BackgroundThe impact of diseases such as Phytophthora foot rot and the replacement of unproductive cultivars by high yielding ones has brought about the disappearance of varieties in Piper species, like any other crop. Black pepper (King of spices), is a major spice crop consumed throughout the world. It is widely cultivated across various parts of the world apart from India. The different cultivars may be genetically related and could be a source of valuable genes for disease resistance and an increase in quantity and quality. Even though Western Ghats in India is believed to be the site of origin of this crop, numerous accessions from the NBPGR have not yet been evaluated. Our study aims to investigate the genetic relatedness in major cultivars of black pepper using Amplified Fragment Length Polymorphism.ResultsAmplified Fragment Length Polymorphic (AFLP) DNA analysis was performed in thirty popular cultivars of black pepper from National Bureau of Plant Genetic Resources (NBPGR), India. Fingerprint profiles were generated initially with, five different primer combinations, from which three primer pair combinations (EAGC/MCAA, EAGG/MCTA and EAGC/MCTG) gave consistent and scorable banding patterns. From 173 scorable markers, 158(> 90%) were polymorphic which shows there is considerable variation in the available germplasm. The dendrogram derived by unweighted pair group method analysis (UPGMA) grouped the accessions into three major clusters and four diverse cultivars with only 30% similarity. Karimunda, a widely grown and popular cultivar was unique in the fingerprint profiles obtained.ConclusionThere are currently few fingerprinting studies using the valuable spice crop black pepper. We found considerable genetic variability among cultivars of black pepper. Fingerprinting analysis with AFLP proved to be an ideal tool for cultivar identification and phylogenetic studies. It shows the high level of polymorphism and the unique characterization of the major cultivars. An extensive range of similarity value between the cultivars was noted (6.01 to 98.13). Further screening of more cultivars will provide valuable information for current breeding programmes.

A collaborative crop specific exploration and collection mission to collect the germplasm and to study the population size of male and female/hermaphrodite trees of Malabar tamarind [Garcinia cambogia (Gaertn.) Desr.] in the area of its diversity was undertaken during July 2002 in Kerala and Karnataka. A total of 56 accessions of Malabar tamarind were collected. Two collections of Malabar tamarind were found to be very specific because of the uncommon fruit colour, which is pinkish red. All the collected accessions are grown at National Bureau of Plant Genetic Resources (NBPGR) Regional Station, Thrissur for characterisation and conservation. Extensive range of variability was found in fruit colour, shape, size and nature of branching and canopy of trees. Characterisation of 13 fruit and five seed characters was done for 51 accessions. The variability was found to be maximum for nipple length (74.8%) and minimum for fruit girth (12.8%). Two promising accessions were identified based on mean fruit weight (161 g) in IC 354028 and mean rind thickness (15 mm) and mean rind weight (125 g) in IC 354019.

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Chromosome morphology is usually studied on the basis of the position of the primary constriction (or centromere or kinetochore), which is a principal landmark in contracted metaphase chromosomes. Cytologists have adopted several methods to determine the centromere locations and described the chromosomes as telocentric (centromere at one end of the chromosome), acrocentric (centromere near one end of the chromosome), submetacentric (centromere nearer to one end of the chro mosome than the other) and metacentric (centromere at or near the middle of the chromosome). These four categories are not sharply distinct, but grade imper ceptibly into each other (Stebbins 1971). The chromosomes are also described as median, nearly median, nearly submedian, submedian, nearly subterminal, sub terminal, nearly terminal and terminal (Sharma and Sharma 1960, Sharma and Choudhury 1964, Adhikary 1963, 1974, Bose and Flory 1965. Thus there exists a great deal of confusion in describing a chromosome on the basis of centromere position. Levan et al. (1964) recognised the location of centromere in median point (M), median region (m), submedian region (sm), subterminal region (st), terminal region (t) and terminal point (T). However, this system did not give due consideration to a number of oftquoted nomenclatures of centromere locations like nearly submedian and nearly subterminal. The system of Levan et al. (1964) was based on a) dif ference (d) between long arm (1) and short arm (s), where the whole chromosome =10 units; b) arm ratio (r) as the ratio of short arm/long arm; and c) centromeric index (i) as 100 s/c in the different regions, where c is the total length of the chro mosome. Nevertheless, this system gave biased preference to the short arm of the chromosome in determining the arm ratio and the centromeric index. The criterion of difference (d) between long arm (1) and short arm (s) is not always helpful as evi dent from our study of karyotypes of Aloe barbadensis and Furcraea gigantea (Abraham and Nagendra Prasad 1979, 1980). Recently, Adhikary (1974) proposed a system incorporating all the possible and up-to-date usage of centromere locations with reference to intermediate regions between terminal and median points. He recognised 4 fixed points and 4 inter mediate regions. The fixed points were median (M), terminal (T), submedian (SM) and subterminal (ST). The intermediate regions were nearly median (nm), nearly terminal (nt), nearly submedian (nsm) and nearly subterminal (nst). This system was based on arm ratios, R1 (short arm/long arm) and R2 (long arm/short arm).