Rape Varieties Research Articles

Chemical Composition of Winter Rape Seeds Depending on the Biostimulators Used

Plant growth regulators may reduce the negative effect of environmental stress factors and can contribute to increasing the quality and quantity of the yield. The aim of the research was to determine the effect of biostimulators on the quality of seeds of three winter rape morphotypes. Three varieties of winter rape were used: Poznaniak (population variety), PX104 (hybrid variety restored with a semi-dwarf growth type) and Konkret (hybrid variety restored with a traditional growth type). The varieties were exposed to three treatments: the biostimulator Tytanit®, the biostimulator Asahi®SL and the biostimulator Silvit®, and the control with no biostimulators. Seeds were analysed for content of crude fat, total fat and crude fibres. The biostimulators reduced total protein content (on average from 0.8 to 1.75 g·kg−1 of d.m.) and increased the concentration of crude fat (on average from 0.71 to 1.93 g·kg−1 of d.m.) and crude fibre (on average from 0.15 to 0.84 g·kg−1 of d.m.) compared to the control. PX104 had the highest content of crude fat and total fat protein, and the lowest in crude fibre. The smallest protein content was found in seeds of the long-stem hybrid Konkret, while crude fat was lowest in the population form (Poznaniak), and crude fibre was lowest in long-stem hybrid (Konkret).

Comparative Assessment of Sporophyte and Gametophyte Thermal Resistance of Winter Rape

The temperature factor is one of the limiting factors for obtaining high yields of crops, so one of the main tasks of selection is to search for temperature-resistant genotypes and to create on their basis the banks of crops with high temperature stability. The first step to solving this problem is to conduct a rapid assessment of the temperature plasticity of large populations and to isolate breeding-valuable genotypes from them. There are numerous methods that allow, in the short term with minimal technical and material costs, to carry out an initial assessment of a large number of genotypes at sporophytic level and differentiate them by resistance to the temperature factor. These methods include the method of estimating pollen populations. These studies have repeatedly been conducted on many cultures, their correctness is due to the expression of a large part of the plant genome, both at the diploid and haploid levels of development and demonstrated by many studies in this direction. The aim of our study was to study the stability of gametophyte and sporophyte of collecting varieties and varieties of winter rape to elevated temperatures, to study the correlation between the heat resistance of sporophyte and gametophyte.

Polymorphism of microsatellite loci in feral populations and commercial varieties of oilseed rape (Brassica napus L.)

Aim. The aim of the work was to compare the polymorphism of commercial varieties and populations of B. napus growing outside cultivation to assess the genetic diversity of feral rapeseed populations in Belarus. Methods. The study assessed genetic diversity according to the data of 7 microsatellite loci genotyping. Results. The results indicate a greater genetic diversity in feral oilseed rape populations. An analysis of the structure of the genotypes distribution in the STRUCTURE software showed the division into three clusters – commertial varieties, feral populations and samples of B. rapa. Conclusions. The established genetic divergence between feral populations and commercial varieties indicates that feral oilseed rape is able to maintain persistent populations in Belarus. In practice, this should be taken into account when assessing the environmental risk when transgenic rape is released into the environment. And in the cultivation of transgenic rapeseed, special attention should be paid to measures to prevent the occurrence of its free-growing populations. Keywords: oilseed rape, feral populations, microsatellite loci, genetic diversity.

