Mutagenesis breeding is a fast and effective breeding method, which has special important significance for the improvement of ornamental plant varieties. Orchids have important ornamental, medicinal, edible and/or cultural value, and broad market prospects. Studies have shown that mutagenesis causes the character changes including plant type, leaf character, flower number, flower size, flower type, flower color, flowering time, ornamental period, insect resistance, disease resistance, stress resistance in orchids, and to date, at least 930 mutants and 16 new orchid cultivars have been generated. This paper reviews the achievements of mutagenesis breeding research in orchids, clarifies current situation and factors affecting the effect of orchid mutation breeding, summaries mutation mechanism of orchids, and finds the methods to further improve the efficiency and effect of orchid mutation breeding. It would provide references for creating new varieties of orchids by better utilizing mutation breeding technology and further clarifying the mutation mechanism of orchids.

Paphiopedilum hirsutissimum (Lindl. ex Hook. f.) Stein is a rare and endangered plant in China with high ornamental value. In order to explore the genetic characteristics of wild P. hirsutissimum resources in Southwest China, and contribute to the protection and utilization of the wild resources, this study used SSR molecular marker to analyze the genetic diversity and population genetic structure of 190 P. hirsutissimum resources which collected from six populations in Guangxi, Yunnan and Guizhou provinces in Southwest China. In this study, the results showed that ten pairs of primers with good amplification effect were selected from 115 pairs of primers, and 50 alleles were detected by 10 pairs of SSR primers of 190 P. hirsutissimum. The average number of alleles (N_a) was five and the average number of effective alleles (N_e) was 2.4835. The average Shannon information index (I) was 0.8592. The average observed heterozygosity (H_o) was 0.4518 and the average expected heterozygosity (H_e) was 0.4387. The average polymorphic information content (PIC) was 0.3996 and the average Nei's expected heterozygosty (h) was 0.4370. In this six wild P. hirsutissimum populations, the number of alleles (N_a) was from 2.8000 to 4.3000. The number of effective alleles (N_e) was from 1.9655 to 2.4060. The observed heterozygosity (H_o) was from 0.3891 to 0.4839. The expected heterozygosity (H_e) was from 0.3795 to 0.4683. The Shannon information index (I) was from 0.6584 to 0.8369, and the Nei's expected heterozygosty (h) was from 0.3648 to 0.4382. In the six wild populations, the genetic diversity of Guangxi Yachang (GYC) and Guizhou Wanfeng Lake (QWF) populations was generally higher (h=0.4382, h=0.4276), while the genetic diversity of Guangxi Mulun (GML) population was relatively low (h=0.3648). Analysis of molecular variance (AMOVA) results showed that genetic variation mainly occurred among individuals within the population (94%), while genetic differentiation within populations was very small (6%). UPGMA cluster analysis based on genetic distance showed that the genetic distance of the six P. hirsutissimum populations was very small, there was no obvious group division and the genetic distance was not completely related to the geographical location. The results of Structure and principal coordinate analysis were consistent with those of UPGMA cluster analysis. Structure and principal coordinate analysis results showed that there was homogenization among the populations, and there was no obvious group division. In summary, the genetic diversity of Paphiopedilum hirsutissimum resources is relatively rich, which can provide a theoretical basis for the protection and utilization of wild P. hirsutissimum resources in Southwest China.

Corynespora leaf fall disease is one of the most severe leaf diseases in major rubber planting countries worldwide, which can cause serious yield and economic losses. The selection, creation, and utilization of resistant germplasms are the most effective prevention and control strategies for this disease. This study evaluated the disease resistance of 821 F₁ populations from three hybrid combinations Yunyan 277-5×IAN 873, RRIC103×Reyan 8-79, Yunyan 277-5×Reken 525 and identified the level of disease resistance. Based on the evaluation results of disease resistance, 32 candidate F₁ generation individual plants were selected from two hybrid combinations that conform to normal distribution. Using three divergent clusters of Corynespora cassiicola and two evaluation methods to identify the resistant candidate F₁ clone seedlings, five resistant germplasms were ultimately obtained by measuring the activity of defense enzymes and analyzing the expression characteristics of disease-related genes in five new resistant germplasms. Further investigation confirmed that the interaction relationship between five new resistant germplasms and multi host C. cassiicola during the infection process. This study provides excellent germplasm materials and a theoretical support for the early selection, cultivation, and utilization of resistant germplasms for the disease resistance of Corynespora leaf fall disease.

