A novel hybrid seed production technology based on a unilateral cross-incompatibility gene in maize

Hybrid seed production technology(SPT)using genic recessive male sterility is of great importance in maize breeding.Here,we report a novel SPT based on a maize unilateral cross-incompatibility gene Zm Ga1F with an extremely low transgene transmission rate(TTR).Proper pollen-specific Zm Ga1F expression severely inhibits pollen tube growth leading to no fertilization.The maintainer line harbors a transgene cassette in an ipe1 male sterile background containing IPE1 to restore ipe1 male fertility,Zm Ga1F to prevent transgenic pollen escape,the red fluorescence protein encoding gene Ds Red2 for the separation of male sterile and fertile seeds,and the herbicide-resistant gene Bar for transgenic plant selection.When the maintainer line is selfed,gametes of ipe1/transgene and ipe1/-genotypes are produced,and pollen of the ipe1/transgene genotype is not able to fertilize female gametes due to pollen tube growth inhibition by Zm Ga1F.Subsequently,seeds of ipe1/ipe1 and ipe1/transgene genotypes are produced at a 1:1 ratio and could be separated easily by fluorescence-based seed sorting.Not a single seed emitting fluorescence is detected in more than 200,000 seeds examined demonstrating that the pollen-tube-inhibition(PTI)-based TTR is lower than what has been reported for similar technologies to date.This PTI-based SPT shows promising potential for future maize hybrid seed production.

Breeding and Application of Guidan 903,a New High-yield and Good-quality Maize Variety

To meet the demand of maize production in Guangxi and even the southwest region of China and realize the upgrading and undating of maize varieties which will continuously improve the yield and quality of maize,a new big-ear maize variety Guidan 903 with high yield,stable yield and good quality was established by the Maize Research Institute of Guangxi Academy of Agricultural Sciences with two self-selected inbred line GRL17349 and GRL21191 as female and male parents seperately.The average yield of this variety were 7429.5 and 7000.5 kg/hm^(2)in Guangxi Maize Regional Trial and Production Test respectively,which increased by 6.3%and 5.6%than the control(Guidan162).It was approved by Guangxi Zhuang Autonomous Region Crop Variety Certification Committee in June 2020(Approval No.Gui sheng yu 2020083).Determined by the Cereal Quality Supervision and Testing Center of Ministry of Agriculture and Rural Affairs(Bejjing),the grain bulk density,ratio of crude protein,crude fat,crude starch and lysine of Guidan 903 were 782 g/L,9.41%,6.19%,71.45%,0.35%respectively.This variety has the characterisics of strong resistance to collapse and disease,good quality,high and stable yield and wide adaptability.Furthermore,its seed yield is high with easy production technology and low cost.

Tracking and Monitoring Leaf Development, Coupling Law and Regulation Techniques during Flowering Period of Hybrid Foxtail Millet (<i>Setaria italica</i>(L.) P. Beauv.) Parental Lines

The determining factor of Setaria italica (L.) P. Beauv. is the coupling of its flowering stage and outcrossing rate which leads to low and unstable seed yields in self-pollinated foxtail millet hybrids and thereby limits their large-scale application. In this study, Datong 27, Datong 29 and gu 83 were screened and identified through meticulous observations of their pollination habitats. High exposure rate, degree of exposure and plump of stigma are good factors to accept foreign pollen. Datong 27 and Datong 29 have some additional characteristics, such as long filaments and exposed and full anthers that contain a large amount of pollen. We transformed into a series of stigma-exposed and plump sterile lines that easily accepted exotic pollen. New restorer lines with anthers that were full of powder and exhibited quick recovery, which improved the parental lines’ heterosexual characteristics. By tracking and monitoring the leaf development of the new sterile and restorer lines, a coupling law of leaf development was determined and a series of flowering control measures were formulated. These factors ensured that the parental lines encounter one another during the flowering stage. By utilizing fertilizer and water, the vitality of the female stigma, amount of powder scattered and powder loosening time were prolonged, which increased hybrid seed yields from 1500 to 3000 kg/hm2. These findings were helpful in resolving the technical problems of seed production that restricted the propagation of foxtail millet hybrids and supporting future large-scale applications.