Authors:J. Zhao, L. Zhong, L. Zou, C. Zhang, L. Peng, W. Xiao, and G. Zhao
The purpose of this study was to investigate the effects of endophytic fungi from tartary buckwheat on the host sprout growth and functional metabolite production. Without obvious changes in the appearance of the sprouts, the exogenous fungal mycelia elicitors notably stimulated the sprout growth and rutin accumulation, and the stimulation effect was mainly depended on the mycelia elicitor species along with its treatment dose. Three endophytic fungi Fat6 (Bionectria pityrodes), Fat9 (Fusarium oxysporum) and Fat15 (Alternaria sp.) were screened to be the most effective candidates for promoting F. tataricum sprout growth and rutin production. With application of polysaccharide (PS, 150 mg/l) of endophyte Fat6, PS (200 mg/l) of endophyte Fat9, and PS (150 mg/l) of endophyte Fat15, the rutin yield was effectively increased to 47.89 mg/(100 sprouts), 45.85 mg/(100 sprouts) and 46.83 mg/(100 sprouts), respectively. That was about 1.5- to 1.6-fold compared to the control culture of 29.37 mg/(100 sprouts). Furthermore, the present study revealed that the biosynthesis of the functional flavonoid resulted from the stimulation of the phenylpropanoid pathway by mycelia polysaccharide treatments. Application of specific fungal elicitors could be an efficient strategy for improving the nutritional and functional quality of tartary buckwheat sprouts.
Authors:X.G. Hu, J. Liu, L. Zhang, B.H. Wu, J.L. Hu, D.C. Liu, and Y.L. Zheng
Grains of 12 accessions of Triticum timopheevii (Zhuk.) Zhuk. ssp. timopheevii (AAGG, 2n = 4x = 28) and one bread wheat cultivar Chinese Spring (CS) and one durum wheat cultivar Langdon (LDN) grown across two years were analyzed for grain iron (Fe) and zinc (Zn) concentrations. All the 12 tested T. timopheevii ssp. timopheevii genotypes showed significantly higher concentration of grain Fe and Zn than CS and LDN. Aboundant genetic variability of both the Fe and Zn concentrations was observed among the T. timopheevii ssp. timopheevii accessions, averagely varied from 47.06 to 90.26 mg kg−1 and from 30.05 to 65.91 mg kg−1, respectively. Their grain Fe and Zn concentrations between years exhibited a significantly positive correlation with the correlation coefficients r = 0.895 and r = 0.891, respectively, indicating the highly genetic stability. Flag leaf possessed twice or three times higher concentrations for both Fe and Zn than grain, and a significantly high positive correlation appeared between the two organs with r = 0.648 for Fe and r = 0.957 for Zn concentrations, respectively, suggesting flag leaves might be indirectly used for evaluating grain Zn and Fe contents. Significant correlations occurred between grain Fe and Zn concentrations, and between grain Zn concentration and the two agronomic traits of plant height and number of spikelets per spike. Both the concentrations were not related to seed size or weight as well as NAM-G1 gene, implying the higher grain Fe and Zn concentrations of T. timopheevii ssp. timopheevii species are not ascribed to concentration effects of seed and the genetic control of NAM-G1 gene. There might be some other biological factors impacting the grain’s Zn and Fe concentrations. These results indicated T. timopheevii ssp. timopheevii species might be a promising genetic resource with high Fe and Zn concentrations for the biofortification of current wheat cultivars.
Authors:L.L. Han, W.G. Xu, L. Hu, Y. Li, X.L. Qi, J.H. Zhang, H.F. Zhang, and Y.X. Wang
To explore the physiological characteristics of the pepc gene in transgenic wheat (Triticum aestivum) plants, PEPC activities in various organs of T3 plants were analyzed at Feekes 6.0, Feekes 10.3 and Feekes 11.1, and compared to control, untransformed wheat cultivar Zhoumai 19. Net photosynthetic rates (Pn) in leaves were also measured at the same stages. At Feekes 11.1, both transgenic and control plants were treated with DCDP. Yield traits were surveyed after harvest. The results indicated that Pn and PEPC activity in the flag leaf of transgenic wheat were significantly higher than those of the control at different stages. At Feekes 10.3, Pn reached the highest value at 28.2 μmol m−2 s−1 and PEPC activity reached the highest value at 104.6 μmol h−1 mg−1. Both factors significantly increased by 21% compared to the control at Feekes 11.1. PEPC activity in the flag leaf of transgenic plants was significantly higher than that of non-leaf organs. Pn of transgenic plants was greatly reduced after DCDP treatment. In the flag leaf of transgenic wheat, Pn was significantly correlated to PEPC activities at 0.01 probability level with a correlation coefficient of 0.8957**. The yield traits of transgenic line 1-27-3, such as 1000-grain weight, single spike weight and harvest index were higher than those of the control. Additionally, the spike weight of 1-27-3 showed an increase of approximately 9.5% compared to the control. These results indicated that the expression of maize (Zea mays) pepc gene was different across various organs of transgenic wheat and across every growth stage. Therefore, we conclude that introducing maize pepc gene into wheat plants can increase their Pn and improve production.
