Abstract
Male sterility is a useful trait in traditional and hybrid wheat breeding. A dwarf male-sterile wheat line that harbors two tightly linked dominant traits, one, the dwarf gene Rht-D1c (originally called Rht10), and the other, the male-sterility gene Ms2 (the two genes linkage group is collectively called RMs2), has been widely used in wheat breeding programs in China. The dominant Ms2 (or RMs2) locus confers complete male sterility in wheat. In this study, we compared the plant height and spike traits in the Ms2 (or RMs2)-isogenic BC2F1 lines that were derived from four soft white winter (SWW) wheat of the US Pacific Northwest (PNW), and the SWW line 'Brundage' that harbored an Ms2 transgene. The dominant Ms2 gene had no essential effects on agronomic traits, including plant height, spikelet length and spikelet numbers per spike, in the BC2F1 plants of SWW wheats and the T-2 transgenic 'Brundage'. In an open pollination environment in field, the Ms2-positive BC2F1 plants had a 79% natural seed-setting rate, but the RMs2-positive BC2F1 plants had only a 60% natural seed-setting rate, suggesting that the Ms2 system is more practical for cross-pollination than the RMs2 one. This difference is probably due to the extreme plant height-reducing effect (45% reduction on average) and the late anthesis effect (3-5 days in general) of the Rht-D1c locus. Collectively, these investigations showed that the dominant Ms2 gene has no detrimental effects on plant and spike growth in five PNW wheat varieties/lines, therefore can become a valuable gene tool for traditional and hybrid breeding in wheat.