Developing Blast Disease Resistance of Jasmine Rice by Phenotypic-Genotypic Simultaneous Selection

Breeding for resistant varieties of rice is known to be the most preferable way of controlling blast disease (Pyricularia oryzae). Identification and introduction of resistance genes into elite rice lines has become possible by the use of molecular markers. KD2-1 line is an isogenic line of KDML105 carrying four resistance genes on chromosome 2, 3, 8 and 12 from IR64 variety. The objective of this research was to transfer blast disease resistant genes from KD2-1 line into RD15 variety by using phenotypic and genotypic selections by the aid of markers. In this study, the four resistance genes were transferred from KD2-1 rice line into a blast susceptible rice variety, RD15. The study resulted in the breeding of four elite rice lines with four resistance genes by phenotypic and foreground selection. The genome-wide SSR marker analysis of the lines showed more than 86.5% background genome recovery of RD15. Pathogenicity assays of the four selected lines exhibited a resistant reaction to all 13 isolates, with agronomic and yield performance, and cooking and eating quality characteristics similar to that of RD15. The phenotypic-genotypic (foreground and background) simultaneous selection strategy is very useful to introduce multiple resistance genes in rice as it is a fast and economical way for identification of anticipated recombinant lines with desired genes

Development of elite indica rice lines with wide spectrum of resistance to Thai blast isolates by pyramiding multiple resistance QTLs

The rice varieties IR64 and Jao Hom Nin (JHN) demonstrated a broad-spectrum resistance against the rice blast pathogens in Thailand. A genomic investigation unravelled many resistance genes residing on four genomic regions, chromosome 2 and 12 in IR64 and 1 and 11 in JHN. A cross between these varieties was made to combine resistance genes into a single genotype. Marker-assisted selection (MAS) was employed to identify F2 and F3 plants carrying a combination of four resistance QTLs in a homozygous fusion. Flanking markers RM212/RM319 and RM144/RM139 to blast resistant QTLs on chromosome 1 and 11 in JHN rice and tightly-linked markers RM208 and RM179 to blast resistant QTLs on chromosome 2 and 12 in IR64 rice variety were used for MAS. The stepwise MAS screening was brought in as a strategy to provide a cost-saving and minimum number of PCR performing to select resistant genotypes. F4 generation, lines carrying all resistant QTLs show a broader spectrum of resistance against 11 representatives of Thai blast pathogen isolates. (Résumé d'auteur

Potential usage of biosynthesized zinc oxide nanoparticles from mangosteen peel ethanol extract to inhibit Xanthomonas oryzae and promote rice growth

In recent decades, the biosynthesis of nanoparticles using biological agents, such as plant extracts, has grown in popularity due to their environmental and economic benefits. Therefore, this study investigated into utilizing ethanol crude extract sourced from mangosteen peel for the synthesis of zinc oxide nanoparticles (ZnO NPs) and assessing their efficacy against the rice blight pathogen (Xanthomonas oryzae pv. oryzae) through antibacterial evaluations. Additionally, the effects of the synthesized ZnO NPs on rice plant growth was investigated. The X-ray diffraction analysis revealed the production of wurtzite ZnO NPs under specific synthesis conditions, exhibiting a crystallite size of 38.71 nm (or 387.122 Å) without any contamination. Analysis of the ultraviolet–visible optical absorption spectrum indicated a characteristic absorption peak at 363 nm, suggesting a calculated band gap energy of 2.88 eV for the ZnO NPs. Furthermore, Fourier transform infrared spectroscopy analysis confirmed the presence of active compounds functional groups from mangosteen peel in the synthesized ZnO NPs. These biosynthesized ZnO NPs demonstrated significant inhibition of X. oryzae pv. oryzae growth, exhibiting an in vitro 50 % inhibitory concentration (IC50) value of 1.895 mg/mL and a minimum inhibitory concentration (MIC) value of 4 mg/mL. The ZnO NPs treatments at two-fold IC50 values significantly enhanced root length, dry biomass, and chlorophyll a content in rice plants. Consequently, the results demonstrated the potential application of biosynthesized ZnO NPs from mangosteen peel extract in green agriculture, as an alternative to excessive antibiotic use, for combating bacterial plant diseases, and for enhancing plant growth

Genetic Mapping of Magnaporthe grisea Avirulence Gene Corresponding to Leaf and Panicle Blast Resistant QTLs in Jao Hom Nin Rice Cultivar

Equipe 5International audienceThe avirulence characteristic of Magnaporthe grisea isolate TH16 corresponding to Jao Hom Nin (JHN) rice cultivar was studied by mapping population of 140 random ascospore progenies derived from the cross between B1-2 and TH16 isolates. Segregation analyses of the avirulence characteristic performing on JHN rice at the seedling and flowering stages were performed in this mapping population. We used the reference map of Guy11/2539 to choose microsatellite DNA markers for mapping the avirulence gene. The genetic map of this population was constructed from 39-microsatellite markers. The genetic map was spanned by covering seven chromosomes with an average distance of 11.9 cM per marker. In mapping population the distribution of pathogenic and non-pathogenic progenies on JHN rice were found to be fitted to 1 : 1 ratio for two of the rice stages, seedling and flowering stages. The Quantitative Trait Loci (QTL) analysis for avirulence genes corresponding to two rice stages were located at the same region on chromosome 2 between markers Pyms305 and Pyms435. The LOD score and percentage of phenotypic variance explained (PVE) on two rice stages were 5.01/16.69 and 6.73/20.26, respectively. These loci were designated as Avr-JHN(lb) and Avr-JHN(pb) corresponding to leaf and panicle blast characteristics. The findings of this study can be the initial step for positional cloning and identifying any function of avirulence genes corresponding to leaf and panicle blast characteristics