Late Maturity Α-amylase Research Articles

Genetic analysis of late-maturity α-amylase in twelve wheat populations

Main conclusionGenetic loci, particularly those with an effect in the independent panel, could be utilised to further reduce LMA expression when used with favourable combinations of genes known to affect LMA.Late maturity α-amylase (LMA) is a grain quality defect involving elevated α-amylase within the aleurone of wheat (Triticum aestivum L.) grains. The genes known to affect expression are the reduced height genes Rht-B1 (chromosome 4B) and Rht-D1 (chromosome 4D), and an ent-copalyl diphosphate synthase gene (LMA-1) on chromosome 7B. Other minor effect loci have been reported, but these are poorly characterised and further genetic understanding is needed. In this study, twelve F4-derived populations were created through single seed descent, genotyped and evaluated for LMA. LMA-1 haplotype C and the Rht-D1b allele substantially reduced LMA expression. The alternative dwarfing genes Rht13 and Rht18 had no significant effect on LMA expression. Additional quantitative trait loci (QTL) were mapped at 16 positions in the wheat genome. Effects on LMA expression were detected for four of these QTL in a large independent panel of Australian wheat lines. The QTL detected in mapping populations and confirmed in the large independent panel provide further opportunity for selection against LMA, especially if combined with Rht-D1b and/or favourable haplotypes of LMA-1.

Development of Novel Monoclonal Antibodies to Wheat Alpha-Amylases Associated with Grain Quality Problems That Are Increasing with Climate Change.

Accurate, rapid testing platforms are essential for early detection and mitigation of late maturity α-amylase (LMA) and preharvest sprouting (PHS) in wheat. These conditions are characterized by elevated α-amylase levels and negatively impact flour quality, resulting in substantial economic losses. The Hagberg-Perten Falling Number (FN) method is the industry standard for measuring α-amylase activity in wheatmeal. However, FN does not directly detect α-amylase and has major limitations. Developing α-amylase immunoassays would potentially enable early, accurate detection regardless of testing environment. With this goal, we assessed an expression of α-amylase isoforms during seed development. Transcripts of three of the four isoforms were detected in developing and mature grain. These were cloned and used to develop E. coli expression lines expressing single isoforms. After assessing amino acid conservation between isoforms, we identified peptide sequences specific to a single isoform (TaAMY1) or that were conserved in all isoforms, to develop monoclonal antibodies with targeted specificities. Three monoclonal antibodies were developed, anti-TaAMY1-A, anti-TaAMY1-B, and anti-TaAMY1-C. All three detected endogenous α-amylase(s). Anti-TaAMY1-A was specific for TaAMY1, whereas anti-TaAMY1-C detected TaAMY1, 2, and 4. Thus, confirming that they possessed the intended specificities. All three antibodies were shown to be compatible for use with immuno-pulldown and immuno-assay applications.

Multiple loci with cumulative effects on late maturity α-amylase (LMA) in wheat

Main conclusionThe cumulative action of combinations of alleles at several loci on the wheat genome is associated with different levels of resistance to late maturity α-amylase in bread wheat.Resistance to late maturity α-amylase (LMA) in bread wheat (Triticum aestivum L.) involves a complex interaction between the genotype and the environment. Unfortunately, the incidence and severity of LMA expression is difficult to predict and once the trait has been triggered an unacceptably low falling number, high grain α-amylase may be the inevitable consequence. Wheat varieties with different levels of resistance to LMA have been identified but whilst some genetic loci have been reported, the mechanisms involved in resistance and the interaction between resistance loci requires further research. This investigation was focused on mapping resistance loci in populations derived by inter-crossing resistant wheat varieties or crossing resistant lines with a very susceptible line and then mapping quantitative trait loci. In addition to the previously reported locus on chromosome 7B for which a candidate gene has been proposed, loci were mapped on chromosomes 1B, 2A, 2B, 3A, 3B, 4A, 6A and 7D. These loci have limited effects on their own but have a cumulative effect in combination with each other. Further research will be required to determine the nature of the causal genes at these loci, to develop diagnostic markers and determine how the genes fit into the pathway that leads to the induction of α-AMY1 transcription in the aleurone of developing wheat grains. Depending on the target environmental conditions, different combinations of alleles may be required to achieve a low risk of LMA expression.

