This is the oldest English language journal in genetics. Founded by W. Bateson and R. C. Punnett in 1910, the Journal of Genetics was later edited by J. B. S. Haldane; later, Haldane and his wife, Helen Spurway brought the journal with them to India. After his death in 1964, Mrs. Haldane continued publication of the journal, with Madhav Gadgil and H. Sharat Chandra (Indian Institute of Science, Bangalore) and Suresh Jayakar (Laboratorio de Genetica Biochimica ed Evoluzionistica, Pavia) as editors, until her own death in 1977. In 1985, with the permission of Haldane’s heirs, the Indian Academy of Sciences resumed publication of the journal. The journal retains its traditional interest in evolutionary research that is of relevance to geneticists, even if not explicitly genetic in nature.

The journal of genetics

Sex chromosomes evolved from autosomes many times across the eukaryote phylogeny. Several models have been proposed to explain this transition, some involving male and female sterility mutations linked in a region of suppressed recombination between X and Y (or Z/W, U/V) chromosomes. Comparative and experimental analysis of a reference genome assembly for a double haploid YY male garden asparagus (Asparagus officinalis L.) individual implicates separate but linked genes as responsible for sex determination. Dioecy has evolved recently within Asparagus and sex chromosomes are cytogenetically identical with the Y, harboring a megabase segment that is missing from the X. We show that deletion of this entire region results in a male-to-female conversion, whereas loss of a single suppressor of female development drives male-to-hermaphrodite conversion. A single copy anther-specific gene with a male sterile Arabidopsis knockout phenotype is also in the Y-specific region, supporting a two-gene model for sex chromosome evolution.

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The asparagus genome sheds light on the origin and evolution of a young y chromosome

Plant population biology: edited by A.J. Davy, M.J. Hutchings and A.R. Watkinson, Blackwell Scientific Publications (28th Symposium of the British Ecological Society), 1988. £40.00 hbk (viii + 478 pages) ISBN 0 632 02349 X

Microbial contamination is a serious problem in temporary immersion systems (TIS) during commercial micropropagation. The use of adequate doses of silver nanoparticles (AgNPs), formulated as Argovit™, is an alternative to reduce the contamination indices and promote development in plants. The aim of this study was to evaluate the antimicrobial and hormetic effects of Argovit on in vitro regeneration of vanilla (Vanilla planifolia) using a TIS. In vitro regenerated shoots were grown in Murashige and Skoog (MS) liquid medium with Argovit at five different concentrations (0, 25, 50, 100 and 200 mg/l) using a temporary immersion bioreactor system (RITA®). At 30 days of culture, contamination percentage was evaluated and shoot regeneration and length were used to determine the hormetic response. Analysis of macro and micronutrient contents was performed. In addition, the effect of Argovit on total phenolic content (TPC), reactive oxygen species (ROS) production, antioxidant capacity (ORAC) and lipid peroxidation (LP-MDA) was determined. Results showed that bacterial contamination was reduced at 50, 100 and 200 mg/l of Argovit. Growth stimulation was observed at 25 and 50 mg/l of Argovit, while significant inhibition was detected at 100 and 200 mg/l of Argovit. Mineral nutrient analysis revealed changes in macro and micronutrient concentrations exerted by Argovit. Moreover, the presence of Argovit induced the production of ROS and increased total phenolic content, antioxidant capacity and lipid peroxidation with a dose-dependent effect. Results suggested that the production of ROS and mineral nutrition are key mechanisms of AgNPs-induced hormesis for vanilla. Therefore, the addition of 50 mg/l of Argovit in the culture media had an antimicrobial and hormetic effect. Use of Argovit could be an efficient strategy for commercial micropropagation of vanilla and other species.

Antimicrobial and hormetic effects of silver nanoparticles on in vitro regeneration of vanilla (Vanilla planifolia Jacks. ex Andrews) using a temporary immersion system

Abscisic acid enhances lead translocation from the roots to the leaves and alleviates its toxicity in Populus × canescens.

Garden asparagus (Asparagus officinalis L.) is an economically important plant with 2n = 2x = 20 chromosomes and a haploid genome size of 1323 Mb (Bennett and Leitch 2003). The karyotype of asparagus consists of five long (L), one medium (M) and four small (S) chromosomes (Löptien 1976). Plants of this dioecious species differ in producing either male or female flowers. The sexual dimorphism in asparagus is controlled by a region located on a pair of homomorphic sex chromosomes (chromosome L5) (Löptien 1979) termed the M locus (Flory 1932; Uno et al. 2002). Maleness is dominant with males normally heterogametic (Mm) and females homogametic (mm). Supermales (MM) can be produced from anther culture or from rarely occurring andromonoecious plants. The identification of chromosome L5 is important for studying sex chromosome evolution in asparagus. However, it was observed that the sex chromosome pair is homomorphic: X and Y chromosomes do not differ in morphology. Telgmann-Rauber et al. (2007) tried to clone the region determining sex in asparagus from its position in the genome. Molecular cytogenetic and sequence analyses of bacterial artificial chromosomes (BACs) flanking M locus indicate that the BAC contain highly repetitive sequences that localize to centromeric and pericentromeric locations on all asparagus chromosomes. However, the L5 chromosome could not be distinguished by BAC-FISH (Telgmann-Rauber et al. 2007). Recently, FISH has become a powerful and useful tool for the direct detection of specific DNA in genome. In this technique, ribosomal DNA genes (45S and 5S rDNA) are commonly used as markers for the physical mapping of plant chromosomes to analyse genomic organization (Nakayama et al. 2001; Lan et al. 2006; Grabowska-Joachimiak et al.

