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Pearl millet marker-assisted selection (MAS) programs targeting adaptation to variable postflowering moisture environments would benefit from quantitative trait loci (QTLs) that improve grain yield across the full range of postflowering moisture conditions, rather than just in drought-stressed environments. This research was undertaken to identify such QTLs from an extensive (12-environment) phenotyping data set that included both stressed and unstressed postflowering environments. Genetic materials were test crosses of 79 [F.sub.2]-derived [F.sub.4] progenies from a mapping population based on a widely adapted maintainer line (ICMB 841) x a postflowering drought-tolerant maintainer (863B). Three QTLs (on linkage group [LG] 2, LG 3, and LG 4) were identified as primary candidates for MAS for improved grain yield across variable postflowering moisture environments. The QTLs on LG 2 and LG 3 (the most promising) explained a useful proportion (13-25%) of phenotypic variance for grain yield across environments. They also co-mapped with QTLs for harvest index across environments, and with QTLs for both grain number and individual grain mass under severe terminal stress. Neither had a significant QTL x environment interaction, indicating that their predicted effects should occur across a broad range of available moisture environments. We have estimated the benefits in grain yield and accompanying changes in yield components and partitioning indices that would be expected as a result of incorporating these QTLs into other genetic backgrounds by MAS.

The availability of recessive genes for early flowering-day length insensitivity offers an opportunity to synchronize the flowering of late-flowering or day length-sensitive parents with that of early-flowering parents without necessarily affecting the flowering of their hybrids, provided that the earlier parent does not carry the same recessive allele. This study evaluated the hypothesis that incorporating the recessive e1 allele for early flowering-day length insensitivity into a late-flowering, photoperiod-sensitive pollinator in pearl millet [Pennisetum glaucum (L.) R. Br.] would synchronize its flowering and improve seed production with earlier-flowering female parents, without affecting the time to flowering or the performance of the resulting hybrids. An [e.sub.1]/[e.sub.1] isoline of the late-flowering pollinator ICMP 85410, produced by six backcrosses, flowered 16 dl earlier under natural day lengths at Patancheru, India, (17 ° N) and 19 d earlier under extended day lengths (equivalent to 29 ° N) than its near isogenic [E.sub.]/[E.sub.1] counterpart. As a consequence, it successfully produced hybrid seed when sown simultaneously with early, male-sterile line 843A, whereas the late isoline failed under the same conditions. The [E.sub.1]/[e.sub.1] versions of eight near-isogenic hybrids (on a range of eight [E.sub.1]/[E.sub.1] male-steriles) flowered an average of 3 d earlier than their [E.sub.1]/[E.sub.1] counterparts in 2 yr of tests under both natural and extended day length conditions at the same location. This earlier flowering had small effects on hybrid yield components, consistent with known effects of earliness in the crop, but did not affect grain yield. The results indicate that the [e.sub.1] allele is a powerful tool for exploiting heterosis between early- and late-flowering parents in pearl millet, which is otherwise difficult to realize without complicated seed production practices., TRADITIONAL CULTIVARS of most tropical cereals depend on strong sensitivity to photoperiod to regulate their time of flowering to match the environment of their origin. Moving such germplasm to other [...]

There is substantial genetic variation for drought adaption in pearl millet in terms of traits controlling plant water use. It is important to understand genomic regions responsible for these traits. Here, F7 recombinant inbred lines were used to identify quantitative trait loci ( QTL) and allelic interactions for traits affecting plant water use, and their relevance is discussed for crop productivity in water-limited environments. Four QTL contributed to increased transpiration rate under high vapour pressure deficit ( VPD) conditions, all with alleles from drought-sensitive parent ICMB 841. Of these four QTL, a major QTL (35.7%) was mapped on linkage group ( LG) 6. The alleles for 863B at this QTL decreased transpiration rate and this QTL co-mapped to a previously detected LG 6 QTL, with alleles from 863B for grain weight and panicle harvest index across severe terminal drought stress environments. This provided additional support for a link between water saving from a lower transpiration rate under high VPD and drought tolerance. 863B alleles in this same genomic region also increased shoot weight, leaf area and total transpiration under well-watered conditions. One unexpected outcome was reduced transpiration under high VPD (15%) from the interaction of two alleles for high VPD transpiration ( LG 6 (B), 40.7) and specific leaf mass and biomass ( LG 7 (A), 35.3), (A, allele from ICMB 841, B, allele from 863B, marker position). The LG 6 QTL appears to combine alleles for growth potential, beneficial for non-stress conditions, and for saving water under high evaporative demand, beneficial under stressful conditions. Mapping QTL for water-use traits, and assessing their interactions offers considerable potential for improving pearl millet adaptation to specific stress conditions through physiology-informed marker-assisted selection. [ABSTRACT FROM AUTHOR]

