BackgroundIntercropping and close planting are important cultivation methods that increase soybean yield in agricultural production. However, plant shading is a major abiotic stress factor that influences soybean growth and development. Although shade affects leaf morphological parameters and decreases leaf photosynthesis capacity, information on the responses of soybean leaf photosynthesis to shading at proteomic level is still lacking.ResultsCompared with leaves under normal light (CK) treatment, leaves under shading treatment exhibited decreased palisade and spongy tissue thicknesses but significantly increased cell gap. Although shade increased the number of the chloroplast, the thickness of the grana lamella and the photosynthetic pigments per unit mass, but the size of the chloroplast and starch grains and the rate of net photosynthesis decreased compared with those of under CK treatment. A total of 248 differentially expressed proteins, among which 138 were upregulated, and 110 were downregulated, in soybean leaves under shading and CK treatments were detected via isobaric tags for relative and absolute quantification labeling in the three biological repeats. Differentially expressed proteins were classified into 3 large and 20 small groups. Most proteins involved in porphyrin and chlorophyll metabolism, photosynthesis-antenna proteins and carbon fixation in photosynthetic organisms were upregulated. By contrast, proteins involved in photosynthesis were downregulated. The gene family members corresponding to differentially expressed proteins, including protochlorophyllide reductase (Glyma06g247100), geranylgeranyl hydrogenase (Ggh), LHCB1 (Lhcb1) and ferredoxin (N/A) involved in the porphyrin and chlorophyll metabolism, photosynthesis-antenna proteins and photosynthesis pathway were verified with real-time qPCR. The results showed that the expression patterns of the genes were consistent with the expression patterns of the corresponding proteins.ConclusionsThis study combined the variation of the soybean leaf structure and differentially expressed proteins of soybean leaves under shading. These results demonstrated that shade condition increased the light capture efficiency of photosystem II (PSII) in soybean leaves but decreased the capacity from PSII transmitted to photosystem II (PSI). This maybe the major reason that the photosynthetic capacity was decreased in shading.Electronic supplementary materialThe online version of this article (10.1186/s12870-019-1633-1) contains supplementary material, which is available to authorized users.

Pepper (Capsicum annuum) is among the important horticultural crops with economic value, and more and more colorful varieties have been marketed. The purple pepper is becoming increasingly popular on the consumer market because of its anthocyanin richness. Here, two cyanidin-based anthocyanins were separated and identified from peels of purple cultivars by HPLC−LC−MS. To study the molecular mechanism of anthocyanin accumulation, the differential expression of genes related to anthocyanin biosynthesis was examined by qRT-PCR and RNA-Seq in peel from green and purple cultivars. These results show that CaANT1, CaANT2, CaAN1, and CaTTG1 are involved in anthocyanin accumulation of pepper. Further investigation suggested that CaANT1, CaANT2, CaAN1, and CaTTG1 can activate anthocyanin accumulation via forming a new MMBW transcription complex.

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