Evaluation of Inherited Resistance Genes of Bacterial Leaf Blight, Blast and Drought Tolerance in Improved Rice Lines

Improved rice lines were developed frome three parents with the resistance or tolerance to bacterial leaf blight,blast and drought stress,respectively,using single-,double-and three-way crosses.The improved lines were assessed for agro-morphological and yield traits under non-drought stress(NS)and reproductive-stage drought stress(RS)treatments.The mean comparison of traits measured between parent plants and progenies(improved lines)were similar,and there were significant and non-significant differences among the parents and improved lines(genotypes)under NS and RS.Smilarly,there was significant and non-significant differences in the interaction among both parent varieties and improved lines for NS and RS.Cluster and 3D-model of principal component analysis did not generate categorical clusters according to crossing methods,and there were no exclusive crossing method inclined variations under the treatments.The improved lines were high-yielding,disease resistant,and drought-tolerant compared with their parents.All the crossing methods were good for this crop improvement program without preference to any,despite the number of genes introgressed.

Sequence related amplified polymorphism (SRAP) reaction system optimization and its application

In this study, three methods such as CTAB,SDS and Shanlichun methods were used to extract genomic DNA from the seedling of rape to find the best method. The principle, characters and application of SRAP were introduced. In order to obtain the optimal SRAP reaction system, the factors including concentrations of DNA, dNTP, etc. of reaction system were modified to better the system of rape. The result showed that the optimum concentrations were15ng DNA template, 0.2mM dNTP, 1.0μM primer and 2.0U Taq enzyme in this 25μL SRAP-PCR system.

Pathogenic and Genetic Diversity of Magneporthe oryzae Populations from Sri Lanka

The present study was undertaken to determine the pathogenic and the genetic diversity of the isolates of M.oryzae collected from the wet,intermediate and dry zones of Sri Lanka with a view to develop rice varieties conferring durable resistance to rice blast.No significant morphological or growth variations existed amongst the isolates studied.The genetic diversity of isolates determined by carrying out Pot2 transposable element based on repetitive-PCR revealed that the majority of isolates （92%） clustered into a single group with 45.4% similarity.The existence of nine pathotypes was identified by observing the reaction type of isolates on 16 different rice lines.Pathotype 1 which was distributed in all zones affected only one differential line.Pathotype 2 which was able to infect six lines was restricted only to the dry zone of Sri Lanka.Of the 16 rice lines,seven lines,K3 （Pik-h）,C101A51 （Piz5）,K1 （Pita）,C105TTP2L9 （Pita）,K59 （Pit）,Shin （Pish） and WHD-1S-75-1-127 （Pi9） had highly effective blast resistance.None of the isolates of the fungus showed any virulence against the seven lines.These seven blast resistant lines can be used in the breeding programmes in Sri Lanka for development of lines conferring durable resistance to rice blast.