Utilization of Rht12 dwarfing gene in seed production of male sterile line

Prospect of Rht12 dwarfing gene used in hybrid wheat was evaluated in this paper. Low yielding of male sterile line seed production still remained a big problem to hinder the commercialization of semi-dwarfing hybrid wheat with Rht3 gene. Wheat plant carrying Rht12 gene was sensitive to exterior GA3. It was possible to condition plant height in field by GA3 treatment. Exploitation of Rht12 in hybrid wheat could facilitate the production of male sterile line seed and result in a higher seed yield. In our breeding scheme, an original Rht12 dwarfing line introduced from China Agricultural University had been crossed and backcrossed with local varieties of Jiangsu province. Preliminary results showed that: the selected Rht12 dwarfing lines displayed good adaptability to the habitat of southern Jiangsu province. Some of these lines were developed into male sterile lines with T. timopheevii cytoplasm subsequently. The plant height of the Rht12 dwarfing lines derived from the same variety differed and ranged from 50 cm to 90 cm. Hybrid F 1s with different plant height might be bred out with the Rht12 dwarfing lines with different plant height. Spraying of 50~100 mg/kg GA3 solution between jointing stage and booting stage could promote plant height of Rht12 dwarfing lines significantly. In a male sterile line seed production trial, the plant height of maintainer sprayed with 50 mg/kg GA3 solution increased from 65 cm to 90 cm. The outcrossed seed set rate of male sterile line went up to 60.4% while that of the control was only 20.2%. Thus a notably higher yield of male sterile line could be obtained. Moreover, the difference of plant height could prevent mingling of maintainer seed and ensure the purity of male sterile line seed. How to solve the problem of late maturity and leaf senescence of Rht12 dwarfing line was also discussed in this paper.