Agave spp. is main resource of hard fiber. Zebra disease, caused by the pathogen Phytophthora nicotianae, is one of the most devastating sisal oomycete diseases. RXLR effector proteins are important cytoplasmic effectors of oomycete and more than 300 RXLR effector genes were identified in the genomes of P. nicotianae. RXLR effectors have the ability to manipulate or suppress host immunity by directly binding host proteins. A typical RXLR effector (named PnRXLR5863) that induced programmed cell death (PCD) was identified from P. nicotianae, but the targets in Agave were still unknown. This study aims to obtain the host plant proteins that are interacting with PnRXLR5863 in A. hybrid No.11648. A normalized cDNA library was constructed by combining Switching Mechanism at 5′ end of RNA Transcript (SMART) and Duplex-Specific Nuclease (DSN) technology. The capacity of cDNA library was 5.32×10⁷ CFU/ml, the independent clones was 1.064×10⁸ CFU, and the lengths of inserts ranged from 0.5 kb to 3.0 kb, with the recombination rate of 100%. A total of 23 proteins interacting with PnRXLR5863 were obtained by sequencing and homology analysis. Some of target proteins involve several physiological events, such as ubiquitination, protein synthesis, protein translation and protein translation, suggesting that PnRXLR5863 effector may act on protein metabolism of Agave spp. This research would lay a foundation for further study of the pathogenic mechanism of PnRXLR5863.

Macadamia nuts contain abundant source of unsaturated fat acid (UFA), but the molecular mechanism of biosynthesis of UFA remains to be further analyzed. Stearoyl acyl-carrier- protein desaturase catalyses the insertion of a double bond into saturated fatty acid bound in saturated acyl chains bound to ACP in higher plant, which is the key enzyme in unsaturated fatty acid biological synthesis pathway. The Macadamia intergrifolia plant as research object, the full-length gDNA and cDNA of SAD gene encoding stearoyl acyl-carrier- protein desaturase were isolated from M. integrifolia using PCR technique. The structure, function and expression pattern of MiSAD were preliminarily studied. The gDNA of SAD was 6947 bp and contained 3 exons and 2 introns. The open reading frame was 1191 bp and encoded 396 amino acids which was highly consistent with the public MtSAD sequence, and SAD was a water soluble enzyme with a total predicted molecular mass of 45.22 kDa and isoelectric point (pI) 5.93 located in chloroplast or plasmids stroma. The amino acid sequences of SAD involved in active site showed highly conserved and significant difference in N-end and C-end. The highly conserved region contained 2 central motifs of E-X-X-H iron atoms which formed the active site of this enzyme. The α-helix and random curl were predominate in the secondary structure. The helix-turning-helix was found in the prediction of tertiary structure for formation of fatty acyl chain binding site. Derived amino acid sequence showed the highest homology 94.2% with Telopea speciosissima, and the homology is above 80%in other species of SAD, close to Nelumbo nucifera in phylogentic tree. The SAD gene expression trends were basically identical by qRT-PCR. The SAD expression were found in root, stem, leaf, flower and macadamia nut, and the highest level was in nut. The expression of SAD gene increased about 90days after and reached the highest level at 100 days, then declined gradually in the following days during the macadamia nut maturation and presenting a normal distribution trend. This study would build a foundation for elucidating the molecular mechanism of MiSAD in biosynthesis of unsaturated fatty acid in macadamia.