Phalaenopsis arunachalensis K. Gogoi & Rinya is reported as a little known species from Medog, Tibet Autonomous Region, China. The detailed morphological descriptions and photos are also provided. This species is similar to P. honghenensis F. Y. Liu, P. wilsonii Rolfe and P. taenialis (Lindl.) Christenson & Pradhan. However, this species has a minutely spurred that bends down, the free part of lateral lobes which are less than half length of the mid-lobe, and dagger-like of lateral lobes ends, which can distinguish from other species.

Ca²⁺ is a second messenger in plant cells, and Ca²⁺-ATPase (ACA/ECA), as an important protein in Ca²+transport, plays a crucial role in ensuring the balance of intracellular calcium ions and abiotic stress in plants. To investigate the biological function of Ca²⁺-ATPase (ACA/ECA) in Hevea brasiliensis, 45 ACA/ECA gene family members were identified from the rubber tree genome using the ACA/ECA protein sequence of the model plant Arabidopsis as a probe, including 38 ACA members and 7 ECA members. Expasy and Plant-mPLoc were used to comprehensively analyze the physicochemical properties, gene structure, chromosomal localization, phylogeny, and expression patterns of the 45 members. Physicochemical properties analysis showed that the number of amino acids encoded by each member was 86-1142, the molecular weight of amino acids ranged from 10 048.04 to 125 412.75 Da, and the protein products were mostly localized on the cytoplasmic membrane, with a few members localized on the endoplasmic reticulum, chloroplast, vacuole, and nucleus. In evolutionary, members of the ACA/ECA family were clearly clustered into ACA and ECA two branches, and rubber tree members were always in close proximity to cassava in both branches, indicating that there was a close relative between rubber tree and cassava during phylogeny. Chromosomal localization revealed that the 45 members of the ACA/ECA family were unevenly distributed across 14 chromosomes and one contig in rubber tree, in which, chromosomes 2 and 9 had the largest member distribution of 11 members. Expression analysis showed that there were obvious differences in the expression of some members in different groups, HbACA31 was expressed the most in leaves, HbACA36 was expressed the most in latex, and the expression of HbACA36 was obviously up-regulated in latex after treatment with ethenol. In addition, we also analyzed the influence of tapping on ACA/ECA gene expression, and found that HbACA36 was at a high expression level during tapping of the two rubber tree varieties, PR107 and Reyan 8-79, and significantly up-regulated during tapping of high-yield variety Reyan 8-79, which speculated that HbACA36 was involved in the regulation of rubber biosynthesis and played an important role. The results presented in this study reveal the physicochemical properties and expression patterns of ACA/CA family members for the first time in rubber tree, and would provide a foundation for further investigation of the biological functions of ACA/ECA genes in H. brasiliensis, especially in the regulation of the rubber production.

The present study revealed the effects of chemical fertilizer reduction patterns on growth, cane yield and fertilizer utilization rate of sugarcane, in order to provide a theoretical basis for the application of mulched drip fertigation and find out the best pattern to reduce fertilizer in sugarcane. Seven different treatments were conducted: no fertilization (CK₀), conventional fertilization (CK₁), mulched drip irrigation + conventional fertilization (CK₂), mulched drip fertigation T₁₀₀ (fertilizer amount equated with CK₁) and T₈₀, T₇₀, T₆₀ (20%, 30% and 40% reduction of fertilizer amount of T₁₀₀). Main agronomic characters, cane yield, sucrose content, sugar yield, economic benefit and nutrient utilization rate of sugarcane were measured in the seven different treatments. The results showed that compared with CK₁, the millable stalk number in CK₂ increased significantly, the tillering rate, plant height, millable stalk number and stalk formation rate in T₁₀₀ were all improved significantly, the effective stalk number and stalk formation rate in T₈₀ and T₇₀ were improved significantly. Compared with CK₁, the cane yield in CK₂, T₁₀₀, T₈₀ and T₇₀ increased significantly by 13.64%, 32.20%, 27.00% and 20.18%, respectively. In the different drip fertigation treatments, there was no significant differences for cane yield between T₁₀₀ and T₈₀, but the cane yield for T₇₀ and T₆₀ decreased significantly in contrast to T₁₀₀. There was no significant difference in sugar content among the different drip fertigation treatments. The change trend of sugar yield and cane yield among the treatments was consistent. Sugar yield in T₁₀₀ and T₈₀ was higher than that in other treatments, and there was no significant difference between that in T₁₀₀ and T₈₀. Compared with CK₁, the net benefit in T₁₀₀ and T₈₀ increased significantly by 4534.4 yuan/hm² and 3953.8 yuan/hm², respectively. The net benefit in T₇₀ and T₆₀ decreased significantly compared with T₁₀₀, and the net benefit in T₆₀ was even 2350 yuan/hm² lower than that in CK₁. The fertilizer utilization rate of all drip fertigation treatments was significantly higher than that of CK₁, and the average utilization rates of nitrogen, phosphorus and potassium fertilizers in T₈₀ were the highest in all the treatments, reached 48.36%, 27.70% and 68.95%, respectively, which was 28.42, 17.95 and 30.71 percentage points higher than that of CK₁, respectively. Overall, in the middle fertility of laterite soil, the application of mulched drip fertigation pattern for T₈₀ could obtain ideal cane yield and benefit.

