The Cytokinins BAP and 2-iP Modulate Different Molecular Mechanisms on Shoot Proliferation and Root Development in Lemongrass (Cymbopogon citratus).

The known activities of cytokinins (CKs) are promoting shoot multiplication, root growth inhibition, and delaying senescence. 6-Benzylaminopurine (BAP) has been the most effective CK to induce shoot proliferation in cereal and grasses. Previously, we reported that in lemongrass (Cymbopogon citratus) micropropagation, BAP 10 µM induces high shoot proliferation, while the natural CK 6-(γ,γ-Dimethylallylamino)purine (2-iP) 10 µM shows less pronounced effects and developed rooting. To understand the molecular mechanisms involved, we perform a protein-protein interaction (PPI) network based on the genes of Brachypodium distachyon involved in shoot proliferation/repression, cell cycle, stem cell maintenance, auxin response factors, and CK signaling to analyze the molecular mechanisms in BAP versus 2-iP plants. A different pattern of gene expression was observed between BAP- versus 2-iP-treated plants. In shoots derived from BAP, we found upregulated genes that have already been demonstrated to be involved in de novo shoot proliferation development in several plant species; CK receptors (AHK3, ARR1), stem cell maintenance (STM, REV and CLV3), cell cycle regulation (CDKA-CYCD3 complex), as well as the auxin response factor (ARF5) and CK metabolism (CKX1). In contrast, in the 2-iP culture medium, there was an upregulation of genes involved in shoot repression (BRC1, MAX3), ARR4, a type A-response regulator (RR), and auxin metabolism (SHY2).

Sex determination in papaya: Current status and perspectives.

Papaya (Carica papaya L.) is an economically significant plant that produces fruit consumed worldwide due to its organoleptic characteristics. Since their commercial production, papaya fruits have faced several problems, such as pests, which have been partly resolved using transgenic varieties. Nevertheless, a principal challenge in this cultivation is the plant's sex determination. The sex issue in papaya is complex because papaya flowers can bear three sex forms: male, female, and hermaphrodite, which affects their fruit production, shape, and yield. Fruits from hermaphrodite plants are preferred more by consumers than female ones, and male plants rarely produce fruits without commercial value. Chromosomes are responsible for sex determination in papaya, denoted as XY for male, XX for female, and XYh for hermaphrodite. However, genes related to sex have been reported but are not conclusive. Factors such as the environment, hormones, and genetic and epigenetic background can also affect sex expression. Therefore, in this review, we will discuss recent research on the sex of papaya, from reported genes to date, their biology, and sexing approaches using molecular markers and their advantages.

Molecular delineation of the Agave Red Worm Comadia redtenbacheri (Lepidoptera: Cossidae).

Comadia redtenbacheri (Hammerschmidt) (Agave Red Worm) is the only member of the family Cossidae that has been described as a phytophagous specialist of the plant genus Agave, which is mainly distributed in México. A new extraction protocol adapted from Stewart Via (1993) has been implemented for sequencing the COI gene from samples collected in five states of the North Central (Querétaro and Zacatecas), South Central (Estado de México) and East Central (Hidalgo and Tlaxcala) regions of México with the purpose of contributing to delineation of the species. A Maximum Likelihood (ML) tree based on these COI sequences as well as COI sequences from other Cossinae species was developed to complement the existing morphological and taxonomic approaches to delineation of this species. As expected, our Comadia samples cluster together within a monophyletic clade that includes four C. redtenbacheri sequences previously reported. This group seems to be consistent with our reconstruction, which is supported by a bootstrap value of over 99%. The closely related branches associated with the latter group include organisms known to be the plant and tree borers of the Cossinae subfamily. The COI sequences from our samples were analyzed to determine the percentage of identity among the C. redtenbacheri in a first attempt to detect differences in the sequence that matches a particular region of México.