Natural rubber is an important strategic material and industrial raw material in China, which mainly originates from rubber tree. The growth cycle of rubber tree is long, and the quality of rubber seedling directly affects the development of rubber industry. The somatic embryo plantlet of rubber tree shows good consistency in the previous studies, and has the advantages of rapid growth and high yield. Hainan Innovation Base for production of Natural Rubber New Planting Material is the base of the current large-scale production of rubber tree somatic embryo plantlets of Reyan 73397 and Reyan 917. In this paper, in order to clarify the large-scale production of the somatic embryo plantlets of rubber tree, the plant height, stem diameter, leaves number and taproot length of Reyan 73397 somatic embryo plantlets from 2018 to 2020 were studied, the differences in each index of the two varieties in 2020 were, compared, and the classification of different varieties in different years were done. The proportions of plant height, stem diameter, leaf number and taproot length of Reyan 73397 were similar in each region from 2018 to 2020. There were no significant differences in plant height, leaf number and taproot length in three years. There were significant differences in stem diameter between 2018 and 2019, and the mean value of the three years was above 2.00 mm, and the difference between the maximum and minimum value was only 0.09 mm. The plant height of Reyan 73397 and Reyan 917 was the same, and the mean value of plant height of both varieties was 8.0 cm. The plant height of the two varieties was mainly 5.0-10.0 cm, accounting for 66.13% and 66.91%, respectively. The stem diameter range of Reyan 73397 and Reyan 917 was 0.80-4.23 mm and 1.13-3.73 mm, respectively. The mean value of the two varieties was 2.11 mm and 2.18 mm, respectively. The stem diameter of the two varieties was highly concentrated between 1.50-3.00 mm, 85.94% and 83.82%, respectively. The leaf number of Reyan 73397 and Reyan 917 was ranged from 0 to 6 and 1 to 4, respectively. The number of leaves of the two varieties was mostly 1 to 3, accounting for 88.82% and 96.32%, respectively. The rate of 2 leaves in Reyan 917 was as high as 52.94%. The average taproot length of Reyan 73397 was 9.5 cm, while that of Reyan 917 was 9.1 cm. The taproot length of both varieties concentrated in the range of 8.0-12.0 cm, accounting for 74.12% and 79.41%, respectively. There were no significant differences in plant height, stem diameter and leaves number between the two varieties in 2020, while there was significant differences in taproot length (P<0.05). The proportion of first-grade plantlets and second-grade plantlets of different varieties in different years (2018—2020) was 19%-22% and 56%-62%. It is concluded that the mass production of rubber tree somatic embryo plantlet is stable, which could provide reference for the popularization of the production technology of rubber tree somatic embryo plantlet.

Fenjiaren is a new Dendrobium variety bred by Sanming Academy of Agricultural Sciences for both ornamental and edible purposes. In factory seedling cultivation, it was found that Fenjiaren had slow cluster bud proliferation, low proliferation coefficient, underdeveloped root system of tissue culture seedlings and other problems, which affecting the large-scale production of this variety. To improve the efficiency of factory seedling cultivation of the variety, the sterile seedlings were used as the explants, the effects of plant growth regulators including 6-BA, NAA, and additives such as banana puree and AC on the proliferation of stem segments and the rooting of seedlings were studied using L₉(3³) orthogonal experiments. The suitable culture medium for the proliferation of stem segments of Fenjiaren was 1/2 MS+6-BA 3 mg/L, banana puree 100 g/L, white sugar 30 g/L, activated carbon AC 1 g/L, and agar powder 5.6 g/L. After 4 months of cultivation, the proliferation coefficient of the stem segment was 5.08. Range analysis indicated that the primary and secondary relationship of the factors was 6-BA>NAA>banana puree. The inter subject effect test showed that 6-BA had a significant impact on the growth rate coefficient (P<0.05). The most suitable culture medium for rooting was 1/2 MS+NAA 1 mg/L+banana puree 100 g/L+white sugar 15 g/L+agar powder 5.6 g/L. After 2 months of cultivation, the growth rate coefficient of the rooting was 12.82, the average plant height of the seedling was 12.66 cm, the average leaf length was 4.02 cm, the average number of roots was 11.80, and the average plant weight was 1.67 g. Range analysis indicated that the primary and secondary relationship of the factors was NAA>AC>banana puree. This study optimized the proliferation and rooting conditions of a new variety of Fenjiaren, which could provide technical reference for the seedling breeding of new varieties of Dendrobium and other Orchid plants.

