Anatomical and Ultrastructural Peculiarities in the Laticifers of Euphorbia antiquorum L.: A Potential Source for the Biofuel Production

The present study was conducted to examine the anatomy, distribution and ultrastructure of laticifer system in phylloclades of Euphorbia antiquorum L. by light and transmission electron microscopy. The phylloclade shows several anatomical characteristics well adapted to the xerophytic environment. Transverse section of E. antiquorum phylloclade displays three distinct regions namely cortical tissue, vascular cylinder and the pith region. Nonarticulated laticifers are present in three tissues, but their frequency varies with the tissue type. Highest laticifer frequency was observed in vascular cylinder (14%) followed by cortex (3.9%) and pith regions (3%). In contrast, laticifer index was greatest in the pith (9.7%) followed by vascular cylinder (6.9%) and in the cortex (4.9%). Laticifers were well recognized by the presence of nucleus and dense cytoplasm rich in ribosomes, mitochondria, plastids, endoplasmic reticulum, two types of vacuoles and osmophilic bodies when compared to the adjacent cells. Histo-chemical tests revealed the presence of phenolics, proteins, terpenoids, starch, alkaloids, indicating that this species may be useful as a potential feedstock for the production of biofuels in future from semiarid or arid environments. The discovery of laticifer system in E. antiquorum was not described earlier could also be of taxonomic value

Doubled haploid production in onion (Allium cepa L.): from gynogenesis to chromosome doubling

Bulb onion (Allium cepa L.) is an allogamous diploid (2n = 16) important for its culinary uses, nutritional value, and medicinal benefits. Despite its economic importance, onion yields and bulb quality are declining, emphasizing the need for new and improved strategies for maintaining and enhancing overall crop quality. Development of inbred lines in onion through traditional breeding is often difficult due to its biennial life cycle, inbreeding depression, and comparatively high heterozygosities. Moreover, genetic research in onion has been hampered by large nuclear genome size. In this regard, gynogenic doubled haploids promise several advantages over inbred lines in support of onion breeding programs and genetic studies. These include complete homozygosity in doubled haploid lines, reduced DNA methylation, elimination of deleterious alleles, and amenability to genetic analysis. This review focuses on the application of in vitro gynogenesis for producing doubled haploids in onion. Factors influencing haploid induction, methods for inducing chromosome doubling and ploidy assessment, evaluation of haploid progenies and doubled haploid lines, and features of doubled haploids potentially useful in crop improvement and genetic studies, are discussed. We identify four major limitations to the success and efficiency of in vitro gynogenesis in onion and discuss strategies for mitigating the negative impacts they pose. This review may be useful to research programs producing doubled haploids in onion or other Allium species using in vitro gynogenesis