Codon bias is an important factor affecting gene expression, and it is also one of the key clues to reflect gene evolution. Orchidaceae plants are the "flagship" group in plant protection, and most species have medicinal and ornamental values, but seeds are not easy to germinate. ABI3 (abscisic acid insensitive 3) gene is the central regulator of ABA signal transduction, involved in seed development and dormancy processes, and is the key factor to regulate plant seed germination. Therefore, in-depth study of codon bias of orchid ABI3 gene can lay a foundation for analyzing the function of the gene and optimizing the codon composition. Using Arabidopsis thaliana ABI3 gene as a probe, 45 Orchidaceae ABI3 genes were screened from the public database (NCBI), and the codon use patterns and preferences were analyzed by bioinformatics programs such as CodonW, SPSS and MEGA. The ENC (effective number of codon) value of the genes ranged from 40.84 to 58.46, of which 82.2% was greater than 52. The average value of CAI (codon adaptation index) was 0.203, far less than 1, indicating that the codon usage bias of ABI3 gene was relatively weak. Neutral plot analysis showed that the slope of the regression curve between GC₁₂ and GC₃ was 0.6103, R²=0.7928 (P<0.05), indicating that the base composition has an important influence on codon bias. In ENC plot analysis, the ENC value of all genes was lower than the expected value, but the difference was small, indicating that the codon of orchid ABI3 gene is mainly affected by base mutation and other factors such as selection pressure. Parity preference analysis showed that most genes were distributed in the right region of the plan, and the use frequency of A/T (U) at codon 3 was higher than that of G/C. Through RSCU and ΔRSCU analysis, 26 optimal codons were identified, including 14 codons ending in A/T (U) and 10 codons ending in T (U), indicating that ABI3 gene of orchid plants relatively prefers to use codons ending in A/T (U), especially codons ending in T (U), which is different from that of most monocotyledonous plants. This study may provide a theoretical basis for the phylogenetic and functional elucidation of ABI3 genes in Orchidaceae and for improving ABI3 gene expression efficiency, as well as facilitating codon biology in plants and the improvement of exogenous genes.

In order to assess the breeding value of HoCP series sugarcane germplasms introduced from USA, 12 HoCP sugarcane clones (HoCP00-1142, HoCP01-517, HoCP01-564, HoCP02-610, HoCP02-623, HoCP03-704, HoCP03-708, HoCP03-716, HoCP05-902, HoCP07-613, HoCP07-617 and HoCP92-648) were used as core parents in 73 sugarcane cross combinations. The effect on combining ability, economic breeding values of height, diameter, effective stem number, sugar content and cane yield for the 11 HoCP sugarcane parents and 73 F₁ population were estimated using the family test method. Significant differences were found for height among HoCP males and cross combinations, whereas no significant differences were detected for height among HoCP females, suggesting that the plant height was affected by only male and cross combination. For the stem diameter, effective stem number, sugar content and cane yield, there were significant differences existed among different HoCP female, male and cross combination, indicating that the four characters were affected by female, male and cross combination. Among the 12 clones, the highest general combining ability for height, diameter, effective stem number, sugar content and cane yield appeared in HoCP03-704, HoCP02-623, HoCP02-610, HoCP07-617, and HoCP92-648 as female, respectively, while HoCP03-704, HoCP02-623, HoCP07-617, HoCP03-708 and HoCP02-623 as male possessed the highest general combining ability for height, diameter, effective stem number, sugar content and cane yield, respectively. The better economy breeding value (EBV) and general combining ability (GCA) in cane yield and sugar content were detected in HoCP02-623, HoCP03-708 and HoCP92-648 as the female, and HoCP01-517and HoCP07-617 as the male, which indicated that the clones could be used as excellent female and male with high-yield and hight-sugar, respectively. Among the 73 cross combinations, the highest special combining ability for height, diameter, effective stem number, sugar content and cane yield appeared in HoCP03-704×'Neijiang 03-218', 'Yuetang 00-236'×HoCP00-1142, 'Yacheng 07-71'×HoCP05-902, 'Yuetang 00-236'×HoCP03-708, HoCP01-564×'Guitang 92-66', respectively. A total of 38 cross combinations showed possitive EBV. The combinations 'Yuetang 94-128'×HoCP01-517, HoCP01-564×'Guitang 92-66', 'Guitang 02-467'×HoCP01-564 had better special combining ability in cane yield, sugar content and EBV than the others, which could be considered as the most important productive families in future breeding program. However, HoCP03-716×'Funong 02-6404', 'Yuetang 99-66'×HoCP01-564 and 'Yuenong 73-204'×HoCP01-564 showed lower special combining ability in five characters and lower EBV than other combinations, suggesting that the combinations did not suit for using as productive families in future breeding program. Therefore, the results would provide helpful information for using HoCP sugarcane parents in cross combination.

Tribe Vandeae belongs to Orchidaceae and is distributed at low altitudes in southern and southeastern Tibet. Due to the limited transportation conditions in the past, understanding of tribe Vandeae species in Tibet was poor. We reporte a less known species of orchids from China: Papilionanthe uniflora (Lindl.) Garay. It was originally only recorded in the Flora of Tibet, but was not included in the Flora of China due to the lack of important features such as flowers. This article provides detailed information about the anatomy of this species for future supplement and revision. The following 12 new recorded species are reported in Tibet: Aerides rosea Lodd. ex Lindl. & Paxton, Cleisostoma aspersum (Rchb. f.) Garay, Cleisostoma linearilobatum (Seidenf. & Smitin.) Garay, Cleisostoma racemiferum (Lindl.) Garay, Cleisostoma simondii (Gagnep.) Seidenf., Gastrochilus affinis (King & Pantl.) Schltr., Gastrochilus prionophyllus H. Jiang, D. P. Ye & Q. Liu, Gastrochilus pseudodistichus (King et Pantl.) Schltr., Phalaenopsis lobbii (Rchb. f.) H. R. Sweet, Taeniophyllum glandulosum Blume, Uncifera obtusifolia Lindl. and Vanda concolor Blume, Uncifera Lindl. is a new recorded genus in Tibet. We providedetailed descriptions of morphological identification and pictures. Mos Vandeae species have important ornamental value, such as Phalaenopsis and Vanda. The findings not only expand orchid resources in Tibet, but also provide basic information for the utilization of ornamental orchids in Tibet.

Exocarpium Citrus Grandis (ECG) is a medicinal plant of Citrus in Rutaceae. It is a medicine that has great effects. To distinguish the 'Zhengmao' and 'Non-zhengmao' germlplasms, 13ECG germplasms were selected, including 'Zhengmao' germplasms ('Dahe huangrong', 'Dahe miye', 'Pingding huangrong', 'Pingding miye', 'Pingding hongrou', 'Shanche zhengmao' and 'Shiwan zhengmao') and 'Non Zhengmao' germplasms ('Shanche fengwei', 'Shanche fumao', 'Shanche jiaxiyang', 'Shanche guangqing', 'Pingding jinqiandu', 'Pingding shishengli'). The botanical morphological traits were measured, active substances were analyzed, and molecular markers were carried by the ISSR and SRAP for distinguishing analysis. There were significant differences in length of leaf, leaf shape index, L^*, a^* and b^*. The leaves of 'Zhengmao' germplasms were slenderer than those of 'Non-zhengmao', the whole leaf was whiter, greener and yellower. There were significant differences in fruit shape and the fruit shape index between 'Zhengmao' germplasms and 'Non-Zhengmao' germplasms. The content of rhubarb glycoside in most 'Zhengmao' germplasms was higher than that of 'Non-zhengmao' samples, except the 'Shanche fumao'. The content of alcohol soluble extract was also significantly different between the germplasms. The clustering results of ISSR and SRAP showed that when the genetic distance of the two molecular markers was 15 cM, the 13 germplasms could be divided into one 'Zhengmao' and three 'Non Zhengmao' groups. The correlation analysis between germplasm botany and medicinal components showed that, when P<0.05, only the fruit shape and fruit shape index were significantly correlated with the content of wild rhubarb glycoside and naringin, the water-soluble extract was significantly positively correlated with L^*. To conclude, when combined with the three identification results, the molecular marker is the most reliable to distinguish the germplasm of ECG, the plant morphology (petal length, fruit shape and fruit shape index) or medicinal components (content of wild rhubarb glycoside and alcohol extract) can also distinguish these germplasm to a certain extent.

