Kopyor versus macapuno coconuts: are these two edible mutants of Southeast Asia the same?

MAIN CONCLUSION: Kopyor and macapuno are two coconut mutants from Southeast Asia that are often described erroneously or interchangeably mismatched due to a lack of research, so future studies are encouraged. Coconut (Cocos nucifera L.; Arecaceae), a widely distributed plant with popular culinary applications, especially of the endosperm, has several nutritional and medicinal benefits. Two coconut mutants are widely recognized in Southeast Asia, namely kopyor and macapuno, specifically in Indonesia and Philippines, respectively. Kopyor coconut is known for its brittle solid endosperm while macapuno coconut is known for its gelatinous solid endosperm. Both mutant types have many other synonyms in other countries. Over many decades, the biology of macapuno coconut, including endosperm anatomy, histology, cytology, physiology, and genetics have been described, while kopyor coconut is still understudied. However, some literature and websites erroneously describe kopyor as macapuno coconut, or consider them interchangeably, which is an unintentional consequence of insufficient scientific research on these coconut mutants. Additionally, in Indonesia, there is another local mutant in Banten called wax coconut ("kelapa lilin") that some researchers claim as the actual Indonesian macapuno coconut due to its strong resemblance to kopyor coconut. Unfortunately, wax coconut is not only understudied, it is rarely documented. Additional evidence of their differences, in terms of morphological, biochemical and genetic characteristics, is needed. Moreover, clear documentation will also be needed for a better comparison. Understanding the differences between kopyor and macapuno coconuts will not only help to further clarify their scientific description in the literature, but will also guide locals, researchers, and industries to characterize similar mutants, if found in specific regions, for future study and bioprospecting.

The term "caline" in plant developmental biology.

In the 1930s, Frits Warmolt Went conducted a number of seminal studies on pea seedlings that had been germinated in the dark and assessed their growth when either the apical parts, cotyledons, or roots were cut off or grafted, to assess whether coplant growth factors assisted auxin in the development of these organs. Went assigned the term "calines" to all auxin-assisting substances, specifically rhizocaline, caulocaline, and phyllocaline in root, shoot (and axillary buds) and leaf development, respectively. Those experiments were based exclusively on growth assays, and no supplementary biochemical or physiological analyses were ever conducted, and additional proof was only provided by Went using pea or tomato. The lack of independent reproducibility by other groups, combined with the fact that the hormonal control of these developmental events in plants is now fairly well-studied event, even at the molecular level, suggests that these growth factors that Went observed 80 years ago either do not exist or are known by some other term in modern plant development. The terms related to "calines" should thus no longer be used in plant developmental biology.

Promoter analysis of the SPATULA (FvSPT) and SPIRAL (FvSPR) genes in the woodland diploid strawberry (Fragaria vesca L.).

The aim of this study was to identify transcription factor (TF) binding sites and cis-regulatory elements (CREs) on the promoters of FvSPR1-like2 (SPIRAL) and FvSPT (SPATULA) genes in the woodland diploid strawberry (Fragaria vesca L.). We identified: (1) MYB59, WRKY25 and WRKY8 TFs which play a role in ethylene signaling; (2) ARF family of TFs which play a role in ARF-mediated auxin signaling on the promoter of FvSPR1-like2 gene; (3) ARR family of TFs which play a role in cytokinin signaling; (4) ERF family of TFs which play a role in ethylene signaling on the promoter of FvSPT. This bioinformatic analysis of TFs and CREs may provide a better understanding of the function of genes involved in, and the mechanism underlying, non-climateric ripening during strawberry fruit maturation.

Cryopreservation of carnation (Dianthus caryophyllus L.) and other Dianthus species.

