The inaccessibility of the zygote and proembryos of angiosperms within the surrounding maternal and filial tissues has hampered studies on early plant embryogenesis. Somatic and gametophytic embryo cultures are often used as alternative systems for molecular and biochemical studies on early embryogenesis, but are not widely used in developmental studies due to differences in the early cell division patterns with seed embryos. A new Brassica napus microspore embryo culture system, wherein embryogenesis highly mimics zygotic embryo development, is reported here. In this new system, the donor microspore first divides transversely to form a filamentous structure, from which the distal cell forms the embryo proper, while the lower part resembles the suspensor. In conventional microspore embryogenesis, the microspore divides randomly to form an embryonic mass that after a while establishes a protoderm and subsequently shows delayed histodifferentiation. In contrast, the embryo proper of filament-bearing microspore-derived embryos undergoes the same ordered pattern of cell division and early histodifferentiation as in the zygotic embryo. This observation suggests an important role for the suspensor in early zygotic embryo patterning and histodifferentiation. This is the first in vitro system wherein single differentiated cells in culture can efficiently regenerate embryos that are morphologically comparable to zygotic embryos. The system provides a powerful in vitro tool for studying the diverse developmental processes that take place during the early stages of plant embryogenesis.

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Establishing an aseptic in vitro culture for Dendrobium, or for any plant in fact, is the most important step towards developing an effective in vitro tissue culture including micropropagation protocol. Success in initial aseptic culture will contribute to the successful production of in vitro cultures that may involve the initiation or formation of callus and/or protocorm-like bodies (PLBs), the induction, regeneration or multiplication of shoots, and the preparation and proliferation of plantlets suitable for acclimatization. The initiation of an aseptic culture is closely related to the appropriate selection of an explant source and its preparation, including its (in vivo) pre-treatment if necessary and subsequent disinfection procedures. Care in the choice of explant and the application of an appropriate disinfection protocol can successfully reduce, or eliminate, contamination in in vitro cultures while reducing the negative impact on plant tissues and plantlet regeneration. Many unique aseptic culture procedures for Dendrobium genus have been reported in the literature, very often specific to particular tissues or genotypes, and this review not only highlights the details of such protocols, but also provides practical advice for novice -and even seasoned -orchidologists who wish to research Dendrobium in vitro, although it is cautioned that there is currently no universal aseptic culture procedure that can be applied to all conditions, all explants or all genotypes.

Anthurium anther culture was successfully established using half-anthers as explants. Explants were cultured on Winarto-Teixeira basal medium (WT-1) containing 0.01 mg/l a-naphthalene acetic acid (NAA), 0.5 mg/l thidiazuron (TDZ), and 1.0 mg/l 6-benzylaminopurine (BAP), or on New Winarto-Teixeira basal medium (NWT-3) supplemented with 0.02 mg/l NAA, 1.5 mg/l TDZ, and 0.75 mg/l BAP for callus initiation. Regenerated calli produced multiple shoots on WT-1, which were then rooted in NWT-3 supplemented with 1% activated charcoal. Plantlets were acclimatized ex vitro using a mixture of burned rice husk, rice husk, and bamboo peat (1:1:1, v/v/v) as the potting medium. There was considerable morphological and cytological diversity of regenerants derived from anther culture, which are described in detail in this study. The callus cluster color ranged from green to light green and had a high regeneration capacity (7.3 and 4.8 shoots/callus cluster), light reddish-yellow callus showed moderate regeneration (2.6 shoots/callus cluster), while reddish-yellow callus had the lowest regeneration capacity (1.5 shoots/callus cluster). Morphological variations clearly observed in regenerants derived from this technique included alterations in plant size, peduncle length, spathe position compared to leaves, the type and number of buds, spathe and spadix color, and spadix length. There were also cytological variations in both in vitro and ex vitro regenerants of anther culture with 23-29% haploids, 5-10% aneuploids, 56-69% diploids, and 3-4% triploids. The results strengthen other studies in which the development of anther cultures, especially via callus formation, resulted in morphological and cytological alterations. These variations have been discussed to great length in this paper.

To improve the micropropagation of Dendrobium 'Gradita 31', coconut water (CW) and fertilizer media were used to enhance growth, proliferation, and germination of protocorm-like bodies (PLBs). PLBs formed when shoots approximately 0.4 cm long were cultured on semi-solid halfstrength Murashige and Skoog (MS) basal medium containing 1 mg L − 1 thidiazuron (TDZ) and 0.5 mg L − 1 N 6 -benzyladenine (BA). After four rounds of 15-d subcultures, PLBs were initially proliferated in liquid half-strength MS medium supplemented with 0.3 mg L − 1 TDZ and 0.1 mg L −1 α-naphthalene acetic acid (NAA) and subcultured monthly into fresh medium. When 15% (v/v) CW was added to half-strength MS medium, optimal growth and proliferation of PLBs resulted with the following principal findings: a maximum of 2.86 g total fresh weight (FW) of PLBs formed from 1 g of PLBs, an average of 0.46 g FW of PLBs added per subculture period, a total of 157.1 PLBs formed, an average of 25.3 PLBs added per subculture period, and a low percentage of PLB browning (20.7%). Half-strength MS medium containing 15% (v/v) CW with Rosasol ® medium (liquid fertilizer; 1.5 g L −1 18 N:18P:18 K+1.5 g L −1 25 N:10P:10 K+ TE) resulted in a similar organogenic outcome with 25.5% PLB browning. PLBs germinated easily and rooted on Rosasol-supplemented plant growth regulator-free medium.In total, 180 Dendrobium 'Gradita 31' plantlets from all treatments were successfully acclimatized with 100% survival on a Cycas rumphii bulk substrate and grew well after repotting in a mixture of wood charcoal and C. rumphii bulk (1:1, v/v).