Regulation of Zn and Fe transporters by the GPC1gene during early wheat monocarpic senescence

Abstract

BackgroundDuring wheat senescence, leaf components are degraded in a coordinated manner, releasing amino acids and micronutrients which are subsequently transported to the developing grain. We have previously shown that the simultaneous downregulation of Grain Protein Content (GPC) transcription factors, GPC1 and GPC2, greatly delays senescence and disrupts nutrient remobilization, and therefore provide a valuable entry point to identify genes involved in micronutrient transport to the wheat grain.ResultsWe generated loss-of-function mutations for GPC1 and GPC2 in tetraploid wheat and showed in field trials that gpc1 mutants exhibit significant delays in senescence and reductions in grain Zn and Fe content, but that mutations in GPC2 had no significant effect on these traits. An RNA-seq study of these mutants at different time points showed a larger proportion of senescence-regulated genes among the GPC1 (64%) than among the GPC2 (37%) regulated genes. Combined, the two GPC genes regulate a subset (21.2%) of the senescence-regulated genes, 76.1% of which are upregulated at 12 days after anthesis, before the appearance of any visible signs of senescence. Taken together, these results demonstrate that GPC1 is a key regulator of nutrient remobilization which acts predominantly during the early stages of senescence. Genes upregulated at this stage include transporters from the ZIP and YSL gene families, which facilitate Zn and Fe export from the cytoplasm to the phloem, and genes involved in the biosynthesis of chelators that facilitate the phloem-based transport of these nutrients to the grains.ConclusionsThis study provides an overview of the transport mechanisms activated in the wheat flag leaf during monocarpic senescence. It also identifies promising targets to improve nutrient remobilization to the wheat grain, which can help mitigate Zn and Fe deficiencies that afflict many regions of the developing world.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0368-2) contains supplementary material, which is available to authorized users.

Characterizing barley seed macro- and micro-nutrients under multiple environmental conditions

“…The leaf senescence and N remobilization have been clearly demonstrated in GPC domain lines (Parrott et al 2011). Even the Zn and Fe amounts had been reported to be associated with GPC1 gene in wheat (Pearce et al 2014), but the Fe enhancement by effect of the GPC locus had not been previously reported for barley seeds. The ions transform of Zn and Fe in phloem in is still not clearly understood, but the GPC-B1 gene has been assumed to encode transporters or chelators for their mobilizations into seeds (Distelfeld et al 2007).…”

Induced Homoeologous Pairing for Transfer of Useful Variability for High Grain Fe and Zn from Aegilops kotschyi into Wheat

“…Several genes responsible for iron and zinc transport have been mapped on group 2 chromosomes of wheat. These genes encode for transporters of the ferric chelate reductase (FRO) family, vacuolar iron transporters (VIT) family, Yellow Stripe-Like (YSL) and ZRT, IRT-like (ZIP) transporters family, and phytosiderophore transporter proteins of the nicotianamine synthase (NAS) family (Pearce et al 2014). Similarly, Fe and Zn uptake transporters have also been localized on group 7 chromosomes including heavy-metal ATPase (HMA) transporters family, vacuolar transporter of natural resistance-associated macrophage protein (NRAMP) family, and ZIP family transporters (Borrill et al 2014;Pearce et al 2014).…”

“…These genes encode for transporters of the ferric chelate reductase (FRO) family, vacuolar iron transporters (VIT) family, Yellow Stripe-Like (YSL) and ZRT, IRT-like (ZIP) transporters family, and phytosiderophore transporter proteins of the nicotianamine synthase (NAS) family (Pearce et al 2014). Similarly, Fe and Zn uptake transporters have also been localized on group 7 chromosomes including heavy-metal ATPase (HMA) transporters family, vacuolar transporter of natural resistance-associated macrophage protein (NRAMP) family, and ZIP family transporters (Borrill et al 2014;Pearce et al 2014). Due to the importance of groups 2 and 7 chromosomes in iron and zinc uptake and transport, in this study, BC 2 F 1 plants were further analyzed for introgression of groups 2 and 7 chromosomes of S k /U k genomes into wheat background through transferable and polymorphic SSR markers.…”

New genetic resources in wheat breeding for an increased grain protein content

“…Они имеются и у твердой пшеницы (Distelfeld et al, 2012). На уровне ДНК сходство между генами Gpc-1 и Gpc-2 составляет 91 %, что указывает на относительно недавнюю дупли-кацию Gpc-2 Pearce et al, 2014).…”

“…Для выяснения функции каждого из генов Gpc семена мягкой пшеницы сорта Express и твердой пшеницы Kronos были обработаны раствором 1 % этилметансульфоната, и с помощью метода Targeting Induced Local Lesions IN Genomes (TILLING) отобраны мутации, приводящие к об-разованию нефункционального белка Pearce et al, 2014). У мягкой пшеницы их носителями ста-ли одиночные мутанты gpc-A1 и gpc-D1, а также двойной мутант gpc-A1/gpc-D1, у твердой пшеницы -одиночные мутанты gpc-A1 и gpc-B2 и двойной -gpc-A1/gpc-B2, у них было блокировано действие соответствующих генов.…”