Critical review on karyotype diversity in lentil based on classical and molecular cytogenetics

Lentil is an annual protein rich valuable edible crop with only one cultivated and six wild taxa. Keeping in mind its narrow gene pool, the genus deserves critical assessment of genomic diversity at the chromosomal level. Genetic diversity represents the heritable variation within and between populations of organisms. Over the decades classical and molecular cytogenetics have played an immense role in the field of crop improvement. Lentil, though grown in different countries, country-wise chromosomal information is inadequate. Critical evaluation of more than seven decades chromosomal information has revealed unique karyotype diversity within the landraces of different countries. Application of fluorescent banding and fluorescent in situ hybridization (FISH) has helped to segregate cultivars based on cultivar specific chromosomal markers and landmarks. Selection of cultivated and wild cultivars based on qualitative and diseases related morpho-traits and new information from this critical review especially on molecular cytogenetics may provide more options for crop improvement. More research in the field of molecular cytogenetics from country specific species and cultivars are needed to enrich the repository of gene pool. Alien gene introgression from extended gene pool through the advanced genomics and biotechnological tools could facilitate the path of sustainable improvement of this crop.

Conservation of floral, fruit and chromosomal diversity: a review on diploid and polyploid Capsicum annuum complex in India

Capsicum as a spice crop, has wild and cultivated forms admired globally, including Indian subcontinent with vast climatic ranges. Systematic representation of the Indian Capsicum is required to address species relationships and sustainable agriculture, in face of unpredictable climatic conditions. We have updated the catalogue of Indian 'C. annuum complex' with 28 landraces and populations from different agro-climatic regions. The agro-climatic influence on the origin of stable chili landraces in India is remarkable, especially in the North East. The floral and fruit morphotype standards and chromosomal attributes have been considered for four distinct 'C. annuum complex' members under three species. The highlights of study are: (1) comparative profiling of Indian Capsicum species revealing less infraspecific variation within C. frutescens and C. chinense than C. annuum, at par with cultivation status, (2) karyotype analysis of some unique diploid landraces of C. annuum, (3) karyotypic confirmation of the polyploid Dalle Khursani landraces exclusive to India. To obtain more information, we attempted to correlate diversity of fruit and floral morphotype with chromosomal diversity. Existence of elite and rare germplasm found in the regional pockets offer great scope for enriching the agricultural tradition. The present dataset may serve as a template to be continuously upgraded by taxonomists, genomicists and breeders.

Karyotype diversity in cultivated and wild Indian rice through EMA-based chromosome analysis

India is known for its diverse cultivated and wild rice germplasm. In today's crop improvement programmes, wild relatives are much-needed genetic repository of valuable traits. Analysis of genetic diversity at the chromosomal level is one cost-effective tool to unlock foundational information related to genetics and plant breeding. Presently, enzymatic maceration and air-drying method (EMA) has been applied for the first time in six cultivated and nine wild Indian rice (diploid and tetraploid). EMA method following Giemsa staining has yielded large numbers of cytoplasm free metaphase plates with distinct chromosome morphology. Detailed analysis has revealed karyotype diversities in terms of total chromatin length (TCL), chromosome morphology and location of sat chromosomes within and between the studied species. Most of the cultivated rice has gained additional amount in TCL during the period of domestication in comparison to their progenitor Oryza nivara. Morphological clarity of the small chromosomes of rice was much required and has helped to identify individual chromosomes in the diverse karyotypes. Diversity in landmark SAT chromosomes is another important observation, not reported previously in Indian rice. Present study has shown that in most of the O. sativa members, the 10th pair contains SAT except one where 6th pair is satellited. On the other hand, diversity of SAT in diploid and tetraplod wild species has been recorded on 5th, 7th and 8th chromosome pairs and on 9th, 12th, 22nd and 23rd chromosome pairs, respectively. Karyomorphometric indices has helped to construct dendrogram to elucidate intraspecies and interspecies relationships. Untapped genetic diversity recorded in Indian rice through chromosomal analysis will be useful to the breeders and genome researchers.

