To improve seed setting rate and get more seeds in siliques of rapeseed, abortion of ovules and seeds were investigated in 36 DH (double hyploid) matrials under 4 pollinating treatments (open pollination, forced selfing, hybridizing and assisted artificial pollination). The initial number of ovules, normal mature seeds and abortion seeds were investigated to better understand the abortion period and causes. The statistic results showed that the initial ovule numbers of different materials had highly significantly variation, ranging from 23.05 to 36.15 with an average of 29.48. After maturing , the seeds number in single silique was 8.82-26.38, with an average of 16.80. The correlation coefficient between the number of ovules and the number of seeds per siliques was 0.77**. On average, 56.19% of the initial ovules could develop into mature seeds and nearly 44% ovules aborted during the seed development. The abortion rate was found to be related to genotype as well. The abortion could be divided into 3 types by ovules diameter as: a (less than 0.1mm), b (between 0.1-1.0 mm) and c (embryo abortion). They occurred in all 36 materials under 4 treatments. Type a and b were the main types of ovule (or seed) abortion, with average occurrences of 19.34% and 7.91% respectively. Type c occurred only 1.54%, which might be related to the ceasing of embryonic developmental. These results indicated that the ovules number was related to genotype, and the abortion occurrence and types were also related to genotype. The cause of abortion might be in stigma development, stigma and pollen recognition, and/or in fertilization and initial embryo development.
Allopolyploid B. napus contains a large number of homologous and redundant genes. It is difficulty to identify novel genes related to important agronomic traits by traditional T-DNA insertional, physical and chemical mutagenesis methods. In this study, a genome-wide inflorescence lhRNAi library of B. napus was constructed by the rolling circle amplification (RCA) - mediated lhRNAi construction technology. Subsequently, the inflorescence lhRNAi library was transformed into B. napus to produce 763 T0 transgetic plants. A total of 74 transgenetic lines exhibited visible mutant phenotypes, including petal reduction in the number, stamen degeneration shrinkage and number reduction, stigma distortion and exposure, dead or closed buds and male sterility. These results demonstrated the construction method of lhRNAi library mediated by rolling circle replication and were successfully applied to rapeseed, which provided an important research platform for the study of gene functions related to rape flower inflorescence development.
To better understand the cold-resistance of winter rapeseed (Brassica napus L.), DNA methylation were investigated using MSAP (methylation sensitive amplified polymorphism) technology on 13 materials with different cold resistance under low temperature (4oC) stress. MSAP results showed that, after 4oC treatment, the weak cold-resistance lines (14 Meiqieshi 7, 14 Meiqieshi 16, 14 Meiqieshi 20, 14 Meiqieshi 3 and Meiqieshi 38 had increased DNA methylation level and had higher methylation degree. The strong cold-resistant lines (15TS306, 14NS52-3, 15TS309, 14NS54-7 and 15TS312) had higher degree of demethylation. Sequence analysis of the differentially methylated fragments showed that 16 of 22 fragments were similar to the known and putative functional enzymes. Among them, At4g02000-like protein had the greatest variation. Cloning and bioinformatics results showed that its isoelectric point was 9.49 and the relative molecular weight was 39.2525kD. In sumarry, after low temperature stress, the strong cold-resistant lines had decreased DNA methylation level with dominant demethylation, while the weak cold-resistance lines had increased DNA methylation level with dominant methylation. In these winter rapeseeds, cold adaptability showed close correlation between differentially methylation patterns of some specific genes.
DELLA protein is a key factor involved in GA regulatory pathways and plays an important role in regulating plant growth and development. In order to reveal the distribution and characteristics of DELLA protein family in Brassica napus, family members, sequence characteristics, evolutionary relationships and tissue expression were analyzed using bioinformatics. The results showed that there were 13 DELLA protein genes in Brassica napus, located in 8 chromosomes with 2 random sequences (chrC09_random and chrCnn_random); The phylogenetic tree analysis found that the family was clustered into 4 subfamilies. One subfamily contains 7 genes, and the second, third and fourth subfamilies each included 2 genes. The expression analysis of different tissues showed tissue-specific expression in each tissue, and BnaA10g17240D, BnaC09g40420D、BnaCnng68300D and BnaC05g47760D were relatively high in each tissue. Among the stems, BnaA06g34810D、BnaA09g18700D and BnaC09g52270D had the highest expression. This study provided a reference for studying the genes functionality in the future.
