Comparative proteomics analysis of peanut roots reveals differential mechanisms of cadmium detoxification and translocation between two cultivars differing in cadmium accumulation

Abstract Background Peanut is one of the most important oil and protein crops, and it exhibits wide cultivar variations in shoot Cd accumulation ability. However, the mechanism of Cd accumulation in peanut shoots has not been well understood. In this study, the root proteomics of two cultivars differing in seed Cd accumulation, Fenghua 1 (F, low Cd cultivar) and Silihong (S, high Cd cultivar), were investigated under 0 (CK) and 2 μM Cd conditions. Results A total of 4676 proteins were identified by proteomics screening. Of them, 375, 1762, 1276 and 771 proteins were identified to be differentially expressed proteins (DEPs) for comparison of FCd/FCK, SCd/SCK, FCK/SCK and FCd/SCd, respectively. Silihong is more sensitive to Cd exposure than Fenghua 1 in terms of root proteomics. A total of 30 and 86 DEPs were identified to be related with heavy metal transport and cell wall modification, respectively. The up-regulation of ABCB25, ABCC14, ABCC2, PDR1 and V-ATPases by Cd exposure in Silihong might enhance vacuolar sequestration of Cd and its efflux from symplast to apoplast. The higher Cd accumulation in the root CWs of Silihong might be resulted from its higher capability of CW modification, in which many proteins such as IRX10L, BGLU12-like, BGLU42, EXLB1, XTH30, XTH6, XYL7, PAL3, COMT, CAD1, and CCR1 were involved. Conclusions The vacuolar sequestration and efflux of Cd as well as its adsorption in CW might be the principal mechanism of cadmium detoxification in Silihong. The higher capacity of Cd accumulation and translocation of Silihong is an inherent characteristics in which ACA8 and ZIP1 might be involved

Transcriptome and physiological analysis of increase in drought stress tolerance by melatonin in tomato.

Drought stress seriously affects tomato growth, yield and quality. Previous reports have pointed out that melatonin (MT) can alleviate drought stress damage to tomato. To better understand the possible physiological and molecular mechanisms, chlorophyll fluorescence parameters and leaf transcriptome profiles were analyzed in the "Micro Tom" tomato cultivar with or without melatonin irrigation under normal and drought conditions. Polyethylene glycol 6000 (PEG6000) simulated continuous drought treatment reduced plant height, but melatonin treatment improved plant growth rate. Physiological parameter measurements revealed that the drought-induced decreases in maximum efficiency of photosystem II (PSII) photochemistry, the effective quantum yield of PSII, electron transfer rate, and photochemical quenching value caused by PEG6000 treatment were alleviated by melatonin treatment, which suggests a protective effect of melatonin on PSII. Comparative transcriptome analysis identified 447, 3982, 4526 and 3258 differentially expressed genes (DEGs) in the comparative groups plus-melatonin vs. minus-melatonin (no drought), drought vs. no drought (minus-melatonin), drought vs. no drought (melatonin) and plus-melatonin vs. minus-melatonin (drought), respectively. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed that DEGs in the four comparative groups were involved in multiple metabolic processes and closely related to hormone signal transduction and transcription factors. Transcriptome data revealed that melatonin changed the expression pattern of most hormone signal transduction related DEGs induced by drought, and improved plant drought resistance by down-regulating the expression of linoleic acid catabolic enzyme genes. These results provide new insights into a probable mechanism of the melatonin-induced protection of photosynthesis and enhancement of drought tolerance in tomato plants

Chromosome-level genome assembly and annotation of the native Chinese wild blueberry Vaccinium bracteatum

Vaccinium bracteatum Thunb., an important native Chinese wild blueberry species, is widely used as a rootstock and in blueberry cultivar breeding, as well as in traditional medicine and local food. We report here the genome sequence of V. bracteatum using a combination of Oxford Nanopore Technologies long-read and Illumina HiSeq short-read sequencing technologies to obtain 65.30 Gb of clean data, achieving 114.60-fold genome coverage. The assembled genome has a total sequence length of 569.81 Mb and consists of 36,756 predicted genes. Repetitive DNA sequences represent 57.78% of the genome sequence. Comparative genomic analysis revealed that a total of 336 gene families had expanded and that 298 candidate genes had undergone positive selection during evolution in V. bracteatum. The divergence of V. bracteatum from the related Rhododendron williamsianum and Rhododendron delavayi occurred ~13−85 million years ago. The genome sequence of V. bracteatum allowed us to identify some important genes associated with traits involved in fruit development, such as flavonoid biosynthesis, sugar and acid metabolism, MYB transcription factor gene expression, and hormone regulation. The differential expression patterns of genes encoding flavonoid biosynthesis enzymes and MYB transcription factors might explain the high flavonoid content of V. bracteatum. This chromosome-level genome assembly provides reference sequences for the identification and characterization of genes important in the improvement of blueberry and related research