Selection and development of superior strains through functional trait-based approach in agarophytic red alga Gracilaria dura (Rhodophyta)

Aim: Gracilaria dura, a red agarophyte, is known for its high-quality agarose content and holds significant potential for commercial applications in aquaculture-related industries. The successful commercial utilization of seaweeds relies heavily on obtaining high-quality seed material with commercially valuable traits. Methodology: This study focuses on employing a functional trait-based approach to develop superior strains of G. dura for commercial aquaculture in India. Cultivation through an open sea farm, variations in growth, agar yield, pigments, antioxidant capacity, and primary productivity among the strains were observed. Results: The daily growth rate ranged from 0.5 to 3.5% per day, while pigment content exhibited variations in the Chlorophyll-a, R-Phycocyanin, and R-Phycoerythrin contents. Antioxidant capacity and gross primary productivity also displayed diverse ranges. From a total of 38 strains of G. dura, three were selected based on their growth and other functional traits, namely ADI0221201, VER0220090, and ADI0221202. Positive correlations were identified between growth and regeneration, as well as growth and Chl-a. Agar content showed a positive association with antioxidant capacity and productivity. 1H NMR analysis identified 12 metabolites as potential biomarkers for G. dura growth. Interpretation: All three selected strains hold promise for future commercial cultivation of Gracilaria dura. Furthermore, six additional strains were selected based on their higher growth and agar yield for targeted breeding and hybridization to enhance desirable traits. Key words: Agarophyte, Aquaculture, Functional traits, Growth, Gracilaria dura, Strain selection