Regulation of plant height and stem elongation has contributed significantly to improvement of cereal productivity by reducing lodging and improving distribution of assimilates to the inflorescence ...and grain. In wheat, genetic control of height has been largely contributed by the Reduced height-1 alleles that confer gibberellin insensitivity; the beneficial effects of these alleles are associated with less favourable effects involving seedling emergence, grain quality, and inflorescence architecture that have driven new research investigating genetic variation of stem growth. Here, we show that TEOSINTE BRANCHED1 (TB1) regulates height of wheat, with TB1 being expressed at low levels in nodes of the main culm prior to elongation, and increased dosage of TB1 restricting elongation of stem internodes. The effect of TB1 on stem growth is not accompanied by poor seedling emergence, as transgenic lines with increased activity of TB1 form longer coleoptiles than null transgenic controls. Analysis of height in a multiparent mapping population also showed that allelic variation for TB1 on the B genome influences height, with plants containing the variant TB-B1b allele being taller than those with the wild-type TB-B1a allele. Our results show that TB1 restricts height and stem elongation in wheat, suggesting that variant alleles that alter the expression or function of TB1 could be used as a new source of genetic diversity for optimizing architecture of wheat in breeding programmes.
Key message
Yield penalty and increased grain protein content traits associated with
Aegilops ventricosa
7D introgression have been mapped for the first time, and they are physically distinct from ...the eyespot resistance locus
Pch1.
Wheat wild relatives represent an important source of genetic variation, but introgression of agronomically relevant genes, such as for disease resistance, may lead to the simultaneous introduction of genetically linked deleterious traits.
Pch1
is a dominant gene, conferring resistance to eyespot and was introgressed to wheat from
Aegilops ventricosa
as part of a large segment of the 7D
V
chromosome. This introgression has been associated with a significant yield reduction and a concomitant increase in grain protein content. In this study, we evaluated both traits and their relationship to the location of the
Pch1
gene. We found that both QTLs were clearly distinct from the
Pch1
gene, being located on a different linkage group to
Pch1
. In addition, we found that the QTL for increased grain protein content was strong and consistent across field trials, whereas the yield penalty QTL was unstable and environmentally dependent. The yield and grain protein content QTLs were genetically linked and located in the same linkage group. This finding is due in part to the small size of the population, and to the restricted recombination between wheat 7D and
Ae. ventricosa
7D
v
chromosomes. Although recombination in this interval is rare, it does occur. A recombinant line containing
Pch1
and
7D_KASP6
, the marker associated with increase in grain protein content, but not
Xwmc221
, the marker associated with the yield penalty effect, was identified.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Breeding for less digestible starch in wheat can improve the health impact of bread and other wheat foods. The application of forward genetic approaches has lately opened opportunities for the ...discovery of new genes that influence the digestibility of starch, without the burden of detrimental effects on yield or on pasta and bread-making quality. In this study we developed a high-throughput in vitro starch digestibility assay (HTA) for use in forward genetic approaches to screen wheat germplasm. The HTA was validated using standard maize and wheat starches. Using the HTA we measured starch digestibility in hydrothermally processed flour samples and found wide variation among 118 wheat landraces from the A. E. Watkins collection and among eight elite UK varieties (23.5 to 39.9% and 31.2 to 43.5% starch digested after 90 min, respectively). We further investigated starch digestibility in fractions of sieved wholemeal flour and purified starch in a subset of the Watkins lines and elite varieties and found that the matrix properties of flour rather than the intrinsic properties of starch granules conferred lower starch digestibility.
