[学术文献] Transcriptomic response in symptomless roots of clubroot infected kohlrabi (Brassica oleracea var. gongylodes) mirrors resistant plants 进入全文
BMC Plant Biology
Background Clubroot disease caused by Plasmodiophora brassicae (Phytomyxea, Rhizaria) is one of the economically most important diseases of Brassica crops. The formation of hypertrophied roots accompanied by altered metabolism and hormone homeostasis is typical for infected plants. Not all roots of infected plants show the same phenotypic changes. While some roots remain uninfected, others develop galls of diverse size. The aim of this study was to analyse and compare the intra-plant heterogeneity of P. brassicae root galls and symptomless roots of the same host plants (Brassica oleracea var. gongylodes) collected from a commercial field in Austria using transcriptome analyses. Results Transcriptomes were markedly different between symptomless roots and gall tissue. Symptomless roots showed transcriptomic traits previously described for resistant plants. Genes involved in host cell wall synthesis and reinforcement were up-regulated in symptomless roots indicating elevated tolerance against P. brassicae. By contrast, genes involved in cell wall degradation and modification processes like expansion were up-regulated in root galls. Hormone metabolism differed between symptomless roots and galls. Brassinosteroid-synthesis was down-regulated in root galls, whereas jasmonic acid synthesis was down-regulated in symptomless roots. Cytokinin metabolism and signalling were up-regulated in symptomless roots with the exception of one CKX6 homolog, which was strongly down-regulated. Salicylic acid (SA) mediated defence response was up-regulated in symptomless roots, compared with root gall tissue. This is probably caused by a secreted benzoic acid/salicylic acid methyl transferase from the pathogen (PbBSMT), which was one of the highest expressed pathogen genes in gall tissue. The PbBSMT derived Methyl-SA potentially leads to increased pathogen tolerance in uninfected roots. Conclusions Infected and uninfected roots of clubroot infected plants showed transcriptomic differences similar to those previously described between clubroot resistant and susceptible hosts. The here described intra-plant heterogeneity suggests, that for a better understanding of clubroot disease targeted, spatial analyses of clubroot infected plants will be vital in understanding this economically important disease.
[学术文献] Draft genome sequence of cauliflower (Brassica oleracea L. var. botrytis) provides new insights into the C genome in Brassica species 进入全文
Cauliflower is an important variety of Brassica oleracea and is planted worldwide. Here, the high-quality genome sequence of cauliflower was reported. The assembled cauliflower genome was 584.60 Mb in size, with a contig N50 of 2.11 Mb, and contained 47,772 genes; 56.65% of the genome was composed of repetitive sequences. Among these sequences, long terminal repeats (LTRs) were the most abundant (32.71% of the genome), followed by transposable elements (TEs) (12.62%). Comparative genomic analysis confirmed that after an ancient paleohexaploidy (γ) event, cauliflower underwent two whole-genome duplication (WGD) events shared with Arabidopsis and an additional whole-genome triplication (WGT) event shared with other Brassica species. The present cultivated cauliflower diverged from the ancestral B. oleracea species ～3.0 million years ago (Mya). The speciation of cauliflower (～2.0 Mya) was later than that of B. oleracea L. var. capitata (approximately 2.6 Mya) and other Brassica species (over 2.0 Mya). Chromosome no. 03 of cauliflower shared the most syntenic blocks with the A, B, and C genomes of Brassica species and its eight other chromosomes, implying that chromosome no. 03 might be the most ancient one in the cauliflower genome, which was consistent with the chromosome being inherited from the common ancestor of Brassica species. In addition, 2,718 specific genes, 228 expanded genes, 2 contracted genes, and 1,065 positively selected genes in cauliflower were identified and functionally annotated. These findings provide new insights into the genomic diversity of Brassica species and serve as a valuable reference for molecular breeding of cauliflower.
[学术文献] Genome-wide identification of stress-associated proteins (SAP) with A20/AN1 zinc finger domains associated with abiotic stresses responses in Brassica napus 进入全文
Environmental and Experimental Botany
Stress-associated proteins (SAP) that contain the A20/AN1 zinc-finger domain play important roles in plants abiotic stress responses. However, little is known about the SAP gene family in Brassica napus (genome AnAnCnCn), was formed by recent allopolyploidy between ancestors of Brassica rapa (genome ArAr) and Brassica oleracea (genome CoCo). To explore the distribution and expression patterns of these genes, a genome-wide identification and a systematic analysis of genes in the SAP family in B. napus were performed. A total of 57 genes encoding SAP were identified, and subsequently classified into 5 groups. In contrast to results seen in other plant species, further analyses of gene structures and conserved protein motifs revealed that a large percentage of the BnaSAP (16/57) genes were A20-type or AN1-type SAP genes, most of which were not found to have homologous genes in B. rapa or B. oleracea. The cis-elements of the BnaSAP promoters, and BnaSAP gene expression levels in different tissues, and under different stress treatments, were also investigated based on RNA-seq data. All the typical A20-AN1-type and AN1-AN1(-C2H2)-type BnaSAP genes were constitutively expressed among all tissues, except 4 members in Group II. In contrast, almost all A20 type and AN1 type members showed very low detection levels in all the tested rapeseed tissues from which the transcriptome data was derived. Additionally, most of the typical A20-AN1-type and AN1-AN1-type BnaSAP genes were found to be induced by multiple stresses and phytohormones. Among the identified BnaSAP genes, four members of Group III (BnaA07g15770D, BnaC06g14100D, BnaC04g27800D, and BnaC08g24010D) were induced following various low-temperature stresses in leaves, and were induced by NaCl and PEG stress in roots. BnaA06g02460D and BnaC06g04440D from Group IV were induced by heat stress, while BnaA06g31640D and BnaC07g25010D from Group V were induced by heat stress and salicylic acid (SA) treatment. This study provides a comprehensive analysis of SAP genes in rapeseed, and may aid in future efforts to identify the functions of A20/AN1-type proteins and the responses of rapeseed under a variety of abiotic stresses.