Plasma membrane intrinsic proteins (PIPs), which belong to the aquaporin (AQP) family within the major intrinsic protein (MIP) superfamily, are known for the high water transport activity at the cell membrane. The subfamily is highly conservative and only includes two phylogenetic groups named PIP1 and PIP2. Natural rubber, an important industrial raw material and strategic material, is mainly derived from Para rubber tree (Hevea brasiliensis Muell. Arg.), a big tree originated in the Amazon basin of South America. As a special tissue for rubber synthesis and storage, the laticiferous cells possess no plasmodesmata with neighboring parenchyma cells, and the water balance is mainly mediated by PIP aquaporins. In previous studies, a highly abundant PIP gene denoted HbPIP1;4 was identified, however, no detectable water transport activity was found when heterologously expressed in Xenopus laevis oocytes, which may be due to its inability to localize to the cell membrane. To uncover the acting site and multimerization features of HbPIP1;4 in vivo, recombinant plasmids pNC-Cam1304-SubN-HbPIP1;4, pNC-BiFC-ECN-HbPIP1;4, and pNC-BiFC-ENN-HbPIP1;4 for subcellular localization and bimolecular fluorescence complementation (BiFC) were successfully constructed. Agrobacterium tumefaciens transformed with above recombinant plasmids were used to infiltrate tobacco (Nicotiana benthamiana), and transiently transformed leaves were subsequently checked using laser confocal microscopy. Compared with wide distribution of fluorescence signals throughout the cell for the control pNC-Cam1304-SubN, signals of pNC-Cam1304-GFP-HbPIP1;4 were restricted to the cell membrane, supporting the plasma membrane localization of HbPIP1;4, which is consistent with the bioinformatics prediction. The result was further supported by the BiFC analysis, which also implied that HbPIP1;4 could form homomultimer, in accordance with the 3D prediction via homology modeling. The results would lay a solid foundation for further uncovering the mechanism of water balance of the laticifer. Nevertheless, PIP aquaporins that could interact with HbPIP1;4 in rubber tree remain to be further characterized.

Bombax ceiba is a deciduous tree belonging to the Genus Bombax in the Malvaceae family. It holds significant importance as an ornamental plant of economic, medicinal and edible value in southern China. It is the city flower of Guangzhou and Panzhihua. The traditional propagation methods for B. ceiba are seed sowing and grafting. However, the seeds are difficult to preserve and easily deteriorate, leading to decreased germination rates. Grafting results in even lower survival rates. Therefore, this experiment aimed to study the tissue culture techniques for the rapid propagation of B. ceiba. In this study, B. ceiba seeds were used as the experimental materials, and different disinfection methods were tested to determine the most suitable method for seed disinfection, aiming to obtain sterile seedlings. Using the sterile seedlings as the explants, various basic culture media, combinations of shoot-inducing hormones, induction and proliferation media for apical and adventitious buds, as well as rooting media, were tested and optimized. Additionally, seedling acclimatization experiments were conducted to explore the optimal basic culture medium, hormone combination, induction and proliferation medium, rooting medium, and seedling acclimatization methods. The results showed that the optimal basic culture medium for B. ceiba tissue culture was MS medium supplemented with 30 g/L sucrose and 7.5 g/L agar. The best disinfection method for B. ceiba seeds was 75% ethanol treatment for 1 min, followed by five rinses with sterile water, 4-hour sterilization with a 50% H₂O₂ solution prepared from 30% H₂O₂, and another five rinses with sterile water. The optimal plant growth regulators for inducing differentiation of apical buds into young shoots were a combination of 6-benzylaminopurine (6-BA) and naphthaleneacetic acid (NAA). The best induction and proliferation medium was MS medium supplemented with 0.5 mg/L 6-BA, 0.5 mg/L indole-3-butyric acid (IBA), 30 g/L sucrose, and 7.5 g/L agar. The optimal rooting medium was half-strength MS medium supplemented with 0.5 mg/L IBA, 30 g/L sucrose, 7.5 g/L agar, and 0.2 g/L activated charcoal. The recommended substrate for seedling acclimatization was a mixture of sand, peat soil, and vermiculite in a ratio of 1∶1∶1. Through the optimization of seed disinfection methods, culture media selection, hormone combinations, and seedling acclimatization experiments, an efficient tissue culture system for B. ceiba was established. This would provide technical support for the in vitro preservation of B. ceiba seedlings, propagation of superior individuals, healthy seedling breeding, and the industrialized production of seedlings, and lay a foundation for the genetic transformation system of B. ceiba.

