Different Roles of Auxins in Somatic Embryogenesis Efficiency in Two <i>Picea</i> Species

• Main Authors: Teresa Hazubska-Przybył, Ewelina Ratajczak, Agata Obarska, Emilia Pers-Kamczyc
• Format: Article
• Language: English
• Published: MDPI AG 2020-05-01
• Series: International Journal of Molecular Sciences
• Subjects: picloram; somatic embryos; spruce; hydrogen peroxide; peroxidases
• Online Access: https://www.mdpi.com/1422-0067/21/9/3394
• ISSN: 1661-6596; 1422-0067

The effects of auxins 2,4-D (2,4-dichlorophenoxyacetic acid), NAA (1-naphthaleneacetic acid) or picloram (4-amino-3,5,6-trichloropicolinic acid; 9 µM) and cytokinin BA (benzyloadenine; 4.5 µM) applied in the early stages of somatic embryogenesis (SE) on specific stages of SE in <i>Picea</i><i> </i><i>abies</i> and <i>P. </i><i>omorika</i> were investigated. The highest SE initiation frequency was obtained after 2,4-D application in <i>P. </i><i>omorika</i> (22.00%) and picloram application in <i>P. </i><i>abies</i> (10.48%). NAA treatment significantly promoted embryogenic tissue (ET) proliferation in <i>P</i><i>. </i><i>abies</i>, while 2,4-D treatment reduced it. This reduction was related to the oxidative stress level, which was lower with the presence of NAA in the proliferation medium and higher with the presence of 2,4-D. The reduced oxidative stress level after NAA treatment suggests that hydrogen peroxide (H₂O₂) acts as a signalling molecule and promotes ET proliferation. NAA and picloram in the proliferation medium decreased the further production and maturation of <i>P. </i><i>omorika</i> somatic embryos compared with that under<i> </i>2,4-D. The quality of the germinated <i>P. </i><i>abies</i> embryos and their development into plantlets depended on the auxin type and were the highest in NAA-originated embryos. These results show that different auxin types can generate different physiological responses in plant materials during SE in both spruce species.