End-use quality of wheat affected by late maturity α-amylase

Late maturity α-amylase (LMA) is associated with elevated α-amylase within the aleurone of wheat grains. The increased α-amylase contributes to a reduced falling number (FN). A reduction in FN also results from preharvest sprouting and frost during grain fill which are associated with poor baking quality. Low FN can also lead to downgrading of wheat at grain receival sites, reducing returns for wheat growers. A population created to investigate LMA expression was used to assess the impact of LMA on dough rheology, pan bread and yellow alkaline noodles. Elevated levels of α-amylase due to LMA were found to have a negative impact on dough development time, stability and mixing tolerance index. Elevated α-amylase also led to darker crust colour and increased loaf volume, however, the improvement in loaf volume was less than that produced by bread improver. The increased α-amylase content associated with LMA also reduced the brightness of cooked and uncooked yellow alkaline noodles and the strength of overcooked noodles. The detrimental effect of LMA on dough rheology and yellow alkaline noodles means that flours produced from LMA-affected grain have reduced utility in some important wheat markets.

Gibberellins in developing wheat grains and their relationship to late maturity α-amylase (LMA)

Main conclusionα-Amylase synthesis by wheat aleurone during grain development (late maturity α-amylase) appears to be independent of gibberellin unlike α-amylase synthesis by aleurone during germination or following treatment with exogenous GA.Late-maturity α-amylase (LMA) in wheat (Triticum aestivum L.) involves the synthesis of α-amylase by the aleurone tissue during grain development. Previous research identified a putative ent-copalyl diphosphate synthase gene, coding for an enzyme that controls the first step in gibberellin biosynthesis, that underlies the major genetic locus involved in variation in LMA phenotype. The reported results for gene transcript analysis, preliminary gibberellin analysis and the effects of DELLA mutants on LMA phenotype appeared to be consistent with involvement of gibberellin but did not provide definitive proof of a causal link. Conversely, several observations do not appear to be consistent with this hypothesis. In this current study, LMA phenotype, gibberellin profiles and ABA content were recorded for experiments involving susceptible and resistant genotypes, gibberellin biosynthesis inhibitors, genetic lines containing different LMA quantitative trait loci and treatment of distal halves of developing grains with exogenous gibberellin. The results suggested that gibberellin may not be a prerequisite for LMA expression and further that the mechanism involved in triggering α-amylase synthesis did not correspond to the model proposed for germination and gibberellin challenged aleurone of ripe grain. The results provide new insight into LMA and highlight the need to investigate alternate pathways for the induction of α-amylase gene transcription, the function of novel 1-β-OH gibberellins and other functions of DELLA proteins in developing grains.

A novel enzymatic method discriminating wheat pre-harvest sprouting from Late Maturity alpha-amylase

The primary quality assessor of wheat grain is the Hagberg Falling Number (FN) method. This is a viscometric test surrogate for α-amylase activity. Despite being used for over sixty years, FN has been increasingly scrutinised due to its low throughput, poor reproducibility and inability to differentiate between the causes of low FN including Pre-harvest Sprouting (PHS) and Late Maturity α-Amylase (LMA). Our study describes initial efforts to analyse a specific wheat flour set tailored for the identification of enzymatic candidates that would allow discrimination between PHS and LMA affected grains. Using the sensitive enzyme-coupled assay substrate R-AMGR3, results suggest that α-glucosidase (exo-α-glucosidase) is a potential enzyme marker candidate to specifically detect sprouted but not LMA-affected grain.

As the number falls, alternatives to the Hagberg-Perten falling number method: A review.