In order to understand the characteristics of the wild seed plant system in Nanning and provide a scientific basis for the conservation and rational development and utilization of biodiversity in the region, the author investigated and analyzed its plant resources, compiled a list of wild seed plants in Nanning using statistical methods of literature collection, line survey and sample survey, judged their affinities with 15 neighboring areas using cluster analysis and principal component analysis, and analyzed their systemic characteristics, the results show that: there are 3574 species of wild seed plants in 197 families and 1114 genera in the region, 24 species of 14 genera in 8 families of gymnosperms and 3552 species of 1100 genera in 189 families of angiosperms. The ratio of the number of seed plant families, genera and species in Guangxi is 77.87%, 60.02% and 42.90% respectively, indicating that the wild seed plants in Nanning are rich and diverse. The ratio of large families is 27.41%, and the number of species contained is 78.44%, which is the main component of the system. Monospecific and oligospecific genera accounted for 85.28% of the total number of genera, but the number of species contained in medium and multiple genera accounted for 51.65% of the total number of species, indicating that the family is rich in species but less differentiated. There are 14 genus-level distribution area types in the region, with rich and complex geographical components, among which tropical components account for 69.55% of the total number of genera and temperate components account for 22.16%, showing obvious tropical attributes and some temperate attributes. 223 rare and endangered plants in the region, rich in species, including Orchidaceae, Camellia petelotii and other endemic plant species, the regional characteristics of Guangxi plants are obvious, and the protection value is high. The system belongs to the Beibu Gulf region and the Yunnan-Guizhou-Guangxi region, and its R/T value (3.08) is in the middle compared with the neighboring regions, similar to the R/T value (2.32) of the six counties on the border of Qian-Guizhou, and the largest difference from the R/T value (8.80) of the coastal zone of Beibu Gulf, and the R/T value is negatively correlated with latitude. In terms of genus-level phytogeographic composition, Nanning was the most similar and closely related to Hainan and Xichu, and the most distant from Murray. Overall, the wild seed flora of Nanning is rich in species, ancient in relics, with more rare and endangered plants, showing a tropical and subtropical transitional nature, reflecting the characteristics of the Beibu Gulf and Yunnan-Guizhou-Guizhou flora.

Laticifer cells present in aging calli of Hevea brasiliensis. Methyl jasmonate (MeJA) and jasmonic acid (JA) belong to jasmonates (JAs). However, the effect of MeJA on laticifer cell differentiation of the rubber tree anther calli is unclear. In the present paper, the effect of MeJA on laticifer cell differentiation of anther calli was systematically studied. MeJA added to media in the range of 0-1 mg/L did not influence the growth of anther calli, while higher concentration of MeJA in media in the range of 2-3 mg/L severely inhibited callus growth. MeJA concentration in media was negatively correlated with callus growth. Histochemical sections showed that low concentration of MeJA in media greatly promoted the differentiation of callus laticifer cells and remarkably increased the occurring frequency, while high concentration of MeJA in media gravely impeded callus laticifer cell differentiation and strikingly decreased the occurring frequency. Among them, 1 mg/L MeJA in media was the optimal concentration to improve the differentiation of laticifer cells in calli. qPCR results showed that when the media were supplemented with MeJA, the change trend of the expression level of genes that was essential in latex biosynthesis, such as small rubber particle protein (SRPP), rubber elongation factor (REF), and cis-prenyl transferase (CPT), was basically consistent with that of the occurring frequency of callus laticifer cells, which further confirmed that MeJA promoted the differentiation of callus laticifer cells. Transmission electron microscopy observation showed that callus laticifer cells contained some specific organelles, such as rubber particles and lutoids. The results of this paper are of great significance for promoting the application of rubber tree callus in the study of laticifer differentiation, and for developing rubber tree novel yield-increasing reagents.

