Evaluation of genetic diversity within asparagus germplasm based on morphological traits and ISSR markers

Asparagus breeding: Future research needs for sustainable production

Productivity in asparagus (Asparagus officinalis L.) is determined in part by (1) the selection of superior, adaptive genetics, (2) matching the selected genetics to the production environment, and (3) managing the crop production system in ways to maximize harvest potential that are sustainable, profitable, and efficient. Over the last 100 years, a considerable effort by asparagus researchers has gone into breeding superior genetic lines, testing those in numerous locations, and studying how asparagus responds to a multitude of inputs (fertilizers, irrigation, fungicides, herbicides, insecticides). Farmers worldwide have benefited from all of these improvements. However, as we look to the future, we need to change our research approaches to deal with widely accepted limitations to asparagus growth that if left unanswered will further erode the long-term sustainability and profitability of the crop. In addition, there is a growing need for increased mechanization to offset labor needs. To effectively harvest asparagus, new plant types with more predictable spear emergence patterns need to be bred. This paper will briefly review the historic content of asparagus research and open a discussion on how to refocus international research efforts to breed superior plant materials to meet the challenges of the future.

Analysis of genetic diversity and population structure in Asparagus species using SSR markers

BACKGROUND

Various Asparagus species constitute the significant vegetable and medicinal genetic resource throughout the world. Asparagus species serve as important commodity of food and pharmaceutical industries in India. A diverse collection of Asparagus species from different localities of Northwest India was investigated for its genetic diversity using simple sequence repeat (SSR) markers.

RESULTS

Polymorphic SSR markers revealed high genetic diversity. Primer SSR-15 amplified maximum of 8 fragments while 3 primers, namely, SSR-43, SSR-63, and AGA1 amplified minimum of 3 fragments. Collectively, 122 alleles were amplified in a range between 3 and 8 with an average of 5 alleles per marker. The size of the amplified alleles ranged between 90 and 680 base pairs. Polymorphism information content (PIC) value varied from a highest value of 0.499 in primer AGA1 to a lowest value of 0.231 in primer SSR-63 with a mean value of 0.376 showing considerable SSR polymorphism. Dendrogram developed on the basis of Jaccard's similarity coefficient and neighbor-joining tree segregated all the studied Asparagus species into two discrete groups. Structure analysis based on Bayesian clustering allocated different accessions to two independent clusters and exhibited low level of individual admixture.

CONCLUSIONS

The genetic diversity analysis showed a conservative genetic background for maximum species of asparagus. Only Accessions of Asparagus adscendens were split into two diverse clusters suggesting a wide genetic base of this species as compared to other species. Overall genetic diversity was high, and this germplasm of Asparagus can be used in future improvement programs. The findings of current research on Asparagus germplasm can make a momentous contribution to initiatives of interbreeding, conservation, and improvement of Asparagus in future.