Dataset Information

Influence of Gene Expression on Hardness in Wheat.

ABSTRACT: Puroindoline (Pina and Pinb) genes control grain texture or hardness in wheat. Wild-type/soft alleles lead to softer grain while a mutation in one or both of these genes results in a hard grain. Variation in hardness in genotypes with identical Pin alleles (wild-type or mutant) is known but the molecular basis of this is not known. We now report the identification of wheat genotypes with hard grain texture and wild-type/soft Pin alleles indicating that hardness in wheat may be controlled by factors other than mutations in the coding region of the Pin genes. RNA-Seq analysis was used to determine the variation in the transcriptome of developing grains of thirty three diverse wheat genotypes including hard (mutant Pin) and soft (wild type) and those that were hard without having Pin mutations. This defined the role of pin gene expression and identified other candidate genes associated with hardness. Pina was not expressed in hard wheat with a mutation in the Pina gene. The ratio of Pina to Pinb expression was generally lower in the hard non mutant genotypes. Hardness may be associated with differences in Pin expression and other factors and is not simply associated with mutations in the PIN protein coding sequences.

SUBMITTER: Nirmal RC

PROVIDER: S-EPMC5065149 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Influence of Gene Expression on Hardness in Wheat.

Nirmal Ravi C RC Furtado Agnelo A Wrigley Colin C Henry Robert J RJ

PloS one 20161014 10

Puroindoline (Pina and Pinb) genes control grain texture or hardness in wheat. Wild-type/soft alleles lead to softer grain while a mutation in one or both of these genes results in a hard grain. Variation in hardness in genotypes with identical Pin alleles (wild-type or mutant) is known but the molecular basis of this is not known. We now report the identification of wheat genotypes with hard grain texture and wild-type/soft Pin alleles indicating that hardness in wheat may be controlled by fact ...[more]

PMID: 27741295

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Project description:The grain hardness index (HI) is one of the important reference bases for wheat quality and commodity properties; therefore, it is essential and useful to identify loci associated with the HI in wheat breeding. The grain hardness index of the natural population including 150 common wheat genotypes was measured in this study. The phenotypic data diversity of HI based on four environments and the best linear unbiased prediction (BLUP) was analyzed. The results showed that the grain HI of the natural population ranged from 15.00 to 83.00, the variation range was from 5.10% to 24.44%, and the correlation coefficient was 0.872-0.980. BLUP value was used to grade and assign the grain HI to hard wheat, mixed wheat, and soft wheat, and the assigned phenotypes were used for genome-wide association analysis. Two types of grain hardness index phenotypic values were used for genome-wide association analysis (GWAS) using a 55K SNP array. A total of five significant association loci (p < 0.001) were excavated, among which four loci could be detected in three or more environments. They were distributed on chromosomes 1A and 7D, and the phenotypic contribution rate was 7.52% to 10.66%. A total of 48 sites related to grain hardness were detected by the assignment method, among which five were stable genetic sites, distributed on chromosomes 1A(2), 3B(1), 4B(1), and 7D(1), with phenotypic contribution rates ranging from 7.63% to 11.12%. Of the five loci detected by the assignment method, two stable loci were co-located in the phenotypic mapping results of the hardness index. One of the loci was consistent with previous reports and located on chromosome 1A, and one locus was unreported on chromosome 7D. Therefore, it may be a feasible attempt to use the assignment method to conduct genome-wide association analysis of the grain hardness index. In this study, a total of five genetic loci for grain hardness stability were excavated, and two of the loci were located in the two phenotypic values, two of which were not reported.

Project description:Grain hardness is an important quality trait of cereal crops. In wheat, it is mainly determined by the Hardness locus that harbors genes encoding puroindoline A (PINA) and puroindoline B (PINB). Any deletion or mutation of these genes leading to the absence of PINA or to single amino acid changes in PINB leads to hard endosperms. Although it is generally acknowledged that hardness is controlled by adhesion strength between the protein matrix and starch granules, the physicochemical mechanisms connecting puroindolines and the starch-protein interactions are unknown as of this time. To explore these mechanisms, we focused on PINA. The overexpression in a hard wheat cultivar (cv. Courtot with the Pina-D1a and Pinb-D1d alleles) decreased grain hardness in a dose-related effect, suggesting an interactive process. When PINA was added to gliadins in solution, large aggregates of up to 13 μm in diameter were formed. Turbidimetry measurements showed that the PINA-gliadin interaction displayed a high cooperativity that increased with a decrease in pH from neutral to acid (pH 4) media, mimicking the pH change during endosperm development. No turbidity was observed in the presence of isolated α- and γ-gliadins, but non-cooperative interactions of PINA with these proteins could be confirmed by surface plasmon resonance. A significant higher interaction of PINA with γ-gliadins than with α-gliadins was observed. Similar binding behavior was observed with a recombinant repeated polypeptide that mimics the repeat domain of gliadins, i.e., (Pro-Gln-Gln-Pro-Tyr)8. Taken together, these results suggest that the interaction of PINA with a monomeric gliadin creates a nucleation point leading to the aggregation of other gliadins, a phenomenon that could prevent further interaction of the storage prolamins with starch granules. Consequently, the role of puroindoline-prolamin interactions on grain hardness should be addressed on the basis of previous observations that highlight the similar subcellular routing of storage prolamins and puroindolines.

Project description:A microarray analysis of wheat grain hardness For both the Heron and Falcon NIL, whole wheat heads were harvested at 6, 15 and 25 days post anthesis (DPA) from glass house grown material and stored at -80 OC. For the other wheat cultivars analysed, heads at approximately 9-10 DPA were used. Eight to ten developing caryopses at the same age and morphological stage of development were selected from a head to represent a sample. Seed collected from a different head represented a replicate sample. Total RNA was isolated from the whole seed following the method of Higgins et al. (1976) with the following modification to remove starch. After the lithium chloride precipitation, the RNA pellet was resuspended in 250 ?l water. Then 3.5 ?l of 3 M sodium acetate (pH 5.3) and 125 ?l ethanol were added and the sample was centrifuged for 10 minutes at 4 OC. The supernatant was transferred to a fresh tube and the RNA was ethanol-precipitated by the addition of 21.5 ?l of 3 M sodium acetate (pH 5.3) and 375 ?l ethanol. The recovery of RNA varied from 0.06-0.5 ?g RNA per mg of tissue and this was dependent on the developmental stage of the seeds used for extraction of the RNA. For the labelling procedure, 50 ?g of total RNA was used for both the Cy3 and Cy5 dyes (Amersham Pharmacia, UK), following the two-step labelling method of Schenk et al. (2000). The Cy3 control (hard wheat) and Cy5 sample (soft wheat) were swapped among the replicate experiments to minimise any bias in cDNA incorporation and photo-bleaching of the fluorescent dyes. The pre-hybridisation of the microarray slides, hybridisation of the target cDNA and subsequent washing of the slides to remove unbound target was performed as per the supplied protocol for the CMT-GAPSTM coated microscope slides (Corning USA). The slides were scanned with a GenePix 4000A microarray scanner (Axon Instruments, Union, CA, USA). The features were analysed using the GenePix Pro 4 software and unsatisfactorily segmented features were either manually adjusted or discarded to ensure the integrity of the data obtained.

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Influence of Gene Expression on Hardness in Wheat.

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Influence of Gene Expression on Hardness in Wheat.

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