沙冬青AmNAC3转录因子基因在抗旱性和抗寒性中的功能鉴定

为了研究强抗逆植物沙冬青Am NAC3转录因子基因在抗旱性和抗寒性中的功能,首先利用半定量RT-PCR方法对该基因进行了表达分析。结果表明,在室内培养的沙冬青幼苗中,Am NAC3有一定量的基础表达,在干旱胁迫下其转录水平明显上调,而在低温胁迫下其表达上调较弱。然后利用5'RACE技术获得该基因的5'端序列及全长cDNA序列,并利用RT-PCR方法克隆到其全长编码区(846bp)。将编码区片段构建到植物表达载体上,利用农杆菌介导法获得转基因拟南芥。进一步分析表明,转基因拟南芥对于干旱和低温胁迫的抗性表型与野生型无明显差异,但其离体叶片的失水率和气孔开度均大于野生型。此外,转基因幼苗中气孔开闭相关基因ABI1和ABI2的表达量降低。这些结果表明,Am NAC3可能主要在响应干旱胁迫和调节气孔开闭及叶片保水性中发挥功能,而在抵抗低温胁迫中无明显作用。     

新疆沙冬青叶片氨基酸和蛋白质的测试与分离以及抗冻蛋白的鉴定结果分析

提取并纯化了新疆沙冬青(Ammopiptanthus nanus)叶片总蛋白,得到了适合新疆沙冬青叶片总蛋白提取的最佳缓冲体系;用DEAE52-C分离了各蛋白质组分,并用SDS-PAG测定了纯度和分子量(14~90 kD之间);氨基酸组成分析显示了新疆沙冬青属内种遗传的一致性。对抗冻活性分析讨论证实了与蒙古沙冬青同属的新疆沙冬青中也含有抗冻蛋白(AFPs)。     

生于豆科植物上的链格孢属真菌一新种

报道生于豆科植物沙冬青Ammopiptanthus mongolicus上的链格孢属真菌一新种,沙冬青链格孢Alternaria ammopiptanthi。此种不同于已从豆科植物上报道的5个长喙链格孢种（复喙链格孢A.multirostrata、决明链格孢A.cassiae、猪屎豆生链格孢A.crotalariicola、瓜尔豆链格孢A.cyamopsidis和长喙链格孢A.longirostrata）,主要是其分生孢子的长喙不分枝和孢身细瘦。研究过的模式标本（PSNXAAFS267852）保存在宁夏农林科学院植物病害标本室。     

干旱胁迫对沙冬青叶片防御光破坏机制的影响

沙冬青(Ammopiptanthus mongolicus (Maxim.) Cheng f.)是生长在沙漠及干旱荒漠地区的常绿灌木.在夏季,其叶片经常遭受中午强光(超过1 500 μmol*m-2*s-1) 胁迫,出现明显的光抑制现象.我们利用便携式光合测定系统(CIRAS-1)和脉冲调制荧光仪(MFMS-2)测定了自然形成的干旱胁迫条件下沙冬青光合和荧光参数的日变化,主要探讨了干旱胁迫对沙冬青叶片防御强光破坏机制的影响.结果表明,正常水分和干旱胁迫下,沙冬青叶片的净光合速率(Pn)、 PSⅡ最大光化学效率(Fv/Fm)和PSⅡ非环式电子传递效率(ΦPSⅡ)在中午都明显降低;相对正常水分条件而言,干旱胁迫下初始荧光(Fo)先下降后上升,荧光的非光化学淬灭(NPQ)上升较快并在一定水平上维持不变.由此推断晴天中午沙冬青叶片在正常水分条件下主要采取依赖叶黄素循环的热耗散机制;而在干旱胁迫条件下主要采取了依赖叶黄素循环的热耗散和PSⅡ反应中心可逆失活两种保护机制.     

沙冬青AmNAC6基因的克隆与功能初步分析

以强抗逆植物沙冬青(Ammopiptanthus mongolicus(Maxim. ex Kom.) Cheng f.)为材料,克隆获得一个NAC转录因子基因Am NAC6的全长cDNA,并对其序列特征、蛋白质亚细胞定位和表达模式进行了分析。研究结果表明,Am NAC6基因的编码蛋白由304个氨基酸组成,具有NAC家族典型的结构特征,亚细胞定位实验证实该蛋白分布于细胞核内。表达图谱分析结果显示,在室内培养的沙冬青幼苗中,Am NAC6的转录水平受干旱、高盐、低温和高温胁迫的影响,其中在干旱诱导下该基因的转录水平上调较为明显;野外生长植株的嫩叶中,该基因的转录水平在中秋和初冬略低于其他季节,春季则低于其在侧根、嫩枝、花蕾和未成熟果荚中的转录水平。此外,本研究还将Am NAC6基因成功地构建到植物表达载体。     

