Millet Could Be both a Weed and Serve as a Virus Reservoir in Crop Fields.

György Pasztor,Erzsebet Nadasy,Zsuzsanna Galbacs N,Andras P Takacs,Emese Demian,Eva Varallyay,Tamas Kossuth

doi:10.3390/plants9080954

György Pasztor, Erzsebet Nadasy + Show 5 more

Open Access

https://doi.org/10.3390/plants9080954

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Abstract

Millet is a dangerous weed in crop fields. A lack of seed dormancy helps it to spread easily and be present in maize, wheat, and other crop fields. Our previous report revealed the possibility that millet can also play a role as a virus reservoir. In that study, we focused on visual symptoms and detected the presence of several viruses in millet using serological methods, which can only detect the presence of the investigated pathogen. In this current work, we used small RNA high-throughput sequencing as an unbiased virus diagnostic method to uncover presenting viruses in randomly sampled millet grown as a volunteer weed in two maize fields, showing stunting, chlorosis, and striped leaves. Our results confirmed the widespread presence of wheat streak mosaic virus at both locations. Moreover, barley yellow striate mosaic virus and barley virus G, neither of which had been previously described in Hungary, were also identified. As these viruses can cause severe diseases in wheat and other cereals, their presence in a weed implies a potential infection risk. Our study indicates that the presence of millet in fields requires special control to prevent the emergence of new viral diseases in crop fields.

Highlights

Millet is used to feed animals and is a popular alternative cereal
Our pilot study shows that small RNA (sRNA) High-throughput sequencing (HTS) can reveal new insights of investigated plants and lead to the description of viruses, Barley yellow striate mosaic virus (BYSMV) and BGV in our case, even if they have not been previously described or are not anticipated at the surveyed location
We found a high infection rate with wheat streak mosaic virus (WSMV) supporting the hypothesis of Schubert and colleagues that viruses can establish themselves in seed production areas and survive on perennial grasses growing at field boundaries [38]

Summary

Introduction

Millet is used to feed animals and is a popular alternative cereal. As an outcome of recent intensification of crop production, it has become a dangerous weed, controlled only with difficulty. Herbicides, based on chloraminothiazine, efficiently repress the growth of dicotyledonous weeds in crop fields and leave monocotyledonous millet without a competitor [1,2,3,4]. Only one of its species, Panicum miliaceum subsp. Miliaceum, is cultivated, but nearly 50 other species are listed as weeds. The results of a recent national weed survey in Hungary revealed that P. miliaceum was the seventh-most prevalent weed, representing 1.44% of the weeds present in the investigated fields. The presence of other Panicum species (P. capillare, P. ruderale, and P. dichotomiflorum) was detected [5]. The germination of maize and millet occurs at the same time, but, with a better transpiration coefficient, lower moisture demand, and an ability to successfully compete for macronutrients, millet overtakes maize in a monoculture and causes substantial damage and yield loss [5,6,7,8,9,10]

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