Nine microsatellite loci were isolated from Primula obconica using the FIASCO protocol. We used 30 individuals from three populations for the assessment of microsatellite variation. Seven loci were detected with microsatellite polymorphism. The number of alleles per locus ranged from three to seven. The average observed heterozygosity and expected heterozygosity ranged from 0.167 to 0.6 and from 0.409 to 0.653, respectively. These microsatellite markers will be useful to assess the genetic variation and genetic structure of P. obconica.
Hai-fei Yan, Xue-jun Ge, Chi-ming Hu and Gang Hao
Yi Zhang, Xiao-Hui Hu, Yu Shi, Zhi-Rong Zou, Fei Yan, Yan-Yan Zhao, Hao Zhang and Jiu-Zhou Zhao
We studied the effects of exogenous spermidine (Spd) on plant growth and nitrogen metabolism in two cultivars of tomato (Solanum lycopersicum) that have differential sensitivity to mixed salinity-alkalinity stress: ‘Jinpeng Chaoguan’ (salt-tolerant) and ‘Zhongza No. 9’ (salt-sensitive). Seedling growth of both tomato cultivars was inhibited by salinity-alkalinity stress, but Spd treatment alleviated the growth reduction to some extent, especially in ‘Zhongza No. 9’. Exogenous Spd may help reduce stress-induced increases in free amino acids, ammonium (NH4 +) contents, and NADH-dependent glutamate dehydrogenase (NADH-GDH) activities; depress stress-induced decreases in soluble protein and nitrate content; and depress nitrate reductase, nitrite reductase, glutamine synthetase (GS), NADH-dependent glutamate synthase (NADH-GOGAT), glutamate oxaloacetate transaminase (GOT), and glutamate pyruvate transaminase (GPT) activities, especially for ‘Zhongza No. 9’. Based on our results, we suggest that exogenous Spd promotes the assimilation of excess toxic NH4 + by coordinating and strengthening the synergistic action of NADH-GDH, GS/NADH-GOGAT, and transamination pathways, all during saline-alkaline stress. Subsequently, NH4 + and its related enzymes (GDH, GS, GOGAT, GOT, and GPT), in vivo, are maintained in a proper and balanced state to enable mitigation of stress-resulted damages. These results suggest that exogenous Spd treatment can relieve nitrogen metabolic disturbances caused by salinity-alkalinity stress and eventually promote plant growth.
Ying Chen, Xinlu Chen, Fei Hu, Hua Yang, Li Yue, Robert N. Trigiano and Zong-Ming (Max) Cheng
Agave species are economically important plants in tropical and subtropical desert ecosystems as ornamentals as well as potential bioenergy crops. However, their relatively long life cycles and the current lack of biotechnology tools hinder their breeding. In this study, an efficient system for micropropagation was developed for Agave americana L. by using basal stems as explants and grown on a modified Murashige and Skoog medium (MSI) or a 1/2 MSI medium supplemented with various concentrations of 6-benzylaminopurine (BA) for shoot proliferation. The highest number of shoots (18.5 shoots/explant) from basal stems was obtained on MSI supplemented with 13.32 μM BA. An efficient shoot regeneration system was also developed from leaf tissues. Combinations of auxin with cytokinin, basal media, and leaf regions were optimized for shoot induction. Adventitious shoot formation from leaf segments was induced and proliferated with combination ranging of 0.54 to 2.68 μM [α-naphthaleneacetic acid (NAA)] with 8.88 to 13.32 μM (BA), and the maximum frequency (≈69%) was obtained with 2.68 μM NAA plus 13.32 μM BA. MSI medium and the basal segment of leaf affected shoot induction. The highest rooting frequency and mean number of shoots occurred in 1/2 MSI containing with 4.92 μM indole-3-butyric acid (IBA) alone (90%, 3.4) or 1.48 μM IBA plus 1.61 μM NAA (92%, 5.2). Survival of in vitro plantlets after transfer and acclimatization to ex vitro conditions was 87%. This is the first complete protocol for micropropagation of A. americana.