The antifungal activity of dark segmented endophytes (DSE) in blueberry roots against Fusarium oxysporum was investigated through the plate confrontation assay, double plate technique, and control effect experiment. The results showed that all the 8 DSE strains could successfully colonize in blueberry roots, leading to the inhibition of F. oxysporum with a maximum inhibition rate of 74.03%. Both volatile substances and fermentation filtrate produced by these 8 DSE strains exhibited certain inhibitory effect on mycelial growth of F. oxysporum, with the highest inhibitory rate of 37.25% for volatile substances and 66.13% for 50% concentration of fermentation filtrate. In the control efficacy test, sterile blueberry tissue seedlings were firstly treated with a certain DSE strain before inoculation with F. oxysporum. The strains FL1 (Thozetella neonive), MJY26 (Phalocephala fortinii), and MF4 (Phalocephala fortinii) showed good biocontrol effects on root rot caused by F. oxysporum, with control effects of 72.76%, 75.86%, and 77.93%, respectively. Inoculation with FL1, MJY26, and MF4 strains significantly increased the activities of phenylalanine ammonia lyase, polyphenol oxidase, and peroxidase antioxidant in blueberry, and also root vigor of these blueberry seedlings, thereby reducing stress caused by F. oxysporum. The DSE strain MF4 showing best inhibitory effect against F. oxysporum was selected for further test. This strain showed a prevention and control effect of 79.27% on Fusarium root rot of blueberry seedlings in pot experiment. The results lay an important foundation for developing DSE microbial agents against blueberry root rot caused by F. oxysporum.

Cotton Verticillium wilt is a major soil borne disease in cotton production, which seriously endangers the yield and quality of cotton. There are two pathotypes of pathogens, defoliating and non-defoliating. The defoliating strains cause cotton leaves to be yellowing, wilting, and defoliating, while the non-defoliating strains only exhibit yellowing and wilting, but without defoliating. The threatening to cotton industry caused by the defoliating Verticillium dahliae strains has been increasing year by year in China. Multiple plant hormones are involved in the physiological defoliation process of cotton, but the function of plant hormones in the pathological defoliation process of cotton is not yet clear. This study analyzed hormone levels, the tissue-specific expression patterns and levels of key genes in hormone pathways, in cotton plants infected with defoliating strain XJ592 and non-defoliating strain XJ511. The functions and variation patterns of plant hormones in the defoliation process were also clarified. Results showed that salicylic acid and ethylene play a positive regulatory role in the process of cotton defoliation induced by V. dahliae, while jasmonic acid, auxin, and cytokinin play a negative regulatory role. Multiple plant hormones co-regulate cotton defoliation.

Rice blast disease is destructive to rice production. Breeding and utilization of resistant varieties are the most economical, effective and environmentally friendly methods to control the rice blast. Identifying the resistance genes of resistant varieties will be beneficial to the selection of new resistant varieties and the distribution of resistant varieties. ‘Yahui2115’ is an elite rice restorer line with broad-spectrum resistance to rice blast. Previous studies have shown that ‘Yahui2115’ contains Pi2. In order to identify other rice blast resistance genes in ‘Yahui2115’, we used the strain M14Ga089 virulent to the monogenic line harboring Pi2 to analyze the segregation of blast resistance in the F2 population of ‘LTH/Yahui2115’. The results showed that the resistance/susceptibility ratio was 3∶1 in the F2 population, indicating that the resistance from ‘Yahui2115’ to strain M14Ga089 was controlled by one dominant gene, which was named Pir2115-1(t). Through extreme recessive population method, Pir2115-1(t) was mapped between SSR markers RM6307 and RM208 on chromosome 2, a locus that contains a known blast resistance gene, Pib. Gene expression analysis showed that Pib in ‘Yahui2115’ was highly induced by Magnaporthe oryzae infection, and sequence analysis showed that the protein sequence encoded by Pib in ‘Yahui2115’ was completely identical to the reported Pib, indicating that ‘Yahui2115’ carries Pib. This study provides the basis for the application of ‘Yahui2115’ in breeding and the variety distribution of its combinations.