Leaf photosynthesis is the energy source of plant life activities. However, some macadamia varieties (Macadamia integrifolia) planted in southern China are prone to generate the etiolated leaves under the continuous high temperature in summer, which seriously affects the shoot growth and fruit production of macadamia trees. In order to explore the mechanism of photosynthetic energy generation in the etiolated leaves of macadamia, the genes related to photosynthetic energy metabolism were identified and screened in this study, based on the previously obtained transcriptome sequencing data from the leaves of HAES344 macadamia at different yellowing stages, and the expression changes of the key genes in photosynthetic energy metabolism were analyzed during leaf yellowing of HAES344 macadamia by qRT-PCR. 96 genes with differential expression in the etiolated leaves of HAES344 macadamia were identified to be related to energy metabolism according to KEGG functional annotation and enrichment analysis, and the number of the differentially expressed genes enriched in the oxidative phosphorylation pathway was the highest, followed by carbon fixation pathway, and the least genes were enriched in the antenna proteins. After screening (RPKM>0.5), a total of 43 genes related to photosynthetic energy metabolism were obtained. Among these genes, the expression level of 27 genes decreased significantly in the yellowed leaves, while the remaining 16 genes did the opposite. Through the qRT-PCR analysis of the relative expression level of key functional genes in the photosynthetic energy metabolism, the CAP10A gene encoding photosystem Ⅱ (PSⅡ) antenna protein, the ATPC and ATPF genes encoding ATPase subunit protein, the enzyme genes related to carbon assimilation (GAPA, GPD, At4g2652 and rbcL), the Os05g0200100 and CXXS1 genes encoding thioredoxin, and the TIC32 gene associated with plastid protein transmembrane transport showed a significant lower transcription level in the etiolated leaves of HAES344 macadamia compared with the normal leaves, while the SIR and APR3 genes related to sulfur metabolism and the PGR5, ndhB and ndhD genes mediating cyclic electron transfer did the opposite, which suggested that the greatly changed expression patterns of genes related to photosynthetic energy metabolism affected the production of photosynthetic energy in the macadamia yellowing leaves. The results of this study would provide a reference for further exploring the mechanism of photosynthetic energy metabolism-related genes in the etiolated leaves of macadamia.

The wood of most tree species of Dalbergia L. f. is well-known in the world. The research on wood anatomy mainly focus on tree species, while the research on vine or climbing plant species is rare. This paper discussed the macroscopic and microscopic wood structures of seven species of vines or climbing plants of Dalbergia L. f., and summarized systematically, and compared with the tree species of D. odorifera, so as to provide a scientific basis for wood identification, species identification, protection, breeding, development and utilization of this genus. The macrostructure showed that the difference between heartwood and sapwood was not obvious, and had little glossy, aromatic and oily when rich in gum. The growth ring was not obvious. The pores were obvious and common rich in gum, which were smaller and sparsely distributed in primary xylem, larger and densely distributed in secondary xylem. Included phloem was round. The microstructures indicated that they were all diffuse-porous wood, single pores, radial multiple pores, pores arrangement dispersed, single perforation, inter-vessel pitting alternate, vestured pitting, elliptical to nearly round, and obvious on the tangential section. Axial parenchyma was abundant and overlapped, paratubular banded, annular tubular. The wood rays were non overlapping, more fine and dense. D. odorifera was diffuse-porous wood to near semi-ring-porous wood, included phloem was absent, pith was smaller, axial parenchyma was mainly winged and polymerized-winged (paratubular banded type) or minimal banding (off tube type), low pores density. To sum up, there are many similarities in the wood anatomical structures of the seven vines or climbing plants of Dalbergia L. f., but there are also significant differences mainly in wood rays, wood rays width and pith core inclusions. Wood rays were mainly homotypic multiple columns, occasionally homotypic uniseriate of D. tsoi and D. yunnanensis. D. pinnata and D. benthamii were similar with homotypic single or multiple columns, while the former also had heterogeneous Ⅲ type rarely. D. hancei and D. peishaensis were similar with mainly heterogeneous uniseriate, occasionally heterogeneousⅠ type, while the former also had heterogeneous Ⅲ type rarely. D. candenatensis was mainly heterogeneous Ⅱ type, followed by heterogeneousⅠtype and heterogeneous uniseriate. The wood rays width of D. hanei and D. peishaensis was 1-2 cells, that of D. pinnata, D. benthamii and D. candenatensis was 1-3 cells, that of D. yunnanensis was 1-4 (mostly 2-3) cells. that of D. tsoi was 1-5 (mostly 3-4) cells. The pith core inclusions was mainly golden yellow, but that of D. tsoi was silver white, and that of D. pinnata was absent or not obvious.

