Screening and identification of key genes regulating fall dormancy in alfalfa leaves

Abstract

Fall dormancy (FD) determines the adaptation of an alfalfa variety and affects alfalfa production and quality. However, the molecular mechanism underlying FD remains poorly understood. Here, 44 genes regulating FD were identified by comparison of the transcriptomes from leaves of Maverick (fall-dormant alfalfa) and CUF101(non-fall-dormant), during FD and non-FD and were classified them depending on their function. The transcription of IAA-amino acid hydrolase ILR1-like 1, abscisic acid receptor PYL8, and monogalactosyldiacylglycerol synthase-3 in Maverick leaves was regulated by daylength and temperature, and the transcription of the abscisic acid receptor PYL8 was mainly affected by daylength. The changes in the expression of these genes and the abundance of their messenger RNA (mRNA) in Maverick leaves differed from those in CUF101 leaves, as evidenced by the correlation analysis of their mRNA abundance profiles obtained from April to October. The present findings suggested that these genes are involved in regulating FD in alfalfa.

Fig 1. Gene ontology functional classification of key candidate genes.

The functional assignments with biological processes, molecular functions, and cellular components are shown based on the number of proteins and the converted corresponding proportion.

Fig 2. Daylength and temperature from April to October.

Fig 3. Plant height of Maverick and CUF101varieties from April to October.

The difference in plant height in Maverick is marked with *. The difference in plant height between Maverick and CUF101 is marked with #. (*, #, p < 0.05; **, ## p< 0.01).

Fig 4. Leaf area of Maverick and CUF101 varieties from April to October.

* and **indicate significant difference at p < 0.05 and p < 0.01, respectively.

Fig 5. mRNA abundance of indoleacetic acid (IAA)-amino acid hydrolase ILR1-like 1 in Maverick and CUF101 varieties from April to October in 2011 and 2016.

* and ** indicate significant difference between August-September and June-July at p<0.05 and p<0.01, respectively.

Fig 6. mRNA abundance of the abscisic acid receptor PYL8 in Maverick and CUF101 varieties from April to October in 2011 and 2016.

** indicates significant difference between September-October and August at p<0.01.

Fig 7. mRNA abundance of monogalactosyldiacylglycerol synthase-3 in Maverick and CUF101 varieties from April to October in 2011 and 2016.

* and ** indicate significant difference between July, August, September, and June at p<0.05 and p<0.01, respectively.

Fig 8. mRNA abundance of Rubisco activase in Maverick and CUF101varieties from April to October in 2011 and 2016.

** indicates significant difference between September, October, July, and August at p<0.01.

Fig 9. mRNA abundance of four differentially expressed genes (DEGs) in Maverick and CUF101 varieties grown under 8h to 16h daylength and artificial growth conditions.

Significant difference in the mRNA content of DEGs at 8h,12h, and 16h of illumination in each variety is marked with *. Significant difference in mRNA content between the two varieties is indicated with # (*, #, p<0.05; **, ##,p<0.01). Error bars indicate standard deviation (SD).

Fig 10. mRNA abundance of four differentially expressed genes (DEGs) in Maverick and CUF101 varieties grown under artificial growth conditions at different temperatures (from 32°C to 16°C).

Significant difference in mRNA content of DEGs between 16°C, 24°C and 32°C for each variety is marked with *. Significant difference in mRNA content between the two varieties is marked with # (*, #, p<0.05; **, ##, p<0.01). Error bars indicate standard deviation (SD).