紫苏油脂合成机制提供理论依据。结果表明：(1)从紫苏转录组数据库中共检测出11个LPAT家族基因,分别命名为PfLPAT1、PfLPAT2 1、PfLPAT2 2、PfLPAT2 3、PfLPAT2 4、PfLPAT4 1、PfLPAT4 2、PfLPAT5 1、PfLPAT5 2、PfLPAT5 3和PfLPAT5 4;PfLPATs编码氨基酸长度介于250~384 aa之间,理论等电点在7.6~9.6之间。(2)基因序列比对结果表明,11个PfLPATs蛋白分别属于3个亚类,其中1型LPAT包含1个基因,2/3型LPAT 包含4个,4/5型LPAT 包含6个。(3)实时荧光定量PCR结果显示,11个LPAT家族基因在 ‘晋紫苏1号’不同组织中均有表达,其中LPAT2 1、LPAT2 2和LPAT2 3在种子中表达量较高,推测其在紫苏种子油脂合成代谢过程中发挥重要作用。该结果为后续紫苏LPAT家族基因的功能研究提供了重要的基因信息。     

梅花新品种‘治章骨红重翠’跨品种群特性机制探究

‘治章骨红重翠’梅是一个具有跨品种群特性的梅花新品种,它同时具有朱砂和绿萼品种群的典型特征,其萼绿、花白、木质部淡暗紫色,但其机制并不清楚。本研究对‘治章骨红重翠’梅、‘豫西朱砂’梅、‘豫西变绿萼’梅表型、花色苷含量和花青素合成通路相关基因的表达量进行测定,结果表明,花瓣、萼片和枝内新生木质部的红色程度与总花色苷含量呈正相关。MYBɑ1、MYB1、bHLH3是影响这3个品种花部与木质部呈现红色的关键转录因子基因,转录因子促进结构基因F3′H、DFR、ANS和UFGT高表达,从而促进红色性状的产生。综合分析后推测,‘治章骨红重翠’梅花瓣白色源于矢车菊合成通路上其他分支FLS、F3′5′H、LAR和ANR基因高表达,谷胱甘肽转移酶(glutathione transferase, GST)基因GST低表达;萼片绿色源于F3′H、DFR和ANS基因低表达;木质部红色源于ANS、UFGT基因高表达。本研究对‘治章骨红重翠’梅跨品种群特性作出初步解释,为梅花花色与木质部颜色的分子育种提供了参考。     

基于藜麦转录组的脂肪酸生物合成途径解析

藜麦营养丰富,油脂含量高,脂肪酸组成理想,是油脂提取物的潜在资源。植物油脂主要以三酰甘油的形式储存在作物种子和果实等器官中,其合成受到环境和基因水平的调控,涉及质体、内质网和油体等多个细胞器。该文基于藜麦转录组数据,对藜麦油脂合成相关的脂肪酸生物合成途径基因进行挖掘,并对基因表达模式进行分析。结果表明:在藜麦中,与脂肪酸生物合成相关的基因序列共87条,涉及乙酰CoA羧化酶和β-酮脂酰ACP合成酶等关键酶,其中编码长链酰基辅酶A合成酶基因和β-酮脂酰ACP还原酶数目最多。通过基因表达模式分析发现,与脂肪酸生物合成相关的基因在种子表达中呈现整体上调模式,可能与种子中油脂形成和积累密切相关。对藜麦乙酰CoA羧化酶亚基编码基因进行分析发现,accD基因在不同组织间无差异表达,表明在藜麦中accD编码的β-CT亚基可能不是影响乙酰CoA羧化酶发挥作用的限制因子。藜麦KASⅡ含有保守结构域,与其他组织相比,编码基因QcFb15、QcFb45和QcFb75在种子中均存在上调表达,参与藜麦脂肪酸碳链延伸及油脂形成。对藜麦脂肪酸生物合成途径相关基因的挖掘,为藜麦油脂合成和积累的研究提供了理论基础,对高油脂藜麦品种选育等后续研究也具有重要启示作用。     