Dendrobium is a class of ornamental plants native to tropical regions, suitable for cultivation in high temperature and high humidity environment, and susceptible to low temperature stress. To investigate the physiological response and cold tolerance of Dendrobium to low temperature stress, Dendrobium 'Sonia Hiasakul' mature (SH) were treated in temperature 15 ℃, 10 ℃ and 5 ℃ for 1 h, 2 h, 4 h, 8 h, and the physiological indexes and morphological changes of SH were surveyed 1 d, 2 d, 4 d, 8 d and 16 d after. The changes of physiological indexes included soluble protein, soluble sugar, free proline, malondialdehyde (MDA), chlorophyll content, electrical conductivity and the defoliation rate of the treated plants. Based on the relative conductivity of different temperature treatments, a Logistic equation was fitted to calculate the half-lethal temperature (LT₅₀) of SH, and a correlation analysis between the half-lethal temperature at low temperature (LT₅₀) and the physiological indexes of cold resistance was conducted, with the aim to investigate the morphological and physiological response characteristics of SH under different low temperature environment and to understand the pattern of its growth and development. The electrical conductivity, free proline, malondialdehyde (MDA) content and the defoliation rate of SH increased significantly with the extension of the stress time and the soluble protein and soluble sugar content fluctuated continuously, in a state of rising, falling, then rising again. The chlorophyll content decreased gradually, reaching the lowest 0.2534 mg/g treated at 5 ℃ for 16 d. Correlation analysis revealed that the free proline, malondialdehyde (MDA), defoliation rate and semi-lethal temperature were all highly significantly correlated and chlorophyll content and semi-lethal temperature were significantly correlated, and it was speculated that the content of the physiological indicators was related to the cold resistance characteristics of SH. The study would provide a theoretical basis for determining the cold tolerance identification index and dealing with cold damage in SH, and lay a foundation for further research on the resistance of Dendrobium hybrids to low temperature damage.

Soil salinization is one of the important factors limiting crop growth. Cultivating new salt-tolerant rice varieties is of great significance to expand rice planting area. In order to explore the change trend of growth and physiology of different varieties of rice seedlings and clarify the salt tolerance of different rice varieties at seedling stage, five rice varieties were used as the experimental materials. The effects of different concentrations of NaCl (0 mmol/L, 70 mmol/L, 140 mmol/L) on the growth and related physiological indexes were studied at rice seedlings using hydroponic method. The principal component analysis and membership function method were used to comprehensively evaluate the salt tolerance of five rice seedlings. The results showed that under salt stress, salt inhibited the root length, root surface area, root volume, root tip number and root mean diameter of all rice varieties in general. The root growth index values of 'HH11' and 'Nipponbare' changed little. The root length, root volume, root surface area and root tip number of '9311' and 'JX99' were significantly inhibited. The average root tip number of 'HD961' was the largest among the five rice varieties. With the increase of NaCl concentration, the plant height and root activity of each variety showed a gradual downward trend, and the total chlorophyll content, relative conductivity, MDA content, proline content and Na⁺/K⁺ of root showed an overall upward trend, and the root Na⁺ and K⁺ contents showed a trend of first increase and then decrease. Among them, the relative electrical conductivity and proline content of '9311' and 'JX99' increased the most, the MDA and root Na⁺/K⁺ of 'Nipponbare' and 'HH11' increased the least, the plant height of Nipponbare decreased the least, and the root activity of 'HH11' decreased the least under salt stress. Principal component analysis showed that three independent comprehensive indexes explained 94.23% of the changes of 16 single indexes under salt stress. Among them, root length, root volume, root tip number, total chlorophyll content, malondialdehyde content and electrical conductivity could be used as the main factors to evaluate salt tolerance at seedling stage, and K⁺, Na⁺/K⁺ and plant height could be used as the secondary factors to evaluate salt tolerance at seedling stage. The results of membership function analysis showed that the salt tolerance of the five rice varieties from strong to weak was 'HH11'>'HD961'>'Nipponbare'>'9311'>'JX99'.