To explore the interrelationships between over-summering inocula of Puccinia striiformis f. sp. tritici (Pst) in different regions of Qinghai Province, we collected Pst samples from autumn wheat seedlings at the early stages of the disease during 2014—2016, identified their virulence on near isogenic wheat lines and assistant differential hosts, and analyzed the virulence diversity of these Pst populations by years and regions. The results showed that a total of 65 virulence types were identified in 106 Pst samples. The Pst populations we tested in this study showed the highest virulence frequency to the stripe rust resistance genes Yr25, Yr29 and YrA, all with a value of 100%, followed by Yr44 of 99.07%. The virulence frequency of these Pst populations to Yr5 and Yr15 was 0, and to the other stripe rust resistance genes were between 45.56% and 97.78% except for the YrTr1 gene (1.76%). This indicated that except for Yr5, Yr15 and YrTr1, the resistance of the remaining 24 resistant genes had been reduced or lost in Qinghai Province. In comparison, the diversity of Pst virulence was the highest in 2016, followed by 2014 and then 2015; Hualong County had the highest virulence diversity, followed by Guide County and then Minhe County. The virulence frequencies of the tested Pst populations to Yr5, Yr15 and YrTr1 during 2014—2016 ranged from 0 to 2.8%, indicating that these three stripe rust-resistant genes are currently effective in Qinghai Province and can be further utilized to control stripe rust of wheat. This study clarifies the virulence types of Pst populations in Qinghai Province and the difference in virulence between Pst populations from different regions of Qinghai Province, providing a theoretical basis for the rational deployment of resistant wheat varieties in Qinghai Province.

The application of molecular marker assisted breeding is limited in rice, which due to unclear resistance gene composition in most rice parent materials and the highly homology of allelic genes. In this study, we designed the functional nucleotide polymorphism markers for Pikp-1, Pikh-1, Pik-1, Pikm-1 and Pi1-1 at the specific polymorphism sites, respectively. Those sites were screened by the allelic genes alignment and then picked out the most specific sites by blasting with 155 rice genomes at Rice Resource Center. Based on those markers, we examined 24 monogenic lines and 109 rice parent lines which using for rice breeding in Sichun basin, and finally identified Pik-1, Pikh-1, Pikp-1, Pi1-1, and Pikm-1 gene from 0, 1, 5, 14, and 20 rice parent lines. Among them, the Pi1 gene was identified by sequencing in ‘Mianhui 365’, which verified the functional markers can distinguish those allelic genes at Pik site, effectively and accurately. It identified a number of rice parent resources with definite resistance gene composition at Pik site and provided reliable molecular markers for Pik-1, Pikh-1, Pikp-1, Pi1-1, and Pikm-1 gene.

Strawberry angular leaf spot is one of the important bacterial diseases in Yunnan in recent years. In this study, a bacterial strain isolated from the strawberry leaf lesion was identified as Xanthomonas fragariae based on morphological, physiological and biochemical analysis, pathogenicity detection, as well as the phylogenetic analysis of the 16S rDNA and hrpB genes. The physiological and biochemical detection showed that the pathogenic bacterium could utilize 26 carbon sources such as D-maltose, D-trehalose, D-cellobiose, sucrose and D-pintobiose. It can react with seven chemical sensitive substances such as nalidixic acid and lincomycin. The pathogenic bacterium had weak salt tolerance, sensitive to acid, and could use organic acids such as L-lactic acid and citric acid. The disease resistance evaluation experiment showed that ‘Benihoppeand’ and ‘Sweet Charlie’ were highly resistant varieties, with disease indexes of 5.95 and 4.76, respectively, and the proportion of highly resistant varieties was 14.28%. The moderately resistant varieties included ‘Portola’, ‘All star’, ‘Yuexiu’, ‘Snow White’, ‘Jingzangxiang’, and ‘Xiangye’, and the proportion of moderately resistant varieties was 42.85%. In conclusion, we identified the pathogenic bacterium of strawberry angular leaf spot, and obtained several disease-resistant strawberry varieties through screening. These results laid a foundation for further research on the characteristics of disease occurrence and prevention methods.