ВЛИЯНИЕ ПРИЕМОВ ПОСЕВА НА УРОЖАЙНОСТЬ И БИОХИМИЧЕСКИЙ СОСТАВ МАСЛОСЕМЯН СОРТОВ ЯРОВОГО РАПСА В СРЕДНЕМ ПРЕДУРАЛЬЕ

The paper presents the results of two-year and three-year studies to clarify the sowing methods of spring rape varieties in the Middle Urals. The reaction of spring rape to the change of the type of coulter and the seeding depth has been revealed. A three-factor field experience was laid in 2016-2018 on the educational and experimental area of Perm State Agro-Technological University. The soil of the experimental plot is sod-small podzol heavy loam. It has been established that in Perm region, the highest yields and gross collection of fat from 1 hectare are formed by agrophytocenoses, sown with anchor coulter to a depth of 3 cm (1.96 tons per hectare and 911 kg per hectare for Ratnik variety and 2.16 tons per hectare and 1005 kg per hectare - for Smilla hybrid, respectively). On average for 2017-2018 years the productivity of the spring rape varieties under study was not different. The planned aim of research is the yield level (at least 2 tons per hectare) on average over two years obtained when sowing a foreign hybrid to a depth of 2 and 3 cm by anchor coulter. The low productivity of spring rape in 2016 did not allow to reach the planned figure on average for three years of research. Spring rape oilseeds were analyzed for biochemical composition in the laboratory for the development of agro-technologies of Perm State Agro-Technological University. The content of raw fat, ash, fiber, nitrogen and protein in the seeds was the same for all studied variants. Two-year studies have shown that the gross yield of fat per 1 ha depended on spring rape productivity, while the fat content in the seeds did not change much (44.94-46.68%). Three-year data confirm the conclusions made on the basis of an analysis of the results of experience for two years.

Breeding of spring turnip rape in the Western Siberia

The territory of the Western Siberia is very suitable for cultivation of cruciferous oil crops (rapeseed and turnip rape) by its biological-climatic potential and soil conditions. Oil crops are widely used for human nutrition, feeding of animals, in any industries and building industry, medicine and perfumery. These crops oil contains many unsaturated fatty acids (oleic, linoleic, linolenic) which are essential in human nutrition. The main task of turnip rape breeding is productivity increase; much attention is paid to oil increase in seeds and improvements of oil quality (low content of glucosinolates in seeds and erucic acid absence in oil). We presented brief characteristics of released turnip rape varieties: productivity (seed yield, oil content and oil yield) and fatty acid composition of oil. The created varieties are differed with their high adaptability to severe Siberian conditions and resistance to the main bio- and abiofactors of environments.

The Influence of Digestate on the Static Strength of Spring Rapeseeds (Brassica napus var. arvensis)

Biogas production occurs during methane fermentation from organic substrates and the mass remaining after fermentation, containing organic matter and valuable minerals having regard to plant nutrition, forms the digestate, which could be useful for fertilizing purposes and very beneficial in the case of the fertilization of rapeseeds. This paper focuses on the use of two forms of fertilization of rapeseeds—digestate and mineral fertilizers—in order to reduce the compressive strength of rapeseeds. The object presents results of compressive strength tests of three rape varieties (Bios, Feliks, Markus). The uniaxial compression tests between two parallel planes were made using a Zwick/Roell Z005 testing machine. Comparative analyses for the analyzed variables were carried out applying parametric and non-parametric statistical tests. On the basis of the conducted research, it was found that the distribution of the increase in the force crushing Bios and Feliks rapeseed varieties in both forms of cultivation was proportional to the increase in their mass. However, with a relatively comparable mass of Bios cv. seeds, in the case of the digestate use, a stronger correlation was found between the seed pressing force and its mass than for the multi-component fertilizer, understanding the need to apply more force to crush the seeds for this form of cultivation. In the conducted tests, the average size of rapeseed diameters of all varieties and forms of cultivation ranged from 1.81–1.95 mm, which indicates their good suitability for industrial purposes.

