Development and exploitation of a set of contiguous segmental substitution lines in pearl millet [Pennisetum glaucum (L.) R. Br.]

Basava, R K (2012) Development and exploitation of a set of contiguous segmental substitution lines in pearl millet [Pennisetum glaucum (L.) R. Br.]. PHD thesis, Osmania University.

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Supervisors NameSupervisors ID
Kavi Kishor, P BOsmani University


Over the past three decades, the application of molecular markers and genetic linkage maps using conventional mapping populations has allowed the identification of specific regions of the genomes controlling polygenic traits, called ‘Quantitative Trait Loci’ (QTLs), in all major crop species including pearl millet. The resolution power of QTL identification is limited in conventional mapping populations due to the overshadowing effect of major QTLs preventing effective estimation of 1) the number of independently segregating minor QTLs and 2) the interactions between pairs of unlinked QTLs. To overcome such limitations and considering the several utilities of introgression lines, the present study aimed to develop a set of pearl millet substitution lines from an advanced backcross population derived from two agronomically elite parental lines viz., ICMB 841 and 863B, which were known to differ for important traits like downy mildew resistance, drought and salinity tolerance, straw ruminant nutritional quality, grain Fe and Zn concentration, and grain and stover yield components. One thousand four hundred and ninety-two progenies (derived from BC5F3, BC5F2 and BC6F1 families) expected to provide coverage across most of each of the seven pearl millet linkage groups were selected for genotyping at 74 marker loci (48 SSR, 21 SSCP-SNP and 5 STS). Based on this genotyping, a total of 124 segmental introgression lines (12 for LG1, 10 for LG2, 10 for LG3, 41 for LG4, 32 for LG5, 12 for LG6 and 17 for LG7) were identified. Among them, 56 were unique introgression segments from 863B in the ICMB 841 genetic background. These contiguous segmental substitution lines (CSSL) provide a nearly ideal set of genetic stocks for fine mapping the multitude of traits for which their parents differ, and use in unraveling the genetic and physiological mechanisms of several agronomically important but complexly inherited traits. The productivity of major crops is severely constrained by biotic stresses and drought stress is a regular occurrence in pearl millet production environments. Hence identification of quantitative trait loci (QTLs) responsible for grain and stover yield, and their maintenance under stress conditions, has become an essential component in pearl millet improvement. To understand the genetic basis of grain and stover yield-related traits of pearl millet, testcross hybrid agronomic performance of selected homozygous introgression lines (ILs), along with their donor and recurrent parents, and a set of sample of recurrent parental allele homozygotes, was evaluated using three genetically diverse, elite inbred pollinators (H 77/833-2, PPMI 301 and RIB 3135-18) under three moisture regimes (fully-irrigated control, late-onset drought stress, and early-onset drought stress conditions) during the summer and kharif seasons at ICRISAT-Patancheru. Twelve phenotypic characters related to grain and stover yield were recorded and line × tester analysis was performed to estimate general combining ability (gca) of each line in each of these environments and across these environments. Several ILs had significant positive gca for grain yield and stover yield, with hybrids showing better performance than that of recurrent parent ICMB 841. Introgression of the 863B-P2 segment between SSR markers Xpsmp2069 and Xpsmp2273 on LG1 for grain yield and Xpsmp2270 and Xpsmp2213 on LG6 for panicle harvest index showed better gca effects than recurrent parent ICMB 841.The present results validate these QTLs which were detected in earlier studies using testcrosses of an F2-derived F4 mapping population based on the same parental lines.

Item Type: Thesis (PHD)
Subjects: Mandate crops > Millets
Others > Genetics and Genomics
Depositing User: Mr Sanat Kumar Behera
Date Deposited: 29 Jun 2012 06:23
Last Modified: 20 Nov 2015 05:04
Acknowledgement: With immense pleasure, I express my deepest sense of gratitude to my supervisor Dr. C. Tom Hash, Principal Scientist, Dryland Cereals Programme, ICRISAT, Patancheru, Hyderabad , for his illuminating guidance, his principles of emphasizing me to understand the concepts of the research project and kind back-up throughout the course of study. I am sincerely obliged and indebted to Prof. P.B. Kavi Kishor, Professor, Department of Genetics, Osmania University, Hyderabad and co-supervisor, for his generous advice, suggestions & guidance and for extending all possible help & support throughout my Ph.D. program. With respectful regards and immense pleasure, I wish to acknowledge and express my heartfelt gratitude to Dr. S. Senthilvel, Senior Scientist, Directorate of Oil Seeds Research, Hyderabad, for his valuable guidance and kind timely help during the process of achieving the final form of this manuscript. I extend my sincere gratitude to Dr. Nepolean, Senior Scientist, Indian Agricultural Research Institute, New Delhi for his valuable suggestions. It gives me pleasure in expressing my heartfelt gratitude to Prof. Vishnupriya, Head, Department of Genetics, Osmania University, Hyderabad and Prof. Pratibha Nallari, Chairperson, Board of Studies in Genetics, Department of Genetics, Osmania University, Hyderabad for their generous help, invaluable academic help and providing necessary facilities for presenting seminars during the course of study. I also like to thank all the other faculty members of the Department of Genetics, Osmania University for their help and cooperation. I express my heartfelt thanks to Dr. Rajeev K. Varshney, Principal Scientist, Applied Genomics Laboratory, ICRISAT, Patancheru, for his kind co-operation and help rendered during my research program at ICRISAT, Hyderabad. With immense pleasure, I express my cordial thanks to Mr. A.G. Bhaskar Raj and Mrs. Seetha Kannan for their kind help and co-operation for successful completion of my project work. I owe a big thanks to all my lab mates, technical staff and administrative staff in Applied Genomics Laboratory and Pearl Millet Breeding Lab, ICRISAT, Patancheru and in the Department of Genetics, Osmania University, Hyderabad for their kind help and co-operation, without which my research would not have been completed. I am very thankful to Learning Systems Unit staff and Library staff at ICRISAT for their help and facilities provided to me during the course of my research work. The Department of Biotechnology (DBT), New Delhi, India is greatly acknowledged for providing the financial assistance to carry out my research project. I convey my whole hearted thanks to all my well wishers and friends for their timely help, cordial affection, moral support and encouragement in many ways. No words could describe the gratitude and sense of obligation I feel for my beloved parents, parents-in-law, Husband, Brothers, Sister and Children for their warm love and for being the strength behind all my endeavors. And I express my deepest adoration to them for their kind cooperation, understanding and help rendered during the course of this study.
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