Yuyan Wang

Improved Plant Growth and Zn Accumulation in Grains of Rice (Oryza sativa L.) by Inoculation of Endophytic Microbes Isolated from a Zn Hyperaccumulator, Sedum alfredii H.

This study is to investigate the possibility of zinc (Zn) biofortification in the grains of rice (Oryza sativa L.) by inoculation of endophytic strains isolated from a Zn hyperaccumulator, Sedum alfredii Hance. Five endophytic strains, Burkholderia sp. SaZR4, Burkholderia sp. SaMR10, Sphingomonas sp. SaMR12, Variovorax sp. SaNR1, and Enterobacter sp. SaCS20, isolated from S. alfredii, were inoculated in the roots of Japonica rice Nipponbare under hydroponic condition. Fluorescence images showed that endophytic strains successfully colonized rice roots after 72 h. Improved root morphology and plant growth of rice was observed after inoculation with endophytic strains especially SaMR12 and SaCS20. Under hydroponic conditions, endophytic inoculation with SaMR12 and SaCS20 increased Zn concentration by 44.4% and 51.1% in shoots, and by 73.6% and 83.4% in roots, respectively. Under soil conditions, endophytic inoculation with SaMR12 and SaCS20 resulted in an increase of grain yields and elevated Zn concentrations by 20.3% and 21.9% in brown rice and by 13.7% and 11.2% in polished rice, respectively. After inoculation of SaMR12 and SaCS20, rhizosphere soils of rice plants contained higher concentration of DTPA-Zn by 10.4% and 20.6%, respectively. In situ micro-X-ray fluorescence mapping of Zn confirmed the elevated Zn content in the rhizosphere zone of rice treated with SaMR12 as compared with the control. The above results suggested that endophytic microbes isolated from S. alfredii could successfully colonize rice roots, resulting in improved root morphology and plant growth, increased Zn bioavailability in rhizosphere soils, and elevated grain yields and Zn densities in grains.

Effect of zinc sulfate fortification in germinated brown rice on seed zinc concentration, bioavailability, and seed germination.

Rice is the staple food for more than half of the worlds population and, hence, the main source of a vital micronutrient, zinc (Zn). Unfortunately, the bioavailability of Zn from rice is very low not only due to low content but also due to the presence of some antinutrients such as phytic acid. We investigated the effect of germination and Zn fortification treatment on Zn bioavailability of brown rice from three widely grown cultivars using the Caco-2 cell model to find a suitable fortification level for producing germinated brown rice. The results of this study showed that Zn content in brown rice increased significantly (p < 0.05) as the external Zn concentrations increased from 25 to 250 mg/L. In contrast, no significant influence (p > 0.05) on germination percentage of rice was observed when the Zn supply was lower than 150 mg/L. Zn fortification during the germination process has a significant impact on the Zn content and finally Zn bioavailability. These findings may result from the lower molar ratio of phytic acid to Zn and higher Zn content in Zn fortified germinated brown rice, leading to more bioavailable Zn. Likewise, a significant difference (p < 0.05) was found among cultivars with respect to the capacity for Zn accumulation and Zn bioavailability; these results might be attributed to the difference in the molar ratio of phytic acid to Zn and the concentration of Zn among the cultivars evaluated. Based on global intake of Zn among the world population, we recommend germinated brown rice fortified with 100 mg/L ZnSO(4) as a suitable concentration to use in the germination process, which contains high Zn concentration and Zn bioavailability. In the current study, the cultivar Bing91185 fortified with Zn through the germination process contained a high amount as well as bioavailable Zn, which was identified as the most promising cultivar for further evaluation to determine its efficiency as an improved source of Zn for target populations.

