Abstract:This study was conducted to compare the growth and yield of one of the commercial hybrid coffee cultivars (Coffea congensis x Coffea canephora) of robusta coffee established from somatic embryogenesis as well as conventional seedlings. Results indicated no statistically significant differences in the growth pattern or the cumulative yield between the somatic embryogenesis derived plants and the seedlings. The genetic fidelity of somatic embryogenesis derived plants and the mother plant was tested using sequence related amplified polymorphism (SRAP) markers. A total of 24 SRAP primers were employed for DNA analysis which produced a total of 153 clear, distinct and reproducible amplicons of variable size. Out of 24 SRAP primers, 9 primers produced amplification patterns which are identical between the mother plants and plants derived from somatic embryogenesis. Cluster analysis revealed more than 95% genetic similarity between the somatic embryogenesis derived plants and the mother plants indicating a high degree of genetic fidelity. The present study clearly demonstrates the usefulness of SRAP markers in genetic fidelity analysis of coffee.

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Coffea canephora Pierre ex Frohener is popularly known as robusta coffee contributes to about 39% of the total world coffee production. Coffea canephora a native to West Africa was introduced to India as early as 1900 AD. However adequate information regarding the diversity and genetic structure of C. canephora germplasm available in India is not yet available. In the present study, sequence related amplified polymorphism (SRAP) and start codon targeted (SCoT) molecular markers were employed to access the genetic diversity and relationships of 58 C. canephora germplasm accessions available in the Indian gene bank. Forty-nine SRAP and thirty-one SCoT primers amplified 632 and 331 fragments respectively, of which 507 (80.22%) and 225 (67.97%) were polymorphic. The average polymorphism information content (SRAP, 0.48; SCoT, 0.37) and resolving power (SRAP, 15.60; SCoT,14.84) revealed high genetic diversity among the accessions The SRAP markers were found more informative with regards to the amount of diversity detected which is evident from effective multiplex ratio (SRAP = 8.59, SCoT = 5.61) and marker index (SRAP = 4.60, SCoT = 2.58). The neighbor-joining clustering revealed that 58 accessions were grouped into four major clusters which were also supported by Principal coordinate analysis. An admixture model-based clustering method in STRUCTURE grouped all the accessions in four subpopulations (K = 4) as similar to NJ clustering. Our study demonstrated the suitability of SRAP and SCoT markers for coffee genetic diversity and discovered thirty-one diverse genotypes in the germplasm that could be integrated into the C. canephora genetic improvement program.

Coffee leaf rust caused by the fungus Hemileia vastatrix (Berk and Br.) is a major disease occurring in coffee plantations. Although the rust fungus exists in different physiological races, the genetic difference between them is meagrely understood. In this study, genetic diversity of 14 identified and two unidentified leaf rust races was determined by sequence‐related amplified polymorphism (SRAP) markers. Of 48 SRAP primer pairs tested, 35 primers are polymorphic and generated 347 distinct scorable fragments. The number of fragments ranged from 4 to 18 with a mean of 9.97 fragments per primer combination. Of the total 347 amplified fragments, 185 fragments (53.31%) are polymorphic with an average of 5.41 fragments per primer combination. The average resolving power (Rp) and the average polymorphism information content (PIC) of the 35 SRAP primer combinations were 13.60 and 0.356, respectively. Of 35 SRAP primer pairs, 15 primer pairs were more informative and generated 25 unique fragments, which are useful for race discrimination. The study demonstrated the existence of genetic variability among various leaf rust races and this information will be helpful in coffee breeding programmes.

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