Maria Matus-Cádiz

Comparative expression of Cbf genes in the Triticeae under different acclimation induction temperatures

In plants, the C-repeat binding factors (Cbfs) are believed to regulate low-temperature (LT) tolerance. However, most functional studies of Cbfs have focused on characterizing expression after an LT shock and have not quantified differences associated with variable temperature induction or the rate of response to LT treatment. In the Triticeae, rye (Secale cereale L.) is one of the most LT-tolerant species, and is an excellent model to study and compare Cbf LT induction and expression profiles. Here, we report the isolation of rye Cbf genes (ScCbfs) and compare their expression levels in spring- and winter-habit rye cultivars and their orthologs in two winter-habit wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) cultivars. Eleven ScCbfs were isolated spanning all four major phylogenetic groups. Nine of the ScCbfs mapped to 5RL and one to chromosome 2R. Cbf expression levels were variable, with stronger expression in winter- versus spring-habit rye cultivars but no clear relationship with cultivar differences in LT, down-stream cold-regulated gene expression and Cbf expression were detected. Some Cbfs were expressed only at warmer acclimation temperatures in all three species and their expression was repressed at the end of an 8-h dark period at warmer temperatures, which may reflect a temperature-dependent, light-regulated diurnal response. Our work indicates that Cbf expression is regulated by complex genotype by time by induction–temperature interactions, emphasizing that sample timing, induction–temperature and light-related factors must receive greater consideration in future studies involving functional characterization of LT-induced genes in cereals.

Phenolic Compounds Contribute to Dark Bran Pigmentation in Hard White Wheat

Unacceptably dark bran color has prevented the white-kernelled variety Argent from meeting grain color marketing standards for hard white wheats (Triticum aestivum L.). The objective of this research was to identify phenolic compounds that negatively affect bran color in white wheat using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and vanillin-HCl and NaOH staining methods. In mature bran, FT-ICR-MS detected derivatives of the flavonol quercetin in varieties Argent and RL4137 (red-kernelled wheat) but not in W98616, a white wheat variety with acceptable grain color. Derivatives of the isoflavone formononetin were more abundant in W98616 relative to RL4137 and Argent. Vanillin-HCl staining indicated that RL4137 sequestered high levels of proanthocyanidin (PA) throughout its entire seed coat, whereas white wheats sequestered PAs as discrete speckles. Argent possessed abundant speckles over its entire seed coat, whereas speckles were almost undetectable in W98616. In mature kernels, flavonoids throughout the seed coat of RL4137 reacted with NaOH, but only the speckles appeared to react in white wheats. W98616 consistently had lighter grain than Argent before and after NaOH treatment. Free and bound phenolic differences in bran samples confirmed that the darker seed coat color of Argent, relative to W98616, was likely due to higher total phenolic acid content. Although isoflavones accumulated in Argent and RL4137, it appears that the majority of the flux through the flavonoid pathway ultimately accumulates quercetin derivatives and PAs. In W98616, PAs accumulate, but it appears that flavonoid biosynthesis ultimately accumulates isoflavones. Argent, compared to W98616, generally accumulated higher levels of total phenolics (flavonols, stilbenes, and PAs) within its darker pigmented bran.

W98616, a white-seeded spring wheat with increased preharvest sprouting

White-seeded spring wheat germplasm line W98616 was selected for improved levels of preharvest sprouting resistance. W98616 has levels of seed dormancy comparable to Columbus, a red-seeded sprouting-resistant cultivar. W98616 has similar test weight, kernel weight, maturity, plant height, grain protein, and kernel hardness, but is lower yielding and 2 d later heading relative to BW264, a hard white wheat cultivar. Key words: Triticum aestivum L., germplasm, white spring wheat, preharvest sprouting resistance

CDC EMDR-4, CDC EMDR-9, and CDC EMDR-14 spring wheats

Early-maturing spring wheat germplasm lines CDC EMDR-4, CDC EMDR-9, and CDC EMDR-14 have high levels of seed dormancy. Their agronomic performance is comparable to that of the cultivar Columbus. These three lines had similar grain protein concentration and kernel hardness relative to the check cultivars, except CDC EMDR-4, which had a soft endosperm texture. Key words: Triticum aestivum L., germplasm, seed dormancy, pre-harvest sprouting resistance

Comparison of Different Methods for Phenotyping Preharvest Sprouting in White-Grained Wheat