By 2018, 39 soybean cultivars were bred in Guangxi, and their pedigrees were studied to analyze the formula, geographical origin and genetic contribution value of nucleus (quality). The results showed that, 39 cultivars（28 spring soybeans and 11 summer soybeans）were traced back to 40 nuclear and 17 cytoplasmic ancestors. The genetic contribution rates of nucleus (cytoplasmics) from native, other provinces and foreign ancestral parents were 39.42% (58.98%), 45.75% (38.46%) and 14.83% (2.56%) respectively. The parents of nuclear ancestors mainly came from southern China, Brazil and the United States with similar local and ecological conditions in Guangxi, the ancestor parents of spring soybean germplasm mainly came from Guangxi, Hubei and Beijing, the ancestor parents of summer soybean germplasms mainly came from Guangxi, Hubei and Shanghai; Since 2006, 96% of soybean cultivars had been bred by parent combination of bred soybean cultivars and foreign introduced soybean cultivars; Eight core spring soybean ancestors such as Jingxizaohuangdou and five core summer soybean ancestors such as Pingguodou were summarized. The genetic basis of soybean varieties in Guangxi was relatively rich, but it was necessary to strengthen the research and utilization of New Germplasms in order to expand the nuclear-cytoplasmic basis of soybean varieties.
GmGBP1 is a gene related to the photoperiod flowering time of soybean. In this experiment, GmGBP1 gene was used as the target, and the plant tissue culture was carried out by the soybean cotyledonary node transformation method to obtain T2 generation GmGBP1 interference transgenic soybean material and molecular detection. The transcript was sequenced to obtain alternative splicing data, and the alternative splicing genes in the sequencing results of WT and GmGBP1-i interference soybean leaves were further verified by RT-PCR. A total of three genes were alternatively spliced, indicating that the decrease of GmGBP1 interference expression caused the alternative splicing of downstream genes, which could affect the flowering time of soybean. This research provided a basis for further study of the function of soybean GmGBP1 gene, and laid a theoretical basis for the mechanism of soybean flowering induction.
Cytochrome P450 CYP82 is in a unique gene family in dicotyledonous plants. To better undrstand its important roles in plant growth and response to biotic and abiotic stresses, soybean gene GmCYP82C4 was homologously cloned and identified. The gene was 1584 bp long, encoding 527 amino acids with a conservative heme-binding domain. Bioinformatics showed that GmCYP82C4 protein was homology with PsCYP82A1 in pea. Subcellular localization showed that GmCYP82C4 was located in plasma membrane. Real-time fluorescence quantitative PCR showed that GmCYP82C4 expression in roots of soybean seedlings was the highest. GmCYP82C4 expression was induced by low temperature, wound (cut) and Phytophthora sojae infection respectively. GmCYP82C4 was responsive to plant hormones as ABA, MeJA (methyl jasmonate), ethylene and SA (salicylic acid). These results suggested that GmCYP82C4 might regulate the response of soybean to stress through hormonal signaling pathway.
To get insight into globulin genes in Arachis duranensis, genome-wide identification and expression analysis of AdARA gene family were investigated using bioinformatics methods. The results showed that A. duranensis contained 9 globulin genes, physicochemical among the family members were not significant, Motif compose of the closely related proteins were similar. Phylogenetic of globulins revealed that evolutionary relationship of globulins accorded with genetic relationship between species. AdARA proteins were conservative in evolution process and under negative selection, but positively selected sites were identified at a clade. By analyzing RNA-seq transcriptome data of cultivar peanut, it showed that 15 Arachin genes were expressed in seed, the expression of 4 Arachin genes greatly exceeded the others, the expression level of 4 Arachin genes were also high at Pattee stage 10.
The biosynthesis of gibberellin（GA）is a process of various enzymatic reactions and is closely related to plant development and stress response. To explore the distribution, structure and activity of sesame GA related genes, sesame genome sequence and transcriptomes from different tissues were studied based on bioinformatics methods. It showed that sesame had 32 GA related genes belonging to 7 different gene families, and these genes were distributed on all chromosomes except the chromosome 5. The protein sequence lengths of the different gene families were quite different. The CPS genes had the longest protein and contained 776 amino acid residues on average. The KAO proteins exhibited a great variation in size, varying from 401 to 834 amino acids. All the proteins encoded by GA related genes were predicted to be hydrophilic proteins. Compared with other species inclusing Arabidopsis, Rice, Soybean, Grape, Sorghum and Tomato, the total number of GA related genes in sesame is not outstanding, but more CPS genes were observed in sesame. Evolution analysis indicated that sesame and tomato had a closer evolution relationship among the seven species. In various sesame tissues, the 7 GA related gene families displayed quite different expression patterns. KS genes were highly expressed in seeds, stem tips and leaves. CPS genes were more active in pericarps and seeds, but were hardly expressed in stem tips and leaves. KAO and KO genes were constitutively and higly expressed in all tissues, while KS and GA3ox genes showed low levels of expression. Among the different tissues, the GA related genes generally showed higher activity in the seed, then in the root tip and in the stem tip. This study provided important genetic information and theoretical references to analyze the characteristics of GA related genes in sesame and its role in different tissues.
