Anthracnose of Onion (Allium cepa L.): A Twister Disease.

The onion (Allium cepa L.) is a lucrative and high-value vegetable-spice crop in India, but it is sensitive to several of diseases caused by fungi, bacteria, viruses, and nematodes, of which a fungal disease, anthracnose, caused by Colletotrichum spp., is a major issue for both onion producers and researchers since it severely affects the bulb production. Twister disease is currently one of the most common problems in onion production, particularly in humid regions, and it reduces productivity while also lowering the value and profitability. Twister disease is visualised by white or pale-yellow water-soaked oval depressed lesions on leaf blades, which are the first symptoms. Lesions expand as the disease advances, and numerous black-coloured, slightly elevated structures/fruiting bodies appear in the middle area, arranged in concentric rings. Curling, twisting, chlorosis of the leaves, and aberrant extension of the neck or pseudo-stem occurs, followed by rotting of the bulb. In an unmanaged crop, an excess gibberellin production by Colletotrichum gloeosporioides and Gibberella moniliformis is suspected to induce twisting and aberrant neck elongation, which will ruin onion productivity. It is difficult and environmentally unfriendly to control these infections. Since, to the best of our knowledge, this is the first review on onion anthracnose, we tried to consolidate information. This review updates our knowledge of the pathogen, including the disease cycle, infection pathways, and disease management techniques. As a result, growers will be benefit from the application of cultural, biological, and chemical measures and the use of resistant varieties.

Surface sterilization for isolation of endophytes: Ensuring what (not) to grow.

Endophytic microbiota opens a magnificent arena of metabolites that served as a potential source of medicines for treating a variety of ailments and having prospective uses in agriculture, food, cosmetics, and many more. There are umpteen reports of endophytes improving the growth and tolerance of plants. In addition, endophytes from lifesaving drug-producing plants such as Taxus, Nothapodytes, Catharanthus, and so forth have the ability to produce host mimicking compounds. To harness these benefits, it is imperative to isolate the true endophytes, not the surface microflora. The foremost step in endophyte isolation is the removal of epiphytic microbes from plant tissues, called as surface sterilization. The success of surface sterilization decides "what to grow" (the endophytes) and "what not to grow" (the epiphytes). It is very crucial to use an appropriate sterilant solution, concentration, and exposure time to ensure thorough surface disinfection with minimal damage to the endophytic diversity. Commonly used surface sterilants include sodium hypochlorite (2%-10%), ethanol (70%-90%), mercuric chloride (0.1%), formaldehyde (40%), and so forth. In addition, the efficiency could further be improved by pretreatment with surfactants such as Triton X-100, Tween 80, and Tween 20. This review comprehensively deals with the various sterilants and sterilization methods for the isolation of endophytic microbes. In addition, the mechanisms and rationale behind using specific surface sterilants have also been elaborated at length.