Cytoplasmic Male Sterility

One of the most striking examples of cytoplasmic heredity can be regarded as cytoplasmic male sterility (CMS) which has been found in many plants – corn, onions, beets, flax. Consider the example of cms maize. Corn – a monoecious plant, the female flowers which are collected in the ear, and male – in a whisk. Sometimes in panicle can be immature anthers with sterile pylosobennostyami cytoplasm. Pollination with pollen from cms, taken from other plants in the progeny gives shape and with sterile pollen.

Consequently, the sign of male sterility is transmitted through the maternal line. Even when all 10 pairs of chromosomes in pollen sterile plants are replaced chromosomes of plants with normal pollen, male sterility is preserved. Cytoplasm, conditional male sterility, can be denoted by vdet and cytoplasm of normal across the beat. Genetic analysis showed that genotype of the plant also affects the sterility of pollen. Cytoplasm tsit5 causes sterility only when the genotype of recessive genes in homozygous state rfrf – tsit5 rfrf. When tsit3 RfRf or tsit5 Rfrf plants have normal pollen fertility. Hence, the Rf gene is able to restore pollen fertility.

Such relations between the cytoplasm and genotype allowed us to develop methodology and to chart the receipt of interlinear hybrids of maize using the cms lines of maize used belong to the so-called "fixer" sterility "reducers" fertility. Fertile lines and varieties, preserving when crossed with a sterile form sterility in the offspring are called "fixer" for sterility, and the lines and varieties, reducing the fertility of offspring plants with cms – "reducing" fertility. I know two types of maize male sterility. Study of Education pollen sterile forms of maize showed that the apparent violation of sporogenesis occur at various stages: some degeneration is completed at the stage of single-core pollen, others – binuclear. Great influence on the manifestation of sterility by external conditions: temperature, humidity, soil and air, as well as the duration of the day. Maize varieties with one or another type of cms have different sensitivities to environmental factors. In plants with Moldovan type cms panicle form anthers, which were not disclosed, the pollen in them unviable, although under certain conditions, can be formed and sustained. In plants with Texas style cms manifestation of sterility, to a lesser extent influenced by external factors, but a sign is expressed much: anthers strongly degenerated and never disclosed. In the selection of both types cms. In addition, there are data about the use of cms and wheat. Received sterile form by crossing two plant species – Aegilops and wheat, are working on the selection of other components for hybridisation, provide the maximum heterosis. Failed to reveal a pair of crosses, which give additional yield by 40-50%.

Tags:

Comments are closed.