This review examines the application, limitations, and potential alternatives to the Hagberg-Perten falling number (FN) method used in the global wheat industry for detecting the risk of poor end-product quality mainly due to starch degradation by the enzyme α-amylase. By viscometry, the FN test indirectly detects the presence of α-amylase, the primary enzyme that digests starch. Elevated α-amylase results in low FN and damages wheat product quality resulting in cakes that fall, and sticky bread and noodles. Low FN can occur from preharvest sprouting (PHS) and late maturity α-amylase (LMA). Moist or rainy conditions before harvest cause PHS on the mother plant. Continuously cool or fluctuating temperatures during the grain filling stage cause LMA. Due to the expression of additional hydrolytic enzymes, PHS has a stronger negative impact than LMA. Wheat grain with low FN/high α-amylase results in serious losses for farmers, traders, millers, and bakers worldwide. Although blending of low FN grain with sound wheat may be used as a means of moving affected grain through the marketplace, care must be taken to avoid grain lots from falling below contract-specified FN. A large amount of sound wheat can be ruined if mixed with a small amount of sprouted wheat. The FN method is widely employed to detect α-amylase after harvest. However, it has several limitations, including sampling variability, high cost, labor intensiveness, the destructive nature of the test, and an inability to differentiate between LMA and PHS. Faster, cheaper, and more accurate alternatives could improve breeding for resistance to PHS and LMA and could preserve the value of wheat grain by avoiding inadvertent mixing of high- and low-FN grain by enabling testing at more stages of the value stream including at harvest, delivery, transport, storage, and milling. Alternatives to the FN method explored here include the Rapid Visco Analyzer, enzyme assays, immunoassays, near-infrared spectroscopy, and hyperspectral imaging.

Late-maturity α-amylase (LMA) testing and its methodological challenges

Wheats affected by late-maturity α-amylase (LMA) contain abnormal amounts of α-amylase with a high isoelectric point (pI), causing their flours to have low falling number (FN), a standard industry test. LMA-affected wheats are often rejected at grain receival points, as low FN is perceived as sign of poor quality. To improve LMA detection and increase screening throughput, an LMA-ELISA has been developed. The present study evaluated the analytical performance of LMA-ELISA and confirmed the correlation between LMA content and enzymatic activity. The LMA-ELISA test demonstrated good discrimination and high precision for intra- and inter-assay measurements. However, results were not reproducible when using three different LMA-ELISA batches acquired in two consecutive years, indicating that LMA-ELISA suffered from batch-to-batch variation. Consistent with previous studies, LMA-ELISA was highly correlated to total α-amylase activity (R = 0.95). LMA-affected flours also had enzymatic activity similar to enzyme-supplemented flours that have been shown to produce some end-products such as bread and noodles that are of satisfactory quality. These results highlight the need to address LMA-ELISA batch-to-batch variation.

Investigating conditions that induce late maturity alpha-amylase (LMA) using Northwestern US spring wheat (Triticum aestivum L.)

AbstractThe wheat industry rejects grain with unacceptably high α-amylase enzyme levels due to the risk of poor endproduct quality. There are two main causes of elevated grain α-amylase: (1) preharvest sprouting in response to rain before harvest and (2) late maturity α-amylase (LMA) induction in response to a cool temperature shock during late grain development. LMA induction was detected in a panel of 24 Northwestern US spring wheat lines. Thus, this problem previously described in Australian and U.K. varieties also exists in U.S. varieties. Because LMA induction results were highly variable using published methods, a characterization of LMA-inducing conditions was conducted in an LMA-susceptible soft white spring wheat line, WA8124. Problems with elevated α-amylase in untreated controls were reduced by raising the temperature, 25°C day/18°C night versus 20°C day/10°C night. LMA induction was not improved by colder temperatures (15°C day/4°C night) versus moderately cold temperatures (18°C day/7.5°C night or 10°C day/10°C night). While previous studies observed LMA induction by heat stress, it failed to induce LMA in WA8124. Thus, not all LMA-susceptible cultivars respond to heat. The timing of LMA susceptibility varied between two cultivars and within a single cultivar grown at slightly different temperatures. Thus, variability in LMA induction likely results from variability in the timing of the grain developmental stage during which cold shock induces LMA. Thus, it was concluded that the visual inspection of grain is needed to correctly identify LMA-sensitive spikes at the soft dough stage of grain development (Zadok's stage 85).

