Field evaluation of transgenic wheat plants stably expressing the HVA1 gene for drought tolerance

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.