An integrated approach has been used to obtain an understanding of the molecular and chemical mechanisms underlying resistance to aphids in cherry-like tomato (Solanum lycopersicum) landraces from ...the Campania region (southern Italy). The aphid-parasitoid system Macrosiphum euphorbiae-Aphidius ervi was used to describe the levels of resistance against aphids in two tomato accessions (AN5, AN7) exhibiting high yield and quality traits and lacking the tomato Mi gene. Aphid development and reproduction, flight response by the aphid parasitoid A. ervi, gas chromatography-mass spectrometry headspace analysis of plant volatile organic compounds and transcriptional analysis of aphid responsive genes were performed on selected tomato accessions and on a susceptible commercial variety (M82). When compared with the cultivated variety, M82, AN5 and AN7 showed a significant reduction of M. euphorbiae fitness, the release of larger amounts of specific volatile organic compounds that are attractive to the aphid parasitoid A. ervi, a constitutively higher level of expression of plant defence genes and differential enhancement of plant indirect resistance induced by aphid feeding. These results provide new insights on how local selection can offer the possibility of the development of innovative genetic strategies to increase tomato resistance against aphids.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Photoperiod insensitivity has been selected by breeders to help adapt crops to diverse environments and farming practices. In wheat, insensitive alleles of Photoperiod-1 (Ppd-1) relieve the ...requirement of long daylengths to flower by promoting expression of floral promoting genes early in the season; however, these alleles also limit yield by reducing the number and fertility of grain-producing florets through processes that are poorly understood. Here, we performed transcriptome analysis of the developing inflorescence using near-isogenic lines that contain either photoperiod-insensitive or null alleles of Ppd-1, during stages when spikelet number is determined and floret development initiates. We report that Ppd-1 influences the stage-specific expression of genes with roles in auxin signaling, meristem identity, and protein turnover, and analysis of differentially expressed transcripts identified bZIP and ALOG transcription factors, namely PDB1 and ALOG1, which regulate flowering time and spikelet architecture. These findings enhance our understanding of genes that regulate inflorescence development and introduce new targets for improving yield potential.
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•Ppd-1 significantly influences the transcriptome of a developing wheat inflorescence•PDB1 regulates photoperiod-insensitive flowering and spikelet termination•ALOG1 suppresses spikelet branching and delays flowering•ALOG1 shares a conserved role in the Triticeae crops wheat and barley
Gauley et al. investigate the influence of Photoperiod-1 (Ppd-1) during early wheat inflorescence development and identify two transcription factors that are regulated by Ppd-1 to control flowering time and inflorescence architecture.
A family of CBF transcription factors plays a major role in reconfiguring the plant transcriptome in response to low-freezing temperature in temperate cereals. In barley, more than 13
HvCBF
genes map ...coincident with the major QTL
FR-H2
suggesting them as candidates to explain the function of the locus. Variation in copy number (CNV) of specific
HvCBF
s was assayed in a panel of 41 barley genotypes using RT-qPCR. Taking advantage of an accurate phenotyping that combined F
v
/F
m
and field survival, resistance-associated variants within
FR-H2
were identified. Genotypes with an increased copy number of
HvCBF4
and
HvCBF2
(at least ten and eight copies, respectively) showed greater frost resistance. A CAPS marker able to distinguish the
CBF2A, CBF2B
and
CBF2A
/
B
forms was developed and showed that all the higher-ranking genotypes in term of resistance harbour only
CBF2A
, while other resistant winter genotypes harbour also
CBF2B
, although at a lower CNV. In addition to the major involvement of the
HvCBF4-HvCBF2
genomic segment in the proximal cluster of
CBF
elements, a negative role of
HvCBF3
in the distal cluster was identified. Multiple linear regression models taking into account allelic variation at
FR-H1
/
VRN-H1
explained 0.434 and 0.550 (both at
p
< 0.001) of the phenotypic variation for F
v
/F
m
and field survival respectively, while no interaction effect between CNV at the
HvCBF
s and
FR-H1
/
VRN-H1
was found. Altogether our data suggest a major involvement of the
CBF
genes located in the proximal cluster, with no apparent involvement of the central cluster contrary to what was reported for wheat.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
8.
Inside the CBF locus in Poaceae Tondelli, Alessandro; Francia, Enrico; Barabaschi, Delfina ...
