Phylogenetic relationships within <Emphasis Type="Italic">Citrus</Emphasis> and its related genera as inferred from AFLP markers

We investigated the phylogenetic relationships among Citrus and its relatives, including 29 genotypes belonging to Citrus, Poncirus, Fortunella, Microcitrus, Eremocitrus, Atalantia and Severinia using AFLP analysis. Cluster analysis was conducted using neighbour joining (NJ) method. The results demonstrated that Poncirus, Microcitrus and Eremocitrus are distant from Citrus. A strong affiliation exists between C. halimii and Fortunella and the results did not support C. halimii as the fourth basic species. Further evidence was provided that P. polyandra should not be the hybrid between trifoliate orange and Citrus genotypes and it deserves species status. Neither the separation of subgenus Papeda and Citrus nor the separation of subgenus Archicitrus and Metacitrus were clearly resolved in the dendrogram. C. ichangesis is a distinct species very different from other Citrus genotypes, and the results showed it is improper to classify it into subgenus Metacitrus. C. reticulata, C. maxima and C. medica were separated into three distinct clusters. Therefore if only cultivated Citrus species are considered, the three basic species concept is acceptable. However, it is not applicable for whole genus Citrus.     

缺铁和重碳酸盐胁迫对枳实生苗矿质元素的影响

采用盆栽沙培试验,研究了缺铁及重碳酸盐胁迫对枳实生苗矿质元素及植株铁营养的影响.结果表明:pH 7.0和8.0的重碳酸盐胁迫提高了枳实生苗P、K和Ca的含量,降低了叶片Fe、Mg、Zn和Cu的含量;pH 8.0的重碳酸盐胁迫降低了根系三价铁螯合物还原酶以及叶片Fe/Mn与K/Ca的比值,提高了根系总酚含量,说明重碳酸盐胁迫严重降低柑橘铁营养.     

干旱胁迫下AMF对枳生长和活性氧代谢的影响

在正常水分和干旱胁迫下,研究丛枝菌根真菌(AMF)Funneliformis mosseae对枳生长和活性氧代谢的影响。结果表明：6 周的干旱处理显著抑制了枳根系菌根侵染率和植株生长。接种AMF能显著增加正常水分和干旱胁迫下枳株高、茎粗、叶片数,也显著降低叶片丙二醛、过氧化氢和超氧阴离子自由基含量,并显著增强叶片超氧化物歧化酶(主要是Mn-SOD和Cu/Zn-SOD)、过氧化物酶和过氧化氢酶的活性。研究揭示了菌根化植株具有更高的抗氧化防御能力,导致较低的氧化伤害,从而增强植物的抗旱性。     

Akebia saponin D promotes differentiation of bone marrow mesenchymal stem cells into osteoblasts through MAPK signaling pathways

AIM:To explore the role of Akebia saponin D(ASD) in the differentiation of rat bone marrow-derived mesenchymal stem cells(BMSCs) into osteoblasts. METHODS:The rat BMSCs were cultured using routine methods. The effects of ASD on the differentiation of MSCs into osteoblasts were observed. The p38 mitogen-activated protein kinase(p38 MAPK) inhibitor SB203580 and extracellular signal-regulated kinase(ERK) inhibitor PD098059 were used to evaluate the mechanisms. The activity of alkaline phosphate(ALP) and content of osteocalcin(OC) were assayed during differentiation. The mRNA expression of osteoprotegerin(OPG) and receptor activator of nuclear factor-κB ligand(RANKL) was determined by real-time fluorescence quantitative PCR. The activity of p38 MAPK and ERK was measured by Western blotting. RESULTS:Six days after treatment with ASD, the mRNA expression of OPG significantly increased, while the mRNA level of RANKL significantly decreased in induced cells. ASD increased the activity of ALP and the content of OC. Moreover, ASD enhanced the activity of both p38 MAPK and ERK, which was inhibited by SB203580 and PD098059. SB203580 and PD098059 also inhibited the positive role of ASD in the differentiation of MSCs into osteoblasts. CONCLUSION:Akebia saponin D significantly enhances differentiation of rat BMSCs into osteoblasts in vitro, which may be mediated by the p38 MAPK and ERK signaling pathways.     

