Development of Broad Spectrum and Durable Bacterial Blight Resistant Variety through Pyramiding of Four Resistance Genes in Rice

Not AvailableBacterial blight (BB) disease caused by Xanthomonas oryzae pv. oryzae is a major biotic constraint on obtaining higher grain yields in rice. Marker-assisted backcross breeding (MABB) was performed by the pyramiding of Xa4, xa5, xa13 and Xa21 resistance genes in the popular variety, Ranidhan. A foreground selection in BC1F1, BC2F1, and BC3F1 progenies detected all the target genes in 12, 7 and 16 progenies by using the closely linked markers from a population size of 426, 410, and 530, respectively. The BB-positive progenies carrying the target genes with a maximal similarity to the recipient parent was backcrossed in each backcross generation. A total of 1784 BC3F2 seeds were obtained from the best BC3F1 progeny. The screening of the BC3F2 progenies for the four target genes resulted in eight plants carrying all the four target genes. A bioassay of the pyramided lines conferred very high levels of resistance to the predominant isolates of bacterial blight disease. In addition, these pyramided lines were similar to Ranidhan in 16 morpho-quality traits, namely, plant height, filled grains/panicle, panicles/plant, grain length, grain breadth, grain weight, milling, head rice recovery, kernel length after cooking, water uptake, the volume expansion ratio, gel consistency,alkali-spreading value, and the amylose content.Not Availabl

First total syntheses of (+)-garvensintriol and (+)-5-epi-garvensintriol

A concise and efficient carbohydrate-based approach for the total syntheses of (+)-garvensintriol and (+)-5-epi-garvensintriol is described in nine and six steps with 20% and 37% overall yield, respectively, starting from a known intermediate. A sequence of Grignard-assisted lactol opening with terminal alkyne, stereoselective keto reduction and oxidative lactonization are the key reactions

Phenotypic and genotypic assessment of elite rice varieties for brown plant hopper (Nilaparvata lugens Stål.) resistance

Popular rice varieties from India which exhibited field resistance against Brown Plant Hopper attack were selected to validate their resistance reaction. Genotyping using twenty-four gene-specific markers for BPH resistance was carried out. Besides this, phenotyping of morpho-economic traits along with resistance reaction was performed. Stepwise regression of phenotypic data showed that the traits viz. trichome number, leaf area and leaf number per tiller were significantly correlated to BPH damage score, while the traits, grains per panicle, tiller number, plant height and leaf number per plant contributed significantly towards seed yield. It was observed that there was a positive association between leaf area and BPH damage while trichome number was negatively associated, causing decreasing value in damage score. In the case of yield, except leaf number per plant, others traits showed a positive association. Further, PCA biplot analysis results confirmed the findings. Phenotypically, the rice variety Hasanta exhibited the highest BPH resistance followed by Jyotirmayee, Mahanadi, Konark and Pratap. Out of the twenty-four gene-specific markers, six markers exhibited polymorphism and RM247 showed the highest polymorphic information content (PIC) value. Cluster analysis of the varieties based on the marker data placed the variety Hasanta in a separate cluster, confirming its distinctness. Genotyping confirmed the genetic nature of BPH resistance in Hasanta variety. The cluster 2.2a included the highest number of varieties based on genetic similarity although it comprised of resistant, moderately resistant and susceptible types. This finding indicated that phenotypic variation within genotypic similar groups might be due to environment or different sources of origin. Hence, this phenotypic and genotypic variation among the genotypes would be useful for selecting elite and potential BPH-resistant donors in a crop improvement program

Total Synthesis of Ivorenolide A Following a Base-Induced Elimination Protocol

A concise and stereocontrolled first total synthesis of Ivorenolide A (<b>1</b>) is reported in 16 longest linear steps with a 13.4% overall yield starting from (+)-diethyl tartrate (DET). Key features are base-induced elimination protocol for the construction of chiral propargyl alcohols in both fragments, Pd-catalyzed cross-coupling of terminal acetylenes, and Shiina’s 2-methyl-6-nitrobenzoic anhydride (MNBA) mediated macrolactonization

Development of Broad Spectrum and Durable Bacterial Blight Resistant Variety through Pyramiding of Four Resistance Genes in Rice

Bacterial blight (BB) disease caused by Xanthomonas oryzae pv. oryzae is a major biotic constraint on obtaining higher grain yields in rice. Marker-assisted backcross breeding (MABB) was performed by the pyramiding of Xa4, xa5, xa13 and Xa21 resistance genes in the popular variety, Ranidhan. A foreground selection in BC1F1, BC2F1, and BC3F1 progenies detected all the target genes in 12, 7 and 16 progenies by using the closely linked markers from a population size of 446, 410, and 530, respectively. The BB-positive progenies carrying the target genes with a maximal similarity to the recipient parent was backcrossed in each backcross generation. A total of 1784 BC3F2 seeds were obtained from the best BC3F1 progeny. The screening of the BC3F2 progenies for the four target genes resulted in eight plants carrying all the four target genes. A bioassay of the pyramided lines conferred very high levels of resistance to the predominant isolates of bacterial blight disease. In addition, these pyramided lines were similar to Ranidhan in 16 morpho-quality traits, namely, plant height, filled grains/panicle, panicles/plant, grain length, grain breadth, grain weight, milling, head rice recovery, kernel length after cooking, water uptake, the volume expansion ratio, gel consistency, alkali-spreading value, and the amylose content

Pfcrt haplotypes and in-vivo chloroquine response in Sundergarh district, Orissa, India

The Plasmodium falciparum chloroquine resistance transporter (Pfcrt) K76T mutation and haplotype (amino acids 72-76) were analyzed as markers of chloroquine (CQ) resistance in the blood samples of patients from two sites of different intensities of malaria transmission (high, n = 70; low, n = 68) in Sundergarh district of Orissa, India and correlated with the in-vivo response. Early treatment failure (ETF) was significantly more frequent in the high endemic area (32.9 vs. 7.4%, P &lt; 0.001), with children below 5 years suffering more. A high frequency of pfcrt K76T mutation was observed in both the areas (87.1 vs. 79.4%, P = 0.22). Patients carrying pfcrt 76T were the most likely to develop ETF (odds ratio 36; 95% CI 3.35-1653.3; P &lt; 0.001). The ratio of 76T:K76 was 22:9 and 11:14, respectively, in high and low endemic areas (odds ratio 3.1; 95% CI 0.9-11.03; P = 0.04), which may be used as a measure of drug pressure. Sequences of pfcrt codons 72-76 showed 16 of the CQ-resistant haplotypes to be SVMNT, 5 CVMNT and 12 CVIET. The CQ-sensitive haplotypes were mostly CVMNK in 10 samples; CVIEK in 2 samples. Both Southeast Asian and South American haplotypes were present, with the latter predominating