The germplasm resources of Amomum tsao-ko (AT) at different altitudes in Nujiang, Yunnan were used as the materials to explore the genetic diversity of the agronomic phenotypic traits of AT germplasm resources at different areas. The genetic diversity of the agronomic phenotypic traits of AT was analyzed by measuring 8 agronomic phenotypic traits, using coefficient of variation, genetic diversity index, variance analysis, correlation analysis, cluster analysis, principal component analysis and comprehensive evaluation. The results showed that there were large variations in the agronomic phenotypic traits, and the variation coefficient was 7.63%-32.51%, among which the variation coefficient of tiller number was the largest. The traits showed good diversity, H' (diversity index) was 1.933-2.355, with an average of 2.024. There were significant differences in the agronomic phenotypic traits among different germplasms. There was a significant positive correlation between fruit longitudinal diameter and fruit shape index and fruit weight. There was a significant positive correlation between fruit transverse diameter and fruit weight. There was a significant negative correlation between fruit shape index and leaf width. Cluster analysis divided the AT germplasm resources at different areas into two groups, among which the AT germplasm resources from the areas of Lushui and from Fugong were clustered into one group. Three principal components were extracted from eight agronomic phenotypic traits, and the cumulative contribution rate reached 76.940%, which could comprehensively reflect most of the information of agronomic phenotypic traits of AT. The comprehensive evaluation results showed that SD12, SD20, SD7, SD17, SD18 and SD5 were ranked in the top six, and the comprehensive performance was better. The genetic diversity of the agronomic phenotypic traits of 24 AT germplasm resources in different areas of Nujiang, Yunnan is relatively rich, and the variability of AT germplasm resources in different areas is obvious. Among them, the agronomic phenotypic traits of SD12, SD20, SD7, SD17, SD18 and SD5 AT are better, which are more suitable for breeding.

The study was aimed to investigate the effects of litchi orchard intercropping Stylosanthes guianensis on soil physicochemical properties and soil bacterial community structure, and to provide theoretical basis for litchi orchard intercropping S. guianensis. Soil samples from litchi orchard intercropped with S. guianensis and litchi monocropping modes were used to determine soil physicochemical properties and analyzed by bacterial amplicon sequencing. After intercropping S. guianensis in litchi orchard, in the soil layer depth of 0-20 cm, nitrate nitrogen content significantly increased by 47.52%, available phosphorus content highly significantly increased by 141.53% and available potassium content highly significantly reduced by 125.59%; in the soil layer depth of 20-40 cm, nitrate nitrogen content highly significantly increased by 76.02%, available phosphorus content highly significantly increased by 48.52%, and available potassium content highly significantly reduced by 188.57%. In terms of alpha bacterial diversity, there were no significant changes in Chao1 index, AEC index, Simpson index and Shannon index in 0-20 cm soil layer and 20-40 cm soil layer after intercropping S. guianensis in litchi orchard. In terms of soil bacterial community structure, the main dominant phyla in the soil samples were all Acidobacteriota, Proteobacteria, Firmicutes, Chloroflexi, Bacteroidota, Verrucomicrobiota, Actinobacteriota, Gemmatimonadota, Myxococcota, Crenarchaeota, and Crenarchaeota were soil-specific relative abundances greater than 1% of the phyla after intercropping S. guianensis at 0-20 cm soil depth; at the genus level, in the 0-20 cm soil layer, Candidatus_Nitrosotalea was the genus with soil-specific relative abundance greater than 1% after intercropping S. guianensis, and at the 0-40 cm soil level, Nitrospira was the genus with soil-specific relative abundance greater than 1% after intercropping S. guianensis, Proteobacteria, Verrucomicrobiota, and Gemmatimonadota increased at all soil depths after intercropping S. guianensis; the results of the redundancy analysis showed that the soil bacterial community was mainly affected by effective phosphorus, nitrate nitrogen, and organic matter. In summary, intercropping litchi orchard with S. guianensis would improve the physicochemical properties and change the structure of soil bacterial community in litchi orchard soil, and play a certain role in optimizing the environmental conditions of litchi orchard soil.

