Au-courant and novel technologies for efficient doubled haploid development in barley (Hordeum vulgare L.).

Bounteous modern and innovative biotechnological tools have resulted in progressive development in the barley breeding program. Doubled haploids developed (homozygous lines) in a single generation is significant. Since the first discovery of haploid plants in 1920 and, in particular, after discovering in vitro androgenesis in 1964 by Guha and Maheshwari, the doubled haploidy techniques have been progressively developed and constantly improved. It has shortened the cultivar development time and has been extensively used in: genetic studies, gene mapping, marker/trait association, and QTL studies. In barley, the haploid occurrence developed gradually from being a sporadic and random process (spontaneous) to haploid development by in vivo method of modified pollination or by in vitro culture of immature male or female gametophytes. Although significant improvement in DH induction protocols has been made, challenges still exist for improvement in areas such as: low efficiency, albinism, genotypic specificity etc. Here, the paper focuses on: haploidization via different in vitro, in vivo techniques, the recent advances technologies like centromere-mediated haploidization, hap induction gene, and Doubled haploid CRISPR. The au-courant work of different researchers in barley using these technologies is reviewed. Studies on different factors affecting haploid induction and work on genome doubling of barley haploids to produce DH lines via spontaneous and induced technologies has also been highlighted.

Genome Wide Association Mapping of Seedling and Adult Plant Resistance to Barley Stripe Rust (Puccinia striiformis f. sp. hordei) in India.

Barley stripe rust is caused by Puccinia striiformis f.sp. hordei, (Psh), occurs worldwide, and is a major disease in South Asia. The aim of this work was to identify and estimate effects of loci underlying quantitative resistance to rust at seedling and adult plant stages. HI-AM panel of 261 barley genotypes consisting of released cultivars from North and South America, Europe, Australia, advanced breeding lines, and local landraces from ICARDA barley program were screened at seedling and adult plant stages for resistance to Psh. Seedling resistance was evaluated with the five prevalent Psh races in India. Screening for the adult plant stage resistance was also performed in two different locations by inoculating with a mixture of the five races used for seedling screeing. The panel was genotyped using DaRT-Seq high-throughput genotyping platform. The genome-wide association mapping (GWAM) showed a total of 45 QTL located across the seven barley chromosomes for seedling resistance to the five races and 18 QTL for adult plant stage resistance. Common QTL for different races at seedling stage were found on all chromosomes except on chromosome 1H. Four common QTL associated with seedling and adult plant stage resistance were found on chromosomes 2, 5, and 6H. Moreover, one of the QTL located on the long arm of chromosome 5H showed stable effects across environments for adult plant stage resistance. Several QTL identified in this study were also reported before in bi-parental and association mapping populations studies validating current GWAM. However 15 new QTL were found at adult plant stage on all chromosomes except the 4H, explaining up to 36.79% of the variance. The promising QTL detected at both stages, once validated, can be used for MAS in Psh resistance breeding program globally.