Zhourui Liang

Conserved and novel heat stress‐responsive microRNAs were identified by deep sequencing in Saccharina japonica (Laminariales, Phaeophyta)

As a temperate-cold species, Saccharina japonica often suffers heat stress when it is transplanted to temperate and subtropical zones. Study the heat stress response and resistance mechanism of Saccharina is of great significance for understanding the acclimation to heat stress under domestication as well as for breeding new cultivars with heat stress resistance. In this study, we identified a set of heat stress-responsive miRNAs and analysed their regulation during the heat stress response. CO (control) and heat stress (HS) sRNA libraries were constructed and sequenced. Forty-nine known miRNAs and 75 novel miRNAs were identified, of which seven known and 25 novel miRNAs were expressed differentially under heat stress. Quantitative PCR of six selected miRNAs confirmed that these loci were responsive to heat stress. Thirty-nine and 712 genes were predicted to be targeted by the seven known miRNAs and 25 novel miRNAs, respectively. Gene function and pathway analyses showed that these genes probably play important roles in S. japonica heat stress tolerance. The miRNAs identified represent the first set of heat-responsive miRNAs identified from S. japonica, and their identification can help elucidate the heat stress response and resistance mechanisms in S. japonica.

AFLP fingerprints of Pyropia yezoensis (Bangiales, Rhodophyta) populations revealed the important effect of farming protocols on genetic diversity

Abstract Continuous and intensive selective breeding reduces the genetic diversity of cultivated Pyropia stock, thereby increasing its susceptibility to diseases, and hindering the sustainable development of the Pyropia industry. To develop new Pyropia germplasms with desirable agronomic traits, a new Pyropia yezoensis strain, “Huangyou No. 1” was bred from a wild subtidal population. In this study, the genetic diversity of this strain was analyzed using AFLP. Totally, 249 loci were obtained, of which 248 were polymorphic with a polymorphism rate of 99.6%, using seven primer pairs. The intra-population polymorphism rates of the populations Wild 1 and Wild 2 were the highest (47.39% and 59.44%, respectively), while they were relatively low (20.88–24.5%) in the cultivated populations. The genetic distances between the breeding Pyropia populations cultivated in the same aquaculture farm were low. Specifically, the F2 offspring of “Huangyou No. 1” and the control cultivar, cultivated using the “never-drying” protocol, were genetically distant from the other populations, including that from the same seedlings, yet cultivated using the “periodic-drying” protocol. The never-drying cultivation protocol had a high likelihood of influencing genetic diversity of Pyropia yezoensis.