Laboratory mutants of Sclerotinia sclerotiorum (Lib) de Bary, resistant to boscalid, have been extensively characterized.  However, the resistance situation in the lettuce field remains largely elusive.  In this study, among the 172 S. sclerotiorum isolates collected from asparagus lettuce field in Jiangsu Province, China, 132 isolates (76.74%) exhibited low-level resistance to boscalid (Bos^LR), with a discriminatory dose of 5 μg mL^–1.  In comparison to the boscalid-sensitive (Bos^S) isolates, most Bos^LR isolates demonstrated a slightly superior biological fitness, as evidenced by data on mycelial growth, sclerotium production and pathogenicity.  Moreover, most Bos^LR isolates showed comparable levels of oxalic acid (OA) accumulation, increased exopolysaccharide (EPS) content and reduced membrane permeability when compared to the Bos^S isolates.  Nevertheless, their responses to distinct stress factors diverged significantly.  Furthermore, the effectiveness of boscalid in controlling Bos^LR isolates on radish was diminished compared to its efficacy on Bos^S isolates.  Genetic mutations were identified in the SDH genes of Bos^LR isolates, revealing the existence of three resistant genotypes: I (A11V at SDHB, SDHB^A11V), II (Q38R at SDHC, SDHC^Q38R) and III (SDHB^A11V+SDHC^Q38R).  Importantly, no cross-resistance was observed between boscalid and other fungicides such as thifluzamide, pydiflumetofen, fluazinam, or tebuconazole.  Our molecular docking analysis indicated that the docking total score (DTS) of the type I resistant isolates (1.3993) was lower than that of the sensitive isolates (1.7499), implying a reduced affinity between SDHB and boscalid as a potential mechanism underlying the boscalid resistance in S. sclerotiorum.  These findings contribute to an enhanced comprehension of boscalid’s mode of action and furnish valuable insights into the management of boscalid resistance.

Salmonella Enteritidis (SE) is a zoonotic and vertically transmitted pathogen, often colonized in the reproductive tract of adult poultry, which can result in direct contamination of eggs and threaten human health.  Previous studies have revealed that some pattern recognition receptors and resistance genes were involved in regulating immune responses to SE invasion in birds.  However, the role of these immune response genes was not independent, and the interactions among the genes remained to be further investigated.  In this study, SE burden and colonization were determined in reproductive tissue after the ducks were SE-infected, and RNA-sequencing was performed to construct co-expression networks by weighted gene co-expression network analysis (WGCNA).  The result showed that SE could be isolated from 22% of infected-birds in any segment of the reproductive tract and the SE was readily colonized in the stroma, small follicle, isthmus, and vagina of the reproductive tracts in morbid ducks.  The top central, highly connected genes were subsequently identified three specific modules in the above four tissues at the defined cut-offs (P<0.01), including 60 new candidate regulators and 125 transcription factors.  Moreover, those 185 differentially expressed genes (DEGs) in these modules were co-expressed.  Moreover, the hub genes (TRAF3, CXCR4 and IL13RA1) were identified to act with many other genes through immune response pathways including NF-kappaB, Toll-like receptor, steroid biosynthesis, and p53 signaling pathways.  These data provide references that will understand the immune regulatory relationships during SE infection, but also assist in the breeding of SE-resistant lines through potential biomarkers.

Auxin response factors (ARFs) play key roles throughout the whole process of plant growth and development, and mediate auxin response gene transcription by directly binding with auxin response elements (AuxREs).  However, their functions in abiotic stresses are largely limited, especially in apples.  Here, the auxin response factor gene MdARF2 (HF41569) was cloned from apple cultivar ‘Royal Gala’ (Malus×domestica Borkh.).  Phylogenetic analysis showed that ARF2 proteins are highly conserved among different species and MdARF2 is the closest relative to PpARF2 of Prunus persica, but they differ at the DNA level.  MdARF2 contains three typical conserved domains including the B3 DNA-binding domain, Auxin_resp domain and AUX_IAA domain.  The subcellular localization demonstrated that MdARF2 is localized in the nucleus.  The three-dimensional structure prediction of the proteins showed that MdARF2 is highly similar with AtARF2, and they contain helices, folds, and random coils.  The promoter of MdARF2 contains cis-acting elements which respond to various stresses, as well as environmental and hormonal signals.  Expression analysis showed that MdARF2 is widely expressed in all tissues of apple, with the highest expression of MdARF2 in root.  Functional analysis with a series of MdARF2 transgenic apple calli indicated that MdARF2 can reduce the sensitivity to ABA signaling and enhance salt tolerance in apple.  In summary, the results of this research provide a new basis for studying the regulation of abiotic stresses by ARFs.