Over the past 10 years, resources have been established for the genetic analysis of pearl millet,Pennisetum glaucum(L.) R. Br., an important staple crop of the semi-arid regions of India and Africa. Among these resources are detailed genetic maps containing both homologous and heterologous restriction fragment length polymorphism (RFLP) markers, and simple sequence repeats (SSRs). Genetic maps produced in four different crosses have been integrated to develop a consensus map of 353 RFLP and 65 SSR markers. Some 85% of the markers are clustered and occupy less than a third of the total map length. This phenomenon is independent of the cross. Our data suggest that extreme localization of recombination toward the chromosome ends, resulting in gaps on the genetic map of 30 cM or more in the distal regions, is typical for pearl millet. The unequal distribution of recombination has consequences for the transfer of genes controlling important agronomic traits from donor to elite pearl millet germplasm. The paper also describes the generation of 44 SSR markers from a (CA)n-enriched small-insert genomic library. Previously, pearl millet SSRs had been generated from BAC clones, and the relative merits of both methodologies are discussed. [ABSTRACT FROM AUTHOR]

Presents a study that attempted to locate pearl millet dwarfing genes d[sub1] and d[sub2], along with the purple foliage color gene P, on a restriction fragment length polymorphism-based skeleton linkage map for the crop. Description of pearl millet; Comparison between semidwarf grain and cereal cultivars and their tall counterparts; Countries where dwarf plants in pearl millet were discovered.

A mapping population of 104 F3 lines of pearl millet, derived from a cross between two inbred lines H 77/833-2 × PRLT 2/89-33, was evaluated, as testcrosses on a common tester, for traits determining grain and stover yield in seven different field trials, distributed over 3 years and two seasons. The total genetic variation was partitioned into effects due to season (S), genotype (G), genotype × season interaction (G × S), and genotype × environment-within-season interaction [G × E(S)]. QTLs were determined for traits for their G, G × S, and G × E(S) effects, to assess the magnitude and the nature (cross over/non-crossover) of environmental interaction effects on individual QTLs. QTLs for some traits were associated with G effects only, while others were associated with the effects of both G and G × S and/or G, G × S and G × E(S) effects. The major G × S QTLs detected were for flowering time (on LG 4 and LG 6), and mapped to the same intervals as G × S QTLs for several other traits (including stover yield, harvest index, biomass yield and panicle number m–2). All three QTLs detected for grain yield were unaffected by G × S interaction however. All three QTLs for stover yield (mapping on LG 2, LG 4 and LG 6) and one of the three QTLs for grain yield (mapping on LG 4) were also free of QTL × E(S) interactions. The grain yield QTLs that were affected by QTL × E(S) interactions (mapping on LG 2 and LG 6), appeared to be linked to parallel QTL × E(S) interactions of the QTLs for panicle number m–2 on (LG 2) and of QTLs for both panicle number m–2 and harvest index (LG 6). In general, QTL × E(S) interactions were more frequently observed for component traits of grain and stover yield, than for grain or stover yield per se. [ABSTRACT FROM AUTHOR]

Drought stress during the reproductive stage is one of the most important environmental factors reducing the grain yield and yield stability of pearl millet. A QTL mapping approach has been used in this study to understand the genetic and physiological basis of drought tolerance in pearl millet and to provide a more-targeted approach to improving the drought tolerance and yield of this crop in water-limited environments. The aim was to identify specific genomic regions associated with the enhanced tolerance of pearl millet to drought stress during the flowering and grain-filling stages. Testcrosses of a set of mapping-population progenies, derived from a cross of two inbred pollinators that differed in their response to drought, were evaluated in a range of managed terminal drought-stress environments. A number of genomic regions were associated with drought tolerance in terms of both grain yield and its components. For example, a QTL associated with grain yield per se and for the drought tolerance of grain yield mapped on linkage group 2 and explained up to 23% of the phenotypic variation. Some of these QTLs were common across stress environments whereas others were specific to only a particular stress environment. All the QTLs that contributed to increased drought tolerance did so either through better than average maintenance (compared to non-stress environments) of harvest index, or harvest index and biomass productivity. It is concluded that there is considerable potential for marker-assisted backcross transfer of selected QTLs to the elite parent of the mapping population and for their general use in the improvement of pearl millet productivity in water-limited environments. [ABSTRACT FROM AUTHOR]

Presents information on the registration of the parental lines of pearl millet and sugar beet. Types of pearl millet and sugar beet developed; Method used in the registration process; Benefits of these varieties.