Sundeep Kumar

Inheritance And Allelic Relationship Of Resistance Genes To Spot Blotch Of Wheat Caused By Bipolaris Sorokiniana

Three varieties viz., Longmai 10, Jinmai and Sanghai, known for their resistance to spot blotch were crossed with a susceptible parent Sonalika. Disease severities of F1’s were intermediate to parents and thus indicated no dominance. Around 150–200 progeny rows of three resistant × susceptible crosses were evaluated in the F3, F4 and F5 generations. Spot blotch severity (%) for each progeny row was measured at three different growth stages viz. 69, 77 and 83 (Zadoks scale, 1974). Based on disease score, F3, F4 and F5 progenies were grouped into three classes: homozygous resistant, homozygous susceptible and segregating. Number of genes was estimated following χ2 and quantitative approach. Two parents showed two genes control while, Jinmai appeared to be under the control of three genes Resistant x resistant crosses were made to confirm the allelic relationship of resistance genes. The F3 progenies of all the crosses did not show susceptible plants. This proved that at least one gene was common among parents for resistance. However, the appearance of transgressive segregants was an indication of the non-allelic relationship. The study indicated the possibility of enhancement of resistance through gene pyramiding.

Study of inheritance and allelic relation of resistance to spot blotch (Bipolaris sorokiniana) of wheat

Six varieties viz., Chirya-1, Chirya-3, Chirya-7, Yangmai-6, Ning-8201 and Ning-8319 known for their resistance to spot blotch were crossed with the most susceptible parent i.e., Sonalika for studying inheritance pattern and establishing allelic relationship among different resistance sources. Disease severity of F1 ’s were intermediate to slightly tilted towards resistant parents and thus indicated either no dominance or partial dominance. Progeny rows of these crosses were evaluated in the F3 and F4 generations. Disease severity for each progeny rows was measured at three different growth stages viz., late anthesis (69), late milk (77) and early dough (83) stages. Based on disease severity, the F3, F4 and F5 progenies were grouped into three classes: homozygous dominant, segregating and homozygous susceptible. Based on this ratio, number of effective genes was estimated following χ2 analysis and quantitative approaches. Chirya-1, Chirya-3, Chirya-7, Yangmai-6 and Ning-8201 showed involvement of two genes in resistance while, Ning-8319 showed the presence of three resistance genes to spot blotch. Resistant × resistant crosses were made to establish the allelic relationship of resistance genes. The F3 progeny of all the crosses did not show susceptible plants. This proved that at least one gene was common among parents for resistance. However, the appearance of transgressive segregants was an indication of the non-allelic relationship. The present study also indicated the possibility of achieving enhanced resistance through gene pyramiding.

The Enigmatic Science of Biotechnology

One of the major challenges that we face in the 21st century is to achieve sustainable growth and development, when we are already faced with a rapidly declining resource base in terms of food, land and water, as a result of population explosion. There are no quick fix solutions to alleviate the sit-uation, but there are many promising new avenues which biotechnology as a science can offer to re-duce the pressure on the limited resources that we have. Biotechnology plays a pivotal role in every major sector of the economy i.e., agriculture, healthcare and industry. However, the full potential of biotechnology can be understood and harnessed only when the ensuing risks and benefits are ana-lyzed and weighed against each other, which would allow us to take an informed and judicious decision, thereafter.

Genetic diversity in the isolates of spot blotch of wheat caused by Bipolaris sorokiniana using RAPD markers

Genetic variation among 20 random iso-lates of Bipolaris sorokinian belonging to five mor-pho-pathological groups was analyzed by DNA finger printing based on RAPD analysis. Twenty random primers of different origin were used. Diag-nostic RAPD bands were generated from fungal DNA. UPGMA cluster analysis clustered the 20 isolates into two distinct groups. Of the 20 isolates, 19 were in the first group, while only one was in the other. An average genetic similarity between both the clusters was only 0.05 (5%). Isolate be-longing to different groups of morpho-pathological traits, were dispersed across several sub-clusters. In general, the classification based on morpho-pathological traits showed about 60% conformity with the grouping based on molecular markers. Re-sults illustrated the potential value of RAPDs for detecting polymorphism among isolates.

Genomics for Crop Improvement-an Indian perspective

Agriculture in India is one of the most prominent sectors in the economy and about 43% of the country‘s land is used for agriculture related activities. The agricultural scenario of our country today is very different from what it was in the last century. Small land holding size, limited water resources, increased demand for food grains due the rapid population explosion, widespread land and water degradation, climate change, are some of the unprecedented challenges our agriculture faces today. In order to achieve sustainable agriculture in such adverse conditions, it is imperative that we adopt new and innovative ways to enhance our agricultural productivity. The science of genomics has opened up a whole new plethora of opportunities and avenues, which can help us achieve enhanced productivity under the present day challenges. The recent advances in the field of genomics offer great potential in hastening our various crop improvement programmes. Efforts must be undertaken to integrate this genomics knowledge and expertise, that we have acquired over the last few decades, into our conventional crop improvement programmes.

Transgenic plants modified for photosynthesis

The rapid global climate change as a result of massive industrialization and the ever increasing demand for food, has compelled the scientists to look for new ways to boost agricultural productivity. In order to achieve this, enhancing the photosynthetic efficiency of crop plants has been a major area of investigation. Plants have been genetically engineered to produce more by increasing their photosynthetic efficiencies. The C3 - C4 pathways have been specifically targeted to modify the photosynthetic nature of plants. It has been suggested that such plants will be better adapted to the future climatic conditions.

Salinity Tolerance in Plants

Salinity is one of the major abiotic stresses, which poses an enormous constraint to crop production. It has been estimated that increased salinization of arable land will result in about 30% land loss within next 25 years. During times when agriculture is already under tremendous pressure, due to the ever increasing world population, it has become imperative that new, innovative methods be adopted to increase the crop productivity. Developing salt tolerant plants through traditional plant breeding and genetic engineering or using a combination of both, will enable farmers to counter the challenge of saline soils. The recent advances in the field of plant genomics, can help us better understand the complexities involved in salinity tolerance and can enable us to fortify the development of salt tolerant crop varieties.