A Single Recessive Photoperiod and Temperature Sensitive Genic Male Sterile Line Yahuang 396a in Cotton

1 present situation and problems of breeding and seed production by using heterosis

1.1 the technique of hybrid seed production by artificial or chemical pollination is simple, any two varieties can be parents of each other, castration and artificial pollination at flowering stage can be used, and chemical male killing hybrid seed production can also be used. The advantage is that it is easy to make full use of the existing variety resources, the selection of hybrids is random, the combination is free, and some combinations can make use of F2. The disadvantage is that the labor intensity is high, the labor is much, the cost is high, and the heterosis of F2 is more declining than that of F1.

1.2 seed production of cytoplasmic male sterile lines this method makes use of the matching of male sterile lines, restorer lines and maintainer lines, without artificial castration, only the pollen of the restorer line is transferred to the male sterile line to complete the hybridization process. Save labor and time, high efficiency and low cost of seed production. Disadvantages: this method is cytoplasmic sterility, the restorer source must be guided by strong restoring factors before it can be transformed into a restorer line, and the restorer line has incomplete restoration and great fluctuation to the male sterile line, so it is difficult to find a strong dominant combination with production and utilization value.

1.3 the single recessive nuclear male sterile two-line hybrid seed production male sterile line can be used not only as the female parent of the hybrid seed production field, but also as the maintainer line of its own reproduction. Advantages: a wide range of restorer lines, all excellent conventional varieties can be used as restoration sources, simple seed production procedure and less labor. Disadvantages: the sterility of male sterile lines is difficult to reach 100%, and the rate of sterile plants can only be close to 50%.

1.4 complete maintainer lines in seed production by single recessive genic male sterility three lines have the general characteristics of polygene inheritance, and there are more restorer lines. Advantages: the maintainer line is close to the complete retention effect and is relatively stable. The male sterile line has the male sterile inheritance of the interaction between major genes and polygenes, and has the characteristics of complete sterility. Restorer lines have a wide range, and it is easy to test and match strong dominant hybrids. Disadvantages: it is difficult to breed the male sterile line itself, and the application area of the maintainer line is narrow.

1.5 the hybrid seed production of double recessive nuclear male sterility is controlled by two pairs of male sterile genes, namely ms5ms5ms6ms6, which can be produced by one-line dual-use method. Advantages: the procedure of seed production is simple, not only the sterile plants in F1MagneF2 but also the male sterile plants in the field can be used in the field production. Disadvantages: when hybrid seed production, 50% or more fertile plants must be pulled out, which is laborious and laborious, and the seed production yield is low and the cost is high.

2 Photoperiod-temperature sensitive genic male sterile line Yahuang396A

2.1 the male sterile line has a sterility of 100%, excellent quality and agronomic characters, high combining ability, sensitive to light and temperature, and fertility transformation can be artificially controlled. Under the condition of high temperature and short day, it becomes a fertile plant, forms bolls naturally, propagates male sterile lines, and no longer needs a special maintainer line. The harvested seeds returned to sterile plants under the condition of high temperature and long sunshine or low temperature and short sunshine, and the sterile plant rate was 100%, which was used to prepare hybrids.

The male sterile line is genic male sterile and has a wide range of restorer lines, so it is easy to transfer sterile genes to parent varieties with good characters, and any crossing or artificial mutagenesis and genetic engineering methods can be transferred into new male sterile lines. The male sterile line has normal bright Corolla and nectaries, which can attract @ # @ 255cm @ or other insects to pollinate and greatly reduce the cost of seed production. The male sterile line also has obvious bud yellow markings. Under normal light, temperature and humidity conditions, the cotyledon stage of 5-7 days after emergence can obviously distinguish fertile plants from male sterile plants, and under abnormal light, temperature and humidity conditions, it can be accurately distinguished from 3 to 5 true leaves at the latest. In case there are fertile plants in the male sterile lines or sterile plants in F1, they can be identified with the naked eye, remove miscellaneous seedlings and ensure purity.

2.2 compared with other forms of hybrid seed production, compared with conventional manual castration or chemical sterilization, the female parent of this method is 100% sterile, and artificial pollination can be changed to honeybee pollination without castration, so the seed production procedure is simple and the cost of seed production is reduced. Compared with the seed production of cytoplasmic male sterile lines, male sterile lines do not need special maintainer lines, artificial pollination, especially restorer lines do not need to be transferred, and any cotton variety can be used as its restoring source to test cross directly. new cotton varieties with high quality, high yield, early maturity and stress resistance can be cultivated as soon as possible as soon as possible. Compared with the single recessive nuclear male sterile two-line method, the rate of sterile plants is increased from 50% to 100%. Without pulling out fertile plants, the seed utilization rate of male sterile lines is more than doubled, labor and time are saved, and the cost is reduced. Compared with the single recessive genic male sterile three-line method, the operation of the male sterile line is simple, the application area is wide, and the fertility transformation can be completed by using the natural environment. Compared with double recessive nuclear male sterility, its sterility is stable, the degree of sterility is higher, and can be transformed into a variety of male sterile lines. Therefore, this method is especially suitable for large-scale mechanized cotton hybrid production.

2.3 Application prospect of photoperiod-temperature sensitive genic male sterile line Yahuang 396A is a major breakthrough in cotton male sterility research at present. It has simple seed production procedure, high seed production efficiency and yield, and solves many bottleneck problems existing in other hybrid seed production methods. it will not only end the history of artificial depollination and hybrid seed production, but also improve cotton quality, which is of great significance to hybrid cotton seed industrialization.

The perennial cotton planting area in China is about 5 million hectares. if we use the photoperiod-thermo-sensitive genic male sterility method to produce seeds and apply F1 in the field, according to the lowest increase of 20%, it can increase lint by more than 2 million tons and increase income by more than 30 billion yuan. it is equivalent to the total yield of 1 million hectares of cotton fields at present, which is equal to 1/4 of the existing cotton fields in China, and has huge economic, social and ecological benefits.