Development of genetic markers linked to straighthead resistance through fine mapping in rice (Oryza sativa L.).

Straighthead, a physiological disorder characterized by sterile florets and distorted spikelets, causes significant yield losses in rice, and occurs in many countries. The current control method of draining paddies early in the season stresses plants, is costly, and wastes water. Development of resistant cultivar is regarded as the most efficient way for its control.

Divergence between sympatric rice- and maize-infecting populations of Rhizoctonia solani AG-1 IA from Latin America.

ABSTRACT The basidiomycetous fungus Rhizoctonia solani anastomosis group (AG)-1 IA is a major pathogen in Latin America causing sheath blight (SB) of rice. Particularly in Venezuela, the fungus also causes banded leaf and sheath blight (BLSB) on maize, which is considered an emerging disease problem where maize replaced traditional rice-cropping areas or is now planted in adjacent fields. Our goals in this study were to elucidate (i) the effects of host specialization on gene flow between sympatric and allopatric rice and maize-infecting fungal populations and (ii) the reproductive mode of the fungus, looking for evidence of recombination.

Mapping quantitative trait Loci responsible for resistance to sheath blight in rice.

Rice sheath blight (ShB), caused by the soilborne pathogen Rhizoctonia solani, annually causes severe losses in yield and quality in many rice production areas worldwide. Jasmine 85 is an indica cultivar that has proven to have a high level of resistance to this pathogen. The objective of this study was to determine the ability of controlled environment inoculation assays to detect ShB resistance quantitative trait loci (QTLs) in a cross derived from the susceptible cv.

The influence of silicon on components of resistance to blast in susceptible, partially resistant, and resistant cultivars of rice.

ABSTRACT The application of silicon (Si) fertilizers reduces the severity of blast, caused by Magnaporthe grisea, in irrigated and upland rice; however, little research has been conducted to examine the epidemiological and etiological components of this reduction. Four cultivars of rice with differential susceptibilities to race IB-49 of M. grisea were fertilized with three rates of a calcium silicate fertilizer and inoculated with the pathogen to test the effects of Si on the following components of resistance to blast: incubation period, latent period, infection efficiency, lesion size, rate of lesion expansion, sporulation per lesion, and diseased leaf area.

Rapid Determination of Rice Cultivar Responses to the Sheath Blight Pathogen Rhizoctonia solani Using a Micro-Chamber Screening Method.

An accurate greenhouse screening method has not been developed previously to identify host response to sheath blight disease caused by Rhizoctonia solani Kühn that causes significant economic losses in rice yield worldwide. The unavailability of a robust screening system in the greenhouse has made it difficult to quantify disease reactions to R. solani, and has hampered studies on the genetics of resistance and plant breeding efforts to improve resistance.