Embryogenesis and plant regeneration from anther culture in loquat (Eriobotrya japonica L.)

The object of this study was to induce embryogenesis and establish plant regeneration system for anther culture in loquat (Eriobotrya japonica L.). Cold pretreatment was a key factor, and supplement of 2,4-D in the media was absolutely necessary for induction of calluses from cultured loquat anthers. The best response of anthers to in vitro culture was obtained when a 48-h cold pretreatment was employed to flower buds at 4 degrees C in darkness. Genotype was a decisive factor for embryo differentiation. When anther-derived calluses of three loquat cultivars, i.e., cv. 'Longquan1', 'Dawuxing' and 'Zaozhong6', were transferred to embryo differentiation medium, embryos were induced only for cv. 'Dawuxing' on MS medium containing 3% sucrose, 0.23 mu M ZT in combination with 0.05 mu M NAA + 0.05 mu M IBA or 0.11 mu M NAA + 0.10 mu M IBA, and the differentiation rates were 3.33% and 10.00%, respectively. The results of histological studies showed that embryos developed through typical globular, heart, torpedo and cotyledon stages after 4 weeks of culture. The treatment designed to mature the embryos on medium containing 3% of sucrose at 4 degrees C under darkness for 4 weeks was effective for subsequent embryo germination and plant conversion, which gave rise to 72.5% plant recovery. Cytological studies showed that 26 plantlets were haploids (n = 17) and the remaining 4 plantlets were diploids for the 30 regenerants tested. (C) 2007 Elsevier B.V. All rights reserved.