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[Objective] The paper was to clarify the occurrence of sugarcane ratoon stunting disease (R.SD) in Hainan sugarcane-growing areas. [Method] In 2019, 270 samples of sugarcane leaves were collected from six main sugarcane-growing areas in Hainan Province, and R.SD was detected by PCR assay with specific primers. [Result] RSD was detected out in 41 out of 270 sugarcane samples, with an average detection rate of 15.19%. The detection rates of RSD were different in six sugarcane-growing areas; the detection rate of RSD in Danzhou sugarcane-growing area was the highest of 22.00%; the detection rate of RSD in Lingao sugarcane-growing area was the lowest of 9.26%. RSD was detected out in 8 out of 10 main sugarcane cultivars, among which Xintaitang 22 suffered the heaviest damage, with the positive detection rate of 45.83%; RSD had not been detected out in Zhongtang 1 and Zhongtang 2, while the positive detection rates of RSD in the remaining seven sugarcane cultivars were 10.00%-31.25%. [Conclusion] RSD commonly occurs in Hainan sugarcane-growing areas. The research results provide a basis for scientific prevention and control of RSD and promotion and application of healthy virus-free sugarcane seedlings. [ABSTRACT FROM AUTHOR]

To understand virus infection situation of integrated demonstration and regional test sugarcane varieties in national sugarcane system in Guilin City, Guangxi Province, leaf samples with or without symptoms were collected from 37 sugarcane varieties, and five kinds of viruses were detected by RT-PCR with specific primers, including Sugarcane yellow leaf virus (SCYLV), Sugarcane streak mosaic virus (SCSMV), Sorghum mosaic virus (SrMV), Sugarcane mosaic virus (SCMV) and Sugarcane bacilliform virus (SCBV). The results showed that SCYLV was detected from four sugarcane varieties, and the detection rate was 10.81%; SCSMV was detected from five sugarcane varieties, and the detection rate was 13.51%; SrMV was detected from four sugarcane varieties, and the detection rate was 10.81%; SCMV had not been found; SCBV was detected from 27 sugarcane varieties, and the detection rate was 72.9%. Additionally, mixed infection of different viruses was widespread, and the total mixed infection rate was 21.62%. Thus, integrated demonstration and regional test sugarcane varieties in national sugarcane system in Guilin City had been seriously infected by viruses, and mixed infection of different viruses was common. The paper will provide a reference for breeding and popularization of antiviral sugarcane varieties. [ABSTRACT FROM AUTHOR]

The yield increase effect was analyzed by planting disease-free sugarcane seedlings, and the differential expression of three monosaccharide transporter genes (SGT1, SGT2 and PST2a) in disease-free and untreated sugarcane seedlings was studied to clarify the functions of these genes on sugarcane yield. The yield was increased by 27.2% by planting disease-free sugarcane seedlings. The expression levels of SGT1, SGT2 and PST2a in leaves of virus-free plants were 1--20 times higher than those in untreated sugarcane plants during the whole growth period. In addition, the expression levels of SGT1 and SGT2 in 1--8 internodes of sugarcane at elongation stage and maturity stage were 1-45 times higher than those in untreated plants. And the expression levels of PST2a in 4-8 internodes of sugarcane plants at elongation stage were 4--7 times higher than those in untreated plants, but there was no difference in expression levels at maturity stage. The functions of different monosaccharide transporters varied among different growth stages. The three kinds of monosaccharide transporters might form a mutual cooperation network, and improved monosaccharide transport efficiency by increasing their self activity to provide more monosaccharide for cell metabolism, favorable for the yield increase of sugarcane stem. [ABSTRACT FROM AUTHOR]

[Objective] The paper was to study the possible mechanism of chitinase gene. [Method] The chitinase gene with inhibitory effect against a variety of pathogenic fungi was cloned and analyzed in this study. [Result] The genome of HAS strain contained an ORF of 834 bp. The homology of coding protein corresponding to ORF with chitosanase [Bacillus subtilis subsp. subtilis str. 168] (ref INP_390566.1) was the highest of 98% (272/277). [Conclusion]Through the analysis of amino acid sequence and secondary structure of the protease, tertiary structure prediction and analysis, HAS strain may play a pivotal role in controlling Sporisorium scitaminea Syd. [ABSTRACT FROM AUTHOR]

Bacillus subtilis HAS had good control effects on sugarcane smut in the field. Colonization dynamics of B. subtilis HAS were studied through biotics marker and pot culture, to understand the bio-control mechanism of the strain and provide experimental basis for commercialization. The results showed that B. subtilis HAS had strong colonization ability, which could be colonized in sugarcane root, stem, leaf and rhizosphere for long time, but the colonization levels were different. The colonization density of B. sutills HAS remained 103 CFU/g soil in the rhizosphere and 102 CFU/g (fresh weight) in the root after inoculation of 60 d. The colonization in the rhizosphere decreased first, then increased and decreased again, and finally stabilized. The colonization in the root first increased then decreased. Meantime, colonization status in stems and leaves showed that the colonization density in stems and leaves was 10 CFU/g (fresh weight), indicating that the colonization level was not high in stem and leaf. [ABSTRACT FROM AUTHOR]

