Allelic variation at the FRIGIDA (FRI) locus is a major contributor to natural variation of flowering time and vernalization requirement in Arabidopsis thaliana. Dominant FRI inhibits flowering by activating the expression of the MADS box transcriptional repressor FLOWERING LOCUS C (FLC), which represses flowering prior to vernalization. Four FRI orthologues had been identified in the domesticated amphidiploid Brassica napus. Linkage and association studies had revealed that one of the FRI orthologues, BnaA3.FRI, contributes to flowering time variation and crop type differentiation. Sequence analyses indicated that three out of the four BnaFRI paralogues, BnaA3.FRI, BnaA10.FRI and BnaC3.FRI, contained a large number of polymorphic sites. Haplotype analysis in a panel of 174 B. napus accessions using PCR markers showed that all the three paralogues had a biased distribution of haplotypes in winter type oilseed rape (P < 0.01). Association analysis indicated that only BnaA3.FRI contributes to flowering time variation in B. napus. In addition, transgenic functional complementation demonstrated that mutations in the coding sequence of BnaA3.FRI lead to weak alleles, and subsequently to flowering time variation. This study for the first time provides a molecular basis for flowering time control by BnaA3.FRI in B. napus, and will facilitate predictive oilseed rape breeding to select varieties with favorable flowering time and better adaption to latitude and seasonal shifts due to changing climate.

Muskmelon pedicel is the fruit stalk of muskmelon and one of the traditional Chinese medicines, which can be used to treat jaundice, diabetes and neuropathy. However, in recent years, agricultural soil heavy metal cadmium (Cd) pollution has become serious, coupled with the imperfect sales management of herbal medicine, increasing the potential health risk of contaminated herbal medicine in the human body. In this paper, the comprehensive quality of contaminated muskmelon was tested. The results showed that Cd stress significantly inhibited the growth of muskmelon plants, reduced the anthocyanin and chlorophyll contents, and increased the fruit size and sweetness of muskmelon. In addition, heavy metal Cd can also cause oxidative stress in plants, resulting in a series of changes in antioxidant enzyme activities. In the experimental group, the content of polyphenols and saponins increased by 27.02% and 23.92%, respectively, after high-concentration Cd treatment, which may be a mechanism of plant resistance to stress. This paper reveals that the content of bioactive substances in Chinese herbal medicine is high, but the harm in heavy metals cannot be underestimated, which should be paid attention to by relevant departments.

As one of the world’s most popular fruits, watermelon (Citrus lanatus) is cultivated in more than 3 million hectares across the globe, with a yearly yield of more than 100 million tons. According to ‘97103’ genome version 1, a previous study has shown that the watermelon genome consists of 11 PIN genes. However, the higher quality ‘97103’ genome version 2 was recently assembled by using PacBio long reads with the benefit of fast development sequencing technology. Using this new assembly, we conducted a new genome-wide search for PIN genes in watermelon and compared it with cucumber and melon genomes. We identified nine, nine, and eight PINs in watermelon, cucumber, and melon, respectively. Phylogenetic analysis revealed a distinct evolutionary history of PIN proteins in watermelon, which is shown by the orphan PIN6 in watermelon. We further conducted an expression analysis of the watermelon PIN genes in silico and by qRT-PCR. ClaPIN6 might not play an essential role during shoot regeneration, which is closely related to species-specific evolution. However, the up-regulated expression patterns of ClaPIN1-1 and ClaPIN1-3 indicated their important roles during shoot regeneration. The result of this research will benefit future studies to understand the regulating mechanisms of auxin in watermelon shoot regeneration.