Key message Typical toxic symptom only occurred in B-toxic C. grandis leaves. B-toxicity induced PCD of C. grandis leaf phloem tissue. The lower leaf free B might contribute to the higher B-tolerance of C. sinensis. Abstract Seedlings of 'Xuegan' (Citrus sinensis) and 'Sour pummelo' (Citrus grandis) differing in boron (B)-tolerance were irrigated with nutrient solution containing 10 (control) or 400 (B-toxic) lM H 3 BO 3 for 15 weeks. Thereafter, the effects of B-toxicity on leaf photosynthesis, chlorophyll, plant B absorption and distribution, root and leaf anatomy were investigated to elucidate the possible B-tolerant mechanisms of Citrus plants. Typical toxic symptom only occurred in B-toxic C. grandis leaves.Similarly, B-toxicity only affected C. grandis photosynthesis and chlorophyll. Although total B concentration in B-toxic roots and leaves was similar between the two species, leaves from B-toxic C. grandis plant middle had higher free B and lower bound B as compared with those from C. sinensis. Effects of B-toxicity on leaf structure were mainly limited to the mesophyll cells and the phloem of leaf veins. Although irregular cell wall thickening was observed in leaf cortex cells and phloem tissue of B-toxic C. grandis and C. sinensis leaves, exocytosis only occurred in the companion cells and the parenchyma cells of B-toxic C. sinensis leaf phloem. Also, B-toxicity induced cell death of phloem tissue through autophagy in C. grandis leaf veins. B-toxicity caused death of root epidermal cells of the two Citrus species. B-toxicity restrained degradation of middle lamella, but did not alter ultrastructure of Golgi apparatus and mitochondria in root elongating zone cells.In conclusion, C. sinensis was more tolerant to B-toxicity than C. grandis. The lower leaf free B and higher bound B might contribute to the higher B-tolerance of C. sinensis.

Post-harvest wet coffee processing is a commonly applied method to transform coffee cherries into green coffee beans through depulping or demucilaging, fermentation, washing, soaking, drying, and dehulling. Multiple processing parameters can be modified and thus influence the coffee quality (green coffee beans and cup quality). The present study aimed to explore the impacts of these parameters, including processing type (depulping or demucilaging), fermentation duration, and application of soaking, on the microbial community dynamics, metabolite compositions of processing waters (fermentation and soaking) and coffee beans, and resulting cup quality through a multiphasic approach. A large-scale wet coffee processing experiment was conducted with Coffea arabica var. Catimor in Yunnan (China) in duplicate. The fermentation steps presented a dynamic interaction between constant nutrient release (mainly from the cherry mucilage) into the surrounding water and active microbial activities led by lactic acid bacteria, especially Leuconostoc and Lactococcus. The microbial communities were affected by both the processing type and fermentation duration. At the same time, the endogenous coffee bean metabolism remained active at different stages along the processing, as could be seen through changes in the concentrations of carbohydrates, organic acids, and free amino acids. Among all the processing variants tested, the fermentation duration had the greatest impact on the green coffee bean compositions and the cup quality. A long fermentation duration resulted in a fruitier and more acidic cup. As an ecological alternative for the depulped processing, the demucilaged processing produced a beverage quality comparable to the depulped one. The application of soaking, however, tempered the positive fermentation effects and standardized the green coffee bean quality, regardless of the preceding processing practices applied. Lastly, the impact strength of each processing parameter would also depend on the coffee variety used and the local geographical conditions. All these findings provide a considerable margin of opportunities for future coffee research.

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To gain more insight into the molecular mechanisms of Colletotrichum gloeosporioides pathogenesis, Agrobacterium tumefaciens-mediated transformation (ATMT) was used to identify mutants of C. gloeosporioides impaired in pathogenicity. An ATMT library of 4128 C. gloeosporioides transformants was generated. Transformants were screened for defects in pathogenicity with a detached copper brown leaf assay. 32 mutants showing reproducible pathogenicity defects were obtained. Southern blot analysis showed 60.4% of the transformants had single-site T-DNA integrations. 16 Genomic sequences flanking T-DNA were recovered from mutants by thermal asymmetric interlaced PCR, and were used to isolate the tagged genes from the genome sequence of wild-type C. gloeosporioides by Basic Local Alignment Search Tool searches against the local genome database of the wild-type C. gloeosporioides. One potential pathogenicity genes encoded calcium-translocating P-type ATPase. Six potential pathogenicity genes had no known homologs in filamentous fungi and were likely to be novel fungal virulence factors. Two putative genes encoded Glycosyltransferase family 28 domain-containing protein and Mov34/MPN/PAD-1 family protein, respectively. Five potential pathogenicity genes had putative function matched with putative protein of other Colletotrichum species. Two known C. gloeosporioides pathogenicity genes were also identified, the encoding Glomerella cingulata hard-surface induced protein and C. gloeosporioides regulatory subunit of protein kinase A gene involved in cAMP-dependent PKA signal transduction pathway.