СЕМЕННАЯ ПРОДУКТИВНОСТЬ СОРТОВ ЯРОВОГО РАПСА В ЗАВИСИМОСТИ ОТ ДОЗ МИНЕРАЛЬНЫХ УДОБРЕНИЙ В УСЛОВИЯХ СРЕДНЕГО ПРЕДУРАЛЬЯ

The article presents the results of two-factor field experience on the influence of mineral fertilizers on the seed productivity of spring rape varieties Ratnik and hybrid Smilla. The studies carried out in 2016-2018 on sod-mezopodzol loam soil training and research experimental fields of the Perm GATU. The positive effect of increasing doses of nitrogen fertilizers, as well as their complex application with phosphorus and potassium on the yield and elements of the yield structure was noted at both sites. Each subsequent increase in the dose of nitrogen in accordance with the scheme of experience led to a significant increase in productivity. The introduction of phosphorus-potassium fertilizers increased the yield of all options in comparison with similar options without their use. The highest yield is typical for the hybrid Smilla (2.95 t/ha), for Ratnik variety the maximum yield was 2.32 t/ha. Hybrid Smilla is more responsive to the use of high doses of mineral fertilizers, its use is preferable in a high culture of agriculture. The introduction of increasing doses of nitrogen fertilizers has led to increased plant safety during the growing season. The maximum number of plants to be harvested was observed when applying phosphorus-potassium fertilizers and nitrogen in doses of 60 kg/ha.the use of complex mineral nutrition led to an increase in the number of plants to be harvested than in similar variants with the introduction of only nitrogen. Leaf diagnostics revealed that the lack of nitrogen is typical for options without fertilizers. Nitrogen application of 120 kg/ha, as well as 90 kg/ha on the phosphorus-potassium background provided a sufficient amount of nitrogen. The maximum dose of N120P60K60 led to excessive accumulation of nitrates in the plant. According to the provision of plants with phosphorus and potassium, a similar pattern was observed: when making a phosphorus-potassium background, the need for these nutrients was absent, and without the use of these fertilizers, plants had a weak need for them. Mineral fertilizers had a positive effect on the number of pods and the weight of 1000 seeds. The maximum values of these indicators are noted when the largest doses of nitrogen and phosphorus-potassium fertilizers are applied.

СКРИНИНГ СОРТООБРАЗЦОВ ЯРОВОГО РАПСА (Brassica napus L.) ПО УСТОЙЧИВОСТИ К ФИТОПАТОГЕНАМ

Diseases are one of the reasons for the decline in yield of rape. Breeders are to create resistant to diseases and pests varieties and hybrids of rape because this culture is widely used in Russia. Nowadays we know about 30 pathogens of cabbage cultures. Among the diseases of rape are alternaria, fusarium, sclerotinia, powdery mildew, fomoz, perinospora, bacteriosis, etc., which cause a shortage of yield from 15 to 70%. Varieties of rape for resistance to alternaria, perinospora, and fusarium were appreciated at the All-Russian Scientific Research Institute of Rapeseed from 2016 to 2018. The most samples of Brassica napus were affected by alternaria in mild and moderate degrees. The degree of damage by perinospora depended on weather conditions and ranged from a very weak level to an average one. The degree of damage by fusarium was from single to weak and it was connected with many years of the research work. Thus, we could isolate samples, weakly susceptible to alternaria; samples, weakly susceptible to perinospora; samples, weakly affected by fusarium.

Detection of waterlogging stress based on hyperspectral images of oilseed rape leaves (Brassica napus L.)

The objective of this study was to investigate the utility of hyperspectral images (HSIs) for the detection of oilseed rape waterlogging stress. We assessed two oilseed rape varieties, the non-hybrid NingYou 22 (NY 22) and hybrid NingZa 19 (NZ 19), and HSIs of oilseed rape leaves under different durations of waterlogging stress (0, 3, and 6 days) were collected to build three datasets (NY 22, NZ 19, and both combined). We extracted red–green–blue (RGB) images and visible and near-infrared (VNIR 400–1000 nm) spectra from a region of interest (ROI) in each HSI. Quadratic discriminant analysis (QDA), k-nearest neighbor (KNN), and support vector machine (SVM) classifiers were used to build classification models for comparing images and spectra of samples under different waterlogging levels among the three datasets, and to conduct training and prediction. From each dataset, 70% of the images were used for training, and the remaining 30% were used for testing. In the classification of full-wavelength HSIs (400–1000 nm), QDA and SVM exhibited high multivariate classification accuracy, reaching 77.37% and 95.90% accuracy, respectively. In contrast, KNN displayed low accuracy, but good identification and prediction ability for variety NZ 19. Six optimal wavebands of 529, 641, 698, 749, 856, and 979 nm were used as input for successive projections algorithm (SPA) classification and analysis. The QDA mode had better classification performance, with identification accuracies of 100% and 94.44%, respectively. Overall, the VNIR classification results exceeded those of image classification. These results show that hyperspectral imaging technology is feasible and useful for the detection of oilseed rape waterlogging stress.