A Major Locus on Wheat Chromosome 7B Associated With Late-Maturity α-Amylase Encodes a Putative ent-Copalyl Diphosphate Synthase

Many wheat varieties have the potential to develop unacceptably high levels of α-amylase in the grains if exposed to a cool temperature shock or simply cool temperature during the early to middle stages of grain filling. This phenomenon is referred to as late maturity α-amylase (LMA). The enzyme persists in the grain until harvest and may result in wheat with a low Falling Number that does not meet receival and export specifications. Resistance to LMA is therefore a valuable target for wheat breeders and wheat industries in general. Genetic evidence implicating a locus on the long arm of chromosome 7B in variation in LMA phenotype was confirmed in this investigation. Through intensive fine-mapping an ent-copalyl diphosphate synthase (CPS), hitherto named LMA-1, was identified as the likely candidate gene associated with variation in LMA phenotype. Single Nucleotide Polymorphisms (SNPs) within the LMA-1 coding sequence of Chinese Spring, Maringa and Halberd result in either prematurely terminated or functionally altered proteins that are associated with useful levels of resistance to LMA. LMA-1 transcripts detected in de-embryonated grain tissue from around 15 days after anthesis, several days before the synthesis of α-amylase, were low in the resistant varieties Chinese Spring and Maringa compared with LMA susceptible genotype Spica. This was associated with a dramatic reduction in the concentrations of intermediates in the gibberellin biosynthesis pathway such as GA19, evidence that LMA-1 was functioning as CPS in the gibberellin biosynthesis pathway. A survey of a large collection of Australian and international wheat varieties distinguished 9 major haplotypes at the LMA-1 locus. Generally, within classes, there was notable variation for LMA phenotype and evidence for genotypes whose resistance is presumed to be due to genetic loci located elsewhere on the wheat genome. Further investigation is required to characterize the sequence of steps between LMA-1 and α-amylase synthesis as well as to gain a better understanding of the role and potential impact of other genetic loci. Diagnostic markers for sources of resistance and SNP variation reported in this study should assist breeders to deploy resistance associated with LMA-1 variants in breeding programs.

Late-Maturity Alpha-Amylase in Wheat (Triticum aestivum) and Its Impact on Fresh White Sauce Qualities.

When wheat experiences a cold-temperature ‘shock’ during the late stage of grain filling, it triggers the abnormal synthesis of late-maturity α-amylase (LMA). This increases the enzyme content in affected grain, which can lead to a drastic reduction in falling number (FN). By commercial standards, a low FN is taken as an indication of inferior quality, deemed unsuitable for end-product usage. Hence, LMA-affected grains are either rejected or downgraded to feed grade at the grain receiving point. However, previous studies have found no substantial correlation between low FN-LMA and bread quality. The present study extends previous investigations to semi-solid food, evaluating the physical quality of fresh white sauce processed from LMA-affected flour. Results show that high-LMA flours had low FNs and exhibited poor pasting characteristics. However, gelation occurred in the presence of other components during fresh white sauce processing. This demonstrates that LMA-affected flours may have new applications in low-viscosity products.