Characterization of some Indian Himalayan Capsicums through floral morphology and EMA-based chromosome analysis

The North Eastern Himalayan (NEH) regions of India are considered as one of the major repositories of the "Capsicum annuum complex" which comprises of three cultivated species namely C. annuum, C. frutescens, and C. chinense. The interspecific delimitation within this large complex is ill-defined due to poorly developed crossing barriers and lack of discontinuous morphological characters. The present study elucidates the relationship among nine different cultivars of three Capsicum species on the basis of floral morphology and karyological parameters for the first time. Different floral characteristics such as margins and constrictions of calyx, type of pedicel, flower size, and color were found to have paramount importance in the species delimitation within the studied members of "C. annuum complex." The present karyomorphometric study explicitly revealed differences between the observed chromosomal data such as karyotype formulae, ordering of satellite bearing chromosome pairs and total diploid chromatin length which aid in resolving interspecific relationship among the studied cultivars of Capsicum. The present analyses unambiguously distinguished all cultivars of C. annuum from the members of C. frutescens and C. chinense and also proposed that among the five cultivars of C. annuum, Ghee lanka was comparatively distant from the other four cultivars on the basis of their karyomorphological characteristics. For the first time karyotype of hottest Indian chili is included in this paper. Comprehensive knowledge on floral morphology and karyotypes of some Himalayan Capsicums not only help to conserve genetic diversity but also help capsicum breeders for their basic and applied research.

Searching chromosomal landmarks in Indian lentils through EMA-based Giemsa staining method

Lentil is one of the oldest protein-rich food crop with only one cultivated and six wild species. India is one important cultivator, producer and consumer of lentils and possesses a large number of germplasms. All species of lentil show 2n = 14 chromosomes. The primary objective of the present paper is to search chromosomal landmarks through enzymatic maceration and air drying (EMA)-based Giemsa staining method in five Indian lentil species not reported elsewhere at a time. Additionally, gametic chromosome analysis, tendril formation and seed morphology have been studied to ascertain interspecific relationships in lentils. Chromosome analysis in Lens culinaris, Lens orientalis and Lens odemensis revealed that they contain intercalary sat chromosome and similar karyotypic formula, while Lens nigricans and Lens lamottei showed presence of terminal sat chromosomes not reported earlier. This distinct morphological feature in L. nigricans and L. lamottei may be considered as chromosomal landmark. Meiotic analysis showed n = 7 bivalents in L. culinaris, L. nigricans and L. lamottei. No tendril formation was observed in L. culinaris, L. orientalis and L. odemensis while L. nigricans and L. lamottei developed very prominent tendrils. Based on chromosomal analysis, tendril formation and seed morphology, the five lentil species can be separated into two distinct groups. The outcome of this research may enrich conventional and biotechnological breeding programmes in lentil and may facilitate an easy and alternative method for identification of interspecific hybrids.

Karyological relationships in Indian species of Drimia based on fluorescent chromosome banding and nuclear DNA amount

The genus Drimia (syn. Urginea), commonly called squill, represents a species complex, infrageneric delimitation being ill-defined due to morphological variability, population variation within species and polyploidy. In the present study, fluorescent chromosome banding and measurements of nuclear DNA content by flow cytometry were performed in five Indian species of Drimia: Drimia indica, Drimia polyantha, Drimia razii, Drimia wightii and Drimia coromandeliana to elucidate taxonomic relationship and obtain possible insights into the evolutionary processes within this group. All taxa analyzed exhibited similar karyomorphology with subtle differences accounted by nucleolar chromosomes. Nuclear DNA content ranged from 20.41 pg/2C in D. polyantha to 40.80 pg/2C in D. coromandeliana and was positively correlated with chromosome number (r = 0.67, P = 0.02) and total diploid chromatin length (r = 0.59, P = 0.06). Fluorescent chromosome banding revealed the presence of CMA(+ve)/DAPI(-ve) signals associated with nucleolar chromosomes presumably coincident with NOR in all species and unique CMA(+ve) signals in diploid populations of D. indica. Satellite polymorphism between homologous NOR-bearing chromosomes was observed which supports hybrid origin of the taxon. UPGMA dendrogram and scatter diagrams based on karyological parameters indicated a close relationship of D. indica, D. razii and D. polyantha while D. wightii and D. coromandeliana appeared distant. D. wightii appeared more close to D. indica than to all other species based on genome size and karyomorphology. As a whole, D. indica showed high intra-specific variability with populations exhibiting intergrading characters with other species. In conclusion, it is likely that hybridization followed by reproductive isolation of polymorphic forms arising by adaptation to different ecological niches resulted in species diversification of Drimia in India, probably from a common ancestor similar to D. indica.

