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Pre-sowing seed treatment with systemic fungicides is a firmly entrenched practice for most agricultural crops worldwide. The treatment is intended to protect the crop against seed- and soil-borne diseases. In recent years, there is increasing evidence that fungicidal applications to manage diseases might inadvertently also affect non-target organisms, such as endophytes. Endophytes are ubiquitously present in plants and contribute to plant growth and development besides offering resistance to biotic and abiotic stresses. In seeds, endophytes may play a role in seed development, seed germination, seedling establishment and crop performance. In this paper, we review the recent literature on non-target effects of fungicidal applications on endophytic fungal community and discuss the possible consequences of indiscriminate seed treatment with systemic fungicide on seed endophytes. It is now well recognized that endophytes are ubiquitously present in all parts of the plant, including the seeds. They may be transmitted vertically from seed to seed as in many grasses and/or acquired horizontally from the soil and the environment. Though the origins and evolution of these organisms in plants are a matter of conjecture, numerous studies have shown that they symbiotically aid in plant growth and development, in nutrient acquisition as well in protecting the plants from abiotic and biotic stresses. Against this background, it is reasonable to assume that the use of systemic fungicides in seed treatment may not only affect the seed endophytes but also their attendant benefits to seedling growth and establishment. While there is evidence to indicate that fungicidal applications to manage plant diseases also affect foliar endophytes, there are only few studies that have documented the effect of seed treatment on seed-borne endophytes. Some of the convincing examples of the latter come from studies on the effect of fungicide application on rye grass seed endophyte AR37. More recently, experiments have shown that removal of seed endophytes by treatment with systemic fungicides leads to significant loss of seedling vigour and that such losses could be partially restored by enriching the seedlings with the lost endophytes. Put together, these studies reinforce the importance of seed endophytes to seedling growth and establishment and draw attention on how to trade the balance between the benefits of seed treatments and the direct and indirect costs incurred due to loss of endophytes. Among several approaches, use of reduced-risk fungicides and identifying fungicide-resistant endophytes are suggested to sustain the endophyte contribution to early seedling growth.

Systemic fungicide seed treatments are routinely used in conventional agriculture to control soil and seed-borne diseases, but little is known about their unintended adverse effects on non-target beneficial fungal endophytes that are known to be involved in plant growth and development. This study evaluated the seed treatment effect of a broad spectrum systemic fungicide, carbendazim (bavistin) on symbiotic association of fungal endophytes in rice and on early seedling growth of rice, green gram, soybean, and cowpea. Seeds were surface sterilized with sodium hypochlorite followed by 0.2% bavistin treatment. Growth of fungal endophytes was significantly affected by the seed treatment with fungicide in rice seedlings, while shoot and root growth was suppressed in all the crops. Quantitative real time PCR showed that the level of expression of two basal transcriptional regulator genes, OsBTF3 and OsNF-YC1 that are required for seed germination and seedling growth significantly decreased in bavistin treated rice seedlings. Re-inoculation of consortia of fungal endophytes onto bavistin treated rice seedlings significantly recovered seedling growth and development. These results suggest that fungicide treatment of seeds affects early seedling growth and has negative impact on beneficial fungal endophytes that are involved in plant growth and development. This study provides information on possible ill effects of fungicide on beneficial fungal endophytes that play key roles in early seedling growth of plants and also open up the prospect to additional research on different crops in vitro and field conditions to determine the consequences of fungicide effects and optimise fungicide application strategies to develop sustainable disease control methods.

Multiple shoot induction in Litchi chinensis Sonn. (litchi) has been achieved by two methods: (1) direct germination of litchi seeds in 6-benzylaminopurine (20 mg l-1)-supplemented MS liquid medium and supported on a filter-paper bridge and (2) in planta treatment with 6-benzylaminopurine (100 microgram on alternate days) of the axillary bud regions of plants germinated and maintained under sterile conditions. While the former method resulted in as many as 27.5 +/- 8.6 shoot buds from the cotyledonary node within 4 weeks, the latter yielded on average approximately 8 shoot buds from each treated node in 8 weeks. The cytokinin treatment in planta consisted of placing sterile filter paper moistened with sterile distilled water over the node and adding different concentrations of 6-benzylaminopurine. Both methods of multiple shoot induction were found to be effective for the five genotypes of litchi that were tested. The shoots elongated and rooted directly in vermiculite after a pulse treatment with IBA (25 mg/ml) for 15 min. Fungus growth which is a serious problem in litchi tissue culture, was controlled using a fungicide, Bavistin, and by eliminating organic nutrients from the growth medium.