[学术文献] Mutation in EMB1923 gene promoter is associated with chlorophyll deficiency in Chinese cabbage (Brassica campestris ssp. pekinensis) 进入全文
Leaf color mutants are widespread in higher plants and can be used as markers in crop breeding or as important material in understanding the regulatory mechanisms of chlorophyll biosynthesis and chloroplast development. A stably inherited plant etiolated mutation (pem) was obtained from its wild-type ‘FT’ (a doubled haploid line of the Chinese cabbage variety ‘Fukuda 50’) by combining 60Co-γ radiation and isolated microspore culture in Chinese cabbage. Compared to the wild-type ‘FT’, the chlorophyll content in the pem mutant was decreased, the photosynthetic capacity was reduced and the chloroplast development was retarded. These physiological changes may lead to a reduction in growth and yield in the pem mutant line. Genetic analysis showed that the mutant phenotype was controlled by the single recessive nuclear pem gene. The pem gene was mapped to a 25.88 kb region on the A03 chromosome. Cloning and sequencing results showed that there was only one DNA sequence variation in this region, which was a 30 bp deletion on the promoter of Bra024218. Its homologous gene encodes EMBRYO DEFECTIVE 1923 (EMB1923) in Arabidopsis thaliana. We therefore predicted that Bra024218 was the mutated gene associated with etiolated leaves in Chinese cabbage. The pem mutant is a useful line for researching chloroplast development and the mechanism of leaf color mutation in Chinese cabbage.
[学术文献] BjuWRR1, a CC-NB-LRR gene identified in Brassica juncea, confers resistance to white rust caused by Albugo candida 进入全文
Theoretical and Applied Genetics
Key message BjuWRR1, a CNL-type R gene, was identified from an east European gene pool line of Brassica juncea and validated for conferring resistance to white rust by genetic transformation. Abstract White rust caused by the oomycete pathogen Albugo candida is a significant disease of crucifer crops including Brassica juncea (mustard), a major oilseed crop of the Indian subcontinent. Earlier, a resistance-conferring locus named AcB1-A5.1 was mapped in an east European gene pool line of B. juncea—Donskaja-IV. This line was tested along with some other lines of B. juncea (AABB), B. rapa (AA) and B. nigra (BB) for resistance to six isolates of A. candida collected from different mustard growing regions of India. Donskaja-IV was found to be completely resistant to all the tested isolates. Sequencing of a BAC spanning the locus AcB1-A5.1 showed the presence of a single CC-NB-LRR protein encoding R gene. The genomic sequence of the putative R gene with its native promoter and terminator was used for the genetic transformation of a susceptible Indian gene pool line Varuna and was found to confer complete resistance to all the isolates. This is the first white rust resistance-conferring gene described from Brassica species and has been named BjuWRR1. Allelic variants of the gene in B. juncea germplasm and orthologues in the Brassicaceae genomes were studied to understand the evolutionary dynamics of the BjuWRR1 gene.
[学术文献] Evaluation of the optimal standardized ileal digestible threonine:lysine ratio in lactating sow diets 进入全文
Camborough PIC sows (n = 291) were fed 1 of 5 dietary treatments to evaluate the standardized ileal digestible (SID) Thr:Lys requirement during lactation. Sows were blocked by parity (1, 2, and 3+) and randomly allotted to 1 of 5 SID Thr:Lys ratios (52, 60, 68, 76, and 84). SID Lys was formulated to 1.03% and SID methionine and cystine (M + C):Lys was 55%. Sows were allowed 5.45 kg feed/day starting on the day of farrowing. All other nutrients met or exceeded the NRC (2012) requirements. Sows were allowed ad libitum access to water, and piglets were cross-fostered within treatment within 24 h of birth. Data collected during the study included sow prefarrow BW, sow weaning weight, starting litter weight, weaning litter weight, piglet mortality, weaning-to-estrus interval, and subsequent total born piglets. Data were analyzed as a randomized complete block design using PROC MIXED with sow as the experimental unit and treatment and parity as fixed effects. Requirement estimation models evaluated were quadratic polynomial, broken-line linear, and broken-line quadratic (BLQ) using PROC NLMIXED. Models that differed in their Bayesian information criterion (BIC) values by at least 2 points were considered to have meaningful differences in their data fit. The best-fit model was based on the best BIC value. As the SID Thr:Lys ratio increased, there was a quadratic response on ADFI (4.73, 4.57, 4.67, 4.55, and 4.60 kg/d; P = 0.001) and percent of sow BW loss (−6.4, −7.89, −7.35, −6.19, and −5.81; P = 0.004). In addition, there was a trend for weaning-to-estrus interval to be affected by the ratio (5.4, 4.4, 4.6, 4.5, and 4.8; P = 0.07). Daily litter gain was also quadratically improved as the SID Thr:Lys ratio increased (2.67, 2.67, 2.78, 2.77, and 2.68 kg/d; P-value = 0.001). For daily litter gain, the BLQ model was determined to be the best fit with an estimated SID Thr:Lys requirement of 65%. In conclusion, the optimal SID Thr:Lys ratio for litter growth was 65.