Oryza officinalis Wall. ex G. Watt has excellent characteristics such as disease and insect resistance, stress tolerance, high biological yield and high light efficiency, and contains many excellent genes. In this study, 199 representative resources collected from all Oryza officinalis distribution sites in Guangxi were used to analyze the genetic diversity and principal components for five important agronomic traits, including heading stage, anther length, grain width, grain length and grain weight. The results showed that O. officinalis from Guangxi had rich genetic diversity, with coefficients of variation of 9.12%, 11.90%, 3.39%, 4.64% and 6.24% for heading stage, anther length, grain width, grain length and grain weight, respectively, and diversity index was 1.4878, 2.0453, 1.7727, 1.1567 and 2.0379, respectively. Principal component analysis showed that the first and second principal components were mainly related to yield traits, with a cumulative contribution rate of 63.759%. The third and fourth principal components had a cumulative contribution rate 16.306% and 15.542%, respectively. The heading stage and anther length were the influential determinants, mainly reflecting the plant growth characteristics. According to the genetic diversity, the seven geographic populations are ranked as follows: Wuzhou (1.6731)>Yulin (1.5784)>Guigang (1.5070)>Nanning (1.3325)>Laibin (1.2131)>Hezhou (0.9629)>Qinzhou (0.3819), and Wuzhou had the highest diversity index, indicating that Wuzhou was the phenotypic diversity center of Oryza officinalis in Guangxi.

Rice (Oryza sativa L.) is an important food crop, and the normal germination of rice seeds is related to the growth and yield of the plant in the later period. The germination begins with water absorption by dry seeds and ends with cotyl elongation. Water transport within and between cells is highly selectively regulated by aquaporins (AQPs). The seeds of cereal are rich in starch. And the endogenous gibberellin can induce the synthesis of hydrolase such as α-amylase in the embryo and secrete them into the starchy endosperm to degrade starch into small molecules for seed germination. Studies have shown that only α-amylase can complete the degradation of starch in rice seeds. Nitric oxide (NO) is a signaling molecule that forms a variety of active nitrogen substances. It also participated in the signaling process of seed dormancy removal. NO donor plays a role in seed germination by enhancing amylase activity. NO donor can promote seed germination by improving the activity of amylase. Rice hybrid seeds of ‘BoⅡ you 767’ were used as experimental materials to investigate the effects of aquaporins (AQPs) and nitric oxide (NO) on the germination of rice seeds. In this study, NO synthesis inhibitors N-(G)-nitro-L-arginine methyl ester (L-NAME) and sodium tungstate (ST), sodium nitroprusside (SNP), an exogenous donor of NO, and mercury chloride (HgCl₂), an activity inhibitor of AQPs, were used to treat rice seeds. The changes of water absorption capacity, amylase activity and starch degradation rate during germination of rice seeds were determined in virtue of apparent analysis and index detection. The results showed that the water absorption capacity, amylase activity and germination rate decreased in the rice seeds treated with 90 mg/L HgCl₂, while the starch content remained high, and the growth of radicle and germ was inhibited. However, NO exogenous donor SNP could reverse the effect of HgCl₂. And the effect of NO synthesis inhibitors L-NAME (15 mmol/L) and ST (80 µmol/L) on the germination of rice seeds was similar to that of HgCl₂. The results indicated that AQPs could induce water uptake, stimulate amylase, accelerate starch degradation and promote seed germination in the early germinating stage of rice seeds through NO. The study would lay a theoretical foundation for improving rice yield.