Clubroot has recently become one of the main diseases of oilseed rape and cruciferous crops in China, which seriously affected the yield of cruciferous crops. Therefore, an efficient method with a high efficiency for molecular detection of P. brassicae was developed for accurate diagnosis in various samples using a pair of specific primers (PbITS1) designed on the basis of ITS (internal transcribed spacer) sequence, and the molecular detection of P. brassicae and disease assessment were carried out by PCR procedure. The results indicated that PCR system could specifically detect P. brassicae without any amplification product from representative soil-borne pathogenic fungi, bacteria, nematodes and endophytes. Sensitivity assay showed that the minimum concentration of template DNA was 1×10-3 ng/μL, the minimum number of spores in the contaminated soil was 1×103 spores/g soil, and the minimum level of spore with seeds was 1×105 spores/g seeds. Moreover, rape and other cruciferous plants (e.g., tissues and seeds) and soils could be applied in this detection system, meanwhile roots and surrounding soils collected from the different growth stages could be used for disease assessment. The benefit of this detection system was convenient, sensitive and specific with a wide range of detectable samples, which provided insights on detection of P. brassicae as well as the diagnosis, monitoring epidemic pattern, and integrated management of clubroot.
Ten peanut lines developed by Oil Crops Research Institute (CAAS, Wuhan, China) were evaluated for resistance and yield loss to peanut stem rot caused by Sclerotium rolfsii under natural disease condition and by artificial inoculation. The results indicated that the wilting rates of these lines ranged from 11.0% to 50.0% under natural disease condition and 7 lines had the wilting rates lower than 30.0%. Peanut yield and wilting rate were significantly negative correlated (r = - 0.72, P<0.05). The wilting rates of these lines (from 66.1% to 94.0%), at two weeks post inoculation in the artificial inoculation experiment, were lower than those (from 66.1% to 97.4%) before harvest, all these lines were susceptible to infection by S. rolfsii. The peanut yield was negatively related with wilting rate by artificial inoculation with the correlation coefficient of -0.85 (P<0.05). The peanut yield loss was higher than 91.7% for the least susceptible line after artificial inoculation. One tolerant line 16-A13440 was identified.
Clubroot is one of the most serious disease in oilseed rape. To explore the resistant molecular mechanism of the interaction between Plasmodiophora brassicae and Brassica napus during early infection, gene differential expression analysis of the clubroot-resistant rapeseed line ZHE-226(R) and clubroot-susceptible line 10159 (S) were performed by RNA-seq. A total of 809 and 1082 genes were commonly up- and down-regulated at 0, 12, 48, 72h post-inoculation (hpi) time points in R line. Pattern recognition receptors (PRRs), chitinase, R gene, WRKY transcription factor, salicylic acid (SA) and jasmonic acid (JA) were involved in the early response to clubroot infection in lines of R and S, but showed different expression patterns. Compared to S line, most of the PRRs genes were down-regulated, R genes were up-regulated and SA genes were down-regulated in earlier stage but up-regulated at 72hpi in R line. Chitinase, WRKY and JA related genes were both induced in R and S lines. These results showed that PTI- mediated by PRRs was significantly induced in S line, but played a small role in R line. ETI-mediated by R gene and resistance signal pathway-mediated by SA played great role in clubroot resistance. This research provided a better understanding of the resistance genes of B. napus in response to P.brassicae, and assistance for clubroot-resistant breeding.