Application of the factor analytic model to assess wheat falling number performance and stability in multienvironment trials

AbstractA factor analytic model was used to characterize data generated with the Hagberg–Perten falling number (FN) method, a measure of wheat (Triticum aestivum L.) quality influenced by genotype‐by‐environment interactions. The FN method detects starch degradation due to the presence of the enzyme α‐amylase in wheat grain such that a low FN indicates high α‐amylase activity and high risk of poor end‐product quality. Because farmers receive severe discounts for low FN, FN data have been collected over multiple years for the Washington State University multilocation variety trials to help farmers and breeders identify lower risk varieties. Analysis of these data to objectively rank varieties is challenging because the dataset is unbalanced and because FN is subject to complex genotype‐by‐environment interactions. Low FN can result from environmental differences at multiple stages in grain development because there are two major causes of α‐amylase accumulation in grain, late‐maturity α‐amylase (LMA) and preharvest sprouting (PHS). A five‐factor analytic model extracted explicit measures of overall performance and of stability in variable environments from historical FN data from the multilocation trial, providing a basis for breeding and planting decisions. Whereas a linear model explained 70.3% of the variation, the five‐factor analytic model accounted for 92.5% of variation in the data. Examination of factor loadings enabled us to separate environments and genotype response to either PHS or LMA, specifically. This is the first application of a factor analytic model to evaluate the end‐use quality trait FN, providing a method to rank varieties for grower decisions and breeder selections.

Evaluation of the impact of heat on wheat dormancy, late maturity α-amylase and grain size under controlled conditions in diverse germplasm

In the Australian wheat belts, short episodes of high temperatures or hot spells during grain filling are becoming increasingly common and have an enormous impact on yield and quality, bringing multi-billion losses annually. This problem will become recurrent under the climate change scenario that forecast increasing extreme temperatures, but so far, no systematic analysis of the resistance to hot spells has yet been performed in a diverse genetic background. We developed a protocol to study the effects of heat on three important traits: grain size, grain dormancy and the presence of Late Maturity α-Amylase (LMA), and we validated it by analysing the phenotypes of 28 genetically diverse wheat landraces and exploring the potential variability existing in the responses to hot spells. Using controlled growth environments, the different genotypes were grown in our standard conditions until 20 days after anthesis, and then moved for 10 days into a heat chamber. Our study showed that our elevated temperature treatment during mid-late filling triggered multiple detrimental effects on yield and quality. We observed a reduction in grain size, a reduction in grain dormancy and increased LMA expression in most of the tested genotypes, but potential resistant lines were identified for each analyzed trait opening new perspectives for future genetic studies and breeding for heat-insensitive commercial lines.

Late-maturity α-amylase expression in wheat is influenced by genotype, temperature and stage of grain development.

Late-maturity α-amylase (LMA) expression in wheat grains can be induced by either a cool temperature shock close to physiological maturity or continuous cool maximum temperatures during grain development. Late-maturity α-amylase (LMA) is a genetic trait in wheat (Triticum aestivum L.) involving the production of α-amylase during grain development, which can result in an unacceptably low Falling Number (FN) in mature grain and consequent grain downgrading. Comparison of the FN test, an α-amylase activity assay and a high pI α-amylase-specific ELISA on the same meal samples gave equivalent results; ELISA was used for further experiments because of its isoform specificity. A cool temperature shock during the middle stages of grain development is known to induce LMA and is used for phenotypic screening. It was determined that a cool temperature treatment of seven days was required to reliably induce LMA. Glasshouse studies performed in summer and winter demonstrated that temperature affected the timing of sensitivity to cool-shock by altering the rate and duration of grain development, but that the sensitive grain developmental stage was unchanged at 35-45% moisture content. Wheat varieties with Rht-B1b or Rht-D1b dwarfing genes responded to a cool-shock only from mid grain filling until physiological maturity, whilst genotypes with Rht8c or without a dwarfing gene expressed LMA in response to a cool-shock during a wider developmental range. A continuous cool maximum temperature regimen (23°C/15°Cday/night) during grain development also resulted in LMA expression and showed a stronger association with field expression than the cool-shock treatment. These results clarify how genotype, temperature and grain developmental stage determine LMA expression, and allow for the improvement of LMA phenotypic screening methods.

Does Late Maturity Alpha-Amylase Impact Wheat Baking Quality?

