Xing Liao

Development of a biologically based fertilizer, incorporating Bacillus megaterium A6, for improved phosphorus nutrition of oilseed rape

Sustainable methods with diminished impact on the environment need to be developed for the production of oilseed rape in China and other regions of the world. A biological fertilizer consisting of Bacillus megaterium A6 cultured on oilseed rape meal improved oilseed rape seed yield (P < 0.0001) relative to the nontreated control in 2 greenhouse pot experiments using natural soil. This treatment resulted in slightly greater yield than oilseed rape meal without strain A6 in 1 of 2 experiments, suggesting a role for strain A6 in improving yield. Strain A6 was capable of solubilizing phosphorus from rock phosphate in liquid culture and produced enzymes capable of mineralizing organic phosphorus (acid phosphatase, phytase) in liquid culture and in the biological fertilizer. The biologically based fertilizer, containing strain A6, improved plant phosphorus nutrition in greenhouse pot experiments resulting in significantly greater available phosphorus in natural soil and in significantly greater plant phosphorus content relative to the nontreated control. Seed yield and available phosphorus in natural soil were significantly greater with a synthetic chemical fertilizer treatment, reduced in phosphorus content, than the biological fertilizer treatment, but a treatment containing the biological fertilizer combined with the synthetic fertilizer provided the significantly greatest seed yield, available phosphorus in natural soil, and plant phosphorus content. These results suggest that the biological fertilizer was capable of improving oilseed rape seed yield, at least in part, through the phosphorus-solubilizing activity of B. megaterium A6.

Genome-Wide Identification and Expression Analysis of NRAMP Family Genes in Soybean (Glycine Max L.)

The NRAMP (natural resistance-associated macrophage protein) family of genes has been widely characterized in organisms ranging from bacteria to yeast, plants, mice, and humans. This gene family plays vital roles in divalent metal ion transport across cellular membranes. As yet, comprehensive analysis of NRAMP family genes has not been reported for soybean. In this study, bioinformatics analysis was conducted to identify 13 soybean NRAMP genes, along with their gene structures, phylogenetic relationships, and transmembrane domains. Expression analysis suggests that GmNRAMP genes function in numerous tissues and development stages. Moreover, soybean NRAMP genes were differentially regulated by deficiencies of N, P, K, Fe, and S, along with toxicities of Fe, Cu, Cd, and Mn. These results indicate that GmNRAMP genes function in many nutrient stress pathways, and might be involved in crosstalk among nutrient stress pathways. Subcellular localization analysis in Arabidopsis protoplasts confirmed the tonoplast or plasma membrane localization of selected soybean NRMAP proteins. Protein-protein interaction analysis found that the networks of three GmNRAMP proteins which putatively interact with nodulin-like proteins, almost distinct from the network that is common to the other 10 soybean NRAMP proteins. Subsequent qRT-PCR results confirmed that these three GmNRMAP genes exhibited enhanced expression in soybean nodules, suggesting potential functions in the transport of Fe or other metal ions in soybean nodules. Overall, the systematic analysis of the GmNRAMP gene family reported herein provides valuable information for further studies on the biological roles of GmNRAMPs in divalent metal ion transport in various soybean tissues under numerous nutrient stresses and soybean-rhizobia symbiosis.

High planting density benefits to mechanized harvest and nitrogen application rates of oilseed rape (Brassica napus L.)

Abstract To evaluate the effects of planting density and nitrogen (N) application rate on agronomic characters, yield and N use of oilseed rape (Brassica napus L.), a split plot experiment was carried out. Two planting densities (1.5 × 105 plant ha−1 and 4.5 × 105 plant ha−1 as main plots) and four N rates (0, 90, 180 and 270 kg ha−1 as sub plots) were designed for two cultivars of Brassica napus. Results indicate that increased planting density could lead to decreased plant height, branch number, canopy layer thickness, effective siliques per plant and harvest index, while branch height and N use efficiency increase. Under a single density, plant height, branch height, branch number, effective siliques per plant and yield increased with increased N application, but the oil content and N use efficiency decreased. For the same target yield (plateau yield) obtained in low-density planting, the N fertilizer requirement decreased by 22.8% and 25.4% in high-density planting in two experimental sites. On the whole, these results demonstrate that increased plant density can improve rape adaptability for mechanized harvest by regulating plant structure, decreasing the N requirement for reaching a target yield and increasing N use efficiency.

Components of a Rice-Oilseed Rape Production System Augmented with Trichoderma sp. Tri-1 Control Sclerotinia sclerotiorum on Oilseed Rape

Sclerotinia sclerotiorum causes serious yield losses on many crops throughout the world. A multicomponent treatment that consisted of the residual rice straw remaining after rice harvest and Trichoderma sp. Tri-1 (Tri-1) formulated with the oilseed rape seedcake fertilizer was used in field soil infested with S. sclerotiorum. This treatment resulted in oilseed rape seed yield that was significantly greater than the nontreated control or when the fungicide carbendizem was used in the presence of this pathogen in field trials. Yield data suggested that the rice straw, oilseed rape seedcake, and Tri-1 components of this treatment all contributed incrementally. Similar treatment results were obtained regarding reduction in disease incidence. Slight improvements in yield and disease incidence were detected when this multicomponent treatment was combined with a fungicide spray. Inhibition of sclerotial germination by this multicomponent treatment trended greater than the nontreated control at 90, 120, and 150 days in field studies but was not significantly different from this control. This multicomponent treatment resulted in increased yield relative to the nontreated control in the absence of pathogen in a greenhouse pot study, while the straw alone and the straw plus oilseed rape seedcake treatments did not; suggesting that Tri-1 was capable of promoting growth. Experiments reported here indicate that a treatment containing components of a rice-oilseed rape production system augmented with Tri-1 can control S. sclerotiorum on oilseed rape, be used in integrated strategies containing fungicide sprays for control of this pathogen, and promote plant growth.

Identification of suitable reference genes in leaves and roots of rapeseed (Brassica napus L.) under different nutrient deficiencies

Abstract Nutrient deficiency stresses often occur simultaneously in soil. Thus, its necessary to investigate the mechanisms underlying plant responses to multiple stresses through identification of some key stress-responsive genes. Quantitative real-time PCR (qRT-PCR) is essential for detecting the expression of the interested genes, of which the selection of suitable reference genes is a crucial step before qRT-PCR. To date, reliable reference genes to normalize qRT-PCR data under different nutrient deficiencies have not been reported in plants. In this study, expression of ten candidate reference genes was detected in leaves and roots of rapeseed ( Brassica napus L.) after implementing different nutrient deficiencies for 14 days. These candidate genes, included two traditionally used reference genes and eight genes selected from an RNA-Seq dataset. Two software packages (GeNorm, NormFinder) were employed to evaluate candidate gene stability. Results showed that VHA-E1 was the highest-ranked gene in leaves of nutrient-deficient rapeseed, while VHA-G1 and UBC21 were most stable in nutrient-deficient roots. When rapeseed leaves and roots were combined, UBC21, HTB1, VHA-G1 and ACT7 were most stable among all samples. To evaluate the stabilities of the highest-ranked genes, the relative expression of two target genes, BnTrx1;1 and BnPht1;3 were further determined. The results showed that the relative expression of BnTrx1;1 depended on reference gene selection, suggesting that its necessary to evaluate the stability of reference gene prior to qRT-PCR. This study provides suitable reference genes for gene expression analysis of rapeseed responses to different nutrient deficiencies, which is essential for elucidation of mechanisms underlying rapeseed responses to multiple nutrient deficiency stresses.

A new method for the preservation of axenic fungal cultures

Microbiological work requires a reliable source of cultures that are not only well defined and taxonomically determined, but are also adequately preserved without changes in their morphological, physiological and genetic traits. Here we describe an easy, cost effective and rapid method for reliably preserving filamentous fungi on cellophane pieces at -80°C for use in laboratory culture collections.

Biological control of Sclerotinia disease by Aspergillus sp. on oilseed rape in the field

ABSTRACT Sclerotinia sclerotiorum causes serious yield losses to many crops worldwide. Aspergillus sp. Asp-4, previously shown to inhibit germination of sclerotia of S. sclerotiorum in vitro and in the field, was evaluated in field trials for suppression of this pathogen on oilseed rape. Spray application of Asp-4 to the soil prior to sowing rice in a rice–oilseed rape rotation resulted in a significant reduction in incidence of Sclerotinia stem rot on oilseed rape compared with the non-treated control in two field trials. This application of Asp-4 also resulted in a significant reduction in germination of sclerotia relative to the non-treated control in these field trials, suggesting that this reduction in sclerotial germination led to disease control. Microscopic examination demonstrated that Asp-4 could effectively colonise external and internal portions of sclerotia of S. sclerotiorum in vitro. Incubation of Asp-4 with sterile sclerotial material induced production of β-glucanase and chitinase activities by this isolate; β-glucanase and chitinase being potentially capable of degrading the glucan and chitin polymeric components of sclerotia. Incubation of Asp-4 with sterile sclerotial material also resulted in a significant reduction in dry weight of this sclerotial material relative to the non-treated control in 96 h in vitro experiments. Experiments reported here indicate that Aspergillus sp. Asp-4 has promise as a biological control agent for S. sclerotiorum on oilseed rape. Experiments reported here suggest that disease control results from inhibition of germination of sclerotial resting structures due to mycoparasitic colonisation by Asp-4.

Earthworms Increased Rape Seed Yield and Colza Oil

A field experiment was conducted to investigate the effects of earthworms (Metaphire guillemi) on the seed yield and oil production of winter oilseed rape (Brassica napus L. cv. Zhongshuang No. 9), which was included inoculated with (E) or without (CK) earthworms treatments in three replicates. The result showed that earthworms significantly increased the seed yield of winter oilseed rape by 23.9% for individual plant and by 30.2% for whole plot levels, which might be due to earthworms significantly increased the pod numbers per plant (42.9%) compared with CK. The present study also showed that, although the seed oil content was significantly decreased by 4.8%, the oil production of winter oilseed rape was significantly increased at both the individual plant (18.1%) and whole plot (24.2%) levels since the increase in seed yield over-rode the decrease in oil content due to earthworm presence. The increased of plant growth and nitrogen (N) accumulation during the vegetative growth stages, and the increased translocation of N to seed during the maturation stages, because earthworms, might be responsible for the increased seed yield and oil production of winter oilseed rape.