不同倍性白姜花切花挥发性成分差异分析

为比较二倍体和四倍体白姜花(Hedychium coronarium)切花挥发性成分差异，采用顶空固相微萃取(HS-SPME)和气相色谱-质谱联用(GC-MS)技术测定了二倍体和四倍体白姜花切花初开期、盛开期和初衰期释放物质种类，通过峰面积归一法测定了各成分的相对含量，建立正交偏最小二乘判别分析(OPLS-DA)模型进行主成分分析和变量重要性投影(VIP)分析。结果表明，白姜花切花挥发性成分包含63种萜烯类、40种苯丙素类和22种脂肪酸衍生物类物质；萜烯类物质相对含量大于其他两类，四倍体白姜花在初开和盛开期挥发物质总质量极显著大于二倍体。二倍体与四倍体挥发性成分的组间差距明显，两个倍性组内差距在正常范围内；挥发性成分约63.7%的代表性特征得到较好聚类；优势成分和劣势成分均是两个倍性白姜花差异的重要成分。在盛开期和初衰期，α-罗勒烯是四倍体特有的且相对含量最大的优势成分，β-罗勒烯是二倍体中相对含量最大且显著多于四倍体的优势成分；二倍体和四倍体共有的优势成分和贡献较大的物质是石竹烯、沉香醇、桉树脑、α-金合欢烯和苯甲酸甲酯等。总体上，二倍体白姜花在四倍化过程中挥发性成分种类和总含量增加，相同倍性不同时期的挥发性成分种类和含量也存在差异，白姜花切花的挥发性成分以萜烯类为主。     

Biodegradation of bisphenol A by bacterial consortia

The effect of light on BPA degradation by an adapted bacterial consortium was investigated. BPA was completely degraded up to 50 mg l⁻¹, and the degradation followed first-order reaction kinetics both in the light and in the dark. The degradation half-life of BPA when the consortium was grown in presence of light was 21.9, 17.2, and 12.6 h for concentrations of 10, 20, and 50 mg l⁻¹, respectively; the degradation half-life of BPA in the dark was 13.1, 10.8, and 10.2 h for concentrations of 10, 20, and 50 mg l⁻¹, respectively. Therefore, light inhibited BPA biodegradation. However, under both conditions, BPA was completely depleted. The bacterial consortium effectively utilised BPA as a growth substrate to sustain a cell yield of 0.95 g g⁻¹ and 0.97 g g⁻¹ in the light and dark, respectively. A total of ten and nine biodegradation intermediates were detected in the light and dark, respectively. Three bacterial metabolic pathways and one photodegradation pathway were proposed to explain their occurrence. This study demonstrated that bacterial consortia may assemble a wide range of catabolic pathways to allow for efficient degradation of BPA, converting BPA to principally bacterial biomass and metabolites exhibiting low or no oestrogenic activity.     

Plant regeneration from embryogenic cell suspensions and protoplasts of dessert banana cv. ‘Da Jiao’ (<Emphasis Type="Italic">Musa paradisiacal</Emphasis> ABB Linn.) via somatic embryogenesis

The ‘Da Jiao’ cultivar of banana (Musa paradisiacal ABB Linn.) is an ideal germplasm to produce new banana varieties resistant to Fusarium oxysporum f. sp. cubense (FOC) race 4, for this cultivar is not only a popular dessert banana in south China, but also bears high resistance to FOC race 4. In this study, we established a homogeneous embryogenic cell suspension (ECS) of ‘Da Jiao’ and obtained regenerated plants from ECS-derived protoplasts via somatic embryogenesis. The ECS was initiated from yellow friable callus induced from immature male inflorescence on M1 medium. A pre-culture was used to select ECS in M2 medium without 2,4-dichlorophenoxyacetic acid for 10 d. Addition of 1.0 mg L⁻¹ abscisic acid to M3 medium could enhance the frequency of somatic embryogenesis by about 2.6-fold. Protoplasts, with a yield range of 5–6 × 10⁶ per milliliter, were isolated from the ECS. About 0.35% of the protoplasts formed microcallus, which contained about 100 cells, after 1 mo of feeder layer culture with ECS of Musa acuminate cv. Mas (AA) as nurse cells. Healthy plantlets (0.14%) were regenerated from the microcallus through somatic embryogenesis.