Borage (Borago officinalis L.) is an important medicinal plant with different culinary, pharmaceutical and industrial properties. Unfortunately, there are no published reports on the establishment of protocols to produce DHs in this species up to now. In this work, we show for the first time the induction of borage microspores to become embryogenic calli, from which haploid embryos are produced. In addition, we evaluated the effect of using different flower bud sizes, carbon sources, concentrations of 2,4-D and BAP, cold (4 C) pretreatments and heat shock treatments. Production of total calli, embryogenic calli and callus-derived embryos was differently affected by the different parameters studied. Our results showed that the use of 5–7 mm-long flower buds, a cold (4 C) pretreatment during 4 days, a 32 C heat shock for 3 days, and the addition of 3 % maltose and 2 mgl-1 2,4-D and 1 mgl-1 BAP to the culture medium, was beneficial for embryo production. Overall, this work demonstrates that DH technology is possible in borage, and opens the door for future improvements needed to finally obtain borage DH plants.
