RESUMEN
The annual Zea mays ssp. mexicana L., a member of the teosinte group, is a close wild relative of maize and thus can be effectively used in maize improvement. In this study, an ICE-like gene, ZmmICE1, was isolated from a cDNA library of RNA-Seq from cold-treated seedling tissues of Zea mays ssp. mexicana L. The deduced protein of ZmmICE1 contains a highly conserved basic helix-loop-helix (bHLH) domain and C-terminal region of ICE-like proteins. The ZmmICE1 protein localizes to the nucleus and shows sumoylation when expressed in an Escherichia coli reconstitution system. In addition, yeast one hybrid assays indicated that ZmmICE1 has transactivation activities. Moreover, ectopic expression of ZmmICE1 in the Arabidopsis ice1-2 mutant increased freezing tolerance. The ZmmICE1 overexpressed plants showed lower electrolyte leakage (EL), reduced contents of malondialdehyde (MDA). The expression of downstream cold related genes of Arabidopsis C-repeat-binding factors (AtCBF1, AtCBF2 and AtCBF3), cold-responsive genes (AtCOR15A and AtCOR47), kinesin-1 member gene (AtKIN1) and responsive to desiccation gene (AtRD29A) was significantly induced when compared with wild type under low temperature treatment. Taken together, these results indicated that ZmmICE1 is the homolog of Arabidopsis inducer of CBF expression genes (AtICE1/2) and plays an important role in the regulation of freezing stress response.
Asunto(s)
Adaptación Fisiológica/genética , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Regulación de la Expresión Génica de las Plantas , Factores de Transcripción/genética , Zea mays/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/biosíntesis , Proteínas de Arabidopsis/metabolismo , Secuencia de Bases , Frío , Congelación , Malondialdehído/metabolismo , Plantas Modificadas Genéticamente , Prolina/biosíntesis , Prolina/genética , ARN de Planta/genética , Estrés Fisiológico/genética , Sumoilación/genética , Factores de Transcripción/biosíntesis , Factores de Transcripción/metabolismo , Zea mays/metabolismoRESUMEN
The annual Zea mays ssp. mexicana L. is a member of teosinte, a wild relative of the Zea mays spp. mays L. This subspecies has strong growth and regeneration ability, high tiller numbers, high protein and lysine content as well as resistance to many fungal diseases, and it can be effectively used in maize improvement. In this study, we reported a Zea mays ssp. mexicana L. transcriptome by merging data from untreated control (CK), cold (4°C) and drought (PEG2000, 20%) treated plant samples. A total of 251,145 transcripts (N50 = 1,269 bp) and 184,280 unigenes (N50 = 923 bp) were predicted, which code for homologs of near 47% of the published maize proteome. Under cold conditions, 2,232 and 817 genes were up-regulated and down-regulated, respectively, while fewer genes were up-regulated (532) and down-regulated (82) under drought stress, indicating that Zea mays ssp. mexicana L. is more sensitive to the applied cold rather than to the applied drought stresses. Functional enrichment analyses identified many common or specific biological processes and gene sets in response to drought and cold stresses. The ABA dependent pathway, trehalose synthetic pathway and the ICE1-CBF pathway were up-regulated by both stresses. GA associated genes have been shown to differentially regulate the responses to cold in close subspecies in Zea mays. These findings and the identified functional genes can provide useful clues for improving abiotic stress tolerance of maize.
RESUMEN
BACKGROUND AND AIMS: Expected increases in world population will continue to make demands on agricultural productivity and food supply. These challenges will only be met by increasing the land under cultivation and by improving the yields obtained on existing farms. Genetic engineering can target key traits to improve crop yields and to increase production on marginal soils. Soil acidity is a major abiotic stress that limits plant production worldwide. The goal of this study was to enhance the acid soil tolerance of wheat by increasing its resistance to Al(3+) toxicity. METHODS: Particle bombardment was used to transform wheat with TaALMT1, the Al(3+) resistance gene from wheat, using the maize ubiquitin promoter to drive expression. TaALMT1 expression, malate efflux and Al(3+) resistance were measured in the T(1) and T(2) lines and compared with the parental line and an Al(3+)-resistant reference genotype, ET8. KEY RESULTS: Nine T(2) lines showed increased TaALMT1 expression, malate efflux and Al(3+) resistance when compared with untransformed controls and null segregant lines. Some T(2) lines displayed greater Al(3+) resistance than ET8 in both hydroponic and soil experiments. CONCLUSIONS: The Al(3+) resistance of wheat was increased by enhancing TaALMT1 expression with biotechnology. This is the first report of a major food crop being stably transformed for greater Al(3+) resistance. Transgenic strategies provide options for increasing food supply on acid soils.