In sunflower, several reports exist in the mapping of resistance genes for important diseases like downy mildew (Vear et al. 2006 Christov 2008) or displayed irregular disease frequency distribution. All these studies were based on either a low number of individuals in the population (Jan and Chandler 1988 Rojas-Barros et al. Similarly, the existence of both single and polygenic inheritance was reported by Naggayya ( 2013). In one type, the inheritance was controlled by a single dominant gene, whereas in the other, it was polygenic. Christov ( 2008) reported the existence of two types of inheritance in wild Helianthus species. Two genes controlling inheritance were proposed by Rojas-Barros et al. Jan and Chandler ( 1988) reported the contribution of a partially dominant gene for resistance. 2015).Ī few studies reported the inheritance of resistance to powdery mildew in sunflower. 1991), and 30–74% in India depending on the disease severity (Dinesh et al. The disease is reported to cause yield losses up to 13% in Mexico (Diaz-Franco 1980), 25% in USA between 19 (Gulya et al. Powdery mildews have a worldwide distribution, but higher intensity on sunflower is reported in the tropical regions (Zimmer and Hoes 1978 Diaz-Franco 1980 Gulya et al. During the last decade, powdery mildew has emerged as a severe problem and has spread rapidly to all sunflower cultivation regions in India (Reddy et al. orontii has been reported to cause powdery mildew disease in the tropical and subtropical regions. The changing disease scenario has become a constant challenge to the breeders and crop protection researchers for the deployment of suitable management strategies. The changing climatic conditions and increased incidence of diseases like powdery mildew, Alternaria leaf spot, and SND had drastically reduced the sunflower area under cultivation and production in India. In India, the major diseases prevalent in sunflower growing areas are SND, Alternariaster leaf spot, powdery mildew, and downy mildew (Basappa and Santhalakshmi Prasad 2005 Reddy et al.
Heluta), and Phomopsis ( Phomopsis helianthi Munt.-Cvetk., Mihaljc. 2001), sunflower necrosis (SND) (Bhat and Reddy 2016), Alternaria leaf spot (Carson 1985), powdery mildew ( Golovinomyces orontii (Castagne) V.P.
2013), rust ( Puccinia helianthi Schwein.) (Shtienberg and Zohar 1992), chlorotic mottle virus (SuCMoV) (Lenardon et al. The important diseases that cause significant yield losses in sunflower are downy mildew, Sclerotinia sclerotiorum (Lib.) de Bary (Gulya et al.
The major constraint for profitable production of sunflower across the globe including India is the vulnerability of the improved cultivars to biotic and abiotic stresses throughout the crop growth stages. Sunflower is one of the major sources of vegetable oil in the world with an area of 26.66 million hectares and production of 51.95 million tons. This is the first report on mapping of powdery mildew resistance in sunflower and paves the way in fine mapping and introgression of resistance for powdery mildew in sunflower through marker-assisted breeding. Quantitative trait loci (QTL) analysis identified three genomic regions for resistance to powdery mildew, two of which mapped on chromosome 10 and one on chromosome 5. The map spanned 1200 cM and included 64 markers distributed along the 17 sunflower chromosomes in the haploid set. Based on the phenotyping and genotyping data, the linkage map was constructed with 93 RILs. Screening of the two population sets was done with 484 sunflower-specific SSR primers of which 175 primers showed polymorphism between the parents. The inheritance was observed as a continuous distribution in a set of 264 F 2 population and 93 recombinant inbred lines (RILs) of a cross between a highly susceptible accession PS 2023 and TX16R. The present investigation has been undertaken to study the inheritance of powdery mildew resistance and to map the quantitative trait loci (QTLs) governing resistance to powdery mildew in a multiple disease resistance line, TX16R (PI 642072). Sources of resistance to powdery mildew incited by Golovinomyces orontii have been identified in wild sunflowers and few exotic lines.