The soil-borne necrotrophic fungus Rhizoctonia solani is one of destructive fungi causing severe yield losses in various important crops.  However, the host defense mechanisms against the invasion of this pathogen are poorly understood.  In this study, we employed an iTRAQ-based quantitative proteomic approach to investigate host proteins responsive to R. solani using the resistant rice cultivar YSBR1.  As a whole, we identified 319 differentially accumulated proteins (DAPs) after inoculation of rice plants with R. solani.  Functional categorization analysis indicates that these DAPs cover a broad range of functions.  Notably, a substantial portion of the DAPs are involved in cell redox homeostasis, carbohydrate metabolism, and phenylpropanoid biosynthesis, or belong to pathogenesis-related proteins, indicating that these processes/proteins play important roles in host defense against R. solani.  Interestingly, all of the DAPs involved in photosynthesis and chlorophyll biosynthetic processes, and part of the DAPs involved in phenylpropanoid biosynthesis, show reduced accumulation after R. solani infection, suggesting that R. solani probably inhibits host photosynthetic system and phenylpropanoid biosynthesis to facilitate infection and colonization.  In conclusion, our results provide both valuable resources and new insights into the molecular mechanisms underlying rice and R. solani interaction.

Genetic linkage maps are important for quantitative trait locus (QTL) and marker-assisted selection breeding.  The wolfberry (Lycium spp.) is an important food and traditional medicine in China.  However, few construction genetic linkage maps have been reported because of the lack of genomic and genetic resources.  In this study, a population of 89 F₁ seedings was derived from a cross between two heterozygous parents, L. chinense var. potaninii ‘BF-01’ (female) and L. barbarum var. auranticarpum ‘NH-01’ (male), in order to construct a genetic linkage map using simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers based on the double pseudo-test cross mapping strategy.  The resulting genetic map consisted of 165 markers (74 AFLPs and 91 SSRs) distributed across 12 linkage groups and spanned a total length of 557.6 cM with an average distance of 3.38 cM between adjacent markers.  The 12 linkage groups contained 3 to 21 markers and ranged in length from 8.6 to 58.3 cM.  Twenty-nine segregated markers distributed in the map were mainly located on LG4 and LG9 linkage groups at P<0.05.  This is the first linkage map of Lycium species using SSR and AFLP markers, which can serve as basis for improving genes and selective breeding of the genome assembly.

We studied gas-exchange, chlorophyll pigments, lipid peroxidation, antioxidant enzymes, and biomass partitioning responses in seedlings of four wolfberry species (Lycium chinense Mill. var. potaninii (Pojark.) A. M. Lu, Lycium chinense Mill., Lycium barbarum L., and Lycium yunnanense Kuang & A. M. Lu) under four water supply regimes.  In all four species, drought affected seedlings in terms of chlorophyll content, net photosynthesis rate (P_n), transpiration rate (E), and lipid peroxidation.  Drought also increased some antioxidant enzyme activities, such as peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX).  Significant changes in dry biomass partitioning also occurred in response to water stress.  In particular, dry biomass of leaves and fruits decreased significantly.  L. chinense Mill. and L. barbarum L. possessed greater drought tolerance and exhibited superior antioxidant processing ability and other related physiological traits compared to the other two species. L. chinense Mill. was the most tolerant to all levels of drought.  In contrast, L. yunnanense Kuang & A. M. Lu was more affected by water supply and had the lowest resistance to drought stress.  These findings would provide some important information regarding genetic resources for future forest tree improvement in relation to drought tolerance.