Improved yield and Zn accumulation for rice grain by Zn fertilization and optimized water management

Zinc (Zn) deficiency and water scarcity are major challenges in rice (Oryza sativa L.) under an intensive rice production system. This study aims to investigate the impact of water-saving management and different Zn fertilization source (ZnSO4 and Zn-EDTA) regimes on grain yield and Zn accumulation in rice grain. Different water managements, continuous flooding (CF), and alternate wetting and drying (AWD) were applied during the rice growing season. Compared with CF, the AWD regime significantly increased grain yield and Zn concentrations in both brown rice and polished rice. Grain yield of genotypes (Nipponbare and Jiaxing27), on the average, was increased by 11.4%, and grain Zn concentration by 3.9% when compared with those under a CF regime. Zn fertilization significantly increased Zn density in polished rice, with a more pronounced effect of ZnSO4 being observed as compared with Zn-EDTA, especially under an AWD regime. Decreased phytic acid content and molar ratio of phytic acid to Zn were also noted in rice grains with Zn fertilization. The above results demonstrated that water management of AWD combined with ZnSO4 fertilization was an effective agricultural practice to elevate grain yield and increase Zn accumulation and bioavailability in rice grains.概要研究目的在生产高度集约化体系下, 研究节水灌溉措施及锌肥对水稻产量及锌积累量的影响。创新要点目前关于干湿交替能否对水稻增产仍存在争议, 对锌含量及生物有效性也鲜有报道。 因此, 针对这些问题, 本文系统地研究影响水稻产量及品质的两大限制性因素, 即锌肥和灌溉方式对稻米锌生物有效性的影响。研究方法采用盆钵试验模拟大田锌肥及水分管理方式, 两种基因型、 两种锌肥种类、 两种水分管理, 三个重复控制误差。 利用电感耦合等离子体质谱(ICP-MS)测定微量元素锌含量, 以精米中植酸含量表征锌生物有效性。重要结论干湿交替在增加了稻米产量、 锌含量及积累量方面效果显著。 干湿交替结合土施硫酸锌肥可以作为水稻生产体系中获得高产、 高锌、 高生物有效性的农艺措施。

Variations of cadmium tolerance and accumulation among 39 Salix clones: implications for phytoextraction

AbstractnWillows (Salix spp.) show large remediation potential for cadmium (Cd)-contaminated sites, with Cd phytoextraction capacity significantly varying among specie and clone levels. In this study, a relatively large number of willow clones (39 clones) from China were evaluated for the differences in Cd tolerance and accumulation exposed to 10xa0μM CdCl2 by hydroponic system for 35xa0days. The clones showed a wide variation of biomass accumulation ranging from growth inhibition to stimulation. Shoot tolerance indexes (TIs) varied between 0.09 and 1.85, and root TIs varied between 0.27 and 1.99 among clones. The large differences in Cd concentration (μgxa0g−1 dry weight, DW) ranged from 64.7 to 663.7 in leaves, from 118.0 to 308.4 in stems, and from 163.9 to 1,426.4 in roots among clones. Leaf translocation factors (TFs) differed from 0.09 to 1.72 and shoot TFs differed from 0.15 to 1.08. Total Cd content of shoots (including leaves and stems) varied between 29.8 and 2,726.52xa0μg plant−1 DW among clones. With respect to TIs, TFs, Cd concentration, and shoot Cd content, the five clones showed higher Cd phytoextraction potential than the other clones. The results support that the selection of willows with enhanced phytoremediation efficiency should be concentrated on the clone level.

Variation in copper and zinc tolerance and accumulation in 12 willow clones: implications for phytoextraction *