沙棘hrh-miR319e靶向转录因子AP4调控种子发育的研究

为探讨沙棘hrh-miR319e与转录因子AP4间的靶向关系,并分析其在种子发育过程中的表达,以不同发育期的种子为材料,运用RNAhybrid软件预测hrh-miR319e成熟体序列与其候选靶基因AP4的3′-UTR区的结合位点,构建pcDNA3.1+pmirGLO-AP4和pcDNA3.1-hrh-mir319e+pmirGLO-AP4载体,用双荧光素酶报告基因检测方法验证hrh-miR319e与候选靶基因AP4间的靶向关系,并采用qRT-PCR方法分析hrh-miR319e与AP4基因在沙棘不同发育期种子中的表达变化。结果显示：(1)生物信息学预测AP4-3′-UTR区与hrh-miR319e成熟体序列完全互补。(2)荧光检测显示pcDNA3.1-hrh-mir319e+pmirGLO-AP4质粒显著抑制荧光素酶活性(P<0.001)。(3)不同发育期种子中hrh-miR319e的表达量总体呈现出先明显上升后明显降低的变化趋势,而AP4基因的表达量则呈现出先降低后上升的趋势;当hrh-miR319e的表达量在花后80 d达到最高水平时,‘新俄3号’种子中为3.146、‘绥棘1...     

茶树SBP box转录因子的比较基因组学与遗传分析

SQUAMOSA启动子结合蛋白(SBP box)是植物特异性转录因子,在植物生长发育中发挥重要作用。该研究利用生物信息学分析方法,对不同‘铁观音’、‘黄棪’、‘舒茶早’和‘龙井43’茶树基因组的SBP基因进行鉴定和比较,通过qRT PCR技术分析CsTGY_SBP家族成员在不同茶树品种中的表达模式,为探究SBP基因在茶树杂种和亲本上的遗传规律提供参考。结果显示：(1)在茶树品种‘铁观音’、‘黄棪’、‘舒茶早’和‘龙井43’基因组中分别鉴定出21个、25个、24个和23个SBP家族基因。(2)系统进化树将其分为8个亚家族,共线性分析发现茶树和拟南芥、葡萄的SBP基因共线性关系与水稻相比更强,同物种内发现‘铁观音’与‘黄棪’的共线性关系更显著。(3)qRT PCR结果表明,CsTGY_SBP5、CsTGY_SBP9和CsTGY_SBP14在F₁‘金观音’中呈中亲表达的模式;大部分CsTGY_SBPs基因在F₁‘黄观音’呈低于双亲表达模式,CsTGY_SBP5和CsTGY_SBP8在F₁‘金牡丹’中显著高于亲本;CsTGY_SBP5、CsTGY_SBP7、CsTGY_SBP12、CsTGY_SBP16和CsTGY_SBP18在F₁‘紫玫瑰’中的表达量显著高于亲本,呈超高亲表达的模式;CsTGY_SBPs基因在F₁‘紫牡丹’中整体表达趋于亲本铁观音,在F₁‘瑞香’中整体呈现低于亲本‘黄棪’的表达模式。研究表明,CsTGY_SBP5在F₁‘金牡丹’和F₁‘紫玫瑰’中的表达均显著高于亲本,推测CsTGY_SBP5可能是茶树杂种优势的重要调控因子。     

