Search

Anther and microspore culture for producing haploid plants are very complex systems and include general effects where the specific effects must be identified and optimized to develop culture systems capable of producing the large numbers of haploids required by breeding programs. These general effects include genotype, physiological state of the source plant, age of the anthers and microspores, preculture treatments, culture conditions, and culture media. Design of experiments (DoE) is an experimental approach specifically designed to identify and optimize the multiple factors that make up complex systems, and is ideally suited for developing in vitro systems to produce haploids. The basic DoE strategy starts by screening multiple factors thought to affect the responses being measured. Screening identifies factors with large and small effects. Factors with large effects are used to manipulate the system, and are moved to the DoE optimization phase such as response surface methodology. Factors with small or trivial effects are eliminated from further consideration, and this simplifies the system. The basic concepts of fractional factorial designs and how to use them are explained. Fractional factorials are the most important DoE screening tool and are the first experiments run before DoE optimization experiments. To illustrate the unique properties of fractional factorials, a detailed example is provided that includes all of the calculations so that no statistical software is required., (© 2021. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is the most serious insect pest of corn (Zea mays L.) in the United States and parts of Europe, and arguably one of the world’s most expensive pests to control. Several diet formulations are currently used by industry and public researchers to evaluate WCR larvae in diet-toxicity bioassays. However, a publicly available diet that produces normative insects that are physiologically similar to WCR larvae reared on corn roots will accelerate development of management technologies. We report a new diet formulation that supports improved weight gain, larval development and survival compared with the only public diet for WCR that is currently available in the refereed literature. The formulation was created by using response surface methods combined with n-dimensional mixture designs to identify and improve the formulation of key ingredients. Weight gain increased two-fold, and survival and molting rates increased from 93% and 90%, respectively when reared on the public diet, to approximately 99% for both survival and molting at 11 days when reared on our new formulation. This new formulation provides a standardized growth medium for WCR larvae that will facilitate comparison of research results from various working groups and compliance with regulatory requirements. [ABSTRACT FROM AUTHOR]

Abnormal physiological responses of plant cultures such as shoot tip necrosis, callus, and hyperhydricity are some of the most difficult challenges in shoot micropropagation, and their causes are not well understood. Five Murashige and Skoog mineral salt factors, which influence the growth of pear shoot cultures, were tested in a five-dimensional surface response experimental design. Pyrus communis ‘Old Home × Farmingdale 87,’ ‘Horner 51,’ and ‘Winter Nelis’; Pyrus dimorphophylla; and Pyrus ussuriensis ‘Hang Pa Li’ shoot cultures were grown on 43 computer-designed treatments to represent the design space of all possible treatment combinations. Analysis of shoot response to these treatments identified the factors that both contributed to physiological disorders and remedied them. Undesirable callus formation was common for pear shoots cultured on standard medium and decreased on formulations with increased NH 4NO 3, Fe, and mesos (CaCl 2, KH 2PO 4, and MgSO 4) for most genotypes. Shoot tip necrosis varied with the genotype, but low mesos or low nitrogen concentrations contributed to the necrosis. Hyperhydricity was more prominent with low mesos or low NH 4NO 3. Hooked and upwardly curled new leaves were seen in most genotypes and resulted from use of low mesos in P. communis and low nitrogen for ‘Hang Pa Li’ and P. dimorphophylla. Fasciation and hypertrophy were seen infrequently and resulted from wide imbalances in several nutrients simultaneously. In general, standard concentrations of Murashige and Skoog iron and micros combined with high mesos and moderate nitrogen compounds produced normal shoots without physiological disorders. [ABSTRACT FROM AUTHOR]

Abnormal physiological responses of plant cultures such as shoot tip necrosis, callus, and hyperhydricity are some of the most difficult challenges in shoot micropropagation, and their causes are not well understood. Five Murashige and Skoog mineral salt factors, which influence the growth of pear shoot cultures, were tested in a five-dimensional surface response experimental design. Pyrus communis ‘Old Home × Farmingdale 87,’ ‘Horner 51,’ and ‘Winter Nelis’; Pyrus dimorphophylla; and Pyrus ussuriensis ‘Hang Pa Li’ shoot cultures were grown on 43 computer-designed treatments to represent the design space of all possible treatment combinations. Analysis of shoot response to these treatments identified the factors that both contributed to physiological disorders and remedied them. Undesirable callus formation was common for pear shoots cultured on standard medium and decreased on formulations with increased NH 4NO 3, Fe, and mesos (CaCl 2, KH 2PO 4, and MgSO 4) for most genotypes. Shoot tip necrosis varied with the genotype, but low mesos or low nitrogen concentrations contributed to the necrosis. Hyperhydricity was more prominent with low mesos or low NH 4NO 3. Hooked and upwardly curled new leaves were seen in most genotypes and resulted from use of low mesos in P. communis and low nitrogen for ‘Hang Pa Li’ and P. dimorphophylla. Fasciation and hypertrophy were seen infrequently and resulted from wide imbalances in several nutrients simultaneously. In general, standard concentrations of Murashige and Skoog iron and micros combined with high mesos and moderate nitrogen compounds produced normal shoots without physiological disorders. [ABSTRACT FROM AUTHOR]