Effects of exogenous hormones on the regeneration of juveniles from Sargassum fusiforme holdfasts

Abstract

During the cultivation of Sargassum fusiforme, sexual reproduction of superior strains can hinder the stable inheritance of their desirable traits and reduce their economic benefits. However, vegetative reproduction of S. fusiforme holdfasts has high potential for subculture. In this study, we investigated the effects of different concentrations of α-naphthaleneacetic acid (NAA), gibberellin (GA3), and 6-benzyladenine (BAP) on the growth and regeneration of S. fusiforme holdfasts. Exogenous application of 1.5, 2 mg·L-1NAA, 1.5 mg·L-1 GA3 or 2, 3 mg·L-1BAP significantly promoted photosynthetic activity and the absorption and utilization of nitrate nitrogen in S. fusiforme holdfasts, thus improving the relative growth rate (RGR) and regeneration rate (RR) and shortening the time for the regeneration of juveniles from S. fusiforme holdfasts to around the 6th day. Among these, the RGR and RR at the end of the culture period with 1.5 mg·L-1 of NAA increased by 118.9% and 67.4%, respectively, compared with those of the control group. However, treatment with 1.5 mg·L-1 GA3 increased the RR of S. fusiforme holdfasts by 58.8% compared with that of the control group. Under BAP treatment at 3 mg·L-1, the RR of S. fusiforme holdfasts increased by 23.4% compared with that of the control group; its promoting effect was thus weaker than that of NAA and GA3. When the concentration of GA3 or BAP was too high (3 mg·L-1; 5 mg·L-1), the RR of the holdfasts decreased by 46.5% and 42.8%, respectively compared with that of the control group. Therefore, exogenous application of NAA at 1.5 mg·L-1, GA3 at 1.5 mg·L-1, and BAP at 3 mg·L-1 can be used to induce regeneration of S. fusiforme holdfasts, shorten the culture time of regenerated seedlings, and obtain more regenerative seedlings, thereby improving economic efficiency.

Asexual proliferative seedling technology for Sargassum fusiforme constructed using tissue culture method

“…We observed that the callus-like/adventitious bud induction rate and number of bud per explant varied widely among explants from different parts of S. fusiforme after tissue culture. The holdfasts and stems of S. fusiforme can serve as primary materials for tissue culture (Luo et al, 2023). Different parts of the stems were cultivated in groups, with adventitious buds more easily induced near the upper stem tip than near the stem base, possibly because S. fusiforme is polarized, similar to other macroalgae.…”

“…However, the traditional method of seedling cultivation leads to the growth of weed algae, which compete with seedlings for nutrients and space, and it is challenging to control the temperature, pH, and light. Even during sexual reproduction, it is difficult to stabilize the inheritance of some heat-and cold-tolerant strains because of crossbreeding (Chen and Zou, 2014;Chen et al, 2019;Luo et al, 2023). Traditional seedling culture conditions are complicated and time-consuming, and the maintenance and replacement of cultivation equipment during cultivation can cause a serious economic burden (Largo et al, 2020;Collins et al, 2022;Arbaiza et al, 2023).…”

“…Tissue culture techniques can be used to induce the production of calluses, budding, and plant development by adding plant growth regulators, which are synthetic (or extracted from microorganisms), along with an organic compound similar to natural plant hormones that regulate the growth and development of biological organisms (Rademacher, 2015;Luo et al, 2023). Uniconazole (UIZ), known as a triazole-type cytochrome P450 enzyme inhibitor, is a plant growth regulator.…”

Phytohormones and Pheromones in the Phycology Literature: Benchmarking of Data-Set and Developing Critical Tools of Biotechnological Implications for Commercial Aquaculture Industry

“…Exogenous application of α-naphthaleneacetic acid (NAA), gibberellin (GA3), and 6-benzyl adenine (BAP) has been used to induce regeneration of Sargassum fusiforme to obtain more regenerative seedlings within a short time, thereby improving economic efficiency [208]. Plant growth hormone (zeatin + phenylacetic acid) has been used for micropropagation in three color morphotypes of Kappaphycus alvarezii var.…”