沙冬青子叶原生质体瞬时表达体系的建立及其AmDREB1蛋白的亚细胞定位

以沙冬青(Ammopiptanthus mongolicus(Maxim.ex Kom.)Cheng f.)幼苗的子叶为材料,对其原生质体的分离、纯化和瞬时表达体系进行了研究。结果表明,子叶原生质体分离的最佳酶解液组成为CPW溶液+3.0%纤维素酶R-10+0.5%离析酶R-10+0.3%半纤维素酶+9.0%甘露醇(p H5.8);最佳酶解条件为室温、避光、40 r/min轻摇14 h。采用W5溶液作为漂洗液将酶解物稀释后进行过滤,将过滤液在4℃、700 r/min条件下离心5 min,所得纯化原生质体的产量约为2.50×106cells/g,活力达到90%;以纯化的原生质体作为受体,利用聚乙二醇(PEG)介导法成功将植物瞬时表达载体p BI-GFP导入其中,转化效率达到50.8%。利用本研究建立的原生质体瞬时表达体系,检测到沙冬青脱水应答转录因子Am DREB1定位于细胞核内。     

沙冬青愈伤组织对培养基的特殊要求和球形胚状分化结构的诱导

通过对沙冬青未成熟子叶进行离体培养,获得了愈伤组织。基本培养基采用Ｂ５,再配合ＭＳ培养基的铁盐成分,对沙冬青未成熟子叶愈伤组织的诱导和生长效果最佳。愈伤组织的诱导和生长对培养基的附加成分要求十分严格,２,４－Ｄ浓度为０．５ｍｇ／Ｌ,６－ＢＡ浓度为０．５ｍｇ／Ｌ,蔗粮不宜超过２％。愈伤组织最初为乳白色透明松散状态,生长比较缓慢,极易褐化死亡。如果培养基中的蔗糖浓度低于２％,两周后未成熟子叶愈伤组织逐     

Biological Characterization of Heat-stable Antifreeze Proteins from Leaves of Ammopiptanthus mongolicus

Antifreeze protein(afp) was purified from the heat stable proteins in the leaves of Ammopiptanthus mongolicus (Maxim.) Cheng f. by two-dimensional electrophoresis-electrophoretic elution. Its molecular weight and pi are about 40 kD and 9.0 respectively, and its thermal hysteresis activity (THA) is 0.9 ℃ at 20 g/L. afp is different from other antifreeze proteins. The N-terminal 20 amino acids of afp is SDDLSFTFNKFVPCQTDILF. alp is abundant in leaves and may play an important role in the antifreeze process in A. mongolicus during the period of ovenwintering.     

Diversity of dark septate endophyte in the roots of Ammopiptanthus mongolicus and its companion plants

Aims Dark septate endophytes (DSE) extensively colonize in plant root tissues in different ecosystems. However, our understanding of the ecological significance of DSE in semiarid and arid lands is limited. The main objective of this study was to compare the community composition and species diversity of DSE in Ammopiptanthus mongolicus and its companion plants in desert habitats. Methods Healthy root samples of Ammopiptanthus mongolicus’s companion plants, Artemisia desertorum, Caragana rosea, Nitraria tangutorum and Caragana korshinskii, were collected separately from four main locations of Ammopiptanthus mongolicus plantation in Dengkou of Nei Mongol, Minqin of Gansu, Yinchuan and Shapotou of Ningxia in July 2013. Important findings A total of 103 strains belonging to seven species (i.e Alternaria, Curvularia, Embellisia, Phialocephala, Phoma, Podospora and Pleosporales) of DSE were isolated from the four types of companion plants by means of morphological identification and molecular identification. Among the seven genera, Alternaria, Embellisia, Curvularia and Podospora are found for the first time in desert ecosystems. Ammopiptanthus mongolicus and its companion plants at the same site had significantly different community composition of DSE. Ammopiptanthus mongolicus and its companion plants at different sites had significantly different DSE diversity index. The colonization and species richness of DSE, especially the species and the quantity of spores were higher in roots of Ammopiptanthus mongolicus than in its companion plants. This study supports the results that DSE can form a better symbiotic relationship with the roots of Ammopiptanthus mongolicus than with its companion plants, and can enhance the ecological adaptability of Ammopiptanthus mongolicus to the extreme desert environment.     

沙冬青AmCaM1基因的克隆及其功能初步分析

钙调素(calmodulins, CaMs)是一类非常保守的Ca2+感受蛋白,在Ca2+信号转导中起重要调节作用。本研究分析了强抗逆植物沙冬青(Ammopiptanthus mongolicus)AmCaM1在非生物胁迫下的表达变化,克隆了该基因并将其构建到植物表达载体上,然后转化拟南芥进行了初步的功能分析。结果表明,AmCaM1的转录水平在低温、干旱和盐胁迫下迅速上调;其cDNA编码区由450 bp组成,编码蛋白含149个氨基酸残基,在其一级结构中具有四个保守的EF-手型基序;将该基因转化拟南芥可提高种子萌发期对水分胁迫的耐性,而对耐盐和耐冷性无明显作用。