Camellia nitidissima belongs to the genus Camellia of theaceae and belongs to the first-level national protection plant, with high ornamental value and medicinal value. However, at present, there are few wild resources of C. nitidissima. It is necessary to find efficient artificial cultivation methods, rapidly propagate excellent C. nitidissima seedlings, and then greatly improve the yield of large-scale cultivation of C. nitidissima. Arbuscular mycorrhizal (AM) fungi can significantly promote plant growth and development, increase crop yield, and enhance plant stress and disease resistance. Inoculation of AM fungi into C. nitidissima has a positive effect on the cultivation of C. nitidissima. Since almost all AM fungal inoculation test involves the growth of mycorrhizal observation and infection rate determination, and AM infection situation observation methods available are not efficient. An efficient dyeing of AM fungi C. nitidissima was reported. In this study, the effects of five dyes (Sudan red Ⅳ, acid fuchsin, trypan blue, aniline blue and acetic acid ink) on AM fungi of healthy plant roots of C. nitidissima were investigated. The results showed that 5% acetic acid ink staining solution had the best staining effect. Mycelia, vesicles, spores and other structures of AM fungi in root cortex cells were clearly visible, and AM fungi could be clearly distinguished from other unknown fungi, and the root staining effect could be preserved for a long time. The mycelia and vesicles of AM fungi stained with Sudan red Ⅳ and acid fuchsin were not in obvious contrast with the background, and the preservation time of acid fuchsin staining was short, which was not conducive to observation. The dyeing effect of aniline blue and trypan blue was slightly inferior to acetic acid ink, and the price was expensive and the experimental cost was high. The last four dyes are suspected of causing cancer, and the long-term use has great potential safety risks to the health of operators. Acetic acid ink dyeing is simple, low toxicity, low cost and excellent dyeing effect. It is suitable for the staining and section observation of AM fungi in the roots of C. nitidissima. The results would provide new ideas for the future application of C. nitidissima mycorrhizal seedlings.

Cassava is the sixth-important grain crop in the world and the major cash crop in Southern China. Now cassava related industries play an important role in the local agricultural economy. Various kinds of diseases often happen and cause serious economic losses in the field, which become an important issue. This paper briefly reviewed the progress of cassava disease research, including the slow development stage from the founding of the P. R China to the 1980s, the fast development stage from the 1990s to the 2010s, and the rapid development stage after the 2010s. The latest research progress is the core part of this paper. Currently, there are four categories and eleven kinds of diseases that harm cassava in China. Cassava bacterial blight (CBB) is the most serious disease, and brown leaf spot occures in the largest area. Cassava mosaic disease (CMD) is the worst disease in the world, which has invaded mainland China. Chinese Academy of Tropical Agricultural Sciences and other institutions have launched the research of disease database construction and intelligent monitoring technology. The researcher had estimated the risk of five kinds of dangerous disease to cassava planting industry of China. For CMD and cassava brown streak disease, the research on the resistance evaluation of the main varieties, damage mechanism of virus, and detection methods were studied. As far as CBB, monitoring technology, genome sequencing of pathogen, pathogenic and copper resistant mechanisms, genetic variation of pathogen populations, selection of resistant germplasm and its function mechanism were investigated. The effective bactericide for CBB was screened, the efficient spraying and biological control technology were formed, along with the stem disinfection method was popularized in the field. In term of CMD, the occurrence area, virus identification, key factors for long range diffusion were confirmed in China, and significant advance was achieved in virus damage and propagation mechanism. The advance of monitoring and control technology on another seven kinds of common diseases was also expounded in this paper. With the development of the national economy, there have been new trends in China's cassava planting industry, such as food consumption and scaling planting. The authors further look forward to the number of participating institutions, the speed of scientific research progress, the boosting role of multidisciplinary integration, and new research hotspots will emerge in the future. This article would help relevant practitioners to better understand the current situation and research progress of cassava diseases in China, and also provide a reference for the research and application of monitoring technologies of other crop diseases in tropical areas.