MAIN CONCLUSION: This paper reviews the cryopreservation of the ornamental, carnation (Dianthus caryophyllus L.), as an important method for the long-term preservation of this plant's germplasm. Carnation (Dianthus caryophyllus L.) is an important ornamental plant that is used as a potted plant as well as a cut flower. Important Dianthus germplasm would benefit from long-term strategies such as cryopreservation. Unlike the in vitro tissue culture literature of this ornamental, which has been studied in considerable detail, and with several genetic transformation protocols, surprisingly, the literature on its cryopreservation is still fairly scant, with barely two dozen or so studies, mostly having employed shoot tips. Early (< 2007) and more recent (2007-2020) cryopreservation techniques for carnation, including ultra-rapid cooling, encapsulation-vitrification, and encapsulation-dehydration, efficiently replaced programmed slow cooling processes used in early studies in the 1980s. Two large gaps (1997-2006, and 2016-2020) in which no carnation cryopreservation studies were published, requires future studies to cover new knowledge to fill gaps in information. Carnation cryopreservation research would benefit from testing a wide range of in vitro explants, new techniques such as the cryo-mesh, improved regeneration protocols for post-cryopreserved material, and the use of low-temperature storage as a mid- to long-term complementary germplasm storage strategy. This mini-review provides details of what has been achieved thus far and future objectives that could fortify cryopreservation research of this ornamental, as well as provide a robust long-term germplasm repository.

Shoot tip necrosis of in vitro plant cultures: a reappraisal of possible causes and solutions.

MAIN CONCLUSION: Shoot tip necrosis is a physiological condition that negatively impacts the growth and development of in vitro plant shoot cultures across a wide range of species. Shoot tip necrosis is a physiological condition and disorder that can arise in plantlets or shoots in vitro that results in death of the shoot tip. This condition, which can spread basipetally and affect the emergence of axillary shoots from buds lower down the stem, is due to the cessation of apical dominance. STN can occur at both shoot multiplication and rooting stages. One of the most common factors that cause STN is nutrient deficiency or imbalance. Moreover, the presence or absence of plant growth regulators (auxins or cytokinins) at specific developmental stages may impact STN. The cytokinin to auxin ratio within an in vitro plant can be modified by varying the concentration of cytokinins used in the culture medium. The supply of nutrients to in vitro shoots or plantlets might also affect their hormonal balance, thus modifying the occurrence of STN. High relative humidity within culture vessels and hyperhydricity are associated with STN. An adequate supply of calcium as the divalent cation (Ca2+) can hinder STN by inhibiting the accumulation of phenolic compounds and thus programmed cell death. Moreover, the level of Ca2+ affects auxin transport and ethylene production, and higher ethylene production, which can occur as a result of high relative humidity in or poor ventilation of the in vitro culture vessel, induces STN. High relative humidity can decrease the mobility of Ca2+ within a plant, resulting in Ca2+ deficiency and STN. STN of in vitro shoots or plantlets can be halted or reversed by altering the basal medium, mainly the concentration of Ca2+, adjusting the levels of auxins or cytokinins, or modifying culture conditions. This review examines the literature related to STN, seeks to discover the associated factors and relations between them, proposes practical solutions, and attempts to better understand the mechanism(s) underlying this condition in vitro.

Rafflesia patma Blume flower organs: histology of the epidermis and vascular structures, and a search for stomata.

MAIN CONCLUSION: A histological study of Rafflesia patma revealed the simplicity of a flower's vascular tissue and epidermal features of flower organs, including their structures and pigmentation. Rafflesia is an endophytic holoparasitic plant that infects Tetrastigma. In a previous study, we characterized the shape of the strands of an endophyte (Rafflesia patma Blume) and hypothesized their distribution. In this study, we deepened our analysis by assessing parts of flower tissue sampled during anthesis, performed surface casting of the abaxial and adaxial sides of the perigone lobe to profile their surface features, and histologically characterized the perigone lobe, perigone tube, and central column base, including the anther and cupula region. The objective of these observations was to compare tissues from different organs and the distribution of cells staining positive for tannin, suberin, and lignin. Observable features in this study were vascular and epidermal tissue. We also observed reduced vascular tissue with xylem and vascular parenchyma in multiple organs. The adaxial epidermis found in the perigone lobes and tube had papillate cells, and their function might be to assist with the emission of odor through chemical evaporation. The abaxial epidermis, also found in perigone lobes and tube, had flattened cells. These, combined with the nearby flattened parenchyma cells, especially in the outermost, early perigone lobe, might provide a tougher (stiffer) outer protective barrier for the flower. The accumulation of tannin in perigone lobes might offer protection to the flower from herbivores prior to anthesis. Although a previous observation indicated the possibility of stomata on the surface of Rafflesia flowers, no stomata were found in this study.

The water-hopping kinematics of the tree-climbing fish, Periophthalmus variabilis.