枳砧椪柑叶片营养元素适宜含量的研究

对枳砧椪柑叶片营养元素含量适宜范围的统计分析表明:采样地点及年份间的差异对叶片元素含量有重要的影响;叶片各元素含量的变异系数差异较大,且微量元素含量的变异系数多显著高于大量元素。初步提出丰产枳砧椪柑叶片元素含量的适宜范围:氮2.90%～3.50%,磷0.12%～0.16%,钾1.00%～1.70%,钙2.50%～3.70%,镁0.25%～0.50%,铜4.0～16.0×10~(-6),锌20.0～50.0×10~(-6),锰20.0～150.0×10~(-6),铁50.0～140.0×10~(-6),硼20.0～60.0×10~(-6).上列标准可作为营养诊断之参考。     

柑橘抗逆基因NAC83的克隆与表达分析

以柚[Citrus maxima（Burm.）Merr.]、枳[Poncirus trifoliata（L.）Raf.]和柠檬[C. limon（L.）Burm. f.]实生苗为试材,使用电子克隆和RT-PCR的方法从中克隆到3个新的NAC蛋白基因,分别命名为CmNAC83、PtNAC83和ClNAC83;并用qRT-PCR技术检测了该基因在ABA、干旱、低温和高盐胁迫处理下的时空表达。结果显示：CmNAC83、PtNAC83和ClNAC83 的cDNA序列全长均为841 bp,都含有750 bp的开放阅读框（ORF）,编码249个氨基酸;推测其蛋白分子质量分别为24.18、28.00和28.15 kD,等电点分别是9.02、9.31和9.30,且均含有NAC家族的N端保守结构域;系统进化树分析表明,该3个蛋白均属于SENU5亚族,与苹果NAC22亲缘关系较近。实时定量qRT-PCR分析显示,NAC83基因能被ABA、干旱、低温和高盐胁迫诱导表达,且在不同的柑橘种类中存在表达差异。可见柚CmNAC83、枳PtNAC83和柠檬ClNAC83是NAC基因家族的成员,可能在柑橘响应非生物胁迫的过程中起了重要作用。     

锌胁迫下水培枳幼苗锌分布及矿质营养元素含量变化

为了解锌胁迫(缺乏或过量)下枳体内锌分布及其他矿质元素含量变化,以30d枳实生幼苗为试材,分别进行锌缺乏(0μmol·L-1)、对照(0.7μmol·L-1)和锌过量(70μmol·L-1)水培处理,70d后测定和分析。结果表明,枳幼苗根、茎和叶中锌含量随处理浓度升高而显著升高,不同器官锌含量为根茎叶,锌胁迫下植株地上部分含锌量比例增加。与对照相比,缺锌处理枳幼苗叶片K、Mn和Cu含量显著降低,叶片Fe含量显著升高,根系Mn含量显著上升,根系Cu含量显著下降。与对照相比,锌过量处理枳幼苗叶片P、Ca、Mg和Cu含量,茎P和K含量,根系Fe和Cu含量均显著升高;叶片K、Fe和Mn含量,茎Ca和Fe含量,根系K和Mn含量均显著降低。各器官不同处理间S含量差异无显著性。相关性分析显示,Zn和Cu含量在枳幼苗根、茎、叶中呈显著或极显著正相关;Zn和Fe含量在叶片和茎中呈极显著负相关,在根中呈极显著正相关。     

缺铁和过量重碳酸盐胁迫下丛枝菌根真菌对枳生长的影响

 采用盆栽沙培试验,研究了缺铁及重碳酸盐胁迫下丛枝菌根(arbuscular mycorrhiza, AM)真菌地表球囊霉（Glomus versiforme）对枳[Poncirus trifoliata (L.) Raf.]实生苗生长及植株铁营养的影响。结果表明,在pH 7.0和pH 8.0的重碳酸盐胁迫下,与未接种处理相比,接种AM真菌显著增加了枳实生苗的株高、茎粗、地上部和地下部干样质量,并且明显促进了叶片叶绿素和活性铁的积累,显著提高了叶片Fe/P的比值,降低了叶片50(10P+K)/Fe的比值,减轻了枳因缺铁引起的黄化现象。     

Using precocious trifoliate orange (Poncirus trifoliata [L.] Raf.) to establish a short juvenile transformation platform for citrus

The precocious trifoliate orange (Poncirus trifoliata [L.] Raf.), an early flowering mutant of P. trifoliata, has a short juvenile phase of about 14 months, significantly shorter than other citrus. In this report, using the stems of precocious trifoliate orange seedlings as explants, an improved protocol mediated by Agrobacterium tumefaciens was developed to evaluate regeneration and transformation frequency. The transformed plants continued to reveal the precocious trait of non-transgenic mature precocious trifoliate orange, and as such could prove to be an efficient system for the verification of gene function in the fruits/flower via genetic transformation in woody plants.