Effect of breeding on nitrogen use efficiency-associated traits in oilseed rape.

Oilseed rape is one of the most important dicotyledonous field crops in the world, where it plays a key role in productive cereal crop rotations. However, its production requires high nitrogen fertilization and its nitrogen footprint exceeds that of most other globally important crops. Hence, increased nitrogen use efficiency (NUE) in this crop is of high priority for sustainable agriculture. We report a comprehensive study of macrophysiological characteristics associated with breeding progress, conducted under contrasting nitrogen fertilization levels in a large panel of elite oilseed rape varieties representing breeding progress over the past 20 years. The results indicate that increased plant biomass at flowering, along with increases in primary yield components, have increased NUE in modern varieties. Nitrogen uptake efficiency has improved through breeding, particularly at high nitrogen. Despite low heritability, the number of seeds per silique is associated positively with increased yield in modern varieties. Seed weight remains unaffected by breeding progress; however, recent selection for high seed oil content and for high seed yields appears to have promoted a negative correlation (r= -0.39 at high and r= -0.49 at low nitrogen) between seed weight and seed oil concentration. Overall, our results reveal valuable breeding targets to improve NUE in oilseed rape.

SECONDARY PLANT RESOURCES AS PROSPECTIVE UNCONVENTIONAL SOURCES OF PECTIС SUBSTANCES

The secondary raw materials have been studied as sources of pectic substances necessary for the endo-ecological protection of the organism in the globally deteriorating living conditions of modern humans. The article reveals the significance and long-term benefits of such sources of pectic substances as fruit and seed coats, which are obtained in considerable quantities as a secondary raw material during the implementation of the technological process, and often do not find rational use. Research has been carried out on new prospective sources of pectin substances – secondary resources of processing soybean Glycine max (L.) Merrill, sainfoin Onobrýchis arenária, rapeseed Brassica napus L. oleifera, Sarepta mustard Brassica juncea (L.) Czern, and black mustard Brassica nigra (L.) W.D.J. Koch, castor bean Ricinus communis L., sunflower Helianthus annuus L. Fruit and seed coats of these plant species have been studied. The prospects of their secondary resources for pectin production have been shown. The assessment of the quantitative and qualitative characteristics of the pectic substances of the objects under study, as well as their fractional composition and analytical indicators, make it possible to characterize the potential functional, technological and therapeutic properties of pectin preparations. It has been indicated that in the polyuronid component (fraction of galacturonic acid), all the studied samples of surface tissues of soybean, mustard, sainfoin, sunflower, one rape variety meet international requirements for food pectin (52.87–73.22%), and one of them, the pectin from seed coat of the Valenta variety, meets the requirements for pectins for medical purposes (75.83%). Pectic substances of soybean, mustard, castor bean varieties are characterized by a high degree of esterification (62.37–76.88%) in contrast to the varieties of sainfoin and sunflower (45.29–55.15%). According to the degree of esterification, rape varieties are close to low-esterified pectiс substances – 59.34–61.48%. The prospects of using seed and fruit membranes as an unconventional secondary plant raw material to improve the environmental performance of production and to obtain a valuable therapeutic-and-prophylactic food ingredient have been substantiated.

Performance of Two Rape (Brassica napus) Cultivars under Different Fertilizer Management Levels in the Smallholder Sector of Zimbabwe

Crop response to fertilizer application depends on the physiological and morphological characteristics of the cultivars, thus causing cultivar differences in growth rate and final yield. A study was carried out in the Zvimba smallholder farming area of Zimbabwe, from November 2016 to February 2017, to investigate the performance of two rape (Brassica napus) cultivars under different nitrogen fertilizer management levels. An experiment was set up in a randomized complete block design, replicated three times, with two rape varieties, Hobson and English Giant, and 5 ammonium nitrate (AN) (34.5% N) fertilizer application rates (200 kg/ha, 300 kg/ha, 350 kg/ha, and 400 kg/ha) as factors. Nitrogen fertilizer rates had a significant (p<0.05) effect on leaf length at 6 WAP and 7 WAP. Nitrogen fertilizer application levels had significant effects on both in-season and total fresh leaf yield. There were no varietal effects on the leaf length (p>0.05), in-season yield and total leaf yield (p>0.05), and there were also no variety ∗ fertilizer application level interaction effects on leaf length, in-season yield and total leaf yield (p>0.05). From the results of this study, English Giant rape would maintain a longer leaf length than Hobson up to the end of the season, but the two cultivars have similar yield response to fertilizers’ application rate. Both the English Giant rape and Hobson rape cultivars can, therefore, be recommended for production in the Mhondoro smallholder farming area of Zimbabwe and other areas with similar climatic and soil characteristics.

