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MARKER – ASSISTED INTROGRESSION OF STOVER QUALITY QTL IN PEARL MILLET

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Title MARKER – ASSISTED INTROGRESSION OF STOVER QUALITY QTL IN PEARL MILLET
 
Creator SRIDEVI, N
 
Contributor SIVARAMAKRISHNAN, S
 
Subject MARKER, ASSISTED, INTROGRESSION, STOVER, QUALITY, PEARL, MILLET
 
Description Pearl millet [Pennisetum glaucum (L.) R. Br.] is an important staple crop
of the semi-arid regions of India and Africa. It is a dual-purpose crop grown both for its
grain and fodder/stover. Crop residues provide the bulk of the livestock feed across South
Asia, but their nutritive value is so low that farmers must supplement these with feed
grains and other concentrates. Improving the nutritive value of the straw/stover and the
efficiency of their use in mixed diets is an important option for increasing livestock
production in the region. Genetic variation in the quality of pearl millet stover can be
exploited to develop improved crop germplasm with stover of high nutritive value and
good digestibility. In this context, marker-aided selection is found an ideal approach to
transfer stover quality traits to elite genetic backgrounds through backcrossing with
minimum linkage drag. To exercise marker-aided selection, a well-saturated molecular
marker linkage map and tightly linked markers are a prerequisite. The first molecularmarker-
based genetic linkage map of pearl millet was generated by Liu et al. (1994). That
map consisted of 181 RFLP markers covering the 7 pearl millet chromosomes and
spanning a genetic distance of a 303 cM, and has since been extended with AFLP and
SSR markers (Breese et al., 2002; Qi et al., submitted). A subset of these markers has
subsequently been transferred to a series of different crosses that segregate for
agronomically important traits. Quantitative trait loci have been mapped for downy
mildew resistance (Jones et al., 1995, 2002), drought tolerance and other genotype ×
environment interactions of grain and stover yield (Yadav et al., 2002, 2003, 2004) and
for characters involved in domestication (Poncet et al., 2000, 2002).
ICRISAT and ILRI Scientists (Hash et al., 2003) have attempted to map the QTL
associated with stover quality as well as grain and stover yield and aspects of drought
tolerance using the RFLP- and SSR-based linkage map of ICMB 841  863B. Testcross
hybrids of 79 progenies from this population were evaluated for stover traits at ICRISAT,
Patancheru. Stem sheath and blade fractions of stover samples taken from different parts
of the plant were evaluated for a number of in vitro estimates of ruminant nutritional
quality. Subsequent QTL analysis detected a putative major QTL for leaf blade quality
from parental line 863B (Hash et al., 2003). This putative QTL has subsequently been
partially introgressed into the genetic background of the more elite parent 841B = ICMB
841 by marker-assisted backcrossing.
Genetic linkage maps have been developed in various pearl millet crosses and
used to detect and map quantitative trait loci (QTLs) contributing to various traits
including stover quality. Information on the position of QTLs relative to marker loci
provides a basis for marker assisted selection (MAS) for quantitative traits. In crops like
pearl millet, barley etc MAS is of particular interest for the development of genotypes
stover quality, grain and malt quality etc because (1) thorough assessment of grain yield
and quality traits is expensive and requires larger grain samples than are normally
available in the early stages of a breeding program. (2) grain yield and quality traits are
subject to considerable environmental variation and genotype x environment interaction.
With MAS for QTLs that affect grain and stover quality, pearl millet breeders
could limit breeding populations to those progeny with the highest probability of having
superior stover quality. Our objective is to assess whether marker-based selection could
be effective in manipulating a QTL region in pearl millet breeding population in which
the QTL region had originally been detected and mapped.
 
Date 2016-08-27T14:11:34Z
2016-08-27T14:11:34Z
2005
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/74124
 
Language en
 
Relation D7348;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD