Concentration and localization of zinc during seed development and germination in wheat

Abstract

In a field experiment, the effect of foliar Zn applications on the concentration of Zn in seeds of a bread wheat cultivar (Triticum aestivum L. cv. Balatilla) was studied during different stages of seed development. In addition, a staining method using dithizone (DTZ: diphenyl thiocarbazone) was applied to (1) study the localization of Zn in seeds, (2) follow the remobilization of Zn during germination, and (3) develop a rapid visual Zn screening method for seed and flour samples. In all seed development stages, foliar Zn treatments were effective in increasing seed Zn concentration. The highest Zn concentration in the seeds was found in the first stage of seed development (around the early milk stage); after this, seed Zn concentration gradually decreased until maturity. When reacting with Zn, DTZ forms a red-colored complex. The DTZ staining of seed samples revealed that Zn is predominantly located in the embryo and aleurone parts of the seeds. After 36 h of germination, the coleoptile and roots that emerged from seeds showed very intensive red color formation and had Zn concentrations up to 200 mg kg ÿ1 , indicating a substantial remobilization of Zn from seed pools into the developing roots (radicle) and coleoptile. The DTZ staining method seems to be useful in ranking flour samples for their Zn concentrations. There was a close relationship between the seed Zn concentrations and spectral absorbance of the methanol extracts of the flour samples stained with DTZ. The results suggest that (1) accumulation of Zn in seeds is particularly high during early seed development, (2) Zn is concentrated in the embryo and aleurone parts, and (3) the DTZ staining method can be used as a rapid, semiquantitative method to estimate Zn concentrations of flour and seed samples and to screen genotypes for their Zn concentrations in seeds.

Speciation and Localization of Arsenic in White and Brown Rice Grains

“…Also, a number of microprobe studies on element location in grain, including rice (17,18), and other members of the Poaceae grain utilized for food (19)(20)(21) have shown strong localization of cations in the aleurone, with most studies focusing on Zn. These studies also observed similar localization in the germ of Zn and other cations.…”

Effect of different foliar zinc application at different growth stages on seed zinc concentration and its impact on seedling vigor in rice

“…The present results together with those of Phattarakul et al (2012) suggest that promoting the Zn content in vegetative tissues by foliar Zn application results in Zn being available for re-translocation into seeds. One of the reasons for the stimulated transport of Zn into seeds after the flowering stage might be related to significant increases in protein biosynthesis during the early stage of seed formation (Martre et al 2003;Ozturk et al 2006). As discussed by Cakmak et al (2010b), increasing seed protein concentrations creates a sink for Zn, and there is a close positive correlation between seed protein and Zn concentrations.…”

“…One of these factors is the time of foliar Zn application. In the case of wheat it was shown that the highest Zn concentration in seed was achieved when foliar Zn was applied after the flowering stage (Zadok's scale 7; Zadok et al 1974) compared to the applications realized before the flowering stage (Ozturk et al 2006;Cakmak et al 2010a).…”

Nutritionally Enhanced Staple Food Crops

“…Barley endosperm and aleurone in contrast, together contain $70% of the total Fe, but only 7%-8% in the embryo (Duffus and Rosie 1976). Zinc in wheat is predominantly located in the embryo and aleurone parts of the seed (Ozturk et al 2006). The Zn concentration in seeds is particularly high during early seed development (i.e., at milking stage); thereafter, its concentration gradually declines until maturity.…”

“…The Zn concentration in seeds is particularly high during early seed development (i.e., at milking stage); thereafter, its concentration gradually declines until maturity. Using ear culture system (Singh and Jenner 1983;Sharma et al 1995), the stable zinc isotope 70 Zn, and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) technique, Wang et al (2011) detected preferential localization of Zn in the aleurone and embryo, as also observed by Ozturk et al (2006), but found a gradient of 70 Zn concentration between crease vascular tissue, aleurone layer, and endosperm, demonstrating that Zn is distributed within the seed through the crease phloem. This suggests that two barriers of Zn transport into wheat seeds may exist: between the stem tissue rachis and the seed, and between the maternal and filial tissues in the seed.…”