A fungal Bipolaris bicolor strain as a potential bioherbicide for goosegrass (Eleusine indica) control

Abstract

BACKGROUND: Tea, one of the most important commercial crops on earth, is strongly affected by weeds on productivity and quality. Bioherbicides are shedding new light on weed control in tea gardens in an economical and safe manner.RESULTS: A pathogenic strain SYNJC-2-2 was isolated from diseased leaves of a noxious weed, goosegrass (Eleusine indica), from a tea garden in Zhejiang Province, China. It was identified as the fungal species Bipolaris bicolor based on the morphological characteristics and phylogenetic analysis. The potential of the B. bicolor strain SYNJC-2-2 as a bioherbicide was assessed by determining its efficacy to control weeds and selectivity to crops, its infection process and the influence of environmental conditions on conidial production and germination. The ED 90 (effective dose of conidia resulting in 90 disease index) of SYNJC-2-2 on goosegrass was 2 × 10 4 conidia mL −1 . Additionally, three Poaceae weeds, Setaria viridis, Microstegium vimineum and Pennisetum alopecuroides, were also extremely susceptible to SYNJC-2-2. SYNJC-2-2 was safe to 14 out of 17 crop species in nine families, especially tea plants. Conidial germination, hyphal growth and appressorial formation occurred within 3 to 6 h on goosegrass leaves. Hyphae invaded leaf tissues mainly through epidermal cell junctions and cracks, causing cell death and necrotic lesions within 2 days on inoculated leaves and killing goosegrass plants within 7 days. Furthermore, SYNJC-2-2 has a strong adaptability to environmental variables and high conidial production capacity on goosegrass juice agar media.CONCLUSION: Bipolaris bicolor strain SYNJC-2-2 has the potential to be developed as a bioherbicide for controlling goosegrass, especially in tea gardens.

Understanding the environmental and herbicide response of Lasiodiplodia theobromae and Bipolaris bicolor isolated from infected Eleusine indica

“…Any increase in acidity or alkalinity had no effect on the germination rate of B. bicolor conidia, which constantly had a rate of 30 to 32% (Figure 1b). In contrast to present findings, Xiao et al (2021) reported that the optimum pH for conidial germination of B. bicolor was 7 whereas high acidity and alkalify at pH 4 and pH 10, respectively could reduce the conidial germination rate substantially…”

“…The present findings on the optimal temperature, pH and photoperiod for conidial germination of B. bicolor do not align with the results of Xiao et al (2021). These discrepancies could be attributable to diverse geographic regions, potentially reflecting adaptation of the fungal pathogen (Kumar et al, 2010).…”

“…On the other hand, B. bicolor's conidial germination rate could be reduced by 24 hours of darkness. Unlike B. bicolor isolates from Malaysia, conidia of B. bicolor from China exhibited the highest germination at fluorescent light (Xiao et al, 2021). Moreover, L. theobromae exhibited 75 to 85% conidial germination rate either at alternating photoperiod or complete darkness.…”

Opportunities for Microbiome Suppression of Weeds Using Regenerative Agricultural Technologies

“…A Bipolaris bicolor strain was isolated from severely diseased leaves of goosegrass (Eleusine indica) in a tea plantation system. Further tests on pathogenicity and host range demonstrated the potential of this strain as a biocontrol agent against Poaceae weeds in tea and broadleaf vegetable production (40). The initial field collection of 10 candidate isolates was obtained from 16 tea plantations through a time-consuming process.…”

Establishment of an Efficient Agrobacterium-Mediated Genetic Transformation System to Enhance the Tolerance of the Paraquat Stress in Engineering Goosegrass (Eleusine Indica L.)

“…Goosegrass ( Eleusine indica L. Gaertn) is one of the top 10 herbicide-resistant weed species distributed throughout the world [ 8 , 9 ]. Although multiple resistances to paraquat, glufosinate, and glyphosate in goosegrass have been reported, the underlying molecular mechanism of herbicide stress responses remains unclear [ 10 , 11 ].…”