The potato rot nematode (Ditylenchus destructor) is a very economically important nematode in agronomic and horticultural plants worldwide.  In this study, 43 populations of D. destructor were collected from different hosts across China, including 37 populations from Chinese herbal medicine plants.  Obtained sequences of ITS-rDNA and D2–D3 of 28S-rDNA genes of D. destructor were compared and analyzed.  Nine types of significant length variations in ITS sequences were observed among all populations.  The differences in ITS1 length were mainly caused by the presence of repetitive elements with substantial base substitutions.  Reconstructions of ITS1 secondary structures showed that the minisatellites formed a stem structure.  Ten haplotypes were observed in all populations based on mutations and variations of helix H9.  Among them, 3 known haplotypes (A–C) were found in 7 populations isolated from potato, sweet potato, and Codonopsis pilosula, and 7 unique haplotypes were found in other 36 populations collected from C. pilosula and Angelica sinensis compared with 7 haplotypes (A–G) according to Subbotin’ system.  These unique haplotypes were different from haplotypes A–G, and we named them as haplotypes H–N.  The present results showed that a total of 14 haplotypes (A–N) of ITS-rDNA have been found in D. destructor.  Phylogenetic analyses of ITS-rDNA and D2–D3 showed that all populations of D. destructor were clustered into two major clades: one clade only containing haplotype A from sweet potato and the other containing haplotypes B–N from other plants.  For further verification, PCR-ITS-RFLP profiles were conducted on 7 new haplotypes.  Collectively, our study suggests that D. destructor populations on Chinese medicinal materials are very different from those on other hosts and this work provides a paradigm for relevant researches.

The cereal cyst nematode, Heterodera avenae, is one of the most economically important pathogens impacting the worldwide production of cereals and is widely distributed in more than 16 regions in China.  The present study used the numbers of nematodes inside the plant roots to evaluate the resistance/susceptibility of different subpopulations of barley Hordeum vulgare (QH2R, QH6R and TB2R) to H. avenae under field and pot conditions.  Nematode development in two highly resistant varieties was also evaluated by in vivo experiment and microscopic observation.  Analyses of 186 selected varieties showed the numbers of susceptible varieties identified with the number of females/cysts per plant (NFP) method were significantly higher than those identified with the Pf/Pi ratio (PPR) method, which indicated that the NFP method rather than the PPR method is more reliable to evaluate the resistance of barley.  The field and pot experiment results indicated that the QH2R subpopulation had lower females/cysts numbers than QH6R and TB2R subpopulations, and eight HR varieties (Sunong 7617, Sunong 7635, Dongyuan 87-14, Rudong 14-46, Rudong 87-57, Rudong 87-8-45, Rudong 88-14-2, and Rudong 88-67-1) were identified in QH2R, with the NFP numbers below 4.2.  Further microscopic observation of nematode development suggested that H. avenae often penetrated less into highly resistant varieties (Sunong 7635 and Dongyuan 87-14) and more frequently failed to develop into females than the susceptible barleys.  The promising resistant varieties identified in the present research might be helpful for breeders to develop CCN-resistant cultivars and control H. avenae populations effectively at low costs.

CatSper is a unique Ca2+ channel-like protein family exclusively expressed in the testis and sperm, and plays important roles in sperm motility, capacitation, acrosome reaction and sperm-egg interactions. Here we studied the mechanism of regulation of CatSper2-dependent Ca2+ influx, extracellular and intracellular Ca2+ on sperm hyperactivated motility. The siRNA duplexes were transfected into the sperm cells by electroporation (EP) to silence the expression of CatSper2. The results for targeted disruption of CatSper2 showed the highest silence efficiency 77.7% (P<0.05), the hyperactivated sperm rate calculated by computer-assisted semen analysis (CASA) analysis of interferenced sperm was significantly lower 11.1% than the control 99.2%. Flow cytometry (FCM) detection of the intracellular Ca2+ concentration of interferenced sperm was 50 nmol L-1 higher than the normal. It was remarkably lower than hyperactivated sperm with 200-1 000 nmol L-1 (P<0.05). It was not sufficient to evoke hyperactivation. To trigger hyperactivation, the sperm were incubated in 50 μmol L-1 thimerosal or 5 mmol L-1 procaine, it sharply increased the intracellular Ca2+ via two different channels. CASA and FCM detection indicated that intracellular Ca2+ is required for initiating hyperactivation while extracellular Ca2+ is essential to maintain the process. We concluded that to mediate sperm hyperactivation, it is essential to inhibit Ca2+ peak present with targeted disruption of CatSper2 expression. This provides important prospective for further exploration of signal channel of sperm hyperactivated motility, potential factors for male infertility and provide further reference to the exploration of male contraceptive drug targets of male reproduction.