The barley HVA1 gene, encoding a member of the group 3 late embryogenesis abundant (LEA) proteins, has previously been introduced into spring wheat cv. Hi‐Line to determine its effect on drought tolerance (Sivamani E, Bahieldin A, Wraith JM, Al‐Niemi T, Dyer WE, Ho T‐HD, Qu R (2000) Improved biomass productivity and water use efficiency under water deficit conditions in transgenic wheat constitutively expressing the barley HVA1 gene. Plant Sci 155, 1–9). T4 progeny from six independent transgenic events (lines 111/1, 1/1, 11/2, 84, 765 and 1201) were tested in nine field experiments over six cropping seasons. In the first two seasons, the total biomass per plot and the grain yield per plot of line 111/1 were higher than those of line 1/1, and higher than those of the wild‐type control in the second season. The grain yield per plot of line 11/2 was significantly lower than that of the transgenic lines 111/1 and 1/1 in the third season, and this line was not tested further. In the fourth season, the plant height and grain yield per plot of line 111/1 were significantly higher than those of the wild‐type control. Under dryland conditions in the fifth season, line 111/1 showed significantly greater plant height, total biomass per plot and grain yield per plot than the wild‐type control in at least two of the four locations, as well as across locations. In the sixth season, newly developed transgenic lines 1201 and 765 significantly overyielded the two original transgenic lines 111/1 and 1/1, the non‐expressing transgenic line 84 as well as the wild‐type control in the three yield attributes and leaf water measurement, namely relative water content (RWC). This result coincided with the rate of HVA1 transgene expression of the different genotypes. Differences in total seed storage protein concentrations between the transgenic lines and the wild‐type control within or across environmental conditions were insignificant. These field trials show that the HVA1 gene has the potential to confer drought stress protection in transgenic spring wheat.

The GUS gene of E. coli, encoding b-glucuronidase, has been widely used as a reporter gene in plant transformation. However, b-glucuronidase activity in transgenic wheat leaf or root tissue is rarely observed or reported. To address this question, we investigated three wheat lines transformed with the GUS reporter gene. We found all three lines expressed GUS mRNA as well as b-glucuronidase protein in their leaf and root tissues as detected by RNA gel blot, ELISA, and immunoblot analyses. However, b-glucuronidase enzyme activity was only detected in pollen grains from the transgenic plants. Fluorometric and histochemical assays performed in the presence of wheat tissue extracts indicated that wheat leaf and root tissues contain inhibitor(s) of b-glucuronidase activity, but pollen grains contain much lower concentrations. Further characterizations indicated that the inhibitor(s) is of low molecular weight (<10 kDa) and is non-proteinaceous.Abbreviation: GUS -b-glucuronidase

BackgroundThe main aim of this study was to improve fungal resistance in bread wheat via transgenesis. Transgenic wheat plants harboring barley chitinase (chi26) gene, driven by maize ubi promoter, were obtained using biolistic bombardment, whereas the herbicide resistance gene, bar, driven by the CaMV 35S promoter was used as a selectable marker.ResultsMolecular analysis confirmed the integration, copy number, and the level of expression of the chi26 gene in four independent transgenic events. Chitinase enzyme activity was detected using a standard enzymatic assay. The expression levels of chi26 gene in the different transgenic lines, compared to their respective controls, were determined using qRT-PCR. The transgene was silenced in some transgenic families across generations. Gene silencing in the present study seemed to be random and irreversible. The homozygous transgenic plants of T4, T5, T6, T8, and T9 generations were tested in the field for five growing seasons to evaluate their resistance against rusts and powdery mildew. The results indicated high chitinase activity at T0 and high transgene expression levels in few transgenic families. This resulted in high resistance against wheat rusts and powdery mildew under field conditions. It was indicated by proximate and chemical analyses that one of the transgenic families and the non-transgenic line were substantially equivalent.ConclusionTransgenic wheat with barley chi26 was found to be resistant even after five generations under artificial fungal infection conditions. One transgenic line was proved to be substantially equivalent as compared to the non-transgenic control.Electronic supplementary materialThe online version of this article (doi:10.1186/s13007-017-0191-5) contains supplementary material, which is available to authorized users.