| Bread wheat (Triticum aestivum L.,2n=6x-42AABBDD) as staple food of the world’s population, is the most widely grown crop in the world. Although it has been bred intensively for hundred of years, significant improvements in yield and quality have been achieved. Due to its limited genetic diversity, bread wheat is constantly threatened by various abiotic and biotic factors, which has limited its improvements in yield and quality. The wild relatives of wheat possess a large number of useful genes, which will be the genetic donor of wheat breeding. An efficient strategy to broaden the genetic base of wheat is to introgress some useful genes of its wild relatives in the tertiary gene pool into wheat through distant crosses. In the present study, we selected and characterized some alien chromosome lines derived from wheat-Psathyrostachys huashanica Keng ex Kuo (2n=2x=14, NsNs) by agronomy, cytogenetics, GISH and SDS-PAGE. The results are as follows:1.596plants of the BC2{[F1×CS]×CS,[F1×CSph2b]×CSph2b and [F1×J-11]×J-11} and BC1F1{[F1×CS] selfed,[F1×CSph2b] selfed and [F1×J-11] selfed} were observed for analyzing the distribution of chromosome numbers. The chromosome numbers of the populations of BC2and BC1F1varied from2n=42to52, and plants with2n=45accounted for the highest frequency (19.6%). The distribution of chromosome numbers in all combinations didn’t fit to normal distribution, indicating that the distribution of chromosome numbers was affected by some genetic factors. There were different main ranges of chromosome numbers and reduced chromosome numbers per a hundred of plants in BC2accessions and BC1F1accessions. These results indicated that the distribution of chromosome numbers was affected by the genotype of the backcrossing parents. The effect of CSph2b higher than CS and J-11, and the effect of CS and J-11were similar in BC2accessions. However, the efficiency of J-11was higher than CS in BC1F1accessions. And chromosome eliminated more rapidly by backcrossing than selfing, and selfing may be facilitated to the screening of recombination between wheat and P. huashanica chromosomes.2. Alien chromosome lines were developed and identified from the BC1F2and BC1F3generations. Five lines with2n=44and one line with2n=46showed regular meiosis and were cytologically stable. Based on chromosome pairing, C-banding and GISH analysis, lines156-4,160-12,160-13,173-2and197-16(2n=44) were alien disomic addition lines with the addition of one pair of the P. huashanica5Ns chromosomes. Line165-2, which had each pair of the P. huashanica chromosomes3Ns and5Ns being added, was an alien double addition line. Nine lines with the P. huashanica chromosome1Ns,2Ns,4Ns or5Ns were alien monosomic addition lines. Robertsonian translocation was observed in lines241-2and241-10. Some chromosomal abnormalities were observed, such as telosomics, lagging of telosomics, and telosomic sister chromatids that moved to one pole at anaphase I and asynchronous chromosome separation at telophase Ⅱ. These results indicated that the presence of alien chromosomes from P. huashanica had influenced the meiosis. Meanwhile, by comparing the series of wheat-P. huashanica chromosome addition lines, the gene(s) for awns were mapped to the P. huashanica5Ns chromosome.3. Nine wheat-P.huashanica addition lines were characterized by Giemsa C-banding, genomic in situ hybridization (GISH) and disease resistance evaluation. Giemsa C-banding and GISH demonstrated that lines163-5,165-1,183-5,240-3and240-4are P. huashanica3Ns chromosome monosomic addition lines; lines183-1and183-20are P. huashanica3Ns chromosome disomic addition lines; line165-20is P. huashanica3Ns and4Ns chromosome double disomic addition lines; and line219-1is P. huashanica INs and3Ns/5A chromosome double disomic addition-substitution lines. All of these addition lines with P. huashanica3Ns chromosome(s) expressed high resistance or immunity to stripe rust. By comparing the series of whea1-P. huashanica chromosomes addition lines, we concluded that the P. huashanica3Ns chromosome carries the gene(s) for resistance or immunity to stripe rust. These addition lines can be used as a donor source of novel stripe rust resistance to wheat breeding programs.4. Two partial amphiploid lines, B113(32plants) and B21(13plants) which were BC1F4, were characterized by Giemsa C-banding and SDS-PAGE and evaluated for stripe rust