Marker assisted backcross breeding was employed to incorporate the blast resistance genes, Pi2 and Pi54 and bacterial blight (BB) resistance genes xa13 and Xa21 into the genetic background of Pusa Basmati 1121 (PB1121) and Pusa Basmati 6. Foreground selection for target gene(s) was followed by arduous phenotypic and background selection which fast-tracked the recovery of recurrent parent genome (RPG) to an extent of 95.8% in one of the near-isogenic lines (NILs) namely, Pusa 1728-23-33-31-56, which also showed high degree of resemblance to recurrent parent, PB6 in phenotype. The phenotypic selection prior to background selection provided an additional opportunity for identifying the novel recombinants viz., Pusa 1884-9-12-14 and Pusa 1884-3-9-175, superior to parental lines in terms of early maturity, higher yield and improved quality parameters. There was no significant difference between the RPG recovery estimated based on SSR or SNP markers, however, the panel of SNPs markers was considered as the better choice for background selection as it provided better genome coverage and included SNPs in the genic regions. Multi-location evaluation of NILs depicted their stable and high mean performance in comparison to the respective recurrent parents. The Pi2+Pi54 carrying NILs were effective in combating a pan-India panel of Magnaporthe oryzae isolates with high level of field resistance in northern, eastern and southern parts of India. Alongside, the PB1121-NILs and PB6-NILs carrying BB resistance genes xa13+Xa21 were resistant against Xanthomonas oryzae pv. oryzae races of north-western, southern and eastern parts of the country. Three of NILs developed in this study, have been promoted to final stage of testing during the Kharif 2015 in the Indian National Basmati Trial.
Grain amaranth is an underutilized crop with high nutritional quality from the Americas. Emerging genomic and biotechnological tools are becoming available that allow the integration of novel breeding techniques for rapid improvement of amaranth and other underutilized crops. Out of thousands of edible plants, only three cereals-maize, wheat and rice-are the major food sources for a majority of people worldwide. While these crops provide high amounts of calories, they are low in protein and other essential nutrients. The dependence on only few crops, with often narrow genetic basis, leads to a high vulnerability of modern cropping systems to the predicted climate change and accompanying weather extremes. Broadening our food sources through the integration of so-called orphan crops can help to mitigate the effects of environmental change and improve qualitative food security. Thousands of traditional crops are known, but have received little attention in the last century and breeding efforts were limited. Amaranth is such an underutilized pseudocereal that is of particular interest because of its balanced amino acid and micronutrient profiles. Additionally, the C photosynthetic pathway and ability to withstand environmental stress make the crop a suitable choice for future agricultural systems. Despite the potential of amaranth, efforts of genetic improvement lag considerably behind those of major crops. The progress in novel breeding methods and molecular techniques developed in model plants and major crops allow a rapid improvement of underutilized crops. Here, we review the history of amaranth and recent advances in genomic tools and give a concrete perspective how novel breeding techniques can be implemented into breeding programs. Our perspectives are transferable to many underutilized crops. The implementation of these could improve the nutritional quality and climate resilience of future cropping systems.
Bakanae or foot rot disease caused by Fusarium fujikuroi (teleomorph: Gibberella fujikuroi, Sawada, Wollenweber) is emerging as a serious disease of rice. A simple, reliable and high-throughput method for screening the disease would enable rapid screening of germplasm aimed at identifying resistance sources, mapping QTLs/genes and developing resistant rice cultivars. In the present study, a highthroughput, reliable bioassay to screen rice germplasm for resistance to bakanae disease was developed and compared with the conventional screening technique. This technique involves soaking of rice seeds in fungal spore suspension (1.0x10 6 spores ml-1) for 24 hours at room temperature. Seedling growth at 30°/25° (±3)°C day/night temperature and 60/80(±10)% day/night relative humidity in glasshouse gave the best results. The new protocol described here produces consistent and reproducible bakanae disease symptoms and enables screening of hundreds of rice germplasm within 15 days without any loss of precision in screening of rice genotypes against bakanae disease. The resistant and susceptible genotypes can be used for developing mapping population and identification of QTLs/genes conferring resistance to bakanae disease.
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