摘要
The selection of heterotic F1 hybrid varieties is a key agronomic strategy for improving crop yields,quality,and disease resistance(Bohra et al.,2016).Large-scale,low-cost hybrid seed production involves generating large populations of female plants,otherwise known as male sterile.Different techniques implying environmentally conditioned nuclear male sterility or mitochondria-driven cytoplasmic male sterility(CMS)have been used to this end,each with their own advantages and disadvantages(Kim and Zhang,2018).Because of its low cost and high purity,CMS hybrid breeding is by far the most widely used hybrid technology and has been implemented in many field and horticultural crops(Bohra et al.,2016).It usually relies on a three-component assembly involving a male-sterile CMS line,a fertility restorer line,and a maintainer one.Crosses between CMS and maintainer lines allow large-scale multiplication of female plants,whereas crosses with the restorer line produce heterotic malerestored hybrids that can thus set fruits(Figure 1).
