High frequency plant regeneration from cotyledonary node explants of Cucumis sativus L. cultivar 'Green Long' via adventitious shoot organogenesis and assessment of genetic fidelity by RAPD-PCR technology

Recent Progress in the Regeneration and Genetic Transformation System of Cucumber

Cucumber (Cucumis sativus L.), belonging to the gourd family (Cucurbitaceae), is one of the major vegetable crops in China. Conventional genetic breeding methods are ineffective for improving the tolerance of cucumber to various environmental stresses, diseases, and pests in the short term, but bio-engineering technologies can be applied to cucumber breeding to produce new cultivars with high yield and quality. Regeneration and genetic transformation systems are key technologies in modern cucumber breeding. Compared with regeneration systems, genetic transformation systems are not yet fully effective, and the low efficiency of genetic transformation is a bottleneck in cucumber cultivation. Here, we systematically review the key factors influencing the regeneration and genetic transformation of cucumber plants, including the selection of genotype, source of explants and forms of exogenous hormones added to the medium, the methods of transgene introduction and co-cultivation, and selection methods. In addition, we also focus on recent advances in the study of molecular mechanisms underlying important agronomic traits using genetic transformation technology, such as fruit length, fruit warts, and floral development. This review provides reference information for future research on improvements in cucumber varieties.

In Vitro Regeneration Potential of White Lupin (Lupinus albus) from Cotyledonary Nodes

The tissue culture regeneration system of Lupinus albus has always been considered as recalcitrant material due to its genotype-dependent response and low regeneration efficiency that hamper the use of genetic engineering. Establishment of repeatable plant regeneration protocol is a prerequisite tool for successful application of genetic engineering. This aim of this study was to develop standardized, efficient protocol for successful shoot induction from cotyledonary node of white lupin. In this study, 5 day old aseptically cultured seedlings were used to prepare three explants (half cotyledonary node, HCN; whole cotyledonary node, WCN; and traditional cotyledonary node, TCN), cultured on four concentrations of M519 medium (M519, ½ M519, 1/3 M519, and ¼ M519), containing four carbohydrate sources (sucrose, fructose, maltose, and glucose), and stimulated with various combinations of KT (kinetin), and NAA (naphthalene acetic acid) for direct shoot regeneration. High frequency of 80% shoot regeneration was obtained on ½ M519 medium (KT 4.0 mg L-1 + NAA 0.1 mg L-1) by using HCN as an explant. Interestingly, combinations of (KT 4.0 mg L-1 + NAA 0.1 mg L-1 + BAP 1.67 mg L-1), and (KT 2.0 mg L-1 + NAA 0.1 mg L-1) showed similar shoot regeneration frequency of 60%. Augmentation of 0.25 g L-1 activated charcoal (AC) not only reduced browning effect but also improved shoot elongation. Among the all carbohydrate sources, sucrose showed the highest regeneration frequency with HCN. Additionally, 80% rooting frequency was recorded on ½ M519 containing IAA 1.0 mg L-1 + KT 0.1 mg L-1 (indole acetic acid) after 28 days of culturing. The present study describes establishment of an efficient and successful protocol for direct plant regeneration of white lupin from different cotyledonary nodes.