Fingerprinting with molecular markers allows precise and rapid variety identification. The present investigation was carried out with the following objectives: (i) to identify informative SSR marker ...allele(s) for fingerprinting popular flax cultivars cultivated in Chhattisgarh state of India, and (ii) to validate the utility of the genotype specific SSR markers in seed genetic purity assessments. A set of 38 SSR markers located across the 30 chromosomes of flax were used for fingerprinting the selected flax cultivars, out of which 28 SSR markers were observed to be informative enough to distinguish the cultivars considered in the study. A set of two SSR markers (LU 1 and LU 7) exhibited unique alleles for four flax cultivars (Kartika, Deepika, Indira Alsi 32 and RLC 92) and could serve as molecular IDs (Identities) for these cultivars. To validate the utility of the SSR markers in genetic purity assessment, certified seed lots of Kartika, Deepika, Indira Alsi 32 and RLC 92 were assessed for their genetic purity using both SSR marker analysis and 18 morphological characters in a grow-out test (GOT). The impurities detected in the SSR marker analysis were 2-3% higher as compared to those detected based on morphological characters in GOT. The results indicated practical utility of the SSR markers in assessing the genetic purity of the flax cultivars.
Asian rice gall midge (Orseolia oryzae) is a major pest across much of south and southeast Asia. This pest is genetically diverse and many gall midge biotypes are known to exist in each country. ...During the last three decades, host plant resistance has proved to be the most effective mechanism of controlling the Asian rice gall midge. Seven genes conditioning resistance to gall midge larvae have been identified in rice (Oryza sativa) and are being used in cultivar improvement programs. However, some of these genes are rendered ineffective by new gall midge biotypes. Increased understanding of genetics, inheritance, allelic relationships and linkage is necessary to maximise the durability of major gene resistance by the pyramiding of these genes. The two genes, Gm-2 and Gm-6(t), are known to confer resistance against a number of biotypes in India and China, respectively. An F^sub 3^ population derived from a cross between Duokang #1 (donor of Gm-6(t)) and Phalguna (donor of Gm-2) was screened against Chinese gall midge biotype 4 at Guangdong, China, and Indian gall midge biotype 1 at Raipur, India. At each location, separately,a single gene governed resistance. The parallel segregation of 417 F^sub 3^progenies for both biotypes at two locations revealed that recombination had occurred between the two genes, establishing that the two genes are not allelic. However, the two genes Gm-2 and Gm-6(t), were found to be linked with a distance of 16.3 cM. A number of lines homozygous at one locus and segregating for the other locus were identified and selected. These lines were selfed to obtain lines homozygous for the favourable alleles at both loci (two locus pyramids). This is the first report on use of conventional host-pest interaction method for pyramiding two closely located Gm-resistance loci of dissimilar effects. The implications of deployment of these pyramids within and across country borders, with reference to the prevailing gall midge populations are discussed.PUBLICATION ABSTRACT
Weed management in rice production is a major constrain leading to low yields. Studies were conducted to assess the competitiveness of different rice varieties and to identify rice genotypes for weed ...competitiveness. The results showed varietal differences in their competitiveness against weeds. The presence of weed overall reduced the yield level from 172.6–1024.3g and 52.6–223.3g in weedy and weed free conditions, respectively. In weedy environment, grain yield showed positive and significant association with panicle length and number of filled grains per plant. The two genotypes identified to be exhibiting weed competitiveness were R 1033-968-2-1 and Kakro.
