The Quarantine Disease Sugarcane Leaf Scald Found in Xinping Sugarcane Area in Yunnan Province

[Objectives]This study was conducted to clarify the pathogens causing suspected sugarcane leaf scald symptoms in sugarcane plants found in the Xinping sugarcane area of Yunnan in 2019.[Methods]The XAF1/XAR1 specific primers of Xanthomonas albilineans were used to detect 8 suspected samples from Xinping County,Yunnan Province.[Results]The specific band 600 bp in size was detected.The sequencing results showed that the sequences detected were all 608 bp,and were 100%identical.The BLAST search results showed that the obtained sequence was 100%identical to the nucleotide sequence of X.albilineans GPE PC73 strain(GenBank accession number:FP565176)from France,and they were located in the same branch of the phylogenetic tree.According to the field symptom diagnosis and molecular identification results,the sugarcane disease in Xinping,Yunnan was confirmed to be the quarantine disease sugarcane leaf scald caused by X.allbilineasn.[Conclusions]The pathogens were identified by molecular biological identification methods,providing a scientific basis for the prevention and control of leaf scald disease in the future.

Establishment and Application of Identification Methods for Resistance to Sugarcane White Leaf Disease(SCWL)

[Objectives]This study was conducted to establish simple, efficient, stable, standardized and practical identification methods for sugarcane resistance to white leaf disease(SCWL), and promote the breeding for sugarcane resistance to SCWL. [Methods]The identification technology of sugarcane resistance to SCWL was systematically studied and explored from the aspects of sugarcane material treatment and planting, inoculation liquid preparation, inoculation method, disease investigation, grading standard formulation, etc., and two sets of simple, efficient, stable, standardized and practical accurate identification methods for sugarcane resistance to SCWL were created for the first time, namely, the seed cane coating inoculation method and the stem-cutting inoculation method at the growth stage. The seed cane coating inoculation method includes the steps of directly screening SCWL phytoplasma, extracting juice from cane and adding 10 times of sterile water to prepare an inoculation liquid, spraying seed cane on plastic film to keep moisture, planting the inoculated materials in barrels in an insect-proof greenhouse for cultivation, investigating the incidence rate 30 d after inoculation, and evaluating the disease resistance according to the 1-5 level standard. The method of stem-cutting inoculation includes the steps of directly screening sugarcane stems carrying SCWL phytoplasma and adding 10 times of sterile water to prepare an inoculation liquid, cultivating the identification materials in an insect-proof greenhouse, dropping 100 μl of the inoculation liquid into each root incision with a pipette gun at the age of 6 months, investigating the incidence rate 20 d after planting, and evaluating the disease resistance according to the 1-5 level standard. [Results] The two methods are similar to the natural transmission method. After inoculation, SCML occurred significantly, with high sensitivity and good reproducibility. The results of resistance identification were consistent with those of natural disease in the field. Through the two inoculation methods and field natural disease investigation, the resistance of 10 main cultivars to SCML was identified, which was true and reliable. [Conclusions] This study can provide standard varieties for identification of SCML resistance in the future.