Authors:Z. L. Li, D. D. Wu, H. Y. Li, G. Chen, W. G. Cao, S. Z. Ning, D. C. Liu, and L. Q. Zhang
Gliadin is a main component of gluten proteins that affect functional properties of bread making and contributes to the viscous nature of doughs. In this study, thirteen novel ω-gliadin genes were identified in several Triticum species, which encode the ARH-, ATDand ATN-type proteins. Two novel types of ω-gliadins: ATD- and ATN- have not yet been reported. The lengths of 13 sequences were ranged from 927 to 1269 bp and the deduced mature proteins were varied from 309 to 414 residues. All 13 genes were pseudogenes because of the presence of internal stop codons. The primary structure of these ω-gliadin genes included a signal peptide, a conserved N-terminal domain, a repetitive domain and a conserved C-terminus. In this paper, we first characterize ω-gliadin genes from T. timopheevi ssp. timopheevi and T. timopheevi ssp. araraticum. The ω-gliadin gene variation and the evolutionary relationship of ω-gliadin family genes were also discussed.
Authors:S. Wang, D. Chen, G. Guo, T. Zhang, S. Jiang, X. Shen, D. Perovic, S. Prodanovic, and Y. Yan
In this work, 9 novel LMW-GS genes (6 LMW-m and 3 LMW-i type) from 4 diploid and 1 tetraploid Aegilops species were amplified and cloned by allelic-specific PCR. Analysis of the deduced amino acid sequences showed that 7 and 2 LMW-GS had 9 and 7 cysteines, respectively. Four LMW-m type subunits genes had an extra cysteine at the C-terminal III, which could form intermolecular disulphide bonds to extend the chains, and therefore would facilitate to form larger gluten polymers. This suggested that these genes are expected to be used as candidate genes for wheat quality improvement. The correlation between specific N-terminal sequences and a decapeptide deletion in the C-terminal II in LMW-GS encoded by D genome was found. Particularly, if LMW-GS possessed a METRCIPG-N-terminal beginning sequences and a decapeptide (LGQCSFQQPQ) deletion in the C-terminal II, they could be encoded by D genome.
Premature termination codons (PTCs) are an important reason for the silence of highmolecular- weight glutenin subunits in Triticum species. Although the Glu-A1y gene is generally silent in common wheat, we here isolated an expressed Glu-A1y gene containing a PTC, named 1Ay8.3, from Triticum monococcum ssp. monococcum (AmAm, 2n = 2x = 14). Despite the presence of a PTC (TAG) at base pair positions 1879–1881 in the C-terminal coding region, this did not obviously affect 1Ay8.3 expression in seeds. This was demonstrated by the fact that when the PTC TAG of 1Ay8.3 was mutated to the CAG codon, the mutant in Escherichia coli bacterial cells expressed the same subunit as in the seeds. However, in E. coli, 1Ay8.3 containing the PTC expressed a truncated protein with faster electrophoretic mobility than that in seeds, suggesting that PTC translation termination suppression probably occurs in vivo (seeds) but not in vitro (E. coli). This may represent one of only a few reports on the PTC termination suppression phenomenon in genes.