紫苏溶血磷脂酸酰基转移酶基因的克隆与功能分析

紫苏(Perilla frutescens)是一种重要食药同源油料作物,种子含油量高达46%−58%,其中α-亚麻酸(C18:3)含量占60%以上。溶血磷脂酸酰基转移酶(lysophosphatidic acid acyltransferase,LPAT)是植物种子三酰基甘油组装过程中的一类关键限速酶。本研究从紫苏发育种子中克隆了其编码基因(PfLPAT2),并利用qRT-PCR技术检测PfLPAT2基因在紫苏不同组织及不同发育时期种子的表达特性。构建PfLPAT2/GFP融合表达载体并通过农杆菌介导瞬时侵染本氏烟草叶片,检测PfLPAT2蛋白的亚细胞定位。构建大肠杆菌(Escherichia coli)表达载体、酵母表达载体和组成型植物过表达载体,分别转化大肠杆菌突变株SM2-1、酿酒酵母(Saccharomyces cerevisiae)野生型菌株INVSc1和普通烟草(Nicotiana tabacum),分析PfLPAT2蛋白的酶活性及生物学功能。结果表明,紫苏PfLPAT2基因ORF为1 155 bp,编码384个氨基酸。功能结构域预测显示PfLPAT2蛋白具有溶血磷脂酸酰基转移酶典型的保守区。PfLPAT2基因在紫苏根、茎、叶、花和开花后10、20、30、40 d的种子中均有表达,且在开花后20 d的种子中高表达。亚细胞定位结果显示PfLPAT2蛋白定位于细胞质。大肠杆菌功能互补测试表明,PfLPAT2可恢复SM2-1细胞膜脂生物合成,具有LPAT酶活性。与非转基因对照相比,转PfLPAT2基因酵母的总油脂含量显著提高,且脂肪酸各组分的含量发生改变,油酸(C18:1)含量增加明显,预示PfLPAT2对C18:1具有较高的底物偏好性。转基因烟草叶片总脂肪酸含量比对照组提高了约0.42倍,C18:1含量增加了约1倍。转基因株系总脂提高和脂肪酸组分的改变表明PfLPAT2异源表达可以促进宿主油脂合成和健康有益型脂肪酸(C18:1和C18:3)的积累。本研究为深入解析紫苏油脂特别是不饱和脂肪酸合成的分子调控机制和改良油料作物油脂品质提供理论依据和基因元件。     

‘嘎拉’苹果及其杂交后代对炭疽叶枯病的抗性机制分析

为解析苹果对炭疽叶枯病的抗性机制,该研究以‘嘎拉’、‘藤牧1号’苹果及其杂交后代等87个苹果品种(系)为试验材料,进行田间调查及人工接种病菌并检测不同品种(系)中病菌生物量,利用SSR分子标记进行基因型鉴定,分析各品种(系)对炭疽叶枯病的抗性差异,利用荧光定量PCR及酶活检测比较分析水杨酸相关基因、抗性酶基因及酶活性水平差异。结果表明：(1)87个苹果品种(系)对苹果炭疽叶枯病的抗性差异明显,‘嘎拉’、‘2 5’、‘19 19’等品种(系)叶片发病严重,表现出对炭疽叶枯病的高感性,‘藤牧1号’、‘40 9’及‘16 16’等品种(系)叶片无病斑或病斑极少,炭疽叶枯病菌含量显著低于感病性品种(系),其抗性显著。(2)SSR标记S0405127和S0304673的基因型鉴定结果与田间表型调查结果相比,准确率分别为93.10%和91.95%,与人工接种结果相比,准确率分别为91.95%和95.40%。(3)SA相关基因的表达模式结果表明,接种炭疽叶枯病菌4 d后,‘藤牧1号’、‘40 9’及‘16 16’等抗性品种(系)中SA合成相关基因MdEDS1、MdPAD4和MdPAL被强烈诱导表达;同时,SA信号转导相关基因MdNPR1、MdPR1、MdPR5的表达显著高于‘嘎拉’等感病品种(系)。(4)接种炭疽叶枯病菌4 d后,‘藤牧1号’、‘40 9’及‘16 16’等抗性品种(系)的MdSOD、MdPOD酶基因表达水平及酶活性显著高于‘嘎拉’、‘2 5’、‘19 19’等感病品种(系)。研究认为,‘藤牧1号’、‘40 9’及‘16 16’等品种(系)通过调控水杨酸合成和信号转导通路及氧化还原相关反应等提高对炭疽叶枯病的抗性,为挖掘抗性基因以及利用优良种质选育抗病品种奠定了基础。     

