Regeneration and micropropagation of Meyer lemon (Citrus x meyeri) supported by polymorphism analysis via molecular markers

Abstract

Abstract Meyer lemon (Citrus x meyeri) is a valuable sweet hybrid Citrus from China, renowned for its unique taste and high nutritional value. The current study aims to establish an efficient micropropagation protocol and to evaluate the potential regenerated somatic embryos induced from in vitro Meyer lemon explants. Shoot tips and epicotyl segments were inoculated in half strength Murashige and Skoog (½ MS) medium supplemented with plant growth regulators (PGRs) for multiple shoot and root induction prior to polymorphism and microscopy analysis. Benzylaminopurine (BAP) treatment at 1\xa0mg L−1 was found optimal in the induction of multiple shoots (100% induction rate) with the average of 3.29\xa0±\xa00.2 shoots. The synergistic effects of 2\xa0mg L−1 BAP and 1.5\xa0mg L−1 Indole-3-acetic acid (IAA) resulted in maximum shoot regeneration frequency (100%) with an average number of 3.6\xa0±\xa00.5 shoots per explant. Woody plant medium (WPM) without PGRs exhibited the highest rooting frequency (100%) and acclimatization of in vitro plantlets yielded 82% survivability. Inter simple sequence repeat (ISSR) and start codon targeted (SCoT) markers revealed no somaclonal variation occurrences between micropropagated plantlets of five subculture cycles and mother plant. Potential indirect somatic embryogenesis was observed from epicotyl segments of in vitro germinated seedlings at an average of 7.3\xa0±\xa01.0 embryos per explant with 80% response in ½ MS with 0.5\xa0mg L−1 thidiazuron (TDZ). Morpho-histological and scanning electron microscopy (SEM) observations confirmed the initiation and developmental features of the embryos. This study has successfully established an efficient micropropagation protocol for Meyer lemon and documented the potential initiation of indirect somatic embryogenesis.