Late maturity α-amylase (LMA) and pre-harvest sprouting (PHS) are both recognized as environmentally induced grain quality defects resulting from abnormally high levels of α-amylase. LMA is a more recently identified quality issue that is now receiving increasing attention worldwide and whose prevalence is now seen as impeding the development of superior quality wheat varieties. LMA is a genetic defect present in specific wheat genotypes and is characterized by elevated levels of the high pI TaAMY1 α-amylase, triggered by environmental stress during wheat grain development. TaAMY1 remains present in the aleurone through the harvest, lowering Falling Number (FN) at receival, causing a down-grading of the grain, often to feed grade, thus reducing the farmers’ income. This downgrading is based on the assumption within the grain industry that, as for PHS, a low FN represents poor quality grain. Consequently any wheat line possessing low FN or high α-amylase levels is automatically considered a poor bread wheat despite there being no published evidence to date, to show that LMA is detrimental to end product quality. To evaluate the validity of this assumption a comprehensive evaluation of baking properties was performed from LMA prone lines using a subset of tall non-Rht lines from a multi-parent advanced generation inter-cross (MAGIC) wheat population grown at three different sites. LMA levels were determined along with quality parameters including end product functionality such as oven spring, bread loaf volume and weight, slice area and brightness, gas cell number and crumb firmness. No consistent or significant phenotypic correlation was found between LMA related FN and any of the quality traits. This manuscript provides for the first time, compelling evidence that LMA has limited impact on bread baking end product functionality.

Evaluation of commercial α‐amylase enzyme‐linked immunosorbent assay (ELISA) test kits for wheat

Background and objectivesThere are few methods in wheat to directly measure α‐amylase, which is the result of preharvest sprouting (PHS) and late maturity α‐amylase (LMA). Both of these conditions are associated with reduced wheat and flour quality. Those methods that do exist for measuring α‐amylase in wheat are based on enzyme activity. The objective of this study was to evaluate commercially available enzyme‐linked immunosorbent assay (ELISA) kits on sound grain, sprouted grain, and grain that had both PHS and LMA.FindingsThree kits were evaluated; human AMY1 and AMY2, and a “plant α‐amylase” kit. The wheat samples were also assayed for α‐amylase activity using the Megazyme SD α‐amylase method. All three ELISA kits functioned very well based on calibration curves (R2 > .99). Of the three, the AMY1 and plant α‐amylase kits appeared to show no useful detection of wheat α‐amylase. The AMY2 kit, however, detected a 2.7‐fold increase in α‐amylase protein in the PHS and PHS/LMA grain lots, similar to a 2.7‐fold difference in activity.ConclusionsIt appears that the particular human AMY2A ELISA kit, and perhaps others, can detect α‐amylase in wheat and may be a useful alternative technology to enzyme kits. These kits may also be useful in predicting PHS and LMA potential damage.Significance and noveltyThus far, α‐amylase studies have focused on enzyme kits, whereas this study examined three commercially available ELISA kits to measure α‐amylase content in sound, sprouted, and PHS/LMA grain. Both PHS and LMA are highly detrimental to grain and result in low prices paid to growers.

QTL analysis of falling number and seed longevity in wheat (Triticum aestivum L.).

Pre-harvest sprouting (PHS) and seed longevity (SL) are complex biological processes of major importance for agricultural production. In the present study, a recombinant inbred line (RIL) population derived from a cross between the German winter wheat (Triticum aestivum L.) cultivars History and Rubens was used to identify genetic factors controlling these two physiological seed traits. A falling number (FN) test was employed to evaluate PHS, while SL was measured using a germination test (and the speed of germination) after controlled deterioration. FN of the population was assessed in four environments; SL traits were measured in one environment. Four major quantitative trait loci (QTL) for FN were detected on chromosomes 4D, 5A, 5D, and 7B, whereas for SL traits, a major QTL was found on chromosome 1A. The FN QTL on chromosome 4D that coincided with the position of the dwarfing gene Rht-D1b only had effects in environments that were free of PHS. The remaining three QTL for FN were mostly pronounced under conditions conducive to PHS. The QTL on the long arm of chromosome 7B corresponded to the major gene locus controlling late maturity α-amylase (LMA) in wheat. The severity of the LMA phenotype became truly apparent under sprouting conditions. The position on the long arm of chromosome 1A of the QTL for SL points to a new QTL for this important regenerative seed trait.