Cassava (Manihot esculenta Crantz) is the sixth-largest food crop in the world, nearly 700 million people in the world tropical regions take it as the primary food source, and it is also an important raw material for the production of starch, modified starch, fuel ethanol and other chemical products and feed in China. It plays an important role in eradicating hunger, poverty alleviation and rural revitalization in tropical areas. Cassava root is rich in starch, which can provide energy for livestock and poultry growth. Cassava stems and leaves are rich in protein, cellulose and vitamins and other nutrients, thereby becoming a high-quality protein feed resource. Energy value of cassava is similar to that of corn, thus boasting great development potential as the feed. In recent years, it has achieved good results in the breeding of livestock and poultry such as pigs, sheep and chickens. Therefore, it is of great significance of using cassava as energy feed and replacing corn and other raw materials to mitigating competition for food between human beings and livestock and improve the economic benefits of breeding. This article comprehensively analyzed the nutritional value of cassava and the research progress of its feed application, and put forward specific suggestions for further research and utilization to provide reference for the development of cassava feed industry in the future.

Chalcone synthase (CHS) is the first limiting enzyme in flavonoid synthesis pathway and plays an important role in flower color formation, growth and development, and abiotic stress. In order to clarify the characteristics of cassava MeCHS gene family and its expression in cassava postharvest physiological deterioration (PPD), the MeCHS gene family was analyzed using bioinformatics, including physicochemical property and subcellular location. qRT-PCR was carried out to detect the expression levels of MeCHS genes in different varieties, different tissues and PPD process. The genes with significant relative expression were selected for cloning and subcellular localization verification. A total of 5 MeCHS gene members were identified in the cassava genome. The secondary structure analysis showed that the MeCHS gene family was mainly composed of α-helices and random coils. Tissue specific expression indicated that the expression levels of MeCHS genes were higher in stems. The major expressed MeCHS genes in cassava were MeCHS1, MeCHS2 and MeCHS3; and the expression levels of these three genes were gradually increase with PPD. MeCHS1, MeCHS2 and MeCHS3 were successfully cloned; and fluorescence transient expression showed that MeCHS1, MeCHS2 and MeCHS3 were localized in the cytoplasm, which was consistent with the predicted results. This study will provide a theoretical basis for further revealing the function of MeCHS gene family and improving the PPD tolerance of cassava.

Protein phosphatase 2C (PP2C) plays a key role in the ABA signaling pathway. In order to investigate the response process of the PP2C gene to abiotic stress in cassava, MePP2CAb gene was cloned from Arg7 in cassava using the RT-PCR technique. Bioinformatic analysis, autoactivation activity analysis, promoter activity analysis, and expression pattern analysis of the MePP2CAb gene under different stress and hormone treatments were conducted. The results showed that (1) the total length of the MePP2CAb gene was 1296 bp, encoding 431 amino acid residues. The MePP2CAb protein had a relative molecular weight of 47.08 kDa and a theoretical isoelectric point of 5.5. It exhibited structural domain characteristics of the PP2C family. Protein sequence analysis showed that MePP2CAb was most similar to PP2C sequences of Hevea rubber and Jatropha jatropha, with consistencies of 82.75% and 74.01%, respectively, and a conserved C-terminal. These results indicated that MePP2CAb belongs to the PP2C family. (2) The expression of the MePP2CAb gene was found to be higher in cassava storage roots, stems, and leaves, with the highest expression observed in storage roots. (3) MePP2CAb demonstrated self-activation activity, and its full-length promoter exhibited high activity. (4) The MePP2CAb gene belongs to the core ABA pathway, and promoter sequence analysis showed that it contained ABRE (abscisic acid responsiveness) elements, MeJA response elements, and a drought-induced motif. Under different stress and hormone treatments, low temperature and SA treatment significantly repressed the MePP2CAb gene, while mannitol, NaCl, ABA, and MeJA significantly induced its expression. In addition, the interaction between MePP2CAb and MePYL1 was also observed. These results suggest that MePP2CAb may be responsive to abiotic stress in cassava, although its role as a positive or negative regulatory factor remains unclear. These results provide a clue for further investigation into the role of the MePP2CAb gene in the ABA signaling pathway and the improvement of cassava's adaptation to abiotic stress.