不结球白菜金属硫蛋白基因的克隆及表达分析

通过RACE技术,从不结球白菜抗病品种‘苏州青’叶片克隆到金属硫蛋白(metallothionein)基因的全长cDNA序列(BcMT2)。序列分析结果表明,BcMT2基因的cDNA全长为528 bp,其中开放阅读框长度为243 bp,共编码80个氨基酸,相对分子质量为8.02×10³ Da,理论等电点是4.61。氨基酸同源系统进化分析表明,不结球白菜BcMT2基因属于Ⅱ类植物MT2基因家族,且与同科植物的进化关系相近,其中与大白菜第5号染色体的基因(Bra029765)相似性最高(100%)。qRT PCR分析表明,BcMT2基因在不结球白菜叶中表达最强;霜霉病菌诱导后,BcMT2基因在抗病品种‘苏州青’中的表达量于48 h达到峰值,而在感病品种‘矮脚黄’中的表达量于72 h达到峰值;盐处理条件下,BcMT2基因在抗病品种‘苏州青’中的表达量于12 h达到峰值,而在感病品种‘矮脚黄’中的表达量于24 h达到峰值;ABA处理下,‘苏州青’中其表达量于24 h达到峰值,且在‘矮脚黄’中BcMT2基因的表达趋势与‘苏州青’类似;干旱处理条件下BcMT2基因的表达在两材料中均受到抑制。BcMT2原核表达分析发现,在37 ℃、1.0 mmol·L^-1IPTG诱导2、4 、6 h后,均检测到了一条蛋白分子质量约为8×10³ Da的表达特异条带,这与预期融合蛋白的相对分子质量的理论值8.02×10³ Da相符。研究表明,不结球白菜BcMT2基因在受到生物胁迫和非生物胁迫等逆境条件下均发挥着重要作用,且BcMT2在大肠杆菌中成功实现融合表达,为进一步进行蛋白水平和转基因功能研究奠定了基础,也为选育高产、优质的不结球白菜新品种提供重要的理论依据。     

New species and new combinations in Peruvian Orchidaceae

seventeen new species and combinations are proposed in the generaChondrorhyncha, Cischweinfia, Cochlioda, Eloyella, Encyclia, Kefersteinia, Koellensteinia, Macroclinium, Rodriguezia, Solenidiopsis, andStenia. All new species are illustrated. A key is provided for 2-flowered species ofMacroclinium, PeruvianSigmatostalix, and PeruvianStenia. Solenidium (Solenidiopsis) peruvianum Schltr. is lectotypified.     

Cyclooxygenase inhibitory and antioxidant cyanidin glycosides in cherries and berries

Anthocyanins from tart cherries, Prunus cerasus L. (Rosaceae) cv. Balaton and Montmorency; sweet cherries, Prunus avium L. (Rosaceae); bilberries, Vaccinum myrtillus L. (Ericaceae); blackberries, Rubus sp. (Rosaceae); blueberries var. Jersey, Vaccinium corymbosum L. (Ericaceae); cranberries var. Early Black, Vaccinium macrocarpon Ait. (Ericaceae); elderberries, Sambucus canadensis (Caprifoliaceae); raspberries, Rubus idaeus (Rosaceae); and strawberries var. Honeoye, Fragaria x ananassa Duch. (Rosaceae), were investigated for cyclooxygenase inhibitory and antioxidant activities. The presence and levels of cyanidin-3-glucosylrutinoside 1 and cyanidin-3-rutinoside 2 were determined in the fruits using HPLC. The antioxidant activity of anthocyanins from cherries was comparable to the commercial antioxidants, tert-butylhydroquinone, butylated hydroxytoluene and butylated hydroxyanisole, and superior to vitamin E, at a test concentration of 125 microg/ml. Anthocyanins from raspberries and sweet cherries demonstrated 45% and 47% cyclooxygenase-I and cyclooxygenase-II inhibitory activities, respectively, when assayed at 125 microg/ml. The cyclooxygenase inhibitory activities of anthocyanins from these fruits were comparable to those of ibuprofen and naproxen at 10 microM concentrations. Anthocyanins 1 and 2 are present in both cherries and raspberry. The yields of pure anthocyanins 1 and 2 in 100 g Balaton and Montmorency tart cherries, sweet cherries and raspberries were 21, 16.5; 11, 5; 4.95, 21; and 4.65, 13.5 mg, respectively. Fresh blackberries and strawberries contained only anthocyanin 2 in yields of 24 and 22.5 mg/100 g, respectively. Anthocyanins 1 and 2 were not found in bilberries, blueberries, cranberries or elderberries.     