Eight germplasm resources of Camellia sect. Chrysantha from Daweishan Mountain of Yunnan province were studied to provide scientific basis and research materials for the exploitation and utilization of Camellia plants. In this study, the leaf length and width of 13 cultivars of Camellia sect. Chrysantha were evaluated by direct observation of leaf phenotype, using five known germplasm resources as the control and mature leaves as the test materials, the content of six mineral elements (Cu, Zn, Fe, Mn, Ca, Mg) was determined by the wet ashing method, the contents of four functional components (tea polyphenols, total polysaccharides, total saponins and total flavonoids) were determined by the UV photometer method, the relationship between them and germplasm resources of Camellia sect. Chrysantha was analyzed by the cluster analysis. The results showed that the leaf shape of 13 Camellia sect. Chrysantha could be divided into two types: elliptic and oblong, and there were great differences in leaf area, leaf color and leaf serration. The highest and lowest content of Cu, Zn, Fe, Mn, Ca and Mg in leaves was 2.1, 1.9, 4.3, 6.6, 1.4 and 1.8 times, respectively. The content of total saponins, tea polyphenols, polysaccharides and flavonoids was 10.9, 5.8, 5.0 and 2.0 times, respectively. The correlation analysis showed that tea polyphenols had a significant negative correlation with leaf length/leaf width, a significant positive correlation with leaf color and leaf quality, and a significant negative correlation with leaf length/leaf width and zinc, there were significant positive correlations between leaf color and manganese, villi and copper. The results of cluster analysis showed that the 13 germplasm resources could be divided into 5 groups when the distance coefficient was 4.5, group I (including ‘Honghe 1’ Camellia sect. Chrysantha, JHC-2, JHC-3, JHC-4) and Group IV (including ordinary Camellia sect. Chrysantha, JHC-8, Camellia pubipetala Wan et Huang) contained relatively high contents of the constituents, JHC-2 and JHC-8 may have higher medicinal and health-care functions, but the mineral element contents and contents were generally higher, so the later development and utilization value was higher. The results of this study would be useful for further studies on the accumulation mechanism of important functional components in Camellia sect. Chrysantha, it would also provide theoretical basis for breeding new varieties of Camellia and further development and utilization of Camellia group plants in the future.

Information management of germplasm resources is the only way to improve the efficiency of germplasm resource management, sharing is an important means to activate the utilization value of preserved germplasm resources and realize the multiplier effect of seed industry, benefit distribution in sharing activities is the original incentive to promote germplasm resource sharing, and benefit ownership certificate is the key basis for benefit distribution. At present, the management of tropical crop germplasm resources is faced with the following problems: decentralized management of resource flow business chain; distortion of information data of resources and business chain; lack of evidence chain of credible benefit distribution of resources. To solve these problems, based on block chain technology, we put forward a kind of block chain system for tropical crop germplasm resources management to solve the problem of information asymmetry, by using decentralization, tamper-resistant, marks keeping in whole process, traceability, collective maintenance, and transparency, so as to realize the many relevant institutions of tropical crop germplasm resources and link collaboration trust and consistent action, effectively address the above issues and challenges. The system can keep marks processed and trace back to source, in full life cycle of tropical germplasm resources, laid the foundation for the combination of agriculture and computer agriculture, and resource traceability issues research. It is of great significance to the efficient management of tropical crop germplasm resources and the mining of potential value.

