The research data on the variation of the resistance to rice blast in the SP_1SP_3 of lijiangxintuanheigu which was susceptible to blast after space-induction showed that 13.7% mutant plants in the SP_1 were resistant to rice blast.In the SP_2 rice space-induced lines,most of the resistant lines had a ratio of (3∶1) or 15∶1 of the deviation of resistance and susceptibility,implying the resistance was controlled by 1 pair or 2 pairs of major genes.In the SP_3 rice space-induced lines,a part of lines whose resistance were controlled by a pair of major genes continued to demonstrate deviation of resistance,but for the lines whose resistance were controlled by 2 pairs of major genes,the resistance generally became stable.By using the L_(R8)-SP_2 population for the molecular markers of the blast resistant genes induced through space mutation,it was found that the resistant gene was in the 9th chromosome and was linked with the SSR marker RM409.
Hybrid rice combinations made by
seven blast resistant cultivars including three durably resistant cultivars and four popular
sterile lines were studied.The qualitative resistances,quantitative resistances and field
resistances in different blast conducive areas were evaluated and compared with the resistant
check IR36 and susceptible check Guanglu'ai 4 respectively.Results indicated that the
combinations with durably resistant donor showed the same durably resistant characteristics
as correspondently durably resistant cultivars. These results suggested that durable resistance
to rice blast could be incorporated into hybrid rice.
The DH104,an indica rice mutant from Huhan B,and eight monogenic lines were subjected to resistance spectrum with 39 isolates collected from Guangdong Province,China.The results showed that DH104 conferred broader resistance spectrum than the eight monogenic lines.To identify and map the blast resistance gene in DH104,a representative isolate GD0193 was used to identify and map R gene from DH104.Isolate GD0193 was used for inoculating a population of F2 derived from the cross between DH104 and highly susceptible variety L101(indica).The results showed that the segregation of resistant(R) and susceptible(S) progenies fitted a 3∶1 ratio in the F2 population(313R∶97S,X2=0.896 1),indicating the R gene was controlled by a single dominant gene,temporarily designed as Pixt(t) gene.The R gene was located between RM136 and RM7213 on chromosome 6 using SSR markers,with genetic distances 4.9 and 1.5 cM respectively.
To evaluate the effect of an integrated control strategy and to quantify the spatial-temporal variation of infected snails in the bottomland areas after the strategy was implemented.Based on the geographic database of infected snail distribution at the village level during 2004 - 2010 in Anxiang county, Hunan province, spatial autocorrelation analysis and spatial scan statistics were applied to analyze the spatial-temporal characteristics on the distribution of infected snails.The number of embankments with infected snails in Anxiang county decreased from 23 in 2004 to 10 in 2010, while the rate of frame with infected snail in embankments decreased from 4.32‰ in 2004 to 0.12‰ in 2010. The spatial distribution of infected snails was nonrandom, only in 2004 and 2005 with Moran's I = 0.21 (P < 0.10) and Moran's I = 0.13 (P < 0.10) respectively. Data from the local spatial auto-correlation analysis showed that the number of villages with H-H types of auto-correlation model had been gradually decreasing. The results of SaTScan statistics appeared the same as from the local spatial auto-correlation analysis, showing that the number of areas with increased risk was decreasing.The comprehensive measures with emphasis on infectious source control seemed effective for schistosomiasis control program. The current distribution characteristics provided us with evidence that the resource assignment could be more reasonably implemented so as to control schistosomiasis in a more effective way.
To evaluate the effect of a comprehensive schistosomiasis control strategy based on buffalo removal in a lake and marshland region.A community intervention trial was carried out in seven pilot villages and seven control villages along Dongting Lake in Anxiang County, Hunan Province. Besides annual routine control measures such as synchronous chemotherapy, molluscicidal spray and health education, all buffaloes and sheep were killed or removed from the pilot areas in 2005, of which the effect was strengthened by other supporting measures such as replacing bovines by agricultural machines, isolating meadows and prohibiting pastures, supplying safe water, and building sanitary lavatories or methane pits. Schistosoma japonicum infection in humans or Oncomelania snails was observed and followed up to the spring of 2011.Three years after the intervention, the infection rates in humans decreased to below 1% with no infected snails found outside the embankment in the pilot villages, but the infection rates still ranged between 2% and 3% in the control villages 4 years after the intervention. The comprehensive measures centered on buffalo removal exempted about 50% of the population from the infection in pilot villages.Buffalo removal is the key element of comprehensive control strategy which could accelerate the control process and promote the elimination of schistosomiasis in lake and marshland regions along the Yangtze River.
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