Cytogenetics of tropical bulbous ornamentals. IX. Breeding systems in Zephyranthes

Summary Zephyranthes is a rather versatile genus and contains self-incompatible and self-compatible taxa coupled with positional barrier between stigma and anthers. The two may augment or run counter to each other. Furthermore, the genus also contains sexual and agamospermous species. The latter are often self-pollinated and pseudogamous. Z. sulphurea (2n=48) when pollinated with Z. candida (2n=40 and 41) has consistently given rise to seedlings with maternal chromosome number and morphology. Z. lancasteri and cv. 20 also behave similarly. This is a strong pointer for their being agamospermous, although a final proof will come from an embryological study. The intraspecific polymorphism within agamospermous taxa in the genus may be the result of autosegregation. On the other hand, the crosses involving sexual species like Z. candida (2n=41) as the female parent have generated a large heterogeneous progeny ranging in chromosome number from 2n=33 to 48 depending upon the number in the male parent. Such versatility of the breeding system together with chromosomal repatterning, hybridization, polyploidy and vegetative multiplication/apomixis explains the origin and preservation of an astonishing range in chromosome numbers from 2n=18 to 96.     

Detection of Fasciola gigantica infection in snails by polymerase chain reaction

Polymerase chain reaction (PCR) was used to detect Fasciola gigantica infection in the snail intermediate host. Fasciola specific primers amplified a 124 bp fragment in PCR when the genomic DNA isolated from F. gigantica infected Lymnaea auricularia snails was used as template. In addition to the 124 bp amplicon, a ladder of DNA fragments representing amplification of the 124 bp repetitive sequences was observed. Genomic DNA of the parasite was used as a positive control, which also gave an amplification of the 124 bp fragment. DNA isolated from non-infected snails was used as a negative control and no amplification of this sequence was observed. This technique is highly specific and sensitive and possesses fairly good prospects of its utility as an epidemiological tool for ascertaining the infectivity status in ubiquitous snail populations.     

Genotyping safflower (Carthamus tinctorius) cultivars by DNA fingerprints

Summary Carthamus tinctorius (2n = 2x = 24) (family Asteraceae), commonly known as safflower, is widely cultivated in agricultural production systems of Asia, Europe, Australia and the Americas as a source of high-quality vegetable and industrial oil. India ranks first in the production of safflower oil. Fourteen cultivars, widely cultivated in various agro-climatic regions of India, have been fingerprinted by RAPD, ISSR, and AFLP markers utilizing 36, 21 primers, and 4 primer combinations, respectively. On an individual assay basis, AFLP has proven to be the best marker system as compared with the other two markers applied as assessed by high discriminating power (0.98), assay efficiency index (33.2), marker index (18.2), resolving power (40.62), and genotype index (0.856). Thirty-six RAPD and 21 SSR primers could differentiate a maximum of eight and four cultivars, respectively, whereas, two AFLP primer combinations could fingerprint all the 14 cultivars. To understand genetic relationships among these cultivars, Jaccard's similarity coefficient and UPGMA clustering algorithm were applied to the three marker data sets. Mean genetic similarities ranged from 0.689 (AFLP) to 0.952 (ISSR). Correlation coefficient comparisons between similarity matrices and co-phenetic matrices obtained with the three markers revealed that AFLP displayed no congruence vis-a-vis RAPD and ISSR data. However, strong correlation was observed between RAPD and ISSR marker systems. This paper reports the start of molecular biology programme targeting nuclear genome of safflower, a major world oilseed crop about whose genetics very little is known.     

A modified protocol for high-quality DNA extraction from seeds rich in secondary compounds

High-quality DNA is a prerequisite for a range of molecular biology experiments and thus DNA extraction is one of the most important steps for several downstream experiments. DNA isolation directly from seeds could save time and effort, particularly for large-scale experiments where growing and maintaining multitude of genotypes in parallel is cumbersome. However, seeds often contain polysaccharides, polyphenols, mucilage, oils, etc., which cause DNA extraction from seeds difficult and sometimes a research limiting step. In the present study, we have considered many previous protocols and optimized these methods to devise a general method for extraction of DNA from the seeds of diverse plant genera. The new SGS buffer (sucrose, glycerol and sodium dodecyl sulphate) was used to extract intact DNA from seeds with yield and quality better than in the previous protocols. Moreover, the proposed protocol is devoid of hazardous and expensive reagents and can be scaled up.     

Cytomorphology of <Emphasis Type="Italic">Gentiana kurroo</Emphasis>: an important endangered bitter plant of temperate Himalaya

Gentiana kurroo, a potent bitter drug plant of Indian subcon- tinent, is under threat due to over exploitation and destruction of natural habitat. We studied the morphophenology and chromosomes of G. kur- roo on both wild and field grown plants, which is very important for proper identification, conservation and domestication. Results reveal that G. kurroo is a perennial herb, and its shoot is represented by flowering branches only. Stem is modified to rhizome. The older rhizomes split into four parts at collar region appearing to fuse together at the ends and is an important diagnostic feature for crude raw materials. Two types of leaves i.e. radical leaves at the base of the plant and cauline leaves on flowering shoot are present. Flowering occurs during September to Octo- ber with 1-9 inflorescences per plant. Inflorescence is terminal monoca- sial cysome type. Flowers are protrandus. Anthesis starts around 7.30 am and continued till 10.0 am. Ovary is bicarpillary syncarpous unilocular. Fruit is Capsule and takes 18 20 days to mature after fertilization. Seeds are very small elliptical and 1 000 seeds weigh to 0.1275 g. Chromoso- mal studies made by usual squash method reveals the species is a ge- nomic allotetraploid with n = 13. The anaphase-I segregation was normal and in none of the cells at Anaphase-I or Telophase-I could any abnor- mality like laggards, bridges, micronuclei etc. be observed.