Nectary structure and nectar characteristics in someBignoniaceae

The nectary structure and chemical nectar composition of 15 species belonging to 12 genera ofBignoniaceae are analyzed. All taxa bear a conspicuous nuptial nectary surrounding the ovary base. The secretory tissue is mostly supplied by phloem branches. The stomata are located in the middle and upper part of the nectary epidermis with an homogeneous distribution. The nuptial nectary is proportionally large in relation to the ovary (15–30%), disregarding the nectary volume. Most species have extranuptial nectaries in both inner and outer surfaces of the calyx. Both kinds of nectaries lack a vascular tissue that straightly supplies them. Nuptial nectar concentration (wt/wt) ranges from 19 to 68%. Sugars and amino acids are found in all species. Half of the species have hexose predominant nectars, the remaining sucrose predominant. Phenols are detected in only three species, whereas reducing acids exclusively inTecoma stans. Alkaloids and lipids were never detected. Extranuptial nectar chemical composition is analyzed in two species:Dolichandra cynanchoides andPodranea ricasoliana. Bees constitute the main flower visitors of the species studied whereas hummingbirds were seen visiting three species. A correlation analysis is performed with the data obtained. There are a few significant correlations which indicate a parallel increase of three parameters: the longer the flower length, the more voluminous the nectary and the higher stomata number, independently of the floral biotype. Phenograms are obtained using 24 floral characters including nectary and nectar data. The clusters obtained do not reflect taxonomic relationships but are useful in the understanding of animal-plant interactions when the flower biotype is considered.This paper is based on a chapter of a doctoral thesis presented at the University of Córdoba (Argentina).     

Conserved sequences in bacterial and viral sialidases

The genes of the bacterial sialidases fromClostridium sordellii G12,C. perfringens A99,Salmonella typhimurium LT-2 andVibrio cholerae 395 sequenced so far were examined for homologies and were compared with sequences of viral sialidases.Each of the bacterial sialidases contains a short sequence of twelve amino-acids, which is repeated at four positions in the protein. All these sequences exhibit significant similarities. Comparing the repeated sequences of the four sialidases, five amino-acids were found to be highly conserved at defined positions: Ser-X-Asp-X-Gly-X-Thr-Trp. Additionally, most of the distances betweeen the four repeated regions are also conserved among the different sialidases. The conserved bacterial sequences show similarity with sialidases of influenza A H7N1 and H13N9.     

Allergenic pollen and pollinosis in Warsaw

Summary Our study of fifty two hay fever patients included twenty six solely allergic to grass pollen and twenty six exhibiting allergy to various pollen species, such as hazel, birch, oak, poplar, andArtemisia. Their total and specific IgE response was evalutated by the immunoenzymatic method, while clinical reactivity was assessed by recording nasal and bronchial symptom scores between mid-March and mid-July. Simultaneously pollen counts were made. Polysensitized patients showed significantly higher levels of both total and specific IgE, which testifies to the enhanced quantitative and qualitative IgE. Multisensitized patients reacted earlier than patients sensitized to grass pollen only, which confirms that non-grass plants flowering only in the spring cause the priming effect on the nasal and bronchial mucosa. The early symptoms may be attributable to tree pollen sensitivity or may refletct higher grass pollen IgE levels in the polysensitized group. Characteristically, nasal symptoms preceded bronchial symptoms of several weeks.On comparing nasal washing from the polysensitized patients to washing from patients with grass pollen, we found much cytological material with the predominance of eosinophils.     