The objective of this study was to investigate the effect of lactic acid bacteria (LAB) inoculums on fermentation quality and in vitro digestibility of corn stover silage. Corn stover was ensiled without (control) or with Lactobacillus plantarum (LP), Enterococcus faecalis (EF), and Enterococcus mundtii (EM) for 45 days. The fermentation characteristics were assessed, and subsequent in vitro dry matter digestibility (DM-D), neutral detergent fiber digestibility (NDF-D), volatile fatty acids (VFA), methane (CH₄ ) production, cellulolytic bacteria proportions and their activities per corn stover silage were also determined. There was no significant difference (P>0.05) among the silage pH, lactic acid, crude protein (CP), water soluble carbohydrates (WSC) and lignocelluloses contents of different treatments. The relative proportions of Ruminococcus flavefaciens and Fibrobacter succinogenes, carboxymethyl-ocellulose and β-glycosidase activities, DM-D, NDF-D, and VFA production of in vitro incubation was higher (P<0.05) for silages inoculated with LP and EF than those of the control silage. Silage inoculated with LP showed the lowest (P<0.05) CH₄ production per unit yield of VFA, which was positively corresponded to the lowest (P<0.05) ratio of acetate to propionate. In summary, the ensiling fermentation quality and subsequent utilization of corn stover silage were efficiently improved by inoculated with L. plantarum.

Stress associated proteins (SAPs) are the A20/AN1 zinc-finger proteins which confer to abiotic stresses in plants.  In this study, TaSAP7-B, including two AN1 domains, was isolated from B genome of wheat (Triticum aestivum L.).  Sequencing analysis on TaSAP7-B illustrated one InDel (insertion-deletion) and one SNP (single nucleotide polymorphism) in the promoter region while no diversity was observed in the coding region.  On the basis of SNP in the promoter region (–260 bp), a dCAPS (derived cleaved amplified polymorphic sequences) marker SNP-260 was developed for TaSAP7-B.  Using a natural population consisting of 262 wheat accessions, significant associations were detected between the marker SNP-260 and agronomic traits, such as plant height (PH), peduncle length (PL), length of penultimate internode (LPI), number of spike per plant (NSP), and 1 000-grain weight (TGW).  Two genotypes were identified using marker SNP-260 in the natural population.  Among them, the genotypes possessing C allele exhibited a higher TGW and shorter PH than the T genotypes.  Hence, base C was considered as the superior allele.  The dCAPS marker of TaSAP7-B can be instrumental for marker-assisted selection for high grain size and short plant height.  

The stress-associated protein (SAP) multigene family is conserved in both animals and plants.  Its function in some animals and plants are known, but it is yet to be deciphered in wheat (Triticum aestivum L.).  We identified the wheat gene TaSAP17-D, a member of the SAP gene family with an AN1/AN1 conserved domain.  Subcellular localization indicated that TaSAP17-D localized to the nucleus, cytoplasm, and cell membrane.  Expression pattern analyses revealed that TaSAP17-D was highly expressed in seedlings and was involved in NaCl response, polyethylene glycol (PEG), cold, and exogenous abscisic acid (ABA).  Constitutive expression of TaSAP17-D in transgenic Arabidopsis resulted in enhanced tolerance to salt stress, confirmed by improved multiple physiological indices and significantly upregulated marker genes related to salt stress response.  Our results suggest that TaSAP17-D is a candidate gene that can be used to protect crop plants from salt stress.  

Citrus fruits are rich in carotenoids. In the carotenoid biosynthetic pathway, lycopene β-cyclase (LCYb, EC:1.14.-.-) is a key regulatory enzyme in the catalysis of lycopene to β-carotene, an important dietary precursor of vitamin A for human nutrition. Two closely related lycopene β-cyclase cDNAs, designated CsLCYb1 and CsLCYb2, were isolated from the pulp of orange fruits (Citrus sinensis). The expression level of CsLCYb genes is lower in the flavedo and juice sacs of a lycopeneaccumulating genotype Cara Cara than that in common genotype Washington, and this might be correlated with lycopene accumulation in Cara Cara fruit. The CsLCYb1 efficiently converted lycopene into the bicyclic β-carotene in an Escherichia coli expression system, but the CsLCYb2 exhibited a lower enzyme activity and converted lycopene into the β-carotene and the monocyclic γ-carotene. In tomato transformation studies, expression of CsLCYb1 under the control of the cauliflower mosaic virus (CaMV) 35S constitutive promoter resulted in a virtually complete conversion of lycopene into β-carotene, and the ripe fruits displayed a bright orange colour. However, the CsLCYb2 transgenic tomato plants did not show an altered fruit colour during development and maturation. In fruits of the CsLCYb1 transgenic plants, most of the lycopene was converted into β-carotene with provitamin A levels reaching about 700 μg g-1 DW. Unexpectedly, most transgenic tomatoes showed a reduction in total carotenoid accumulation, and this is consistent with the decrease in expression of endogenous carotenogenic genes in transgenic fruits. Collectively, these results suggested that the cloned CsLCYb1 and CsLCYb2 genes encoded two functional lycopene β-cyclases with different catalytic efficiency, and they may have potential for metabolite engineering toward altering pigmentation and enhancing nutritional value of food crops.