nan Vinod

Wheat rusts in India: Resistance breeding and gene deployment -A review

This review paper presents the history of rust resistance breeding and deployment of resistant cultivars in different geographical areas of India. Much has been accomplished in controlling the wheat rusts through deploying resistant cultivars carrying diverse resistance genes in India. The genetic diversification in wheat has not only proved critical in developing resistant cultivars but also in the understanding of disease epidemiology and its dynamics and has gradually reduced the magnitude and frequency of epidemics. The gene Lr26 in combination with Lr13, Lr23 and Lr34 and the Agropyron segment carrying Lr24/Sr24 have played a crucial role in providing durable resistnace and protecting wheat from any epidemic threat to stable wheat production. In recent years, wheat has achieved relatively higher production stability as compared to other cereal crops by adopting strategic gene deployment. Only marginal increase in wheat area is recorded but the strategic deployment of rust resistance genes is most protective of crop production and crucial in sustaining the production levels.

Molecular and Morpho-Agronomical Characterization of Root Architecture at Seedling and Reproductive Stages for Drought Tolerance in Wheat.

Water availability is a major limiting factor for wheat (Triticum aestivum L.) production in rain-fed agricultural systems worldwide. Root architecture is important for water and nutrition acquisition for all crops, including wheat. A set of 158 diverse wheat genotypes of Australian (72) and Indian (86) origin were studied for morpho-agronomical traits in field under irrigated and drought stress conditions during 2010–11 and 2011-12.Out of these 31 Indian wheat genotypes comprising 28 hexaploid (Triticum aestivum L.) and 3 tetraploid (T. durum) were characterized for root traits at reproductive stage in polyvinyl chloride (PVC) pipes. Roots of drought tolerant genotypes grew upto137cm (C306) as compared to sensitive one of 63cm with a mean value of 94.8cm. Root architecture traits of four drought tolerant (C306, HW2004, HD2888 and NI5439) and drought sensitive (HD2877, HD2012, HD2851 and MACS2496) genotypes were also observed at 6 and 9 days old seedling stage. The genotypes did not show any significant variation for root traits except for longer coleoptiles and shoot and higher absorptive surface area in drought tolerant genotypes. The visible evaluation of root images using WinRhizo Tron root scanner of drought tolerant genotype HW2004 indicated compact root system with longer depth while drought sensitive genotype HD2877 exhibited higher horizontal root spread and less depth at reproductive stage. Thirty SSR markers were used to study genetic variation which ranged from 0.12 to 0.77 with an average value of 0.57. The genotypes were categorized into three subgroups as highly tolerant, sensitive, moderately sensitive and tolerant as intermediate group based on UPGMA cluster, STRUCTURE and principal coordinate analyses. The genotypic clustering was positively correlated to grouping based on root and morpho-agronomical traits. The genetic variability identified in current study demonstrated these traits can be used to improve drought tolerance and association mapping.

Genetics and mapping of a new leaf rust resistance gene in Triticum aestivum L. × Triticum timopheevii Zhuk. derivative ‘Selection G12’

A Triticum timopheevii-derived bread wheat line, Selection G12, was screened with 40 pathotypes of leaf rust pathogen, Puccinia triticina at seedling stage and with two most commonly prevalent pathotypes 77-5 and 104-2 at adult plant stage. Selection G12 showed resistance at both seedling and adult plant stages. Genetic analysis in F1, F2 and F2:3 families at the seedling stage revealed that leaf rust resistance in Selection G12 is conditioned by a single incompletely dominant gene. The leaf rust resistance gene was mapped to chromosome 3BL with SSR markers Xgwm114 and Xgwm547 flanking the gene at a distance of 28.3 cM and 6 cM, respectively. Based on the nature of resistance and chromosomal location, it is inferred that Selection G12 carries a new gene for leaf rust resistance, tentatively named as LrSelG12.

Central Wheat Hs562'-A High Yielding Wheat Variety for Timely Sown Production Conditions of Northern Hill Zone

Dharam Pal1*, Madhu Patial1, KV Prabhu2, J Kumar1,7, Santosh Watpade1, RN Yadav3, Sanjay Kumar2, RK Sharma2, GP Singh2,8, Rajbir Yadav2, Vinod2, Anju M Singh2, SV Sai Prasad4, IS Solanki6,9, M Sivasamy5, JB Sharma2, PK Singh2, Neelu Jain2, Niharika Mallik2, Kiran Gaikwad2, Tapas Ranjan Das6, Vikas5, Jaya Prakash5, JB Singh2, Divya Ambati4, Vaibhav Singh2, AN Mishra4, Shivadhar2 and Ajay Arora2 1ICAR-IARI, Regional Station, Shimla, India 2ICAR-Indian Agricultural Research Institute, New Delhi, India 3ICAR-Indian Agricultural Research Institute, Regional Station, Karnal, India 4ICAR-Indian Agricultural Research Institute, Regional Station, Indore, India 5ICAR-Indian Agricultural Research Institute, Regional Station,Wellington, India 6ICAR-Indian Agricultural Research Institute, Regional Station,Pusa, India 7ICAR-NIBSM, Raipur, India 8ICAR-Indian Institute of Wheat and Barley Research, Karnal, India 9ICAR-Krishi Bhawan, New Delhi

Cytogenetic analysis and mapping of leaf rust resistance in Aegilops speltoides Tausch derived bread wheat line “Selection 2427” carrying putative gametocidal gene(s)

Leaf rust (Puccinia triticina) is a major biotic stress affecting wheat yields worldwide. Host-plant resistance is the best method for controlling leaf rust. Aegilops speltoides is a good source of resistance against wheat rusts. To date, five Lr genes, Lr28, Lr35, Lr36, Lr47, and Lr51, have been transferred from Ae. speltoides to bread wheat. In Selection2427, a bread wheat introgresed line with Ae. speltoides as the donor parent, a dominant gene for leaf rust resistance was mapped to the long arm of chromosome 3B (LrS2427). None of the Lr genes introgressed from Ae. speltoides have been mapped to chromosome 3B. Since none of the designated seedling leaf rust resistance genes have been located on chromosome 3B, LrS2427 seems to be a novel gene. Selection2427 showed a unique property typical of gametocidal genes, that when crossed to other bread wheat cultivars, the F1 showed partial pollen sterility and poor seed setting, whilst Selection2427 showed reasonable male and female fertility. Accidental co-transfer of gametocidal genes with LrS2427 may have occurred in Selection2427. Though LrS2427 did not show any segregation distortion and assorted independently of putative gametocidal gene(s), its utilization will be difficult due to the selfish behavior of gametocidal genes.