In vitro Root Culture : An Alternative Source of Bioactives in the Rare Aphrodisiac Herb Chlorophytum borivilianum Sant et Fern

Chlorophytum borivilianum is a rare, near-endemic high value root crop. The fasciculated roots of the plant have the potential to synthesize valuable bioactives having aphrodisiac, anti stress and immuno modulatory properties. The present investigation describes an alternative protocol for the development of a stable, fast growing, non-transformed root culture system in C. borivilianum and the simultaneous quantitative analysis of total steroidal saponins, amino acids and sugars. Liquid MS fortified with various concentrations and combinations of BA (0.44 - 8.8 µM), Kn (0.23 µM) and NAA (0.27 - 5.4 µM) was effectively used for the development of root culture system. High performance thin layer chromatography (HPTLC) was used for quantification and comparative analysis of bioactives from in vitro and in vivo grown tuberous roots. D. O. I.  http://dx.doi.org/10.3329/ptcb.v23i2.17505 Plant Tissue Cult. & Biotech. 23(2): 133-146, 2013  (December)

Improved taxol yield in cell suspension culture of Taxus wallichiana (Himalayan yew)

Cell culture of Taxus wallichiana Zucc (= T. baccata ssp wallichiana Zucc. Pilg.) (Himalayan yew) has been established and taxol-producing cell lines selected by cell line cloning. Cell line NC110 derived from needle leaf of a 40-year-old tree growing in Darjeeling Himalayas produced 0.018% taxol in B5 basal medium supplemented with 2,4-D (2 mg/l), kinetin (0.5 mg/l), and casein hydrolysate (0.5%). This cell line has been maintained for over 2 years. Significant enhancement in the level of taxol (0.05%) was obtained in this cell line by supplementation of the basal medium with 5 mg/l of IAA-phenylalanine instead of 2,4-D without adversely affecting cell growth. IAA-glycine also enhanced taxol level (0.03%) while IAA alone (1-10 mg/l) was ineffective in inducing taxol accumulation. Using three different cell lines with different taxol-producing capacities, it has been demonstrated that 2,4-D and IAA-phenylalanine when present alone favour growth and taxol production but when combined enhance biomass to a maximum (six-fold in NC110) without enhancing taxol accumulation, suggesting that a two-stage culture may be beneficial for optimising taxol accumulation in cell culture of T. wallichiana.

In vitro propagation of cashewnut

In vitro plant propagation was developed for seedling shoot tips, leaf axils, and cotyledonary nodes of cashew, Anacardium occidentale. Factors affecting multiplication rate included age of explant source, explant type, medium composition, light requirements, and transfer frequency. Cotyledonary nodes produced more buds than other explant types. Nodes had a 90% viability when transferred daily to fresh medium containing activated charcoal for 7 d while exposed to continuous dark. Cultures were then exposed to low light illumination with weekly transfers. The phytohormone composition producing the most buds was 2.32 μM kinetin, 9.12 μM zeatin and 4.40 μM BA. The highest frequency of rooted shoots was obtained by treating shoots with the bacterium, Agrobacterium rhizogenes. Plants also were recovered by induction of roots using auxin treatment on propagated shoots.

Micropropagation of Cephaelis ipecacuanha rich

Shoot cultures of ipecac, Cephaelis ipecacuanha Rich. were established by inoculating seedling nodal explants onto modified Murashige and Skoog's medium supplemented with 8 mg/l kinetin, 0.05 mg/l NAA and 200 mg/l adenine. Upto 12 new axillary shoots per explant were induced after 12 weeks incubation. Shoot cultures were also established by placing shoot tips on medium containing 0.1-0.25 mg/l NAA with 8 mg/l kinetin for 4 weeks and then to shoot multiplication medium for 8 weeks. The multiplication was maintained over several passages. Shoots were rooted using 2 mg/l IBA and normal plants were re-established.