Gradual daylength sensing coupled with optimum cropping modes enhances multi-latitude adaptation of rice and maize

Photoperiod Genes Contribute to Daylength-Sensing and Breeding in Rice

“…The Hd1-DTH8-Ghd7-PRR37 module regulates rice daylength-sensing in rice, and natural variation in the underlying photoperiod genes changes the daylength-sensing processes, which play a vital part in the adaptation of rice cultivars to multi-latitude regions [ 16 , 24 ]. To expand this analysis to photoperiod genes, we collected the DNA sequences for Hd1 , DTH8 , Ghd7 , PRR37 , SE5, OsGI , Ehd1 , and ELF3-1 from 115 rice germplasm resources (70 indica , 30 japonica , 12 Aus , and 3 Bus ) [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 ], and looked for polymorphisms ( Figure 4 ).…”

“…A suitable flowering time allows rice plants to make full use of light and temperature resources to maximize yield [ 16 , 55 ]. Indica rice cultivars with the genotype Hd1 DTH8 Ghd7 PRR37 are characterized by extremely low expression of florigen when the daylength is longer than 13 h, and fail to flower under natural LD conditions [ 24 ]. However, our results also indicate that the time to flowering of DJ and Nip ( japonica , Hd1 DTH8 Ghd7 PRR37 genotype) was about 145 days at 41°40′ N ( Figure S3a ), which exceeds the suitable growing season.…”

“…Diverse combinations of the Hd1 , DTH8 , Ghd7 , and PRR37 genes mediate the multiple daylength-sensing processes to improve the latitude adaptation [ 16 ]. However, optimal cropping modes coupled with proper daylength-sensing processes can enhance rice multi-latitude adaptation [ 24 ]. Mutations in some circadian clock genes and photoreceptor genes greatly affect the daylength-sensing processes and yield-related traits, resulting in a mismatch between the growth period of crops and the arable season.…”

“…When the 100 × 10 −4 < Hd3a or RFT1 expression, we defined them as being highly inactivated. Subsequently, we obtained the florigen gene-expression heatmap according to the methods previously described [ 16 , 24 ]. The daylength data for different latitudes were collected using the Rise and Set Times app developed by S. Vdovenko ( (accessed on 30 January 2020)).…”

“…Hd1hd1 dth8dth8 and hd1hd1 DTH8dth8 are the two major genotypes of indica hybrid rice that improve latitudinal adaptation in East Asia [ 16 ]. Shanyou63 (SY63), an outstanding hybrid rice variety in China because of its high yield and widespread geographical distribution, harbors the Hd1hd1 dth8dth8 genotypic module, is associated with gradual daylength-sensing and underlies the molecular basis of the wide adaptability to photoperiod exhibited by this variety [ 24 ]. Ghd7 plays a crucial role in flowering by repressing the expression of Ehd1 , Hd3a , and RFT1 [ 16 , 25 ].…”