Abstract
In order to understand the effects of low nitrogen (LN) stress on the growth and development in different genotypes of Chinese cabbage, the L40 genotype with high nitrogen utilization and the L14 genotype with LN utilization were selected as experimental materials. Field experiments and indoor hydroponic methods were used to study the different responses of two Chinese cabbage genotypes to low nitrogen levels. In this study, we also analyzed the genome-wide gene expression profiles of L40 and L14 in response to LN stress by high-throughput RNA sequencing technology. The results reveal that the L40 root system responds better to LN compared with L14. After LN stress, L40 can effectively absorb and transport and store it in the ground. It is precisely because of this characteristic of the L40 genotype that LN treatment did not have a significant effect on the chlorophyll (Chl) content and net photosynthetic rate (Pn) of the L40 Chinese cabbage compared with the L14 Chinese cabbage. These two different Chinese cabbage genotypes were shown to have differently expressed genes related to nitrate transport, auxin synthesis, and glutamate dehydrogenase synthesis. These genes function in the nitrogen pathway, which are important candidates for understanding the molecular host-response mechanisms to LN stress.
Highlights
Nitrogen (N) is one of the most essential elements for crop growth and development and is a main component of amino acids, proteins, nucleic acids, Chl, enzymes, and many kinds of vitamins
This study found that LN treatment did not cause a significant decrease in the Chl content and photosynthetic rate (Pn) of L40, but it was not the case in L14
LN stress increased most of the root parameters in both L14 and L40, but the degrees in L14 were more significant than those L40, with the exception of TRL
Summary
Nitrogen (N) is one of the most essential elements for crop growth and development and is a main component of amino acids, proteins, nucleic acids, Chl, enzymes, and many kinds of vitamins. Studies have shown that auxins play a significant role in the growth and development of plant roots [4]. The overuse of chemical fertilizer coupled with long-term continuous cropping and other problems leads to the deterioration of the physical and chemical properties of vegetable planting soil and a decline in vegetable quality year after year, which seriously reduces the economic benefits of farmers [19]. We used two different genotypes of Chinese cabbage to investigate the effects of LN on the accumulation and distribution of nutrients in the roots and shoots of different genotypes at different growth stages. The5n57u0mber o4f4,L06470,-1s3p3ecific DEG9s8.i2n8 response to90L.5N3%was 1198 8(38.6688%up and 83030d,0o0w0 n) and 45656(11940 up and 316 down) for the shoots and roots, respectively (Figure 6).
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