[Objective] The paper aimed to screen sugarcane varieties and species layout suitable for Hainan sugarcane area. [Method] Using mixed spores of Ustilago scitaminea Sydow, smut resistance of 21 major sugarcane varieties in national sugarcane regional trial as well as ROC22 and ROC16 were identified through artificial inoculation test and field natural incidence. [Result] Yunzhe99-596, Yuegan42, Guitang29 and Funong39 reached highly resistant and resistant levels to smut in artificial inoculation test. [Conclusion] Most of the varieties showed better resistance to smut in newly planted sugarcane and ratoon sugarcane except Yunzhe 03-103, Liucheng 03-1137 and ROC22. [ABSTRACT FROM AUTHOR]

The present study was to screen and identify a biocontrol strain with antagonistic effect against Sporisorium scitaminea Sydow. 16S rDNA gene fragments were amplified by universal primers P0 and P6. The results showed that 16S rDNA gene fragment with the size of 1 533 bp was obtained, and its sequence had the homology of 99% with the sequence of Bacillus subtilis. The morphological characteristics of the strain were as follows: the mycelium of strain HAS was short-rod shape, and could move; Gram staining was positive; 3% KOH solubility test was negative; flagellum was grown around the cells; spores were grown in the middle, elliptic, and cysts were slightly swelled. The strain was preliminarily identified as B. subtilis. Dual culture with pathogenic fungi showed that the strain had good inhibitory effect against various pathogenic fungi causing diseases on sugarcane and other crops. Therefore, strain HAS isolated in the study was identified to be B. subtilis, which had good control effect against S. scitaminea. [ABSTRACT FROM AUTHOR]

A biocontrol strain HJX1, which had good inhibitory effect against Fusarium oxysporwn f. sp. cubense, was identified as Bacillus subtilis based on traditional morphology, 16S rRNA gene sequence and fatty acid profiles. The sequence of 16S rRNA gene had 99% homology to B. subtilis according to the DNA fragment of 1 521 bp amplified with a pair of universal primers, P0 and P6, of bacteria. Confront culture with pathogenic fungi showed that this strain had good inhibitory effect against 10 pathogenic fungi. [ABSTRACT FROM AUTHOR]

[Objective] The paper was to study control effects of 12 kinds of insecticides on sugarcane pests at different periods. [Method] By field experiment, the control effects of different insecticides against sugarcane pests at planting stage, seedling stage and tillering stage of sugarcane were studied. [Result] After seedcane was treated by Chlorantraniliprole, Durivo and Seed soaking, the dead heart seedlings were significantly reduced in fields, and the control effects were 87.13% ± 12.87%, 85.22% ± 14.78%, 82.71% ± 17.29%, respectively; Durivo (seedling emergence rate is 63.00% ± 10.30%) and Seed soaking (seedling emergence rate is 57.75% ± 4.50%) could also significantly enhance seedling emergence rate. After "removal-irrigation" treatment during seedling stage, the control effects of Flubendiamide (76.26% ± 4.31%) and Chlorantraniliprole (61.66% ± 6.65%) against sugarcane stem borer were significantly higher than Virtako (60.17% ± 7.06%) , Deltamethrin(38.75% ± 9.88%) , lambda-cyhalothrin (54.06% ± 6.83%) , 18% Dimehypo AS (37.98% ± 10.31%) and Dipterex (38.64% ± 9.34%) . During tillering stage, with the increased application of 3.6% Dimehypo GR in cultivation and earthing up, the control effect on stem borer was significantly increased, and the control effect reached (72.03% ± 17.06%) as the dosage was 120 kg/hm2 ; when the dosage of phoxim exceeded 30 kg/hm2, the control effect on underground pests reached 44.00% ± 14.80% , and the control effect did not have significant difference as the dosage was ranged from 30 kg/hm2 to 60 kg/hm2. [Conclusion] The paper provided scientific basis for selection of different control methods, different chemicals and dosages against pests during different periods. [ABSTRACT FROM AUTHOR]

[Objective] The paper was to identify strain HN-1 against banana wilt disease and to determine its antagonism. [Method] The strain HN-1 was obtained from the soil in fields heavily infected by Fusarium oxysporum f. sp. cubense ( FOC ). Antagonism of the strain against F. oxysporum was tested via dual-culture and inhibition test on spore germination. [Result] HN-1 effectively inhibited mycelial growth and spore germination of F. oxysporum. Strain HN-1 was identified as Brevibacillus brevis according to its characteristics in morphology, physiology and biochemistry and its 16S rDNA sequence. The strain showed high inhibition effect on 15 species of fungal pathogens in the dual-culture trials with fungal pathogens. [Conclusion] The study provides theoretical basis for application of strain HN-1 in agricultural fields. [ABSTRACT FROM AUTHOR]

Bacillus subtilis HJX1 , a bioeontrol strain of Fusarium oxysporum f. sp. cubense, could inhibit growth of several plant pathogenic fungi in vitro. To understand its mechanism of fungistasis, we extracted crude protein from fermentation broth of the strain HJX1 through ammonium sulfate precipitation, and preliminarily studied fungistatic activities at different conditions. Tin; results showed that the crude protein was insensitive to protease K, trypsin or ultraviolet radiation. The fungistatic activity was unchanged when treated in water batch at 40 °C, 60 °C , 80 °C or 100 °C for 30 min, and the fungistatic activity maintained 60% when treated at 121 °C for 30 min. [ABSTRACT FROM AUTHOR]