Dormancy in white-grained wheat: Mechanisms and genetic control

Dissertação de Mestrado em Ecologia, apresentada ao Departamento de Ciências da Vida da Faculdade de Ciências e Tecnologia da Universidade de Coimbra

Notes for genera: basal clades of Fungi (including Aphelidiomycota, Basidiobolomycota, Blastocladiomycota, Calcarisporiellomycota, Caulochytriomycota, Chytridiomycota, Entomophthoromycota, Glomeromycota, Kickxellomycota, Monoblepharomycota, Mortierellomycota, Mucoromycota, Neocallimastigomycota, Olpidiomycota, Rozellomycota and Zoopagomycota)

Compared to the higher fungi (Dikarya), taxonomic and evolutionary studies on the basal clades of fungi are fewer in number. Thus, the generic boundaries and higher ranks in the basal clades of fungi are poorly known. Recent DNA based taxonomic studies have provided reliable and accurate information. It is therefore necessary to compile all available information since basal clades genera lack updated checklists or outlines. Recently, Tedersoo et al. (MycoKeys 13:1--20, 2016) accepted Aphelidiomycota and Rozellomycota in Fungal clade. Thus, we regard both these phyla as members in Kingdom Fungi. We accept 16 phyla in basal clades viz. Aphelidiomycota, Basidiobolomycota, Blastocladiomycota, Calcarisporiellomycota, Caulochytriomycota, Chytridiomycota, Entomophthoromycota, Glomeromycota, Kickxellomycota, Monoblepharomycota, Mortierellomycota, Mucoromycota, Neocallimastigomycota, Olpidiomycota, Rozellomycota and Zoopagomycota. Thus, 611 genera in 153 families, 43 orders and 18 classes are provided with details of classification, synonyms, life modes, distribution, recent literature and genomic data. Moreover, Catenariaceae Couch is proposed to be conserved, Cladochytriales Mozl.-Standr. is emended and the family Nephridiophagaceae is introduced

Wheat grain preharvest sprouting and late maturity alpha-amylase

Preharvest sprouting (PHS) and late maturity α-amylase (LMA) are the two major causes of unacceptably high levels of α-amylase in ripe wheat grain. High α-amylase activity in harvested grain results in substantially lower prices for wheat growers and at least in the case of PHS, is associated with adverse effects on the quality of a range of end-products and loss of viability during storage. The high levels of α-amylase are reflected in low falling number, the internationally accepted measure for grain receival and trade. Given the significant losses that can occur, elimination of these defects remains a major focus for wheat breeding programs in many parts of the world. In addition, the genetic, biochemical and molecular mechanisms involved in the control of PHS and LMA as well as the interactions with environmental factors have attracted a sustained research interest. PHS and LMA are independent, genetically controlled traits that are strongly influenced by the environment, where the effects of particular environmental factors vary substantially depending on the stage of grain development and ripening. This review is a summary and an assessment of results of recent research on these important grain quality defects.Daryl J. Mares, Kolumbina Mrv

Quantitative trait locus analysis of late maturity alpha-amylase in wheat using the doubled haploid population Cranbrook x Halberd

Mapping of the late maturity α-amylase (LMA) gene using quantitative trait locus (QTL) analysis represents an important step in identification of potential molecular markers that would greatly improve efficiency and accuracy of screening for LMA. QTL controlling the expression of LMA in wheat were detected in a doubled haploid (DH) cross/population derived from wheat (Triticum aestivum L. em. Thell) cultivars Cranbrook (LMA source) and Halberd (non-LMA). The DH population and parents were sown in replicated trials at Narrabri with sowing times differing by 2 weeks. Cool temperature treatment of detached tillers was used to induce expression of LMA in lines carrying the defect. The number of grains in ripe, treated tillers that contained high pI (malt, germination type) α-amylase isozymes was measured using an ELISA antibody kit highly specific for high pI isozymes. QTL analyses were conducted separately for each sowing, but results from both sowings were consistent and indicated that there was a highly significant (P < 0.001) QTL on the long arm of chromosome 7B (accounting for 31% of the variation in the first experiment), with Cranbrook contributing the higher value allele. A second QTL that accounted for 13% of the variation was found close to the centromere on chromosome 3B. Although it was less important than the QTL on 7B it was nevertheless still significant (P < 0.05).K. Mrva and D. J. Mare

Screening methods and identification of QTLs associated with late maturity alpha-amylase in wheat

The original publication can be found at www.springerlink.comThe synthesis of high levels of germination-type (high pI isozymes) α-amylase was induced in wheat genotypes prone to late maturity α-amylase (LMA) following the exposure of detached tillers to cool temperature during grain development. The detached tiller method was successfully applied to a range of genotypes and to a doubled haploid (DH) population derived from the cross Cranbrook (LMA genotype) x Halberd (low amylase). The number of grains in ripe, treated tillers that contained high pI α-amylase isozymes was measured using an ELISA antibody kit highly specific for high pI isozymes. Quantitative trait loci (QTL) controlling the expression of LMA in wheat were detected in DH population Cranbrook x Halberd. The DH population and parents were sown in 2 replicated sowings at the same location with sowing times differing by 2 weeks. QTL analyses were conducted separately for each sowing, but results from both sowings were consistent and indicated a highly significant (p<0.01) QTL on the long arm of chromosome 7B, with Cranbrook contributing the higher value allele. A second QTL with less significant effect was found on the long arm of chromosome 3B, on the basis of data from the first sowing.Kolumbina Mrva and Daryl Mare

Induction of late maturity alpha-amylase in wheat by cool temperature

Wheat genotypes prone to late maturity α-amylase (LMA) produced high levels of germination-type (high pI isozymes) α-amylase following exposure to cool temperature during grain development. Plants grown in the glasshouse, plants grown in the field and transplanted to the glasshouse after flowering, and tillers taken from field or glasshouse grown plants all responded in a similar manner. Plants or detached tillers can therefore be used in screening tests to identify germplasm with the LMA genotype. The cool temperature treatment was effective when applied continuously from shortly after flowering until near-ripeness, or when limited to the phase of grain development (26–35 days after anthesis) in LMA-prone genotypes that appears to be most sensitive to cool temperature. Based on these observations, guidelines for screening wheat germplasm are proposed and the advantages of using detached tillers discussed. The detached tiller method was successfully applied to a range of genotypes, some of which were known to be prone to LMA, and to a doubled haploid population derived from the cross Janz (low amylase) BD159 (LMA genotype). The preliminary data from this population were consistent with control by a single gene and similar therefore to the model proposed previously for cv. Spica