Cassava is an important food crop in tropical regions, and one of the main breeding goals is to cultivate new lines with high β-carotene, low cyanogenic glucoside and waxy taste. In order to screen promising edible lines from breeding materials, the study developed a MATE-SNAP marker based on a mutation of G→A in the coding region of cyanogenic glucoside transporter gene MATE which resulted to amino acid change and affected its transmembrane structure stability. Combining with the β-carotene PSY2-SNAP and waxy quality GBSSⅠ-SNAP markers, 12 parent lines, carrying 1-2 target alleles, were selected from 50 cassava germplasms, and totally hybridized 10 cross-combinations according to flowering period among different years. Firstly, 134 erect or middle branched candidate lines were screen out through seedling, transplanting and preliminary field trial. Secondly, 13 edible promising lines which aggregated 2-3 target alleles, were chosen by using MATE/PSY2/GBSSⅠ-SNAP markers together. The content of of cyanogenic glucoside in root flesh was determined by spectrophotometry, the value of SC9 was 49.24 μg/g, and those of 13 promising lines were in the range of 38.82-76.51 μg/g; the content of β-carotene in root flesh was determined by acetone colorimetry, the value of SC9 was 184.75 μg/hg, and those of the six yellow-root lines were within the limits of 101.58-154.10 μg/hg; the content of amylopectin in root flesh was determined by dual wavelength spectrophotometry, the values of P13-1 and V7-14, whose alleles were GG that genotyped by GBSSⅠ-SNAP marker, was 82.46% and 83.79%, respectively. Based on this, 5 lines, A5-138, A2-213, P7-6, V4-8 and V4-19, were found to be the potential new edible cassava varieties by taste grading. In conclusion, marker-assisted selection can quickly and accurately screen out the target lines from breeding materials and improve the efficiency of cassava genetic improvement.

Edible cassava is an important food crop in the world and a characteristic potato crop in South China. New edible varieties with high β-carotene and excellent comprehensive quality are one of the important directions of cassava breeding. Manihot esculenta Crantz cv. Gui 9 was obtained from immature fruits, using embryo rescue technology, which were harvested from in-bred crossing population using XX048 as the female. The main characters of the variety were erect plant type, tubers distributed horizontally, cylindrical conical in shape, tubers of light brown skin, pink endothelium and orange flesh. The fresh tuber yield was (45.12±7.04) t/hm² and (40.84±3.88)t/hm² respectively in the regional test and production test. The starch content of fresh tuber detected was 26.3%, β-carotene content was 454 μg/100 g, hydrocyanic acid content was 10-20 mg/kg, tatal sugar content was 2.0 g/100 g, dietary fiber and potassium content was 4.43 g/100 g and 553 mg/100 g respectively. Gui 9 is an edible cassava variety in China with the highest β-carotene content in tuber at present, rich in β-carotene, dietary fiber and minerals, fresh taste crisp and sweet, known as "carrot cassava", with unique advantages in color and taste in cooking and making cassava juice. Gui 9 has high yield and strong adaptability with moderately resistance to cinnabar Tetranychus mites, and is suitable for dense planting and mechanical harvesting. It could be popularized in cassava producing areas such as Guangxi, Guangdong, Hainan and Jiangxi provinces. The breeding of Gui 9 would provide variety support for the development of cassava food, and promote the quality improvement, efficiency increase and sustainable development of cassava industry.

MNP (multiple nucleotide polymorphism, MNP) is a new molecular marker technology emerged with the development of molecular marker technology. While genotyping by target sequencing (GBTS) amplifies only one SNP site in one amplicon, MNP can amplify multiple SNP sites simultaneously in one amplicon based on GBTS. This technology has the features of low cost, high detection efficiency, flexible application and wide adaptability, Compared with SNP, MNP has better ability to differentiate varieties. In order to establish a rapid, accurate and efficient method for cassava variety identification and to screen MNP molecular markers suitable for cassava variety identification, this study screened highly polymorphic regions and designed primers in the whole genome range, and finally obtained 623 cassava MNP marker loci in the whole genome range, the cassava MNP markers were evaluated using 28 cassava varieties. The results showed that the MNP marker typing reproducibility was up to 100%. 4.07±1.68 alleles were detected in 28 cassava varieties, with a maximum of 12 alleles. When all cassava varieties were compared one by a one, 99.47%(376/378) of the differences between pairs were greater than 46%, with the proportion ranging from 0.3% to 81.0%, with a mean value of 71.78%. Meanwhile, MNP markers can be used for identification in the breeding process. In conclusion, the cassava MNP molecular markers developed in this study have high reproducibility, polymorphism and variety differentiation ability, and could be widely used for research on germplasm diversity, new variety breeding and variety identification of cassava.

