Dataset Information

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

ABSTRACT: Many wheat varieties have the potential to develop unacceptably high levels of ?-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 ?-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 ?-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 ?-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.

SUBMITTER: Derkx A

PROVIDER: S-EPMC7952997 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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

Derkx Adinda A Baumann Ute U Cheong Judy J Mrva Kolumbina K Sharma Niharika N Pallotta Margaret M Mares Daryl D

Frontiers in plant science 20210226

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 bre ...[more]

PMID: 33719315

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Project description:Salinity stress impairs plant growth and causes crops to yield losses worldwide. Reduction of in vivo gibberellin acid (GA) level is known to repress plant size but is beneficial to plant salt tolerance. However, the mechanisms of in vivo GA deficiency-enhanced salt tolerance in maize are still ambiguous. In this study, we generated two independent maize knockout mutant lines of ent-copalyl diphosphate synthase (one of the key enzymes for early steps of GA biosynthesis), zmcps-1 and zmcps-7, to explore the role of GA in maize salt tolerance. The typical dwarf phenotype with lower GA content and delayed leaf senescence under salinity was observed in the mutant plants. The leaf water potential and cell turgor potential were significantly higher in zmcps-1 and zmcps-7 than in the wild type (WT) under salt stress. The mutant plants exhibited a lower superoxide anion production rate in leaves and also a downregulated relative expression level of NAPDH oxidase ZmRbohA-C than the WT maize under salt stress. Also, the mutant plants had higher enzymatic activities of superoxide dismutase (SOD) and catalase (CAT) and higher content of soluble sugars and proline under salt stress. The Na+/K+ ratio was not significantly different between the mutant maize plants and WT plants under salt stress conditions, but the Na+ and K+ content was increased in zmcps-1 and zmcps-7 leaves and shoots. Na+ fluorescent dye staining showed that the mutant leaves have significantly higher vacuolar Na+ intensity than the WT maize. The expression level of vacuolar Na+/H+ exchanger gene ZmNHX1 and vacuolar proton pump genes ZmVP1-1 and ZmVP2 were upregulated in the zmcps-1 and zmcps-7 plants under salinity, further proving that in vivo GA deficiency enhanced vacuolar Na+ sequestration in zmcps-1 and zmcps-7 leaves cells to avoid Na+ cytotoxicity. Together, our results suggested that maintaining ROS homeostasis and enhancing vacuolar Na+ sequestration could be involved in GA deficiency-improved maize salt tolerance.

Dataset Information

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

Publications

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

Similar Datasets

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