SUMMARY: Charcoal rot, caused by Macrophomina phaseolina, is the most prevalent and important disease of crop plants such as sunflower. Although it is monotypic and no physiological races have been reported, it has high genetic variability resulting in a wide host range, which in turn means that crop rotation is not an effective strategy to combat the disease. The current paper reviews the adverse effects of this disease and summarizes the present state of knowledge about charcoal rot severity and its impact on crop production.

Chenopodium quinoa manifests adaptability to grow under varying agro-climatic scenarios. Assessing quinoa germplasm’s phenotypic and genetic variability is a prerequisite for introducing it as a potential candidate in cropping systems. Adaptability is the basic outcome of ecological genomics of crop plants. Adaptive variation predicted with a genome-wide association study provides a valuable basis for marker-assisted breeding. Hence, a panel of 72 quinoa plants was phenotyped for agro morphological attributes and association-mapping for distinct imperative agronomic traits. Inter simple sequence repeat (ISSR) markers were employed to assess genetic relatedness and population structure. Heatmap analysis showed three genotypes were early maturing, and six genotypes were attributed for highest yield. The SD-121-07 exhibited highest yield per plant possessing green, glomerulate shaped, compact density panicle with less leaves. However, SJrecm-03 yielded less exhibiting pink, intermediate shape, intermediate density panicles with less leaves. The phenotyping revealed strong correlation of panicle architecture with yield in quinoa. A genome-wide association study unraveled the associations between ISSR makers and agro-morphological traits. Mixed linear modes analysis yielded nine markers associated with eight traits at p ≤ 0.01. Moreover, ISSR markers significantly associated with panicle shape and leafiness were also associated with yield per plant. These findings contribute to the provision of authenticity for marker-assisted selection that ultimately would support quinoa breeding programs.

Microsatellites are simple sequence repeats (SSR) of 1-6 nucleotides. They appear to be ubiquitous in higher organisms, both in animal and plant genomes and involving repetitive as well as unique sequences, although the frequency of microsatellites varies between species. They are abundant, dispersed throughout the genome and show higher levels of polymorphism than do other genetic markers. These features coupled with their ease of detection have made them useful markers. Their potential for automation and their inheritance in a co-dominant manner are additional advantages when compared with other types of molecular markers. SSRs are highly polymorphic, genome specific, abundant and co-dominant, and have recently become important genetic markers in cereals including wheat and barley. Key words: Simple sequence repeat, allelic diversity, polymorphism, co-dominance, microsatellites, genetic diversity.

A good culture system provides considerable quantities of highly regenerable target tissues. Embryogenic callus cultures are ideal for micro-projectile-mediated transformation, because regenerable cells are not very stable. Effective exploitation of genetic transformation requires good regeneration systems. We selected three sugarcane genotypes for the establishment and optimization of good in vitro regeneration systems, viz., S-2003-us-359, S-2006-sp-30, and S-2003-us-165. Three callus induction media were investigated. These media were composed of Murashige and Skoog (MS) medium salt plus 1, 2, and 3 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D). Medium with 3 mg/L 2,4-D gave the greatest mass of embryogenic calli. The calli produced on the three callus induction media were transferred to 18 types of regeneration media (RM1-RM18). They varied with respect to plant growth regulators and sucrose levels but the basal medium was MS. Two levels of sucrose (30 and 40 g/L), three levels of 2,4-D (0.1, 0.25, 0.5 mg/L) and three levels of 6-benzylaminopurine (0, 0.25 and 0.5 mg/L) were studied in the regeneration media. The effects of callus age on regeneration were evaluated by transferring the calli to regeneration media after 15, 21, 28, and 35 days of culture. The 21-day-old callus of the genotype S-2003-us-359 on RM3 yielded the largest number of plants and was selected as the best for transformation. Six RAPD DNA primers were used to check genetic stability; this medium did not affect the sugarcane genomes.