Tuber slices of newly introduced potato cultivars （cvs） in Libya, namely Spunta, Pamela, Daisy, Daifla, Atlas and Apollina were tested for their susceptibility to soft rot bacterium （Erwinia carotovora subsp, carot...Tuber slices of newly introduced potato cultivars （cvs） in Libya, namely Spunta, Pamela, Daisy, Daifla, Atlas and Apollina were tested for their susceptibility to soft rot bacterium （Erwinia carotovora subsp, carotovora）. Atlas cv was proved to be the most susceptible cv, meanwhile, Daisy cv was the most resistant one. The activities of pectolytic and oxidative enzymes in diseased tubers were profoundly higher than these in healthy ones. The highest enzymatic activities of pectin methyl esterase （PME） and polygalacturonase （PG） were observed in diseased tubers of Daifla cv. However, diseased tubers of Spunta gave the highest activities of polymethyl galacturonase （PMG）. On the other hand, the highest significant activities of the enzyme PME in healthy tubers was detected in Pamela cv compared to other cvs. Moreover, there were insignificant differences in PG and PMG enzymes activities between healthy tubers of the different cvs. The cv Daisy gave the highest activity of the enzyme peroxidase （PO） in diseased tubers, whereas the highest activity of enzyme polyphenol oxidase （PPO） was detected in infected tubers of Atlas cv. Concerning healthy tubers, the highest activities of enzymes PO and PPO were noticed in Atlas and Pamella cvs respectively as compared to other cvs. Electrolyte leakage from plant cells was estimated by measuring electrical conductivity as indicator for permeability changes in potato tissues. Values of electrolyte leakage in infected tubers of all tested cvs showed significant increase compared with those of healthy ones, especially, with the most susceptible one.展开更多
The peritrophic membrane plays an important role in the defense system of the arthropod gut. The digestive tract is considered one of the major tissues targeted by white spot syndrome virus （WSSV） in shrimp. In this...The peritrophic membrane plays an important role in the defense system of the arthropod gut. The digestive tract is considered one of the major tissues targeted by white spot syndrome virus （WSSV） in shrimp. In this study, the nucleotide sequence encoding peritrophin-like protein of Litopenaeus vannamei （LvPT） was amplified from a yeast two-hybrid library of L. vannamei. The epitope peptide of LvPT was predicted with the GenScript OptimumAntigenTM design tool. An anti-LvPT polyclonal antibody was produced and shown to specifically bind a band at -27 kDa, identified as LvPT. The LvPT protein was expressed and its concentration determined. LvPT dsRNA （4 pg per shrimp） was used to inhibit LvPT expression in shrimp, and a WSSV challenge experiment was then performed with reverse gavage. The pleopods, stomachs, and guts were collected from the shrimp at 0, 24, 48, and 72 h post-infection （hpi）. Viral load quantification showed that the levels of WSSV were significantly lower in the pleopods, stomachs, and guts of shrimp after LvPT dsRNA interference than in those of the controls at 48 and 72 hpi. Our results imply that LvPT plays an important role during WSSV infection of the digestive tract.展开更多
文摘Tuber slices of newly introduced potato cultivars （cvs） in Libya, namely Spunta, Pamela, Daisy, Daifla, Atlas and Apollina were tested for their susceptibility to soft rot bacterium （Erwinia carotovora subsp, carotovora）. Atlas cv was proved to be the most susceptible cv, meanwhile, Daisy cv was the most resistant one. The activities of pectolytic and oxidative enzymes in diseased tubers were profoundly higher than these in healthy ones. The highest enzymatic activities of pectin methyl esterase （PME） and polygalacturonase （PG） were observed in diseased tubers of Daifla cv. However, diseased tubers of Spunta gave the highest activities of polymethyl galacturonase （PMG）. On the other hand, the highest significant activities of the enzyme PME in healthy tubers was detected in Pamela cv compared to other cvs. Moreover, there were insignificant differences in PG and PMG enzymes activities between healthy tubers of the different cvs. The cv Daisy gave the highest activity of the enzyme peroxidase （PO） in diseased tubers, whereas the highest activity of enzyme polyphenol oxidase （PPO） was detected in infected tubers of Atlas cv. Concerning healthy tubers, the highest activities of enzymes PO and PPO were noticed in Atlas and Pamella cvs respectively as compared to other cvs. Electrolyte leakage from plant cells was estimated by measuring electrical conductivity as indicator for permeability changes in potato tissues. Values of electrolyte leakage in infected tubers of all tested cvs showed significant increase compared with those of healthy ones, especially, with the most susceptible one.
基金Supported by the National Basic Research Program of China(973 Program)(No.2012CB114403)the China Agriculture Research System-47(CARS-47)
文摘The peritrophic membrane plays an important role in the defense system of the arthropod gut. The digestive tract is considered one of the major tissues targeted by white spot syndrome virus （WSSV） in shrimp. In this study, the nucleotide sequence encoding peritrophin-like protein of Litopenaeus vannamei （LvPT） was amplified from a yeast two-hybrid library of L. vannamei. The epitope peptide of LvPT was predicted with the GenScript OptimumAntigenTM design tool. An anti-LvPT polyclonal antibody was produced and shown to specifically bind a band at -27 kDa, identified as LvPT. The LvPT protein was expressed and its concentration determined. LvPT dsRNA （4 pg per shrimp） was used to inhibit LvPT expression in shrimp, and a WSSV challenge experiment was then performed with reverse gavage. The pleopods, stomachs, and guts were collected from the shrimp at 0, 24, 48, and 72 h post-infection （hpi）. Viral load quantification showed that the levels of WSSV were significantly lower in the pleopods, stomachs, and guts of shrimp after LvPT dsRNA interference than in those of the controls at 48 and 72 hpi. Our results imply that LvPT plays an important role during WSSV infection of the digestive tract.