The spatial and temporal distribution of predatory and phytophagous mites in field-grown strawberry in the UK

Extensive sampling of strawberry plants in everbearing and June-bearing strawberry plantations and on potted plants showed that different species of mites were spatially separated. Of the two phytophagous species recorded, Tetranychus urticae was most abundant on old leaves and Phytonemus pallidus on folded leaves and flower/fruit clusters. Predatory phytoseiid mites were found on all plant parts but different species were spatially separated; Neoseiulus cucumeris and N. aurescens were found mostly on folded leaves and clusters, and N. californicus and Phytoseiulus persimilis on old and medium aged leaves. No Typhlodromus pyri were found in the field plantations. These patterns of distribution did not change over sampling dates in summer and early autumn. An understanding of this within-plant zonation of mite species is important when studying predator–prey interactions and when designing sampling strategies for strawberry. A programme to sample the entire mite system on strawberry should be stratified to include all the above mentioned parts of the plant. Different sampling protocols, as appropriate, are required for sampling different pest species and their associated predators.     

Amino acids and sugars in nectar,and their putative evolutionary significance

Individual amino acids and sugars from flower nectar of 32 plant species with different pollination systems were quantified and compared. Data show that there is no correlation between sugar and amino acid concentration. Furthermore there is no correlation between composition and concentration of amino acids and evolutionary advancement, nor any direct relation with pollination systems. However, higher sugar concentrations are often linked with more advanced morphological characters. Nectars from pierced or damaged flowers or nectars contaminated with pollen exhibit modifications and increases in amino acid composition. The presence of proline probably indicates such pollen contamination. Most pollinating animals depend on flower nectar in their energetic requirements, yet innumerable alternative amino acid and protein sources exist. Future research has to consider the relationship between nutritional requirements of pollinating animals and dependence on flower nectars.Dedicated to Prof. Dr.L. van der Pijl, Den Haag, in honour of his 80th birthday.     

Occurrence of ochratoxin A and ochratoxigenic mycoflora in corn and corn based foods and feeds in some South American countries

Cereals and cereal- derived products constitute the base of human and animal feeding in South American countries. This review attempts to give an overview of the ochratoxin A (OTA) occurrence and potential sources of OTA contamination in those products. The environmental conditions as humidity and temperature in the colonization of the substrates by Aspergillus section Nigri isolated from corn kernels were also discussed. The available information on the ochratoxigenic mycoflora and OTA presence in corn, corn based food and feed is limited. Only few surveys have been carried out in Argentina, Ecuador and Brazil; which showed that Aspergillus niger aggregate and A. ochraceus species would be the main source of OTA. It’s possible to emphasize that, the species A. carbonarius has not been isolated from these substrates and Penicillium verrucosum was isolated only from pig feeds of Argentinean samples in low percentage. Studies about the ecophysiology of ochratoxigenic fungi and OTA occurrence are in progress in Latin America to reduce the impact of this toxin in the food chain. Carina E. Magnoli, Stella M. Chiacchiera, Ana M. Dalcero—Members of the Research Career Andrea L. Astoreca—Fellowship of CONICET     

Seed morphology and anatomy in someAnnonaceae

Twelve species ofAnnonaceae, namelyAncana sp.,A. stenopetala, Annona cherimola, A. montana, A. muricata, A. squamosa, Bocagea sp.,Bocageopsis canescens, two species ofUnonopsis, Xylopia aromatica, andX. emarginata, were investigated with respect to the morphology and anatomy of the seed. They show the basic structural pattern characteristic of annonaceous seeds: perichalaza, fibrous mesotesta, and rumination developed by both integuments. However, several differential characters, some of them never previously described, were found: All taxa exhibit an additional endotestal mechanical layer which forms the micropylar plug except inAncana. InAncana the plug is built by the inner integument. Aril, sarcotesta and pits on the seed surface are present in some taxa and show different origin and structure. Special anatomical adaptations possibly functioning during germination are described. The results obtained from the investigated taxa are discussed and compared with published data on seed structure inAnnonaceae.