Geographical cline of DNA variation within the F intersterility group of Heterobasidion annosum in Italy

Eighty-six Heterobasidion annosum isolates, mainly belonging to the F intersterility group and obtained from 32 different geographical localities in Italy, were subjected to genetic analysis by the Random Amplified Polymorphic DNA (RAPD) markers. The similarity between F and S groups was higher than that between F and P. In UPGMA Cluster Analysis, the F isolates originating from the same locality usually grouped in the same cluster. The isolates also showed a tendency to group at the level of larger geographical areas. Within the F group, isolates from the south of the Italian peninsula showed the highest genetic variation and northern isolates from the Alpine regions showed the lowest. This indicates a gradual cline along the peninsula. The genetic variability in the Italian F group is discussed in relation to the past and present distribution of the host species in Italy and Europe.     

Two-year development of southern pine seedlings and associated vegetation following spray-and-burn site preparation with imazapyr alone or in mixture with other herbicides

Eight herbicide combinations containing imazapyr alone or in mixture with glyphosate, triclopyr, or picloram+2,4-D were applied July–August 1991 at each of three upland sites in the southeastern U.S., with or without a subsequent broadcast burn in September. Seedlings of loblolly (Pinus taeda L.) or slash (P. elliottii Engelm. var. elliottii) pine were planted that winter. Second-year (August 1993) vegetation responses indicate that broadcast burning, in combination with herbicides, was associated with increased abundances of grasses, forbs, and shrubs and decreased abundances of vines and hardwood trees. In the presence of burning, imazapyr-in-mixture treatments were associated with a high abundance of grass (53% cover) and a mean size of pines less than that of seedlings growing in imazapyr-alone treatments. In the absence of burning, imazapyr-alone treatments were associated with a high abundance of blackberry (21% cover), an average height of hardwoods (131 cm) exceeding that of pines (71 cm), and a mean size of pines less than that of trees growing in imazapyr-in-mixture treatments. Hardwood height in the absence of burning was less when imazapyr was combined with glyphosate (75 cm) than with triclopyr (102 cm). Regardless of the presence or absence of burning, size of pines and abundance of shrubs and hardwoods did not differ between imazapyr rates of 0.56 and 0.84 kg acid equivalent/ha or among herbicides applied in mixture with imazapyr.     

甜菜SSR反应体系优化及重要农艺性状分子标记

[目的]为选育优质甜菜新品种,利用SSR法筛选与高糖、高产、耐盐相关的分子标注.[方法]研究对甜菜SSR-PCR反应体系进行优化,并利用SSR分子标记方法和分离群体分组分析法(Bulked SegregateAnalysis,BSA)对具有高糖/低糖、低产/高产、耐盐/不耐盐三种重要农艺性状的甜菜亲本和F2代植株进行分析.[结果]研究建立了适宜甜菜的SSR-PCR反应体系为:20μL反应体系中含l×Buffer、2.0 mmol/LMg2+、1.5 uTaq DNA聚合酶、0.20 mmol/L dNTP、1.5 μmol/L引物、60 ng DNA模板.依据优化体系,对不同农艺性状的甜菜亲本与F2代进行SSR-PCR扩增分析,高糖性状获得了200和100 bp两条与高糖性状连锁的标记,250和230 bp两条与高产性状连锁的标记,550、250和100 bp三条与耐盐性状紧密连锁的分子标记.[结论]研究获得的7条特异条带是与甜菜重要农艺性状连锁的分子标记,将为甜菜的育种工作提供重要的理论基础.     

绵羊LDHβ基因的生物信息学分析及其在不同剩余采食量绵羊肝脏和肌肉组织中的表达

【目的】为鉴定绵羊乳酸脱氢酶β(lactate dehydrogenase B,LDHβ)基因的分子特征,研究其在不同剩余采食量绵羊肝脏和肌肉组织中的表达差异.【方法】测定了137只‘湖羊’公羔的剩余采食量(residual feed intake,RFI),按RFI进行排序,分别筛选出RFI最高(high-residual feed intake,H-RFI)和RFI最低(low-residual feed intake,L-RFI)的羊各15只,屠宰后,采集肝脏和肌肉组织,利用Q-PCR技术检测绵羊LDHβ基因分别在H-RFI和L-RFI羊肝脏和肌肉中表达量,并利用生物信息学软件构建了该基因的系统进化树和预测其结构与功能.【结果】绵羊LDHβ基因开放阅读框(open reading frame,ORF)为1 005bp,编码334个氨基酸,其蛋白质分子质量为36 479.43U,理论等电点为6.40.绵羊LDHβ基因与山羊的亲缘关系较近,其次为牛,序列同源性高.功能结构域预测结果显示,该基因编码产物在内质网中参与辅酶因子生物合成的可能性最高.Q-PCR结果显示,绵羊LDHβ-mRNA基因在L-RFI羊肝脏和肌肉中表达量均显著低于H-RFI羊(P0.01).【结论】绵羊LDHβ基因作为能量代谢的关键酶参与绵羊饲料效率的调控.