Effect of ACC oxidase gene AhACOs on salt tolerance of peanut / 生物工程学报

ACC oxidase (ACO) is one of the key enzymes that catalyze the synthesis of ethylene. Ethylene is involved in salt stress response in plants, and salt stress seriously affects the yield of peanut. In this study, AhACO genes were cloned and their functions were investigated with the aim to explore the biological function of AhACOs in salt stress response, and to provide genetic resources for the breeding of salt-tolerant varieties of peanut. AhACO1 and AhACO2 were amplified from the cDNA of salt-tolerant peanut mutant M29, respectively, and cloned into the plant expression vector pCAMBIA super1300. The recombinant plasmid was transformed into Huayu22 by pollen tube injection mediated by Agrobacterium tumefaciens. After harvest, the small slice cotyledon was separated from the kernel, and the positive seeds were screened by PCR. The expression of AhACO genes was analyzed by qRT-PCR, and the ethylene release was detected by capillary column gas chromatography. Transgenic seeds were sowed and then irrigated with NaCl solution, and the phenotypic changes of 21-day-seedings were recorded. The results showed that the growth of transgenic plants were better than that of the control group Huayu 22 upon salt stress, and the relative content of chlorophyll SPAD value and net photosynthetic rate (Pn) of transgenic peanuts were higher than those of the control group. In addition, the ethylene production of AhACO1 and AhACO2 transgenic plants were 2.79 and 1.87 times higher than that of control peanut, respectively. These results showed that AhACO1 and AhACO2 could significantly improve the salt stress tolerance of transgenic peanut.

Breeding on a new peanut variety Yuhua91 with high oleic acid content / 生物工程学报

Yuhua91 is a new peanut variety with high oleic acid content bred by Qingdao Agricultural University. The crossing was conducted with Luhua11 as female parent and with Kainong1715, an F435-type variety with high oleic acid content as male parent. The real F1 hybrids were screened by sequencing on PCR amplification products, and those homozygotes with bb genotype in F2 populations were screened by the same sequencing method as above. The content of oleic and linoleic acid was measured on the kernels harvested from F2 single plants by near infrared ray method, and those kernels whose content of oleic was above 80%, oleic and linoleic acid ratio was above 10.0 were obtained and planted into a row, with pedigree method for subsequent selection breeding. Yuhua91 has some characters of small pod, light and obvious pod texture, 148.06 g per 100 pods, 63.31 g per 100 kernels, 75.15% shelling percentage, long elliptic seed kernel, pink seed coat, without crack, white endotesta. Its content of protein, oil, oleic acid, linoleic acid and palmitic acid was 26.57%, 52.72%, 80.40%, 2.50% and 5.57% respectively. Yuhua91 has other characters of strong seedlings, compact pod areas, and moderate resistance to leaf spot disease and bacterial wilt. Average pod yield is 215.79 kg per Mu, 15.27% higher than the control variety Huayu20. Average seed kernels yield is 157.33 kg per Mu, 21.64% higher than the control variety Huayu20. Yuhua 91 has been registered on department of agriculture in 2018, and the registration No. is GPD peanut (2018) 370210, fit for growing in Shandong Province.

Breeding peanut variety Yuhua 7 by fast neutron irradiation and tissue culture / 生物工程学报

Creating new germplasms and breeding new cultivars in peanut by radiation mutagenesis and tissue culture were conducted in this study, aiming to develop new breeding method of peanut. Mature seeds from Luhua 11, the most commonly grown peanut cultivar in Northern China, were treated by fast neutron irradiation. Then the embryo leaflets were separated from the irradiated seeds and inoculated on the media, and the regenerated seedlings were obtained through somatic embryogenesis pathway. The regenerated seedlings were grafted, acclimated and then transplanted into field and the selfed pods were harvested from 83 regenerated plants. The progenies were selected by the pedigree method, and 107 mutants were obtained from the progenies of the 83 regenerated plants. Different mutants showed obvious variation in many agronomic traits, including main stem height, branch number, pod shape and size, seed coat color, inner seed coat color, oil content and protein content etc. Yuhua 7, a new peanut variety with low oil content, early maturity and waterlogging tolerance was obtained. The yield of Yuhua 7 was over 14% higher than that of the mutagenic parent Luhua 11, and the oil content of kernels was 47.0%, lower than that of parent Luhua 11 with 52.1% oil content. Yuhua 7 had passed peanut variety regional multi-location trials in Liaoning Province in 2016 and its average yield was 13.8% higher than that of the control variety Baisha 1017. It had also passed national peanut variety registration, and the registration ID is "GPD peanut (2018) 370105". The results show that irradiation mutagenesis combined with tissue culture is an effective method for creating new germplasm and breeding new varieties of peanut.

Breeding of peanut variety Yuhua 4 by in vitro mutagenesis / 生物工程学报

The embryonic leaflets of peanut (Arachis hypogaea) variety Huayu 20 were used as explants and pingyangmycin as a mutagen to induce somatic embryos. Four weeks after the inoculation, the survived explants were transferred to somatic embryo germination medium containing screening reagent hydroxyproline, and finally 15 regenerated plants were obtained. Pedigree breeding method was used during the following selection breeding, and three lines with significantly increased yield and 23 lines with high oil content were obtained from these mutant offsprings. The line with both high yield and high oil content has passed peanut variety multi-location in Anhui province and was named "Yuhua 4". Its yield was 16.63% higher than that of the control variety Baisha 1016, ranking the first in all the testing varieties. Yuhua 4 showed the characteristics of early maturity, small pod and high oil content. The oil content of kernels was 56.10%, higher than that of original parent Huayu 20 with 49.50% oil content, tested by the Ministry of Agriculture of Oil and Products Quality Supervision, Inspection and Test Center (Wuhan), and the yield was 15% higher than that of Huayu 20. It was concluded that in vitro mutagenesis and target screening was an effective way on creating new germplasm and breeding new variety in peanut.