HSP90 is a key component in maintaining intracellular homeostasis, and it controls multiple cellular processes by regulating the maturation, stability, activity and turnover of its substrates. Rubber tree (Hevea brasiliensis Müll. Arg.) is an important source for the production of natural rubber, which has thousands of industrial uses and a high socioeconomic value. Using PCR technique, an HSP90 family member gene, named HbHSP90.6 gene (GenBank accession number: OP375588), was cloned from rubber tree variety Reyan73397 latex, and the sequence analysis showed that its coding region (CDS) was 2112 bp. Physicochemical analysis showed that its relative molecular weight was 80 774.85 Da, isoelectric point was 5.04, instability coefficient was 38.98, and total average hydrophilicity was -0.610, presumably HbHSP90.6 protein is a stable hydrophilic protein. The results of conserved structural domain analysis and multiple sequence alignment showed that HbHSP90.6 contained a structural domain of PTZ00272 and a highly conserved MEEVD motif, which is a member of the HSP90 family. Phylogenetic analysis showed that HbHSP90.6 clustered with Arabidopsis AtHSP90.1 (NM_124642.4) and rice OsHsp90-1 (LOC_Os04g01740) with 92.34% and 86.44% homology, respectively. Tissue expression analysis showed that the gene expression of HbHSP90.6 gene in latex was significantly higher than that in root, flower, branche, stem and leaf, and the expression of HbHSP90.6 gene in latex reached 283-fold relative to flowers, presumably the HbHSP90.6 gene may be involved in intracellular transport of latex tubes and regulation of latex metabolism. Mechanical wounding treatment in latex significantly upregulated the expression of HbHSP90.6 gene by 19 fold compared to the pretreatment pair, and it is hypothesized that HbHSP90.6 gene is involved in mechanical wounding regulated physiological and metabolic activity responses in rubber trees. The expression of HbHSP90.6 gene reached the highest level at 6 h of treatment with the phytohormones ethephon, jasmonic acid and 3-Indoleacetic acid, which were 45 fold, 17 fold and 6 fold higher than before treatment, respectively. The expression of HbHSP90.6 gene was significantly upregulated at 12 h after brassinosteroids treatment, reaching 50 fold of the pretreatment expression, presumably the HbHSP90.6 gene is involved in phytohormone mediated transcriptional regulation. Subcellular localization was performed by constructing a 35S::HbHSP90.6::GFP fusion expression vector, and the results showed that the HbHSP90.6 gene was localized in the cytoplasm and nucleus, which was consistent with the predicted results of subcellular localization. The results of this study would provide a thorough basis for elucidating the molecular mechanisms of HbHSP90.6 gene in plant hormone signaling-regulated stress and latex metabolism in rubber trees.

To lay a foundation for the scientific evaluation of the ornamental traits of Primulina, 40 species of the Primulina were used as the experimental materials. The analytical hierarchy process was applied and four first-level indicators including foliage traits, flower traits, plant characteristics and cultivation performance to construct the constraint hierarchy were selected, then 14 secondary indexes including leaf shape, leaf pattern, leaf color, flower color and pattern, corolla size, flower quantity, flowering period, leaf arrangement, plant type compactness, peduncle shape, cultivation difficulty, pest and disease were selected to construct a comprehensive evaluation system for the ornamental traits of Primulina. The results showed that among the four first-level indexes, the weight of cultivation performance was 34.0%, which is the highest, followed by plant characteristics (26.6%), flower traits (24.0%), and foliag traits (15.4%). Among the 14 second-level indexes, the weight of cultivation difficulty, peduncle shape, leaf pattern and leaf arrangement on the ornamental value of Primulina all exceeded 10.0%. The weight of cultivation difficulty was 17.2%, which is a key indicator affecting the ornamental value of Primulina. According to the established scoring criteria, 40 species of Primulina were assigned, combined with the weight to calculate the scores, and divided into three grades: Grade Ⅰ (score over 3.5), 10 species with high ornamental value; Grade Ⅱ (score 3.0-3.5), 20 species with medium ornamental value; Grade Ⅲ (score below 3.0), 10 species with low ornamental value. Among them, the species rated as high ornamental value (Grade Ⅰ) are: P. Cleopatra, P. Snow Angel, P. guizhongensis, P. Stardust, P. qintangensis, P. Blue Mood, P. liujiangensis, P. hochiensis var. rosulata, P. Flying Wings and P. macrorhiza, these 10 species of Primulina are easy to cultivate and have outstanding performance in flower viewing, foliage and plant types, which can be used as excellent hybrid parents to participate in breeding, and can also be directly promoted to the market; the species classified as low ornamental value (Grade Ⅲ) are often difficult to cultivate, with poor stress resistance, and peduncle shape are poor, lack of characteristic flower color and pattern. The 40 species of Primulina are divided into 5 categories according to their ornamental values by cluster analysis, and the species with complementary traits can be selected as parents to produce better hybrid varieties.