In this communication, we describe the water-hopping kinematics of the dusky-gilled mudskipper (Periophthalmus variabilis), and by doing so elucidate an entirely new form of fish locomotion that has yet to be reported in the public domain. Water-hopping is defined herein as an ability to hop once, or in succession, on the surface of water without full submergence and without a fin-guided glide. We find that taxiing on the water surface is the predominating kinematic movement used for the execution of successful water-hops. We observe that an initial concentric ripple forms as the mudskipper impacts the water, and that subsequent taxiing on the water surface generates a sinusoid-like ripple pattern in the water prior to take off. Interestingly whilst airborne, the pectoral fins of P. variabilis appear to remain stationary, only to be deployed upon contact with the water. When landing back onto the surface of the water, P. variabilis makes the initial contact via its pelvic region, occasionally extending its pectoral fins during its descent. The reasons for pectoral and pelvic fin extension are unclear, however, there may be either aerodynamic or hydrodynamic benefits in its doing so. This motion furthermore prepares the mudskipper for either, a follow-on water-hop, or a discontinuation of movement altogether, as the body of the mudskipper becomes aligned in a way conducive to either. P. variabilis will launch and land using both, horizontal surfaces such as littorals, and inclined-to-vertical surfaces such as rocks and trees.

The significance of pelvic fin flexibility for tree climbing fish.

In this article, we compare the characteristics of biomechanical attachment exhibited by two morphologically different mudskipper species, Boleophthalmus boddarti (with fused pelvic fins) and Periophthalmus variabilis (with unfused pelvic fins). P. variabilis is a tree and rock climber while B. boddarti dwells in the muddy shallows and is unable to climb. Our aim in this article is to determine whether it is predominantly chemical or morphological properties of the pelvic fins from each species that may allow P. variabilis to climb trees whilst preventing B. boddarti from doing the same. To fulfil our objective we perform friction and suction resistance tests, Fourier transform infrared spectroscopy of the mucosal secretions under the fins, direct geometrical measurements and finite element modelling. We find that B. boddarti has considerable resistance to pull-off forces, while P. variabilis has greater frictional resistance. Both species produce mucopolysaccaharides that we suggest aid Stefan adhesion to different substrates. P. variabilis fins are, nevertheless, considerably more flexible than those of B. boddarti and we conclude that P. variabilis is consequently able to maintain a more intimate surface area of contact with underlying material, which aids Stefan adhesion, increases frictional resistance, and helps it to climb trees.

Rafflesia spp.: propagation and conservation.

MAIN CONCLUSION: The propagation of Rafflesia spp. is considered to be important for future development of ornamental and other applications. Thus far, the only successful propagation technique has been grafting. This mini-review succinctly emphasizes what is known about Rafflesia species. Members of the genus Rafflesia (Rafflesiaceae), which are holoparasitic plants known to grow on a host vine, Tetrastigma sp., are widely spread from the Malayan Peninsula to various islands throughout Indonesia. The plant's geographical distribution as well as many other aspects pertaining to the basic biology of this genus have still not been studied. The young flower buds and flowers of wild Rafflesia hasseltii Suringar, Rafflesia keithii Meijer and Rafflesia cantleyi Solms-Laubach are used in local (Malaysia and Indonesia) traditional ethnomedicine as wound-healing agents, but currently no formal published research exists to validate this property. To maintain a balance between its ethnomedicinal and ornamental use, and conservation, Rafflesia spp. must be artificially cultivated to prevent overexploitation. A successful method of vegetative propagation is by host grafting using Rafflesia-impregnated Tetrastigma onto the stem of a normal Tetrastigma plant. Due to difficulties with culture contamination in vitro, callus induction was only accomplished in 2010 for the first time when picloram and 2,4-D were added to a basal Murashige and Skoog medium, and the tissue culture of holoparasitic plants continues to be extremely difficult. Seeds harvested from fertile fruit may serve as a possible method to propagate Rafflesia spp. This paper provides a brief synthesis on what is known about research related to Rafflesia spp. The objective is to further stimulate researchers to examine, through rigorous scientific discovery, the mechanisms underlying the ethnomedicinal properties, the flowering mechanisms, and suitable in vitro regeneration protocols that would allow for the fortification of germplasm conservation.