resistance. All15partial amphiploid plants analysed were aneuploids with either50(8plants),51(6plants) or54(I plant) chromosomes. Some of them showed regular meiosis and all the P. huashanica chromosomes were included, although not in a single plant. SDS-PAGE analysis of the45plants showed that34expressed some specific bands representing high molecular weight glutenin subunit (HMW-GS) and41had bands representing P. huashanica low molecular weight glutenin subunit (LMW-GS), including two new subunits. All45plants were highly resistant (10) or immune (35) to stripe rust mixed races CYR-30, CYR-31, Shuiyuan7and Shuiyuan14. These amphiploid plants could be useful germplasm for enhancing stripe rust resistance and might improve wheat grain quality.Cadmium (Cd) is a toxic trace pollutant for all living organisms that can accumulate to high concentrations in soil from industrial processes and phosphate fertilizers. It can accumulate in plants causing cellular damage, leading to a disruption of physiological processes, and them inducing the responses at the biochemical-physiological level and on signal transduction pathways. Cd has been recognized as a contributing factor to human diseases, such as renal proximal tubular dysfunction and the bone disease called itai-itai. There are cultivar differences in seed Cd accumulation in soybean [Glycine Max (L.) Merr] and many cultivars accumulate high Cd concentrations in seed when grown on Cd-contaminated soils. These cultivars can exceed the proposed Codex upper limit. Soybean has long been a staple food for humans, especially as soymilk, tofu and oil. Consumption, either directly or indirectly, of seed with high levels of Cd could be a human health concern. In the present study, based on a major gene or QTL controlling seed Cd accumulation in soybean has been located on linkage group K between the SSR markers Sat119and SatK176, two cultivars, Westag97(a low Cd accumulator) and AC Hime (a high Cd accumulator), were used to evaluate reference genes for normalization of qRT-PCR analysis of differentially expressed genes in soybean exposed to Cd, and clone, expressed and functionally analyze GmHMA3w limiting Cd translocation in soybean. The results are as follows: 5. Due to no study has concentrated on identifying multiple reference genes for normalization of qRT-PCR data in soybean under exposure to heavy metal stress treatments, we evaluated the expression stability of ten candidate housekeeping genes in leaves, roots and stems of two soybean cultivars exposed to increased Cd concentrations. Under evaluation of geNorm’ and NormFinder, ACT3, PP2A, ELF1B and F-box were the four best reference genes, based on geNorm and NormFinder analysis, for these gene expression studies. These four genes also may be suitable for normalization of gene expression in soybean under exposure to other heavy metals which have similar properties and effects as Cd. Both geNorm and NormFinder analyses revealed that G6PD, UBC2, TUB, and ELF1A could not be used as reference genes for normalization in these experimental conditions.6. A candidate gene, Glycine max heavy metal associated protein3(GmHMA3), which encodes a heavy metal transporter belonging to the P1B-type ATPase family, was selected for analysis. Sequence analysis of20diverse soybean cultivars detected a single nucleotide change in this gene in all high seed Cd accumulators. A single nucleotide polymorphism (SNP) marker was developed and used to genotype166F8RILs by high resolution melt (HRM) analysis. Segregation analysis mapped the GmHMA3to0.3cM away from the Cdal gene previously tagged by the SSR markers, SatK147, SacK149and Saatk150. Marker-trait association analysis also indicated that the wild type allele, GmHMA3w, is tightly associated with low seed Cd concentration. Expression level studies revealed that GmHMA3is only expressed in root. Functional assay of the GmHMA3gene in yeast indicated that GmHMA3w encodes a Cd/Zn transporter, which sequesters Cd and Zn into vacuoles or other place in roots, thereby limiting the Cd and Zn accumulations in soybean seed.7. Some metal transporters of plant can transport multi-metals. Although GmHMA3w is a Cd and Zn transporter, it can not transport Fe, Pb and Co. Due to GmHMA3was mis-localized on endoplasmic reticulum in yeast, GmHMA3w increased the sensitive of Cd and Zn. |
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