Abstract
Maize is highly sensitive to water deficit but has high transpiration and biomass production, leading to a substantial water demand. Genetic engineering can overcome reproductive isolation and utilize drought-tolerant genes from distant species. Ammopiptanthus nanus is a relic of the Tertiary glaciation that can adapt to harsh environmental conditions. In our previous study, five maize homozygous T8 lines overexpressing the AnVP1 gene from Ammopiptanthus nanus were generated and showed the enhancement of drought tolerance. However, the recipient inbred line Zh-1 was poor in yield and agronomic performance. In the present study, the AnVP1 gene was backcrossed from donor parent L10 (one of the five T8 lines) into recurrent parent Chang 7-2 (one of the elite parents of the commercial hybrid Zhengdan 958). In total, 103 InDel markers were developed and used for assisted background selection. After two generations of foreground selection through glufosinate spraying, the detection of CP4 EPSP MAb1 strips, and the PCR amplification of the AnVP1 gene, along with the similarity of agronomic traits to the recurrent parent, and background selection assisted by these InDel markers, the transgenic AnVP1 gene became homozygous in the BC2 lines. The average recovery rate of the genetic background of the recurrent parent reached 74.80% in the BC1 population and 91.93% in the BC2 population, respectively. The results of RT-PCR and RT-qPCR indicated the stable expression of the AnVP1 gene in the two ultimately selected BC2F3 lines, BC2-36-12 and BC2-5-15. The drought tolerance of these two BC2F3 lines were significantly improved compared to the recurrent parent Chang 7-2, as revealed by their wilting phenotype and survival rate of seedlings. This improvement was related to the enhancement of water-retention ability, as indicated by higher RWC and the reduction in damage, as shown by the decrease in REL, MDA, and H2O2 under drought stress. The result of field evaluation in two arid and semi-arid environments indicated that the drought tolerance of Chang 7-2 was significantly improved. This study suggests that the improved Chang 7-2 can be crossed with Zheng 58 to develop the transgenic commercial hybrid Zhengdan 958.
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Claims 11
Claim · model-written summary
The marker set comprised 103 InDel markers for background selection.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In total, 103 InDel markers were developed and used for assisted background selection.”
t0“Maize”
Claim · model-written summary
AnVP1 became homozygous in BC2 lines after selection.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the transgenic AnVP1 gene became homozygous in the BC2 lines.”
t0“Maize”
Claim · model-written summary
Recurrent parent background recovery averaged 74.80% in BC1.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The average recovery rate of the genetic background of the recurrent parent reached 74.80% in the BC1 population and 91.93% in the BC2 population, respectively.”
t0“Maize”
Claim · model-written summary
Recurrent parent background recovery averaged 91.93% in BC2.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The average recovery rate of the genetic background of the recurrent parent reached 74.80% in the BC1 population and 91.93% in the BC2 population, respectively.”
t0“Maize”
Claim · model-written summary
AnVP1 expression was stable in line BC2-36-12.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The results of RT-PCR and RT-qPCR indicated the stable expression of the AnVP1 gene in the two ultimately selected BC2F3 lines, BC2-36-12 and BC2-5-15.”
t0“Maize”
Claim · model-written summary
AnVP1 expression was stable in line BC2-5-15.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The results of RT-PCR and RT-qPCR indicated the stable expression of the AnVP1 gene in the two ultimately selected BC2F3 lines, BC2-36-12 and BC2-5-15.”
t0“Maize”
Claim · model-written summary
The two BC2F3 lines showed significantly improved drought tolerance against Chang 7-2.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The drought tolerance of these two BC2F3 lines were significantly improved compared to the recurrent parent Chang 7-2, as revealed by their wilting phenotype and survival rate of seedlings.”
t0“Maize”
Claim · model-written summary
The improved lines had higher relative water content under drought.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This improvement was related to the enhancement of water-retention ability, as indicated by higher RWC and the reduction in damage, as shown by the decrease in REL, MDA, and H2O2 under drought stress.”
t0“Maize”
Claim · model-written summary
REL, MDA and H2O2 decreased under drought stress in the improved lines.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This improvement was related to the enhancement of water-retention ability, as indicated by higher RWC and the reduction in damage, as shown by the decrease in REL, MDA, and H2O2 under drought stress.”
t0“Maize”
Claim · model-written summary
Field evaluations in two arid and semi-arid environments indicated improved drought tolerance of Chang 7-2.
- Material
- Chang 7-2e0
- Outcome
- drought tolerancee0
- Direction
- improvede0
- Setting
- two arid and semi-arid environmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The result of field evaluation in two arid and semi-arid environments indicated that the drought tolerance of Chang 7-2 was significantly improved.”
t0“Maize”
Claim · model-written summary
The authors propose crossing improved Chang 7-2 with Zheng 58 to develop Zhengdan 958.
- Material
- improved Chang 7-2e0
- Outcome
- crossed with Zheng 58 to develop the transgenic commercial hybrid Zhengdan 958e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This study suggests that the improved Chang 7-2 can be crossed with Zheng 58 to develop the transgenic commercial hybrid Zhengdan 958.”
t0“Maize”