Authors:K.J. Deng, J.P. Zhou, X.H. Wu, G. Sun, T. Wang, A.T. Tang, X.L. Zheng, and Y. Zhang
It is well demonstrated that wheat-rye 1BL/1RS translocated chromosome leads to some valuable novel traits such as disease resistance, high yield and functional stay-green after anthesis. To understand the physiological mechanism of 1BL/1RS translocation responsible for osmotic stress, two wheat cultivars, CN12 and CN17, carrying the translocated chromosome and MY11 without the translocated chromosome were employed in the study. During 5-day osmotic stress, fresh weight inhibition, chlorophyll content, soluble protein content, MDA concentration, antioxidant enzymes activity and free polyamines content were examined. CN12 and CN17, especially cultivar CN17, registered greater biomass and minor oxidative damage compared with their wheat parent. Meanwhile, the concentration of Spd and Spm in CN17 was significantly higher than the others. In addition, we found a positive correlation of fresh weight inhibition (FWI) and Put concentration, and a negative one with the parameters (Spd + Spm): Put ratio, indicating the importance of higher polyamine (Spd and Spm) accumulation on the adaptation to osmotic stress. Therefore, we proposed that the accumulation of higher polyamines (Spd and Spm) should play an important role on the adaptation of 1BL/1RS translocation lines to osmotic stress and might be important factors for the origin of novel traits introduced by 1BL/1RS.
Authors:N. Niu, Y.X. Bai, S. Liu, Q.D. Zhu, Y.L. Song, S.C. Ma, L.J. Ma, X.L. Wang, G.S. Zhang, and J.W. Wang
Studies of the pollen abortion mechanism in thermo-sensitive male sterile lines may provide a strong foundation for breeding hybrid wheat and establishing a theoretical basis for marker-assisted selection. To investigate the cause of pollen abortion in Bainong thermo – sensitive male sterile (BNS) lines, we analyzed the properties of pollen grains, changes in the tapetum and microspores in different anther developmental stages, and the distribution and deposition of nutrient substances in microspores. We found that tapetum degraded in the early uninucleate stage in sterile BNS (S-BNS), which was earlier than that of fertile BNS (F-BNS) tapetum. Large amounts of insoluble polysaccharides, lipids, and proteins were deposited until the trinucleate pollen stage in the nutritive cells in F-BNS. At the binucleate stage, the vacuoles disappeared and pollen inclusion increased gradually. At the trinucleate stage, these nutrients would help pollen grains mature and participate in fertilization normally. Therefore, early degradation of the tapetum, which inhibits normal microspore development, and the limited content of nutrient substances in pollen may be the main factors responsible for male sterility in BNS lines.
Authors:Z.L. Li, H.Y. Li, G. Chen, X.J. Liu, C.L. Kou, S.Z. Ning, Z.W. Yuan, M. Hao, D.C. Liu, and L.Q. Zhang
Seven Glu-A1m allelic variants of the Glu-A1mx genes in Triticum monococcum ssp. monococcum, designated as 1Ax2.1a, 1Ax2.1b, 1Ax2.1c, 1Ax2.1d, 1Ax2.1e, 1Ax2.1f, and 1Ax2.1g were characterized. Their authenticity was confirmed by successful expression of the coding regions in E. coli, and except for the 1Ax2.1a with the presence of internal stop codons at position of 313 aa, all correspond to the subunit in seeds. However, all the active six genes had a same DNA size although their encoding subunits showed different molecular weight. Our study indicated that amino acid residue substitutions rather than previously frequently reported insertions/deletions played an important role on the subunit evolution of these Glu-A1mx alleles. Since variation in the Glu-A1x locus in common wheat is rare, these novel genes at the Glu-A1mx can be used as candidate genes for further wheat quality improvement.
Authors:N. Niu, Y. L. Song, F. Wei, H. M. Liu, S. M. Ma, H. Y. Zhao, and G. S. Zhang
In this study, we employed electron microscopy to investigate the cytogenetic and embryologic mechanisms of parthenogenesis induced in the 1BL/1RS male sterile lines of wheat. Analysis of the root tips and acid polyacrylamide gel electrophoresis indicated that all of the male sterile lines and their maintainer lines were 1BL/1RS translocation lines, whereas the restorer lines were non-1BL/1RS translocation lines. Furthermore, the chromosomes of 1BL/1RS wheat lines with T. aestivum cytoplasm and Aegilops cytoplasm (include Ae. kotschyi, Ae. ventricosa, Ae. variabilis) paired abnormally at different rates during meiotic metaphase I (MMI). The translocated segment size of the 1RS chromosome and the specific nuclear–alloplasm interaction impaired the pairing of homologous chromosome in the background of the specific Aegilops cytoplasm at MMI. In addition, the frequency of abnormal chromosomal pairing was directly affected by the frequency of haploid production induced by parthenogenesis. The results of this study provide significant insights into the mechanism of parthenogenesis, which is probably due to the abnormal fertilization of synergid cells in alloplasmic 1BL/1RS wheat.