To find the optional cultivation measure for synergistic improvement of yield and potassium use efficiency, oil sunflower field experiments were carried out from 2015 to 2017 under 3 plastic mulching cultivation modes in semi-arid area in Gansu Province. Oil sunflower cultivar Longkuiza 3 was used. The 3 modes included open field (Z1), full plastic-film double-furrow sowing (Z2), and full plastic-film double-furrow sowing with supplemental irrigation (Z3). The 4 potassium rates were 0 (K0), 48 (K48), 84 (K84) and 120 kg/hm2 (K120). Results showed that plastic mulch cultivation and potassium rate had significant effects on yield, dry matter accumulation and potassium use efficiency. The interaction between modes and potassium rates was significant. The effects on grain yield, dry matter accumulation and potassium utilization efficiency were in the order of Z3>Z2>Z1 with significant differences. Compared to Z1 mode, Z3 modes increased yield and potassium utilization efficiency 170.1% and 103.9% respectively; and B modes increased yield and potassium utilization efficiency 184.3% and 143.7%. Yield and dry matter accumulation were both increased under potassium rates in the order of K120>K84>K48>K0. The significant differences were found between the potassium rates except between K120 and K84. With the increase of potassium rates, potassium partial factor productivity was decreased, while potassium agronomic efficiency and utilization efficiency were improved. The latter two traits reached the peaks under 84 kg/hm2. It indicated that synergistic improvement could be acheived on oil sunflower yield and both potassium agronomic efficiency and utilization efficiency. In summary, in this experimental field condition, the C mode (full plastic-film double-furrow sowing with supplemental irrigation) and 84 kg/hm2 potassium rate were the optimal, and the effect of supplementary irrigation was obvious.
In order to investigate the allelopathy autotoxicity of oil flax stubble and identify the organic compounds responsible for its autotoxicity, aqueous extracts of stubble root, stem and leaf were prepared respectively. Different concentrations of gradient aqueous extracts were set for seed germination and seedling growth experiments. The autotoxic effects were determined by measuring germination potential, germination rate, seeding length and root weight, etc; and the main autotoxic chemical substances of the stubble root, stem and leaf were analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that the stubble root, stem and leaf aqueous extracts of oil flax inhibited the seed germination and seedling growth in a dose-dependent manner. With the increase of aqueous extract concentration, the aqueous extract from the stubble leaves reached the critical concentration first, followed by the aqueous extract of stubble stem, and finally the aqueous extract of the stubble root. The synthesis effect showed that the relationship between the aqueous extract of different stubble organs and the autotoxicity is that stubble leaf ＞ stubble stem ＞ stubble root. Eight, twenty-one and fourteen compounds were identified in aqueous extracts of root, stem and leaf, respectively, including acids and esters. The most abundant autotoxins was palmitic acid. These results showed that aqueous extracts of oil flax stubble significantly affecteds seed germination and seedling growth, which maycould be one of the main cause of continuous cropping obstacles of oil flax.
Peanut is an important oil and economic crop in China. The object was to determine the ecological suitability of peanut planting counties in China. 13 indexes of climate and soil were selected. These indexes were closely related to peanut production. Chinese county in the administrative divisions was evaluated as investigation unit. By using 2005-2014 climate and soil basic data, the database of ecological suitability evaluation was established through ArcGISplatform. Analytic hierarchy process, fuzzy data method and comprehensive index model were used to obtain the evaluation index. Results led to 4 different grades including the most suitable (0.70-0.89), suitable (0.56-0.70), sub-suitable (0.42-0.56), and unsuitable (0.11-0.42). Among the 4 grades, the suitable grade contained the most evaluation units, and the others were in the order of sub-suitable, most suitable and unsuitable. The grades were zonal distributed. With the most suitable area as the center, suitable and sub-suitable areas were extended to both sides. The areas of the most suitable and suitable grades were mainly distributed in plains, basins, valley areas and oasis, which were concentrated in Guangxi, Shandong, Chongqing, Henan and other 9 provinces. The distribution was consistent with current situation of peanut production in China.
Peanut is one of the most important oil crops in the world. Up to now, 81 species of Arachis are identified and arranged in 9 infrageneric taxonomic sections according to its morphological characteristics, geographical distribution and cross-compatibility. Cultivated peanut has a very narrow genetic base, which is a fundamental limitation to crop improvement using only cultivated germplasm. Compared with cultivars, wild peanut species have high genetic diversity, can adapt to a series of complex environments and are important sources for resistance to biotic and abiotic stress. An increasing number of studies showed that many wild species of peanut were highly resistant to root-knot nematode, late leaf spot and rust. In recent years, new tools for genetic and genomic analysis, provided better efficiency in using wild peanut resources in crop improvement. This paper reviewed the wild species of peanuts and introduced the wild peanut with disease resistance to assist the genetic improvement of peanut.
Powdery mildew is one of the main diseases in flax, due to climate warming on earth, the disease bursted and prevailed in the main cultivated areas occasionally, which severely disrupted the yield and quality of flax. This article summarized the progresses of powdery mildew in flax, the incidence characteristics and regularity of the disease, identification and selection of resistant germplasm resources, inheritance of resistance and resistant genes, control strategies for the disease. The problems in recent research were analyzed and suggestions were made, which could provide references for associated research.
