Marker‐assisted backcross breeding to combine multiple rust resistance in wheat

A widely grown but rust susceptible Indian wheat variety HD2932 was improved for multiple rust resistance by marker‐assisted transfer of genes Lr19, Sr26 and Yr10. Foreground and background selection processes were practised to transfer targeted genes with the recovery of the genome of HD2932. The near‐isogenic lines (NILs) of HD2932 carrying Lr19, Sr26 and Yr10 were individually produced from two backcrosses with recurrent parent HD2932. Marker‐assisted background selection of NILs with 94.38–98.46% of the HD2932 genome facilitated rapid recovery of NILs carrying Lr19, Sr26 and Yr10. In the BC₂F₂ generation, NILs were intercrossed and two gene combinations of Lr19+Yr10, Sr26 + Yr10 and Lr19+Sr26 were produced. A total of 16 progeny of two gene combinations of homozygous NILs of HD2932 have been produced, which are under seed increase for facilitating the replacement of the susceptible HD2932 with three of the sixteen improved backcross lines with resistance to multiple rusts.     

Herbal drugs: Standards and regulation

The use of herbal drugs for the prevention and treatment of various health ailments has been in practice from time immemorial. Generally it is believed that the risk associated with herbal drugs is very less, but reports on serious reactions are indicating to the need for development of effective marker systems for isolation and identification of the individual components. Standards for herbal drugs are being developed worldwide but as yet there is no common consensus as to how these should be adopted. Standardization, stability and quality control for herbal drugs are feasible, but difficult to accomplish. Further, the regulation of these drugs is not uniform across countries. There are variations in the methods used across medicine systems and countries in achieving stability and quality control. The present study attempts to identify the evolution of technical standards in manufacturing and the regulatory guideline development for commercialization of herbal drugs.     

Recent developments in genome editing and applications in plant breeding

Increasing genetic variation beyond natural variation is an important aim in plant breeding. In the past 70 years, random mutagenesis by irradiation or by chemicals has created numerous mutants which have been frequently used in breeding. However, their application is hampered by the mutational load due to many background mutations. In the past 10 years, new techniques for site‐directed mutagenesis have been introduced to plant breeding which are commonly referred to as “genome editing.” Among these, the CRISPR/Cas9 system turned out to be the most efficient and easy to apply. DNA is cleaved by a nuclease precisely at a target site where a mutation is likely to be beneficial. The DNA is healed by the cellular repair system either by error‐prone non‐homologous end joining or by homologous recombination, by which small DNA fragments can be inserted at the target site. In this review, we describe the application of targeted mutagenesis to crop plants and the modification of agronomically important traits, which could have direct impacts on plant breeding.     

Combination of different marine algal extracts as biostimulant and biofungicide

This study investigates the efficiency of seaweed liquid fertilizer (SLF) prepared from combinations of different seaweeds (Sargassum polyphyllum, Turbinaria ornata, Gelidiopsis sp., Padina tetrastomatica, Gracilaria corticata) as a stimulant for the growth of Vigna radiata (Mung) as well as its antagonistic activity against fungal pathogens (Alternaria solani, Rhizoctonia solani., Sarocladium oryzae). 100% SLF was prepared, which was further diluted to 60%, 40%, and 20%. Seeds were soaked in four different concentrations of the SLF (20%, 40%, 60%, and 100%) for 12 hr and planted. After 60 d, the root and shoot length were increased by 14% and 16%, respectively, with SLF (100%). The carbohydrate and protein concentrations were also increased by 70% and 86%, respectively, at 100% SLF. The concentration of chlorophyll a, chlorophyll b, and carotenoids were found to be increased by 20%, 43%, and 28%, respectively, with 100% SLF. Further, the SLF (60% and 100%) successfully inhibited the growth of fungal pathogen A. solani but the other tested strains were found to be resistant. The present study indicates that 100% SLF concentration acts as both biostimulant and biofungicide for A. solani and thus, this SLF could be used as a potential alternative to the chemical fertilizers.     

Molecular characterization of <Emphasis Type="Italic">Triticum militinae</Emphasis> derived introgression lines carrying leaf rust resistance

Triticum militinae Zhuk. et Migusch. belongs to timopheevii [Triticum timopheevii (Zhuk.) Zhuk.] group of wheats with 2n = 4x = 28 chromosomes and genome formula A^tA^tGG. Triticum militinae Zhuk. et Migusch. is known to carry resistance to fungal diseases including rusts and powdery mildew. Genes from timopheevii wheat can be incorporated into cultivated wheat by either direct hybridization or through development of amphiploids. Three T. militinae derived introgression lines (ILs) Triticum Militinae Derivative (TMD) 6-4, TMD7-5 and TMD11-5 were selected for the current study based on cytological stability. All three ILs showed resistance against wide spectrum of Indian pathotypes of leaf rust. More than 1200 SSR markers were used for genotyping of ILs and parental lines. The ILs showed variable and multiple introgressions in different chromosomes of A, B and D genome of wheat. The introgression points were distributed mostly in the distal regions though significant introgressions were also observed in proximal regions of some chromosomes. The extent of introgression in ILs TMD6-4, TMD7-5 and TMD11-5 was 2.8, 8.3 and 8.6% respectively. The set of ‘informative markers’ in the Molecularly Tagged Chromosome Regions (MTCR) of T. militinae origin can also be used in future for tagging of genes associated with traits of economic importance apart from leaf rust resistance. The transferability of Triticum aestivum L. SSR markers to T. militinae was 96.4% for A genome, 95.8% for B genome and 84.3% for D genome. Transferability of wheat SSR markers to T. militinae can be used in preparing genetic maps in timopheevii group of wheats.