<div>Background: Pigeonpea [Cajanus cajan (L.) Millsp.], an important grain legume crop that is predominantly cultivated in tropical and sub-tropical regions of the world (Nene and Sheila, 1990). &nbsp;Crop wild relatives (CWR) are valuable source of novel alleles for economic traits which when transferred to cultivated species adapt well to changing biotic stresses, farming practices, market demands and climatic conditions. Under proposed study the detailed symptomatology, cultural, morphological and pathogenic characteristics of the causal agent and molecular identification of the pathogen were identified. 
 
Methods: Of the total 79 accession of wild relatives of pigeonpea (Cjanus cajan) planted in the experimental fields of ICAR- Indian Institute of Pulses Research (IIPR), Kanpur during 2017-18, one accession (ICP-817) of Rhynchosia bracteata was found to be affected by a disease characterized by leaf and stem blight symptoms. Disease symptoms appeared in January&ndash;February, 2017 and 2018. Presence of water soaked lesions on the leaves and stem which later turned chalky in appearance, cottony white mycelium on the affected plant parts along with black coloured irregularly circular sclerotia resembled those of white mold fungus Sclerotinia sclerotiorum (Lib) de Bary were &nbsp;observed. 
 
Result: Pathogenicity of the fungus was proved using detached leaf/twig inoculation techniques. Morphological characters and the sequences of internal transcribed spacer (ITS) region of the fungus confirmed the causal agent of the disease to be Sclerotinia sclerotiorum (Lib) de Bary. This is the first report of the Sclerotinia sclerotiorum on Rhynchosia bracteata not only in India but also in the world. &nbsp;</div>

<div>Identification and Characterization of Sclerotinia sclerotiorum (Lib.) de Bary Associated with Rhynchosia bracteata Benth. Ex Bak. of Wild Derivatives of Pigeonpea from India</div>

Background: The germination of pollen and the growth of pollen tubes are preconditions for fertilization and seed development. A complete knowledge of pollen viability will help in a proper understanding of pollination and fertilization in plants. Pollen from different cultivated and wild species of Cajanus were used to study the influence of different medium components on Cajanus pollen germination. This study established a reliable medium for pollen germination in Cajanus cajan by modifying the Brewbacker and Kwack (BK) medium to enhance understanding of pollination and fertilization dynamics. 
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Methods: The in vitro pollen germination studies were carried out in Pre-breeding department at the International Crops Research Institute for the Semi-Arid Tropics, Hyderabad, India. We developed 108 distinct media formulations by systematically varying concentrations of key constituents: sucrose (10%, 30%, 40%), boric acid (0, 100, 250 ppm), calcium nitrate (100, 300 ppm), magnesium sulfate (100, 200, 300 ppm), potassium nitrate (100 ppm) and polyethylene glycol 6000 (15%). 
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Result: Optimal results were achieved with medium G, which contained 30% sucrose, 100 mg/l boric acid, 100 mg/l calcium nitrate, 100 mg/l potassium nitrate, 100 mg/l magnesium sulfate and 15% PEG, yielding 69.5% pollen germination. When tested on wild relatives (Rhynchosia bracteata, Cajanus platycarpus and Cajanus scarabaeoides), this optimized medium demonstrated over 70% germination efficiency with robust pollen tube development. The improved medium shows promise for facilitating inter-specific and inter-generic hybridization where biological barriers exist, potentially enabling in vitro pollination/fertilization approaches to introgress valuable traits for pigeonpea variety development. 
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Identification and Characterization of Sclerotinia sclerotiorum (Lib.) de Bary Associated with Rhynchosia bracteata Benth. Ex Bak. of Wild Derivatives of Pigeonpea from India

Optimization and Development of Pollen Germination Medium for Cultivated and Wild Cajanus Pollen in vitro