Plant science (Limerick),
January 2011, 2011, 2011-Jan, 2011-01-00, 20110101, Volume:
180, Issue:
1
Journal Article
Peer reviewed
▶CBFs and their regulon are major determinants of low-temperature tolerance. ▶ In grass genomes CBFs are structured in clusters of tandemly duplicated genes. ▶ Differential expansion of the CBF ...clusters exists among and within Poaceae species. ▶ CNVs may contribute to phenotypic diversity in temperate Poaceae. ▶ Different mechanisms could play an important role in chilling resistance in tropical Poaceae.
Several molecular evidences have been gathered in Poaceae that point out a central role of the CBF/DREB1 transcription factors in the signal transduction pathways leading to low-temperature tolerance, although to a quite different extent between crops originating from either temperate or tropical climates. A common feature of the CBF/DREB1 genes in Poaceae is their structural organization at the genome level in clusters of tandemly duplicated genes. In temperate cereals such as barley and wheat, expansion of specific multigene phylogenetic clades of CBFs that map at the Frost Resistance-2 locus has been exclusively observed. In addition, copy number variants of CBF genes between frost resistant and frost sensitive genotypes raise the question if multiple copies of the CBF/DREB1s are required to ensure freezing tolerance. On the other hand, in crops of tropical origin such as rice and maize, a smaller or less-responsive CBF regulon may have evolved, and different mechanisms might determine chilling tolerance. In this review, recent advances on the organization and diversity at the CBF cluster locus in the grasses are provided and discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Low temperature is a major factor limiting rice growth and yield, and seedling is one of the developmental stages at which sensitivity to chilling stress is higher. Tolerance to chilling is a complex ...quantitative trait, so one of the most effective approaches to identify genes and pathways involved is to compare the stress-induced expression changes between tolerant and sensitive genotypes. Phenotypic responses to chilling of 13
Japonica
cultivars were evaluated, and Thaibonnet and Volano were selected as sensitive and tolerant genotypes, respectively. To thoroughly profile the short-term response of the two cultivars to chilling, RNA-Seq was performed on Thaibonnet and Volano seedlings after 0 (not stressed), 2, and 10 h at 10 °C. Differential expression analysis revealed that the ICE-DREB1/CBF pathway plays a primary role in chilling tolerance, mainly due to some important transcription factors involved (some of which had never been reported before). Moreover, the expression trends of some genes that were radically different between Thaibonnet and Volano (i.e., calcium-dependent protein kinases
OsCDPK21
and
OsCDPK23,
cytochrome P450 monooxygenase
CYP76M8,
etc.) suggest their involvement in low temperature tolerance too. Density of differentially expressed genes along rice genome was determined and linked to the position of known QTLs: remarkable co-locations were reported, delivering an overview of genomic regions determinant for low temperature response at seedling stage. Our study contributes to a better understanding of the molecular mechanisms underlying rice response to chilling and provides a solid background for development of low temperature-tolerant germplasm.
Full text
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Yield penalty and increased grain protein content traits associated with Aegilops ventricosa 7D introgression have been mapped for the first time, and they are physically distinct from the eyespot ...resistance locus Pch1. Wheat wild relatives represent an important source of genetic variation, but introgression of agronomically relevant genes, such as for disease resistance, may lead to the simultaneous introduction of genetically linked deleterious traits. Pch1 is a dominant gene, conferring resistance to eyespot and was introgressed to wheat from Aegilops ventricosa as part of a large segment of the 7D
chromosome. This introgression has been associated with a significant yield reduction and a concomitant increase in grain protein content. In this study, we evaluated both traits and their relationship to the location of the Pch1 gene. We found that both QTLs were clearly distinct from the Pch1 gene, being located on a different linkage group to Pch1. In addition, we found that the QTL for increased grain protein content was strong and consistent across field trials, whereas the yield penalty QTL was unstable and environmentally dependent. The yield and grain protein content QTLs were genetically linked and located in the same linkage group. This finding is due in part to the small size of the population, and to the restricted recombination between wheat 7D and Ae. ventricosa 7D
chromosomes. Although recombination in this interval is rare, it does occur. A recombinant line containing Pch1 and 7D_KASP6, the marker associated with increase in grain protein content, but not Xwmc221, the marker associated with the yield penalty effect, was identified.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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