​Establishment of a Regeneration System for Wild Alfalfa in Alxa, China

Abstract

Background: The Alxa Region in Inner Mongolia, northwest China is a desert grassland area. Wild alfalfa growing in this area is a precious wild plant resource that can provide resources for improving the stress resistance of alfalfa varieties. Alfalfa is a cross-pollinated plant and its genes are commonly heterozygous. Therefore, establishing a complete tissue culture regeneration system for a single plant is an effective method of protecting wild plant resources. This study used the bud and leaf of wild alfalfa from the Alxa Region as explants to establish an efficient and stable tissue culture regeneration system. Methods: Two kinds of wild alfalfa tissues were selected as explants. Different concentrations and types of plant growth hormones and regulators were tested, to determine the optimal medium for callus induction, differentiation and rooting culture, including 6-Benzylaminopurine (6-BA), Kinetin (KT), 2, 4-Dichlorophenoxyacetic acid (2, 4-D), Naphylacetic acid (NAA), Indole-3-butyric acid (IBA) and activated carbon (AC). Result: The callus induction rate was 93.3% when the bud of wild alfalfa was used as an explant for propagation. With a basic medium (Murashige and Skoog medium with Ca2+, Mg2+ and Mn2+ halved) and hormone regulator (6-BA, KT, NAA, AC), the differentiation rate and rooting rate reached as high as 66.67% and 93.33%, respectively. When leaves were used as explants, the callus induction rate and differentiation rate were 100% and 73.33%, respectively. In the rooting culture process, adding IBA (0.2 mg/L) and AC (0.5 mg/L) to the medium improved the rooting rate of wild alfalfa. Both buds and leaves can be used as explants for plant tissue regeneration and culture, which can help expand and preserve wild alfalfa resources.