In recent years, molecular markers have been utilized for a variety of applications including examination of genetic relationships between individuals, mapping of useful genes, construction of linkage maps, marker assisted selections and backcrosses, population genetics and phylogenetic studies. Among the available molecular markers, microsatellites or simple sequence repeats (SSRs) which are tandem repeats of one to six nucleotide long DNA motifs, have gained considerable importance in plant genetics and breeding owing to many desirable genetic attributes including hypervariability, multiallelic nature, codominant inheritance, reproducibility, relative abundance, extensive genome coverage including organellar genomes, chromosome specific location and amenability to automation and high throughput genotyping. High degree of allelic variation revealed by microsatellite markers results from variation in number of repeat-motifs at a locus caused by replication slippage and/or unequal crossing-over during meiosis. In spite of limited understanding of the functions of the SSR motifs within the plant genes, SSRs are being widely utilized in plant genome analysis. Microsatellites can be developed directly from genomic DNA libraries or from libraries enriched for specific microsatellites. Alternatively, microsatellites can also be found by searching public databases such as GenBank and EMBL or through cross-species transferability. At present, EST databases are an important source of candidate genes, as these can generate markers directly associated with a trait of interest and may be transferable in close relative genera. A large number of SSR based techniques have been developed and a quantum of literature has accumulated regarding the applicability of SSRs in plant genetics and genomics. In this review we discuss the recent developments (last 4-5 years) made in plant genetics using SSR markers.

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Bamboos (family Poaceae) are the most beautiful and useful plants on the Earth, mainly found in the tropical and sub-tropical regions of the world. Bamboos are fast growing and early maturing, but lack of proper management of bamboo resources is leading to rapid reduction of the existing bamboosetum. Bamboo propagation through seeds is limited due to long flowering cycle of upto 120 years, seed sterility and short seed viability. Infrequent and unpredictable flowering events coupled with peculiar monocarpic behaviour i.e. flowering once before culm death, and extensive genome polyploidization are additional challenges for this woody group. Similarly, vegetative propagation by cuttings, offsets and rhizomes are also inadequate to cope up with the demand of planting stock due to large propagule size, limited availability, seasonal dependence, low multiplication rate and rooting percentage. Therefore, attempts have been made to propagate bamboos through in vitro techniques. In vitro flowering has also been achieved successfully in some bamboo species. Classification systems proposed to date need further support, as taxonomic delineation at lower levels is still lacking sufficient resolution. Tremendous advancement in molecular markers holds the promise to address the needs of bamboo taxonomy (systematics and identification) and diversity studies. Successful application of molecular marker techniques has been achieved in several bamboo species although, more studies are required to understand the population structure and genetic diversity of bamboos in a better way. In addition, some efforts have also been made to clone important genes from bamboos and also for genetic transformation using Agrobacterium and particle bombardment methods. An overview of the recent developments made in improvement of bamboos through in vitro propagation, molecular marker technologies, cloning, and transformation and transgenics has been presented. The future potential of improvement of bamboos using modern biotechnological tools has also been discussed.

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