Molecular studies in sugarcane are relatively limited because of the complex genetic structure, long life cycle and non availability of reliable sugarcane specific molecular markers. The use of DNA markers for the genetic analysis and manipulation of desirable agronomic traits has become an increasingly useful tool in sugarcane breeding. The objective of the present study was to evaluate the polymorphic potential of sugarcane microsatellite markers developed at National Research Centre on Plant Biotechnology, IARI, New Delhi in high and low sugar lines. These microsatellites markers were screened and validated for their polymorphic, genetic diversity, cross-transferability and comparative linkage mapping potential in high and low sugar bulk of two segregating progenies and 20 each, cultivated high and low sugar commercial varieties. One hundred sixty eight (28%) of the microsatellite markers were found to be highly robust and polymorphic with PIC values ranging from 0.51% to 0.84%. Forty three (0.26 %) markers contained dinucleotide repeats, fifty seven (0.34 %) markers contained trinucleotide repeats, twenty five (0.15 %) and forty three (0.26 %) markers contained composite repeats. The number of observed allele ranged from 2 to 11, with an average of five alleles detected per locus. A total of 977 polymorphic DNA bands were identified, with their fragment size ranging from 20 to 1380 bp. These microsatellite markers are an ideal resource for use in managing sugarcane germplasm, trait mapping and marker assisted breeding strategies. The wide cross -species transportability of these markers may extend their value to research involving other Saccharum species complex.

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Basmati is a premium quality rice of India which is highly priced in the international market. Pusa Basmati 1, an elite Basmati rice variety is highly susceptible to rice blast caused by Magnaporthe oryzae. Therefore, pyramiding blast resistance genes is essential to effectively combat the blast disease and increase the durability of resistance genes. The blast resistance genes Pi9 and Pita have been earlier demonstrated to be effective in Basmati growing regions of the country. Therefore, in the present study, monogenicnear isogenic lines Pusa 1637-18-7-6-20 and Pusa 1633-3-8-8-16-1 carrying Pi9 and Pita, respectively, were intercrossed to generate pyramided lines through marker assisted foreground, background and phenotypic selection for recurrent parent phenotype. The pyramided lines carrying Pi9+Pita were found to be either at par or superior to the recurrent parent Pusa Basmati 1 for agro-morphological, grain and cooking quality traits. Further, these pyramided lines were also found to show resistance against three virulent pathotypes of M. oryzae namely, Mo-nwi-kash 1, Mo-nwi-lon2 and Mo-ei-ran1, when evaluated under artificial inoculation conditions as well as in the natural epiphytotic conditions of uniform blast nursery at two locations. The developed pyramided lines are the potential sources of blast resistance genes in the Basmati improvement program and can also be released for commercial cultivation after required testing.

BACKGROUNDNutrient deficiency in humans, especially in children and lactating women, is a major concern. Increasing the micronutrient concentration in staple crops like rice is one way to overcome this. The micronutrient content in rice, especially the iron (Fe) and zinc (Zn) content, is highly variable. The identification of rice genotypes in which there are naturally high Fe and Zn concentrations across environments is an important target towards the production of biofortified rice.RESULTSPhenotypic correlations between grain Fe and Zn content were positive and significant in all environments but a significant negative association was observed between grain yield and grain Fe and Zn. Promising breeding lines with higher Zn or Fe content, or both, were: IR 82475‐110‐2‐2‐1‐2 (Zn: 20.24–37.33 mg kg−1; Fe: 7.47–14.65 mg kg−1); IR 83294‐66‐2‐2‐3‐2 (Zn: 22–37–41.97 mg kg−1; Fe: 9.43–17.16); IR 83668‐35‐2‐2‐2 (Zn: 27.15–42.73 mg kg−1; Fe: 6.01–14.71); IR 68144‐2B‐2‐2‐3‐1‐166 (Zn: 23.53–40.30 mg kg−1; Fe: 10.53–17.80 mg kg−1) and RP Bio 5478‐185M7 (Zn: 22.60–40.07 mg kg−1; Fe: 7.64–14.73 mg kg−1). Among these, IR82475‐110‐2‐2‐1‐2 (Zn: 20.24–37.33 mg kg−1; Fe: 7.47–14.65 mg kg−1) is also high yielding with 3.75 t ha−1. Kelhrie Cha (Zn: 17.76–36.45 mg kg−1; Fe: 7.17–14.77 mg kg−1), Dzuluorhe (Zn: 17.48–39.68 mg kg−1; Fe: 7.89–19.90 mg kg−1), Nedu (Zn: 18.97–43.55 mg kg−1 Fe: 8.01–19.51 mg kg−1), Kuhusoi‐Ri‐Sareku (Zn: 17.37–44.14 mg kg−1; Fe: 8.99–14.30 mg kg−1) and Mima (Zn: 17.10–45.64 mg kg−1; Fe: 9.97–17.40 mg kg−1) were traditional donor genotypes that possessed both high grain Fe and high Zn content.CONCLUSIONSignificant genotype × location (G × L) effects were observed in all traits except Fe. Genetic variance was significant and was considerably larger than the variance of G × L for grain Zn and Fe content traits, except grain yield. The G × L × year variance component was significant in all cases. © 2020 Society of Chemical Industry

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