Variations in cadmium accumulation and distribution among different oilseed rape cultivars in Chengdu Plain in China.

Cadmium (Cd) is a widespread toxic heavy metal trace pollutant worldwide. The ability of Cd absorption and accumulation highly varies among different species and varieties. In order to screen oilseed rape cultivars which are appropriate for cultivation and application in Cd-contaminated soils, we conducted the field trial of 32 oilseed rape varieties in Shifang County of Chengdu Plain. The various biomass, Cd accumulation, and distribution patterns were investigated via determining the Cd concentration in different plant tissues. Moreover, the food safety risks of rapeseeds were finally assessed. The results indicated diverse responses to Cd stress appeared in various tested varieties, including plant biomass, seed yield, Cd concentration, and proportion in different tissues. And most Cd were concentrated in non-edible parts. Through cluster analysis, we found that Nanchongjie, Pengzhoubai, and J-25 belong to high-biomass and high-Cd-accumulated groups in experimental cultivars, which indicated that they could possess more biomass and gather higher Cd content in overground part, so they could be great materials for phytoremediation in Cd-polluted area. Besides, combined with the risk assessment of food safety in rapeseeds, cultivars 72A and 47 with the traits of high yield, low-Cd concentration, and low food safety risk can be considered as suitable materials to widely plant as cash crop. These results provide valuable reference for practical planting and application of oilseed rape in Cd-polluted areas.

Partial stem resistance in Brassica napus to highly aggressive and genetically diverse Sclerotinia sclerotiorum isolates from Australia

Sclerotinia sclerotiorum is a fungal pathogen that causes stem rot in oilseed rape (Brassica napus). Previously, B. napus accessions with partial stem resistance to a Canadian S. sclerotiorum isolate (#321) were identified using a stem test in which flowering plants were inoculated with mycelium plugs. The present study examined the partial stem resistance of four of these accessions, PAK54, PAK93, DC21 and K22, following inoculation with Australian isolates. Mycelial compatibility groups and intergenic spacer (IGS) region haplotypes were identified among 71 isolates from Australian oilseed rape and lupin fields. Eleven genetically diverse isolates showed differences in aggressiveness when inoculated onto nine oilseed rape varieties and one Chinese accession. Isolates CU8.24, CU10.17 and CU11.19 were selected based on genetic diversity, growth rate in vitro and high aggressiveness in the initial screen and subsequently inoculated onto the four B. napus accessions. These accessions developed significantly smaller lesions compared with the susceptible control varieties (‘AV Garnet’ and ‘Westar’), with the average frequency of soft and collapsed lesions being less than 20% in PAK54, DC21 and K22, 29% in PAK93 and greater than 88% in the susceptible controls. Microscopic examination revealed that hyphae were typically confined to the stem cortex in the smallest lesions, but could be found in the stem pith in larger lesions. These results show that B. napus accessions PAK54, PAK93, DC21 and K22 can be used in Australia for development of varieties with partial stem resistance to S. sclerotiorum.