Cassava leaves are rich in abundant flavonols, and efficient extraction and analysis methods are crucial for the evaluation of flavonol content in the cassava leaves. This study aims to optimize the extraction and detection methods for four flavonols (myricetin, rutin, nicotiflorin, narcissoside) in cassava leaves and to analyze the influence of different cassava varieties, harvesting periods, and maturity on the content of these flavonols. The results indicated that using a 50% ethanol-water solution, a liquid-to-material ratio of 1∶50 (g/mL), an ultrasonic extraction temperature of 50 ℃, and an ultrasonic extraction time of 60 minutes could effectively extract the four flavonols in the cassava leaves. The combination of different C18 chromatographic columns in HPLC-DAD effectively separated the four flavonoids present in the cassava leaves. The results of the method validation showed that the four flavonols exhibited good linear correlations within a certain concentration range, with R² values of 0.9999, 0.9999, 0.9999 and 0.9998, respectively. The detection limits ranged from 6.0 mg/kg to 10.0 mg/kg, and the quantification limits ranged from 20.0 mg/kg to 32.0 mg/kg. The detection method demonstrates good system adaptability, with retention time and peak area relative standard deviations (RSD) being less than 1%. The samples showed good stability in terms of intra-day, inter-day, and intra-month variations, with RSD in content variations ranging from 0.44% to 3.57%. The average recovery rates of the method ranged from 92.68% to 109.14%, all with RSD values less than 6.0%. Utilizing the established extraction and analysis methods, the study analyzed the content of the four flavonols in 30 cassava germplasm resources. Rutin and nicotiflorin maked up 93.50% to 99.30% of the total flavonol content in the cassava leaves, with the levels primarily determining the total flavonol content. However, the correlation order for the total flavonol content among different varieties was rutin>narcissoside>nicotiflorin>myricetin. Analysis of flavonol content in the cassava leaves from different harvest times and maturity levels of cassava germplasm revealed that in most cases, the levels of rutin, nicotiflorin and narcissoside were higher in the leaves harvested at 270 days compared to those harvested at 180 days, with myricetin varying by variety. Except for SC09, the levels of myricetin, rutin and nicotiflorin were higher in the young leaves compared to the tender and mature leaves in different cassava germplasms. The content of narcissoside in mature leaves (except for flower leaf cassava) was higher than that in young leaves and tender leaves. The results would provide an evaluation basis for the development and utilization of cassava flavonols in the selection of raw materials and quality control, and lay a foundation for revealing the accumulation rules of cassava flavonols.

Using compact varieties SC205, GR4 and umbrella varieties SC12, SC15 as the experimental materials, five treatments of 9, 36, 63, 90 leaves remained and no leaves removed were designed to study the differences of chlorophyll fluorescence and fresh tuber root yield to clarify the differences of chlorophyll fluorescence of functional leaves in different growth stages and leaves remained treatments and the effects of leaves number on fresh tuber root yield. The results showed that with the increase of leaves, the fresh tuber root yield increased, and the tuber root number, the fresh weight of stems and leaves and the harvest index increased first and then decreased. The average of tuber root yield per plant of 9, 36, 63, 90 and no leaf removed treatments was 0.94 kg, 2.22 kg, 2.65 kg, 2.91 kg and 3.35 kg, respectively. The maximum fluorescence yield (F_m) and maximum quantum yield (F_v/F_m) of compact varieties were higher than those of umbrella varieties. F_m and F_v/F_m of compact varieties was 0.885 and 0.739, respectively, and those of umbrella varieties was 0.838 and 0.707, respectively. The minimum fluorescence yield (F₀) of compact type was smaller than that of umbrella type, and that for the two plant type varieties was 0.219 and 0.231, respectively. F₀, F_m, F_v/F_m, ETR and Y(Ⅱ) decreased with the progress of leaf removed. With the increase of PAR, ETR increased gradually, and Y(Ⅱ) decreased sharply first and then slowly. The variation trend of chlorophyll fluorescence of cassava varieties with different plant types was the same, but the variation rule of different leaves was different. The ETR and Y(Ⅱ) of cassava functional leaves increased slightly when the number of leaves remained was small.