Efficacy of Plant Extracts on Morphology and Cultural Characteristics of Bipolaris sorokiniana, Causing Black Point Disease of Wheat in Bangladesh

Black point of wheat caused by Bipolaris sorokiniana (Bs) is very destructive disease of wheat in Bangladesh and all over the world. The symptoms of diseases caused by Bipolaris sorokiniana can vary depending on the host plant and environmental conditions. The conidia of Bs germinate from two poles, which differ physiologically as indicated by the rate, growth character, of length, breadth and number of septa on different media. The aim of this study was to evaluate the efficacy of selected plant extracts on the morphology and cultural characteristics of the fungus Bipolaris sorokiniana causing black point disease in wheat crops in Bangladesh. The efficacy of fifteen plant extracts on the growth and characteristics of Bs was conducted in vitro in 2019-2020. The treatments were: Untreated control, T1—Black berry Leaves, T2—Guava Leaves, T3—Lantena camera leaves, T4—Eucalyptus Leaves, T5— Turmeric Leaves, T6—Khoksha Leaves, T7—Papaya leaves, T8-Gurlic Bulb, T9—Chili dust, T10—Nigella seeds, T11—Turmeric dust, T12—Cloves, T13— Bohera fruits, T14—Black pepper and T15—Neem leaves. After 15 days of inoculation of Bipolaris sorokiniana, colony color and shapes were Gerrish blackish, greenish blackish, greyish blackish and shapes were round or irregular. In our study, conidia color was dark brown to light brown, conidiophore color was brown, dark brown, grayish brown, dark olivaceous, light brown and conidia shapes were elliptical, oblong or slightly curved. The septation of conidia was 2 - 5 and highest septation was seen in T4 and T14 treatments. The highest conidial length was 17.79 μm recorded in T2 treatment and lowest was 6.62 μm T9 treatment where conidial breath was 8.27 μm in control and lowest was 3.79 μm in T8 treatment. Mycelial growth rate of Bipolaris sorokiniana was different in different treatments in different days after inoculation (DAI) where at 7 DAI, % reduction of mycelial growth over control was highest in Bohera and Neem Leaves treatments respectively.

Screening and Identification of Biocontrol Strains against Bipolaris sorokiniana

Bipolaris sorokiniana is an important disease causing wheat root rot. Different biocontrol strains were screened with the pathogen as the target. A total of 210 strains of bacteria and fungi preserved in the laboratory were preliminarily and secondarily screened by plate confrontation culture. The 17 strains of bacteria and 36 strains of fungi with good bicontrol effect were screened. Eventually, the best fungal strain and the best bacterial strain were obtained. The ITS fragments of fungi were amplified by PCR, and the target band of 571 bp was obtained. The 16 S gene frag-ments of bacteria were amplified by PCR, and the target band of 1 455 bp was obtained. Through morphological observation, the screened strains were identified. Finally, the bicontrol fungus was confirmed as Trichoderma asperellum and the bacterium was Bacillus amylofaciens.

Transgenic expression of TaTLP1, a thaumatin-like protein gene, reduces susceptibility to common root rot and leaf rust in wheat

Thaumatin-like protein (TLP) plays an important role in combating plant pathogen infection.Common root rot caused by Bipolaris sorokiniana and leaf rust caused by Puccinia triticina (Pt) are major fungal diseases in wheat.The disease responses of TaTLP1-overexpressing transgenic lines (TaTLP1-OE) were evaluated after inoculation with each pathogen.The TaTLP1-OE lines had no apparent differences in tiller number and 1000-kernel weight from the wild type Jinan Wheat No.1 (JW1),whereas resistance to leaf rust and common root rot was improved,resulting from activated peroxidase and b-1,3-glucanase after B.sorokiniana infection,and reactive oxygen species-related genes were upregulated in Ta TLP1-OE lines after Pt infection.These results indicated that stable expression of TaTLP1 increased resistance against both diseases.