ABSTRACT The objective of this study was to identify a suitable method for phenotyping preharvest sprouting (PHS) resistance in white bread wheat. Forty doubled-haploid (DH) lines derived from a cross between two white-grained spring wheats (Triticum aestivum L.) cultivar Argent (nondormant) and wheat breeding line W98616 (dormant) were evaluated for germination frequency, Falling Number (FN), and α-amylase activity in dry and water-imbibed seeds and spikes. The α-amylase activity in dry seeds or spikes did not differ significantly between parent lines or lines of the DH population. Wetting of seeds or spikes for two days caused a five- to sevenfold increase in α-amylase activity but only in Argent and the nondormant subgroup (49–100% germination) of the DH lines. A positive association (r = 0.60***) was detected between germination frequency and α-amylase activity in imbibed seeds and spikes. Germination frequency could not be correlated to FN or α-amylase activity in dry-harvested seeds. FN showed a str...

Morphological variation within and among five annual Phalaris species

Accessions of annual canarygrass (Phalaris canariensis L.; 2n = 2x = 12) held within germplasm collections generally lack adequate genetic characterization for utilization in crop improvement. The objective of this study was to assess the level of morphological variation of accessions of five annual Phalaris species, including 49 annual canarygrass, 48 P. minor Retz. (2n = 4x = 28), 24 P. brachystachys (2n = 2x = 12), 19 P. paradoxa L. (2n = 2x = 14), and three P. angusta Nees ex Tris. (2n = 2x = 14). In 1993 and 1994, accessions were grown under growth chamber and greenhouse conditions, respectively. Eighteen morphological traits were measured on five plants per accession. Phalaris canariensis had intermediate culm height, wider penultimate leaves, shorter and wider panicles, and larger caryopses relative to the other four species. The six qualitative traits were monomorphic in all five species, except for glume pubescence in P. brachystachysand inflorescence type in P. paradoxa. The limited variation wi...

Puroindoline allele diversity in Canadian and northern US hard spring wheat varieties differing in kernel hardness

Kernel hardness, one of the most important factors in determining the end-use suitability of wheat (Triticum aestivum L.), is largely influenced by puroindoline proteins a (PINA) and b (PINB). Soft texture is wildtype (Pina-D1a/Pinb-D1a) with hard texture being determined by either Pina-D1 gene deletion or point mutations in Pinb-D1a. The objectives of this study were to determine kernel hardness indices (HI) and Pina-D1/Pinb-D1 allelic diversity in a diverse set of 81 Canadian (representing eight wheat classes) and 49 US hard spring wheat varieties. Varieties were grouped into two experimental sets grown in replicated trials in 2004–2006 at Saskatoon, SK. Variation existed among varieties with HI means ranging from 21.7 (CDC Zorba) to 72.7 (AC Morse) in exp. 1 and from 25.0 (HY320) to 66.1 (Norlander) in exp. 2. Only AC Andrew, CDC Zorba, and Red Fife were soft kernel textured and carried the wildtype Pina-D1a/Pinb-D1a alleles. The majority of Canadian varieties were Pina-D1a/Pinb-D1b (69%), while a grea...

Multiplexed PCR to screen for a major QTL carrying fusarium head blight resistance in Sumai-3 wheat

After the initial identification of microsatellites linked to economically important traits of interest, the additional investment to simplify the screening procedure for more routine use is of interest to plant breeders. The objective was to simplify an acrylamide gel based marker-assisted selection (MAS) method to facilitate high-through put screening for Qfhs.ndsu-3BS, a major quantitative trait locus carrying fusarium head blight (FHB) resistance in Sumai-3 wheat (Triticum aestivum L.). Method simplifications included incorporating the use of (1) 96-well DNA extractions, (2) multiplexed PCR reactions using microsatellite primers gwm493 and gwm533, and (3) agarose gels. Our modified FHB-MAS method was verified by screening six resistant (Sumai-3, ND2710, McVey, BacUp, HY644, and Alsen) and 52 susceptible parents and subsequently used to screen 5567 common wheat breeding lines developed from Sumai-3 derivatives. This simple and rapid method allows for the screening of 1000 lines per week, which can be u...

Line 211 spring wheat

Red-seeded spring wheat germplasm line 211 has high levels of seed dormancy. Its agronomic performance is comparable to that of the cultivars Katepwa and AC Domain. Line 211 has a heavier kernel with soft endosperm texture. Key words: Triticum aestivum L., germplasm, seed dormancy, pre-harvest sprouting resistance