The plant nuclear genome is largely composed of mobile DNA, which can rearrange genomes and other individual gene structure and also affect gene regulation through various promoted activities: transposition, insertion, excision, chromosome breakage, and ectopic recombination. Ty1-copia-like retrotransposon is a widespread class of transposable elements in the plant kingdom, representing a large part of the total DNA content. Here, a novel retrotransposon-like sequence was isolated and identified as the Ty1-copia-like reverse transcriptase domain (named here CLCoy1), based on the homology of known elements. Fluorescence in situ hybridization, revealed that CLCoy1 was mainly located in telomeric and sub-telomeric regions along the Citrus chromosomes. CLCoy1 composes 3.6% of the genome and, interestingly, while transposons are mostly specific to a species, this element was identified in other Citrus species such as Citrus aurantium, Fortunella margarita and Citrus paradisi, but undetected in Poncirus trifoliata. We also determined that wounding, salt and cell culture stress produced transcriptional activation of this novel retroelement in Citrus limon. The novel Ty1-copia-like element CLCoy1 may have played a major role in shaping genome structure and size during Citrus species evolution.
In vitro organogenesis was studied using Citrus limon L. Burm cv. ‘Primofiore’ leaf explants. The purpose of the present study was to optimize conditions for callogenesis and organogenesis of C. limon. Explants of C. limon were cultured on 16 different media supplemented with various combinations of plant growth regulators, both auxins and cytokinins, such as 6-benzylaminopurine (BAP), naphthalene acetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), and kinetin. The best shoot induction was obtained when the leaf explants were cultured on Murashige & Tucker media supplemented with 3.5 mg·L-1 BAP. Histological investigation revealed most likely the initial phase of development of leaf explants during in vitro regeneration of C. limon. t
A experiment was conducted to investigate the efficacy of different plant derivatives against the development of the green gram pest Callosobruchus chinensis (L). fed on green gram seeds Vigna radiate for one month period. The leaf extracts of lemon (Citrus lemon), mint (Mentha arvensis) and black pepper seed (Piper nigram) powders were evaluated for their growth, adult mortality and oviposition inhibition of Callosobruhus chinensis. The results revealed that the extracts of all the three plant products caused a considerable reduction in the number of bruchids. Among the treatments Piper nigram were found to be effective in destroying the pest.