Background: Cryopreservation is the best way for long-term in vitro preservation of plant germplasm resources. The preliminary studies found that reactive oxygen species (ROS) induced oxidative stress and ice-induced membrane damage are the fundamental causes of cell death in cryopreserved samples. How to improve plant cryopreservation survival rate is an important scientific issue in the cryobiology field. Results: This study found that the survival rate was significantly improved by adding single-wall carbon nanotubes (SWCNTs) to plant vitrification solution (PVS) in cryopreservation of Agapanthus praecox embryogenic callus (EC), and analyzed the oxidative response of cells during the control and SWCNTs-added cryopreservation protocol. The SWCNTs entered EC at the step of dehydration and mainly located around the cell wall and in the vesicles, and most of SWCNTs moved out of EC during the dilution step. Combination with physiological index and gene quantitative expression results, SWCNTs affect the ROS signal transduction and antioxidant system response during plant cryopreservation. The EC treated by SWCNTs had higher antioxidant levels, like POD, CAT, and GSH than the control group EC. The EC mainly depended on the AsA-GSH and GPX cycle to scavenge H₂O₂ in the control cryopreservation, but depended on CAT in the SWCNTs-added cryopreservation which lead to low levels of H₂O₂ and MDA. The elevated antioxidant level in dehydration by adding SWCNTs enhanced cells resistance to injury during cryopreservation. The ROS signals of EC were balanced and stable in the SWCNTs-added cryopreservation. Conclusions: The SWCNTs regulated oxidative stress responses of EC during the process and controlled oxidative damages by the maintenance of ROS homeostasis to achieve a high survival rate after cryopreservation. This study is the first to systematically describe the role of carbon nanomaterial in the regulation of plant oxidative stress response, and provided a novel insight into the application of nanomaterials in the field of cryobiology.

Https://doi.org/10.18632/oncotarget.4011 Hai-Long Li, Li Han, Hai-Rong Chen, Fei Meng, Qing-Hua Liu, Zhen-Qiang Pan, Jin Bai, Jun-Nian Zheng

Maximizing rice yield potential has always been the focus of high-yield rice cultivation research. For high-yield rice cultivation and breeding, more research into the link between yield and yield components is essential. In this experiment, 38 rice varieties with different yield types and 185 rice varieties as materials were chosen. The relationships between yield and yield components were studied. The regulation effects of total nitrogen application rate (TNAR) on yield and yield components were observed. The results showed that (1) the grain yield of high-yield varieties was 189.3−195.6%, 76.1−77.7%, and 27.0−28.7% higher than that of super-low-yield, low-yield, and medium-yield varieties, respectively. Compared with rice varieties with other yield types, rice varieties with high-yield type have a higher total number of spikelets. (2) The spikelet number per panicle and total number of spikelets were significantly positively linked with grain yield, but significantly negatively correlated with filled grains and grain weight. (3) With an increase in TNAR (0−340 kg ha⁻¹), the panicles, spikelet number per panicle, and total spikelets of rice varieties with different yield types increased gradually, and the filled grains and grain weight decreased gradually. The higher the TNAR, the more obvious the decrease in filled grains and grain weight. The grain yield of rice varieties with different yield types was the highest under the TNAR at 250 kg ha⁻¹. The main factor contributing to its high yield was the substantial increase in total spikelets. The above results showed that increasing the spikelet number per panicle and total spikelets played a material role in improving rice yield.

The determination of the grades and interval of quantitative characteristics is an important job while we draft new distinctness, uniformity and stability (DUS) test guidelines. Grading criteria should be adjusted because of the effect of year and site; it is also a key task to establish applicable criteria in the DUS test. Excellent criteria will improve the accuracy of the DUS evaluation. In this study, we analyzed the variability and distribution patterns of nine quantitative characteristics of 251 anthurium varieties. Three methods were used to establish the grade criteria: the two standard deviation methods, the two LSD_0.05 methods and the multiple comparison method. The results showed that the coefficient of variation within varieties varied from 6.96% to 10.11%. The quantitative characteristics observed in this study did not follow a normal distribution, except spadix thickness at the middle and spathe size. In most characteristics, the standard deviations and LSD_0.05 were similar, except for spathe size. The state interval set by multiple comparison methods for every characteristic was variable, and its mean was about 1.25 times that of the other two methods. The process of establishing grading criteria using the multiple comparison method was simpler, and the criteria were more accurate, with a lower error rate.

Due to its high nutritional value, broccoli (Brassica oleracea var. italica Plenck) is one of the most popular vegetables worldwide. This study assessed 36 phenotypic characteristics of 111 broccoli varieties to understand the phenotypic diversity of new broccoli varieties and improve their breeding speed with advantages and characteristics in China, including 108 new varieties and three varieties of common knowledge. The genetic diversity, the principal component, and the cluster of phenotypic characteristics of broccoli varieties were further investigated. The results showed that the coefficients of variation of 36 characteristics ranged between 11.18 % and 94.99 %, with their diversity index between 0.26 and 1.82. The 111 broccoli varieties were further classified into eight groups, primarily attributed to the differences in phenotypic characteristics, including curd weight, main stem thickness, plant development degree, plant height, and anthocyanin coloration. The cumulative contribution rate of the first five principal components reached 81.186 %, corresponding to 12 representative phenotypic traits. The analysis indicated that the phenotypic characteristics of broccoli were rich in diversity, especially for several characteristics appreciated by the market, such as weight, curd firmness, and anthocyanin coloration. This study revealed the basic information on the genetic diversity of new broccoli varieties in China from 2017 to 2019 and provided potential breeding strategies for broccoli to meet diverse market demands.

The cryopreservation of Anthurium andraeanum germplasm resources is extremely important for the production and selection of new varieties. At present, the cryopreservation procedure for the callus of A. andraeanum has not been established. In this study, the leaves of A. andraeanum were used as explants to culture the callus. The cryopreservation procedure of the callus by vitrification was initially established by using the orthogonal experimental method of four factors and three levels in the preculture, loading, and dehydration steps. Furthermore, the vitrification-based cryopreservation was optimized by changing the preculture temperature and loading solution and adding exogenous substances to the plant vitrification solution (PVS2). In this procedure, the callus was precultured at 25 °C for 2 d, and loaded in 50% PVS2 at 25 °C for 60 min. The callus was dehydrated with PVS2 containing 0.08 mM reduced glutathione (GSH) at 0 °C for 60 min. After rapid-cooling in liquid nitrogen for 1 h, it was rapid-warming in a water bath at 40 °C for 90 s and unloaded for 30 min. After 1 d of recovery, the cell relative survival rate of the cryopreserved callus was 64.60%. The results provide a valuable basic and effective method for the long-term conservation of A. andraeanum germplasm resources.