The quality of Lily cut flower was determined by the quality of bulbs. During the process of vernalization and flower bud differentiation, sugar massively accumulated in the bulb, which influenced the bulb development. However, the details of sugar genes’ regulation mechanism for these processes were not fully understood. Here, morphological physiology, transcriptomes and gene engineering technology were used to explore this physiological change. Seventy-two genes of 25 kinds of sugar metabolism-related genes were annotated after re-analyzing transcriptome data of Oriental hybrid lily ