Ergosterol is an important component of the fungal cell membrane and represents an effective target of chemical pesticides. However, the current understanding of ergosterol biosynthesis in the soybean root rot pathogen Fusarium oxysporum remains limited. In addition, the regular use of fungicides that inhibit ergosterol synthesis will seriously harm the ecological environment and human health. Bacillus subtilis is gradually replacing chemical control as a safe and effective biological agent; to investigate its effect on ergosterol synthesis of F. oxysporum, we verified the biological function of the FoERG3 gene of F. oxysporum by constructing knockout mutants. The results showed that knocking out FoERG3 blocked ergosterol biosynthesis, restricted mycelial growth, and increased the sensitivity to external stressors (NaCl, D-sorbitol, Congo Red, and H2O2). The increased permeability of the cell membrane promoted increased extracellular K+ levels and decreased mitochondrial cytochrome C contents. Treatment with suspension of B. subtilis HSY21 cells resulted in similar damage as observed when treating FoERG3-knockout F. oxysporum cells with ergosterol, which was characterised by deformity and swelling of the mycelium surface; increased membrane permeability; decreased pathogenicity to soybeans; and significantly decreased activities of cellulase, β-glucosidase, amylase, and pectin-methyl galactosylase. Notably, deleting FoERG3 resulted in a significant lag in the defense-response time of soybeans. Our results suggest that FoERG3 strongly influences the virulence of F. oxysporum and may be used as a potential antimicrobial target by B. subtilis HSY21 to inhibit ergosterol synthesis, which supports the use of B. subtilis as a biological control agent for protecting against F. oxysporum infection.
Due to the complexity of genome background in sugarcane,gene trangsformation has been one of the most useful ways for sugarcane genetic improvement.But low efficiency and instablility are the major problems for gene transformation in sugarcane.After years of sugarcane transformation research,a fast and efficient gene transformation system has been developed in our lab.20% of transformation efficiency,90% of selection efficiency and only four months of transformation duration make it a low cost transformation approach.
Sugarcane Bacilliform Guadeloupe A Virus (SCBGAV, genus Badnavirus, family Caulimoviridae) is an emerging, deleterious pathogen of sugarcane which presents a substantial barrier to producing high sugarcane earnings. The circular, double-stranded (ds) DNA genome of SCBGAV (7.4 Kb) is composed of three open reading frames (ORF) that replicate by a reverse transcriptase. In the current study, we used miRNA target prediction algorithms to identify and comprehensively analyze the genome-wide sugarcane ( Saccharum officinarum L.)-encoded microRNA (miRNA) targets against the SCBGAV. A total of 28 potential mature target miRNAs were retrieved from the miRBase database and were further analyzed for hybridization to the SCBGAV genome. Multiple computational approaches—including miRNA-target seed pairing, multiple target positions, minimum free energy, target site accessibility, maximum complementarity, pattern recognition and minimum folding energy for attachments— were considered by all algorithms. Only 4 sugarcane miRNAs are selected for SCBGAV silencing. Among those 4, sof-miR396 was identified as the top effective candidate, capable of targeting the vital ORF3 which encodes polyprotein of the SCBGAV genome. miRanda, RNA22 and RNAhybrid algorithms predicted hybridization of sof-miR396 at common locus position 3394. A Circos plot was created to study the network visualization of sugarcane-encoded miRNAs with SCBGAV genes determines detailed evidence for any ideal targets of SCBGAV ORFs by precise miRNAs. The present study concludes a comprehensive report towards the creation of SCBGAV-resistant sugarcane through the expression analysis of the identified miRNAs.
Phytophthora root and stem rot caused by Phytophthora sojae is a world wide destructive soybean disease,it may attack plants at any growth stage,causing root and stem rot.The principle of POD activity changes in roots,stems and leaves of soybean varieties with different resistance to Phytophthora sojae and the effect of POD on resistance to this disease were researched.The results showed that the POD activities of leaves in resistant soybean varieties increased compared with the susceptible soybean varieties at most of the pathogenicity stages,and it was also higher than that of control.The reaction of POD in roots and stems increased at most of the pathogenicity stages,however,the change extent was relatively low.
The present study aims to screen and identify a biocontrol strain,which could antagonize the growth of sugarcane Sporisorium scitaminea Sydow effectively.The sequence of 16S rRNA gene has 99% identity to Bacillus subtilis according to the amplified fragment of 1 533 bp with a pair of universal primers,P0 and P6,of bacteria.From above,HAS strain with short rod,Gram positive,negative reaction of 3% KOH solubility experiment,flagellum around,spore in the middle,elliptic,slightly swelled was identified as B.subtilis based on morphology and biotechnology.It could effectively restrain the growth of sugarcane S.scitaminea.On co-culture plates this strain showed high suppression effect on many fungal pathogens involved in sugarcane and other crops.
Based on the conserved sequence of Petunia hybrida anthocyain transcriptional activator gene wd40(an11)and tomato wd40 mRNA(113964R)from GenBank,the conserved fragment of stwd40 transcriptional activator gene was cloned from the purple potato coat.The 3'-end and 5'-end of this gene were amplified by using RACE technique separately.Sequence analysis showed that the nucleotide sequence of this gene is 1 292 bp,containing a complete open reading frame and encoding 326 amino acids.The stwd40 amino acid sequence is similar to anthocyanin transcriptional activator protein wd40 from large number of species,and the homology is 86% with the Petunia hybrida anthocyain transcriptional regulatory gene an11.The results of RT-PCR expression analysis showed that stwd40 expressed in leaves,stems,tuber skins,tuber fleshes and roots of purple potato and the leaves,tuber skins,tuber fleshes of white potato with different expression levels.It is suggested that the stwd40 is constitutive expressed in potato.
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