Karyotype of asparagus by physical mapping of 45S and 5S rDNA by FISH.

The effects of exposure to heavy metals, copper (Cu) and lead (Pb) in the
 soil, separately and in combination, were examined in Safflower (Carthamus
 tinctorius L.). Plant growth and development, GSH level and GSH2 expression
 at seedling, branching, and flowering stages were studied. Cu at lower
 concentrations had a stimulating effect on seedling height and root length. A
 significant positive correlation was observed between heavy metal
 concentrations and inhibition of plant growth. Plant height, root length and
 lateral root numbers decreased progressively with increasing concentrations
 of Cu and Pb. Except at the seedling stage, the metal mixture elicited a
 synergistic effect on safflower growth and development. The GSH content was
 significantly reduced in both safflower roots and leaves at increased
 concentrations of heavy metals, with the exception of the treatment with a
 low concentration of Cu that resulted in a slightl increase in GSH content at
 the seedling and branching stages. RT-PCR analysis revealed a negative
 correlation between GSH2 expression levels and metal concentration. Short
 exposure to low concentrations of Cu induce an increase in GSH synthesis to
 preserve normal plant growth, whereas prolonged exposure and large Cu and Pb
 concentrations affect the GSH metabolic chain, and are severely toxicity. The
 findings obtained in this study enhance our understanding of the role of the
 GSH pool in the response of plants to heavy metal-induced stress, and serve
 as a basis for improved cultivation of safflower.

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Plant growth, development and change in GSH level in safflower (Carthamus tinctorius L.) exposed to copper and lead

Asparagus officinalis is an economically and nutritionally important vegetable crop that is widely cultivated and is used as a model dioecious species to study plant sex determination and sex chromosome evolution. To improve our understanding of its genome composition, especially with respect to transposable elements (TEs), which make up the majority of the genome, we performed Illumina HiSeq2000 sequencing of both male and female asparagus genomes followed by bioinformatics analysis. We generated 17 Gb of sequence (12×coverage) and assembled them into 163,406 scaffolds with a total cumulated length of 400 Mbp, which represent about 30% of asparagus genome. Overall, TEs masked about 53% of the A. officinalis assembly. Majority of the identified TEs belonged to LTR retrotransposons, which constitute about 28% of genomic DNA, with Ty1/copia elements being more diverse and accumulated to higher copy numbers than Ty3/gypsy. Compared with LTR retrotransposons, non-LTR retrotransposons and DNA transposons were relatively rare. In addition, comparison of the abundance of the TE groups between male and female genomes showed that the overall TE composition was highly similar, with only slight differences in the abundance of several TE groups, which is consistent with the relatively recent origin of asparagus sex chromosomes. This study greatly improves our knowledge of the repetitive sequence construction of asparagus, which facilitates the identification of TEs responsible for the early evolution of plant sex chromosomes and is helpful for further studies on this dioecious plant.

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Analysis of transposable elements in the genome of Asparagus officinalis from high coverage sequence data.

Male and female spinach (Spinacia oleracea L, 2n = 12) were karyotyped by chromosome measurements and subjected to fluorescence in situ hybridization with 45s rDNA The chromosome complement comprised two long nearly subtelocentrics, two short subtelocentrics, two acrocentrics, and six submetacentrics. The X and Y chromosomes were not distinguished by morphological analysis; thus, six obvious 45s rDNA sites were labeled with Texas red and clearly observed as red signals on three pairs of chromosomes. Among the three pairs of signal sites, a pair of the largest one was located on the short arms of chromosome 5, which is a satellite chromosome. Another prominent signal site was found on the short arms of chromosomes 2 and 6. However, from single images with 45s rDNA (red) of male or female spinach, weak 45s rDNA sites labeled with Texas red were observed on chromosomes 1 and 3. The weak 45s rDNA signals site were located on the large arm of chromosome 3 of both male and female spinach. Interestingly, differe...

https://www.tandfonline.com/doi/pdf/10.1080/00087114.2012.760879

Identification of sex chromosome of spinach by physical mapping of 45s rDNAs by FISH

Spinach (Spinacia oleracea L.) is a diploid dioecious plant with a pair of homomorphic sex chromosomes X and Y. Plant DNA methylation, a known process for genome epigenetic modification, regulates gene expression in plants. To explore the effects of DNA methylation on spinach growth and sexual development, spinach seeds were treated with the demethylating reagent 5-azaC. The resulting phenotypes were then investigated, including germination percentage, root length, plant height, flowering time, and sexual phenotype. Results showed that 5-azaC at a low concentration (30 µM) only slightly influenced spinach development but promoted seed germination. The germination percentage, root length, and plant height negatively correlated with 5-azaC at 100–1000 µM. The flowering time significantly reduced at all four treatments with 5-azaC. In addition, 5-azaC influenced the sexual phenotype of spinach and remarkably increased the percentage of monoecious individuals. These results may suggest that vegetative and reproductive growth are both epigenetically regulated by DNA methylation.

Long-Dou Lu

Papers

Karyotype of asparagus by physical mapping of 45S and 5S rDNA by FISH.

Plant growth, development and change in GSH level in safflower (Carthamus tinctorius L.) exposed to copper and lead

Analysis of transposable elements in the genome of Asparagus officinalis from high coverage sequence data.

Identification of sex chromosome of spinach by physical mapping of 45s rDNAs by FISH

Effect of 5-azaC on the growth, flowering time and sexual phenotype of spinach