Induced chlorophyll mutations. I. Mutagenic effectiveness and efficiency of EMS, HZ and SA in mungbean

A systematic and comparative study on the frequency and spectrum of chlorophyll mutations induced by ethylmethane sulphonate (EMS) — an alkylating agent, hydrazine hydrate (HZ) — a base analogue and sodium azide (SA) — a respiratory inhibitor, was carried out in two mungbean varieties, namely, PDM-11 and NM-1. Awide spectrum of chlorophyll mutants was obtained in the M₂ generation. All these chlorophyll-deficient mutants were lethal except maculata, viridis and virescent. Chlorina followed by xantha types were predominant in both the varieties. EMS treatments induced the highest frequency of chlorophyll mutations followed by HZ and SA. The frequency of chlorophyll mutations was dose-dependent and increased with the mutagen concentration. Based on effectiveness in both varieties, the order of mutagens was HZ > SA > EMS. Two criteria viz., pollen sterility (Mp/S) and seedling injury (Mp/I) were taken into consideration to determine the efficiency of the mutagens. EMS was found to be the most efficient mutagen followed by HZ and SA. Moderate concentrations of the mutagens were the most effective and efficient in inducing mutations.     

TILLING: an alternative path for crop improvement

Rising global temperatures, changing precipitation patterns, spread of insects and diseases, and slow development of crop varieties acclimatized to new environments have produced a food crisis situation in some developing countries. Although transgenic technologies came to the rescue, they faced numerous hurdles on the journey to reach the farm soil, which has necessitated innovation of out-of-the-box technologies for crop improvement. One such non-transgenic method, which exploits the ever-increasing sequence data and combines it with traditional and modern methods to induce and extract mutants, is Targeting Induced Local Lesions IN Genomes (TILLING). With the success of TILLING in monocots, dicots, autopolyploids, allopolyploids, and triploids, we expect this technique to help develop many mutant crop varieties in the next few decades. We trust this review will be useful for researchers engaged in crop improvement around the globe.     

Soil-Test-Based Balanced Nutrient Management for Sustainable Intensification and Food Security: Case from Indian Semi-arid Tropics

In the semi-arid tropics (SAT), there exists large yield gaps (two- to four-fold) between current farmers’ yields and achievable yields. Apart from water shortages, soil degradation is responsible for the existing gaps and inefficient utilization of whatever scarce water resource is available. On-farm soil fertility testing across different states in Indian SAT during 2001–2012 showed widespread new deficiencies of sulfur (46–96 percent), boron (56–100 percent), and zinc (18–85 percent) in addition to already known phosphorus (21–74 percent) and nitrogen (11–76 percent, derived from soil carbon). Based on these results, a new fertilizer management strategy was designed to meet varying soil fertility needs at the level of a cluster of villages by applying a full nutrient dose if >50 percent fields were deficient and a half dose in the case of fields <50 percent deficient. Improved nutrient management significantly increased crop productivity in groundnut (Arachis hypogaea) (17–86 percent), sorghum (Sorghum bicolor) (30–55 percent), soybean (Glycine max) (10–40 percent), and maize (Zea mays) (10–50 percent) with favorable benefit-cost ratios (1.43–15.2) over farmers’ practice. Nutrient balancing improved nitrogen-fertilizer-use efficiency in respect of plant uptake from soil, transport into grain, use efficiency in food production, and grain nutritional quality. Balanced-nutrient-managed plots showed better postharvest soil fertility. Residual benefits of sulfur, boron, and zinc were observed in up to three succeeding seasons. Results of soil-test-based nutrient-management trials have sensitized policy makers in some states for desired policy orientation to benefit millions of smallholders in the Indian SAT.     

Variability in the yield of benzophenanthridine alkaloids in wildcrafted vs cultivated bloodroot (Sanguinaria canadensis L.)

Populations of bloodroot [Sanguinaria canadensis L. (Papaveraceae)] are found throughout the eastern forests of North America, with particular abundance in the southern Appalachian Mountains. Increasingly, it is finding use in Europe as a nonantibiotic animal feed supplement to promote weight gain. As efforts to cultivate this herb are underway, there is a need to understand the effect of agronomic permutations on both the dry mass rhizome yield and the yield of benzophenanthridine alkaloids. Month-to-month variability of the concentration of the alkaloids sanguinarine and chelerythrine in both cultivated and wildcrafted bloodroot was examined. The alkaloid yield was consistently higher, but more variable, in wildcrafted plants. On average, cultivated rhizomes were both larger and more consistently sized than those that were wildcrafted. The concentration of a suite of trace elements was measured in soil that was collected concomitantly with each plant accession. Differences in element profiles were compared against alkaloid yields.