In vitro fermentation and in situ rumen degradation kinetics of summer forage brassica plants

The aim of the present study was to assess and compare the nutrient concentration, the in vitro fermentation and the in situ rumen degradation characteristics of Brassica rapa ssp. rapa L. (turnips) and Brassica napus ssp. biennis L. (forage rape). Five varieties of each species were established in three field replicates and were organised in a randomised complete-block nested design. All varieties were harvested and further analysed for chemical composition, in vitro gas-production kinetics, volatile fatty acid (VFA) production and in situ degradation kinetics of dry matter (DM) and crude protein. Turnips showed higher ash, total sugars, raffinose, sucrose, glucose and fructose concentrations (P < 0.001) than did forage rape. Turnip varieties differed in their sucrose, glucose, fructose and total soluble sugar concentration (P < 0.001), whereas rape varieties differed in their neutral detergent fibre concentration (P = 0.004) and digestible organic matter on a DM basis (P < 0.01). Regarding DM-degradation parameters, turnips had a higher soluble fraction ‘a’ (P < 0.01) and a lower insoluble, but potentially degradable fraction ‘b’ (P < 0.01) than did rape, but the fractional degradation rate ‘c’ (0.18/h) was similar to that of rape. Rates of gas production were slightly higher (P = 0.018) for turnip than for rape. No effects for brassica species nor for varieties within species were detected (P > 0.05) for total in vitro VFA production, as well as for the relative proportions of acetate, propionate, butyrate, branch chained VFA and the actetate:propionate ratio. Our study showed that most of the differences that were observed in terms of chemical composition and degradation kinetics did not result in differences in in vitro fermentation products.

Identifying oilseed rape varieties with high yield and low nitrogen fertiliser requirement

Reducing the fertiliser nitrogen (N) requirement of oilseed rape (Brassica napus L.) whilst maintaining yield will be beneficial for both growers and the environment. The aim of this paper was to identify differences in fertiliser N requirement between varieties and investigate simple in-field methods to rapidly identify varieties that can maintain high yield whilst requiring lower optimal N rates (‘HYLO’ varieties) to aid breeding for lower N fertiliser requirement. Four field experiments were conducted in the UK during seasons 2011-12 or 2012-13 on a range of soil types. Each experiment included 21 elite open pollinated and hybrid varieties. Each variety was grown at seven levels of N fertiliser ranging from zero to super-optimal (340 or 400 kg N/ha). Measurements of seed yield and seed oil content were combined to calculate gross output yield, i.e. seed yield adjusted for oil content. Linear plus exponential yield response curves were fitted to calculate the economically optimum N rate (Nopt) of each variety and the associated nitrogen use efficiency (NUE) was calculated at the Nopt. Across varieties, gross output yield responses to optimum N fertiliser, compared with yields at nil N rates, were significant, ranging from 1.3 to 2.7 t/ha between sites. Nopt ranged from 117 to 286 kg N/ha between sites giving experimental average yields at Nopt (Yopt) of 3.0 to 4.6 t/ha. Varietal yield ranges at Nopt within each experiment ranged from 0.6 to 1.7 t/ha, and there was a positive trend for yield to increase with date of variety introduction by 0.24 t/ha per decade. Significant variety x N fertiliser rate interactions were measured for gross output yield in two out of four experiments and significant varietal differences in Nopt were measured in one experiment ranging from 195 kg N/ha to 296 kg N/ha. There was no correlation between Nopt and Yopt indicating that improving varietal yield potential will not necessarily increase N requirement. Significant varietal differences in NUE were measured at Nopt ranging from 13.5 to 15.9 kg of gross output yield per kg of N supply from soil residues and fertiliser. Seed with low N and high oil content, and high biomass harvest index could be useful indicators of high NUE. However, no single trait correlated consistently with varietal variation in NUE. The yield difference between sub- and super-optimal N rates was positively correlated with Nopt. Further research is required to develop new experimental approaches for measuring yield at more than one N level on small experimental plot areas and to investigate a wider range of genotypes.

RNA-directed DNA methylation and seed development: an unexpected difference between Arabidopsis thaliana and Brassica rapa.

RNA-directed DNA methylation and seed development: an unexpected difference between Arabidopsis thaliana and Brassica rapa.

Hidden Effects of Seed Quality Breeding on Germination in Oilseed Rape (Brassica napus L.).