A biotechnological approach to directly assess the impact of elevated endogenous α‐amylase on Asian white‐salted noodle quality

Flours from engineered wheat grain overexpressing a single α‐amylase type 3 (TaAMY3) were compared to flour from germinated grains to study the impact of elevated levels of α‐amylase on small‐scale noodle quality. The results showed that α‐amylase alone significantly reduced cooking time and increased cooking loss but had no detrimental effect on flour color, noodle color, or firmness. Noodles produced from sprouted grains were significantly detrimentally affected for all the above quality characteristics, in particularly after 24 and 48 h imbibition. A strong correlation was observed between the decrease in unextractable polymeric protein (UPP) levels, and noodle firmness. These findings raise important questions as to the supposition that α‐amylase is the source of the adverse effects of pre‐harvest sprouting (PHS) and late maturity α‐amylase (LMA) on Asian white‐salted noodles and highlights the usefulness of applying biotechnology in elucidating how flour components affect end product quality.

Genetic analyses using GGE model and a mixed linear model approach, and stability analyses using AMMI bi-plot for late-maturity alpha-amylase activity in bread wheat genotypes.

Low falling number and discounting grain when it is downgraded in class are the consequences of excessive late-maturity α-amylase activity (LMAA) in bread wheat (Triticum aestivum L.). Grain expressing high LMAA produces poorer quality bread products. To effectively breed for low LMAA, it is necessary to understand what genes control it and how they are expressed, particularly when genotypes are grown in different environments. In this study, an International Collection (IC) of 18 spring wheat genotypes and another set of 15 spring wheat cultivars adapted to South Dakota (SD), USA were assessed to characterize the genetic component of LMAA over 5 and 13 environments, respectively. The data were analysed using a GGE model with a mixed linear model approach and stability analysis was presented using an AMMI bi-plot on R software. All estimated variance components and their proportions to the total phenotypic variance were highly significant for both sets of genotypes, which were validated by the AMMI model analysis. Broad-sense heritability for LMAA was higher in SD adapted cultivars (53%) compared to that in IC (49%). Significant genetic effects and stability analyses showed some genotypes, e.g. 'Lancer', 'Chester' and 'LoSprout' from IC, and 'Alsen', 'Traverse' and 'Forefront' from SD cultivars could be used as parents to develop new cultivars expressing low levels of LMAA. Stability analysis using an AMMI bi-plot revealed that 'Chester', 'Lancer' and 'Advance' were the most stable across environments, while in contrast, 'Kinsman', 'Lerma52' and 'Traverse' exhibited the lowest stability for LMAA across environments.

New insight in cereal starch degradation: identification and structural characterization of four α-amylases in bread wheat

AbstractGrain α-amylase presents an apparent paradox for the wheat community. Despite the necessity of α-amylase for the seed germination process, high levels of amylase activity in the grain are considered detrimental for grain quality. Wheat α-amylases (EC 3.2.1.1) are endohydrolases belonging to the GH13_6 subfamily, one of the most studied subclasses of glycoside hydrolase (GH) family GH13. However, no comprehensive study had been done so far to describe and catalogue all the wheat α-amylase isoforms, despite compelling information on the involvement of two α-amylases on economically important issues for the international cereal community, namely pre-harvest sprouting and late maturity α-amylase. This study describes for the first time the genomic localization, nucleotide and amino acid sequences, phylogeny and expression profile of all known α-amylases in wheat, including a hitherto unknown fourth isoform here designated as TaAMY4. Isoform profiling strongly suggested α-amylases to be working in partnership to achieve complete degradation of a starch granule, whereas expression profiling revealed a potential involvement of TaAMY4 in the late maturity α-amylase problem.