Willows (Salix spp.) have shown high potential for the phytoextraction of heavy metals. This study compares variations in copper (Cu) and zinc (Zn) tolerance and accumulation potential among 12 willow clones grown in a nutrient solution treated with 50 μmol/L of Cu or Zn, respectively. The results showed differences in the tolerance and accumulation of Cu and Zn with respect to different species/clones. The biomass variation among clones in response to Cu or Zn exposure ranged from the stimulation of growth to inhibition, and all of the clones tested showed higher tolerance to Cu than to Zn. The clones exhibited less variation in Cu accumulation but larger variation in Zn accumulation. Based on translocation factors, it was found that most of the Cu was retained in the roots and that Zn was more mobile than Cu for all clones. It is concluded that most willow clones are good accumulators of Zn and Cu.概要研究目的柳树(Salix spp.)已广泛用于修复重金属污染, 而且修复效率与树种及无性系有关。 目前涉及柳树研究主要为铜(Cu)和锌(Zn)的毒性效应, 而不是富集能力。 本研究以中国常见的柳树无性系评价对Cu 和Zn 耐性与富集能力。创新要点目前大多数研究仍集中Cu 和Zn 对柳树的毒性效应, 尤其是Cu, 对它们富集能力仍没有评价。 中国为柳树的主要分布区。 本文以12 种优良的常见柳树无性系, 通过温室营养液法评价对Cu 和Zn 耐性及富集潜力差异。 利用柳树无性系的耐性与富集变异, 旨在选择高耐性与高富集的无性系, 提高环境修复效率和加快修复进程。研究方法选择高生物量12 种柳树无性系, 采用温室营养液培养法添加Cu 或Zn 处理, 测定生物量参数并计算耐性指数, 估计耐性差异; 用原子吸收法测定组织中金属浓度并计算金属位移系数, 评价富集差异。重要结论无性系对Cu 和Zn 耐性显著不同, 生物量变化从无影响、 抑制到促进生长。 无性系对Cu 耐性高于对Zn 耐性, 无性系对Zn 富集变异幅度大于对Cu 富集变异幅度。 Cu 主要富集于根部, 而Zn 较易运输到地上部分。 总之测定的大部分柳树无性系为Cu 与Zn 高富集植物, 显示出较高的植物提取能力。

Effect of ferrous sulfate fortification in germinated brown rice on seed iron concentration and bioavailability

The present study evaluated the effectiveness of germination and iron fortification on iron concentration and bioavailability of brown rice. Iron fortification during germination process with 0.05-2 g/L ferrous sulfate increased the iron concentration in germinated brown rice from 1.1 to 15.6 times than those in raw brown rice. Based on the recommended dietary allowance of iron, maximum germination rate and γ-aminobutyric acid, we recommend the brown rice fortified with 0.25 g/L FeSO(4) as a suitable fortification level to use in germination process. Iron fortification during the germination process has a positive effect on iron concentration and bioavailability. A significant difference was observed among the cultivars in respect to the capacity for iron accumulation and bioavailability. Germination alone could improve in vitro iron solubility, but had no effect on iron bioavailability in Caco-2 cell, the additional fortification process should be combined to get high amount of bioavailable iron from the brown rice.

Variations of growth, nitrogen accumulation and nitrogen use efficiency among 18 willow clones under two nitrogen regimes

Willows (Salix spp.) have excellent capacity for acquiring nutrients, and are widely used for removing excess nutrients in wastewater purification system. In this study, 18 willow clones were evaluated in terms of growth parameters, nitrogen (N) accumulation and N use efficiency under two N regimes (low N and high N) with a sand culture system. Clonal differences were observed in biomass production, relative growth rate, N accumulation and use efficiency under two N regimes, which were contributed to the clone level. For all clones, nitrogen use efficiency was lower under high N condition than under low N condition. Nitrogen removal efficiency differed by 7-fold (low N regime) and 10-fold (high N regime) based on shoot N contents between the lowest and the highest clone. Among all the clones, J799 had the highest N content in shoots, showing largest N removal potential. These results confirmed that growth analysis and nutrient use strategy are efficient method of selecting Salix clones for improving the N removal potential.

Cadmium Accumulation and Tolerance in Seven Ornamental Willow Genotypes

Cadmium (Cd) accumulation and tolerance in seven ornamental willow genotypes were investigated at different Cd levels (0, 5, 25, 50, and 100xa0µM) through hydroponic culture in a greenhouse. Severe phytotoxic symptoms in leaves and roots including leaf chlorosis and root browning were noticed when grown at ≥u200950xa0µM Cd. All genotypes showed high tolerance to low Cd levels (5xa0µM and 25xa0µM Cd), in contrast to high Cd levels (i.e. 50xa0µM and 100xa0µM) that severely disturbed plant growth of all genotypes. Cadmium concentrations reached 165.0–1251.0xa0µgxa0g−1 DW in leaves, 22.9–331.2xa0µgxa0g−1 in stems among the genotypes at 5–25xa0µM Cd, and Cd mainly accumulated in the roots. Although willow tissues can accumulate relatively high Cd concentrations under high Cd levels (≥u200950xa0µM), they are not suitable for phytoextraction of Cd due to poor growth.