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Fructokinase (FRK) and fructokinase-like (FLN), belonging to the phosphofructokinase B type subfamily, share substantial sequence similarity, and are crucial in various plant physiological processes. However, there is limited information regarding what functionally differentiates plant FRKs from FLNs. Here, a total of three CsFRKs and two CsFLNs were identified from the cucumber genome. Their significant difference lay in the structure of their G/AXGD motif, which existed as GAGD in CsFRKs, but as G/ASGD in CsFLNs. Comparative phylogenetic analysis classified CsFRKs and CsFLNs into five sub-branches consistent with their quite different exon/intron organizations. Both transcriptome data and RT-qPCR analyses revealed that CsFRK3 was the most active gene, with the highest expression in the majority of tissues tested. Moreover, the expression levels of two putative plastidic genes, CsFRK1 and CsFLN2, were significantly positively associated with chlorophyll accumulation in the chlorophyll-reduced cucumber mutant. Briefly, both CsFRK and CsFLN genes were involved in the development of sink tissues, especially CsFRK3. CsFRK1 and CsFLN2 were recognized as candidates in the chlorophyll biosynthesis pathway of cucumber. These results would greatly assist in further investigation on functional characterization of FRKs and FLNs, especially in the development and chlorophyll biosynthesis of cucumber. [ABSTRACT FROM AUTHOR]

Radish (Raphanus sativus L.) is an important worldwide root vegetable crop. Little information of the GRAS gene family was available in radish. Herein, a total of 51 GRAS family members were firstly identified from radish genome, and unevenly located onto nine radish chromosomes. Expression analysis of RsGRAS genes in taproot displayed that RsSCL15a and RsSHRc were highly expressed in the radish cambium, and its expression level was increased with the taproot thickening. Comparative transcriptome analysis revealed that the expression patterns of RsGRAS genes varied upon exposure to different abiotic stresses including heavy metals, salt and heat. The expression level of six RsGRAS genes including RsSHRc was increased under chilling stress in two radish genotypes with different cold tolerance. Further analysis indicated that RsGRAS genes could respond to cold stress rapidly and the expression of RsSHRc was up-regulated at different development stages (cortex splitting and thickening stages) under long-term cold treatment. Transient expression of RsSHRc gene in radish showed that RsSHRc possessed the reliable function of eliminating reactive oxygen species (ROS), inhibiting the formation of malondialdehyde (MDA) and promoting to accumulate proline under cold stress. Together, these findings provided insights into the function of RsGRAS genes in taproot development and chilling stress response in radish. • The GRAS gene family was comprehensively characterized in radish. • Expression analysis indicates RsSHRc might be involved in radish taproot thickening. • Transient expression analysis revealed RsSHRc gene could enhance cold tolerance of radish plants. [ABSTRACT FROM AUTHOR]