Intense selection for specific seed qualities in winter oilseed rape breeding has had an inadvertent negative influence on seed germination performance. In a panel of 215 diverse winter oilseed rape varieties spanning over 50 years of breeding progress in winter-type rapeseed, we found that low seed erucic acid content and reduced seed glucosinolate content were significantly related with prolonged germination time. Genome-wide association mapping revealed that this relationship is caused by linkage drag between important loci for seed quality and germination traits. One QTL for mean germination time on chromosome A09 co-localized with significant but minor QTL for both seed erucic acid and seed glucosinolate content. This suggested either potential pleiotropy or close linkage of minor factors influencing all three traits. Therefore, a reduction in germination performance may be due to inadvertent co-selection of genetic variants associated with 00 seed quality that have a negative influence on germination. Our results suggest that marker-assisted selection of positive alleles for mean germination time within the modern quality pool can help breeders to maintain maximal germination capacity in new 00-quality oilseed rape cultivars.

Identification of cold stress responsive microRNAs in two winter turnip rape (Brassica rapa L.) by high throughput sequencing

BackgroundLow temperature is a major abiotic stress affecting the production of rapeseed in China by impeding plant growth and development. A comprehensive knowledge of small-RNA expression pattern in Brassica rapa under cold stress could improve our knowledge of microRNA-mediated stress responses.ResultsA total of 353 cold-responsive miRNAs, 84 putative novel and 269 conserved miRNAs, were identified from the leaves and roots of two winter turnip rape varieties ‘Longyou 7’ (cold-tolerant) and ‘Tianyou 4’ (cold-sensitive), which were stressed under − 4 °C for 8 h. Eight conserved (miR166h-3p-1, miR398b-3p, miR398b-3p-1, miR408d, miR156a-5p, miR396h, miR845a-1, miR166u) and two novel miRNAs (Bra-novel-miR3153-5p and Bra-novel-miR3172-5p) were differentially expressed in leaves of ‘Longyou 7’ under cold stress. Bra-novel-miR3936-5p was up-regulated in roots of ‘Longyou 7’ under cold stress. Four and five conserved miRNAs were differentially expressed in leaves and roots of ‘Tianyou 4’ after cold stress. Besides, we found two conserved miRNAs (miR319e and miR166m-2) were down-regulated in non-stressed roots of ‘Longyou 7’ compared with ‘Tianyou 4’. After cold stress, we found two and eight miRNAs were differentially expressed in leaves and roots of ‘Longyou 7’ compared with ‘Tianyou 4’. The differentially expressed miRNAs between two cultivars under cold stress include novel miRNAs and the members of the miR166 and miR319 families. A total of 211 target genes for 15 known miRNAs and two novel miRNAs were predicted by bioinformatic analysis, mainly involved in metabolic processes and stress responses. Five differentially expressed miRNAs and predicted target genes were confirmed by quantitative reverse transcription PCR, and the expressional changes of target genes were negatively correlated to differentially expressed miRNAs. Our data indicated that some candidate miRNAs (e.g., miR166e, miR319, and Bra-novel-miR3936-5p) may play important roles in plant response to cold stress.ConclusionsOur work indicates that miRNA and putative target genes mediated metabolic processes and stress responses are significant to cold tolerance in B. rapa.

The genetic background modulates the intensity of Rpv3‐dependent downy mildew resistance in grapevine

AbstractGrape varieties with resistance to downy mildew (DM) carry alien chromosome segments in Vitis vinifera backgrounds. We previously showed that the largest descent group shares a non‐vinifera haplotype at the locus Rpv3. Here, we performed a common garden experiment with 76 varieties to evaluate the level of field resistance across four years. All varieties exhibited effector‐triggered immunity (ETI)‐associated necrosis. On a scale of 1–9, the median OIV452 value for foliar resistance was 7.1 in the resistant lineage vs. 3.2 in vinifera controls. Genotype, year and their interaction significantly affected the level of resistance. Some resistant genotypes showed high mean values of OIV452 and low variance among years. Other resistant genotypes showed lower mean OIV452 and higher variance. They were capable of activating ETI, but the intensity was inadequate to restrict pathogen growth under highly conducive conditions. Rpv3‐dependent responses were stronger in highly native genetic backgrounds and tended to attenuate in late backcross generations. Genetic backgrounds donated by European winegrapes of the convarietas occidentalis provided on average higher levels of Rpv3 resistance than backgrounds of orientalis table grapes.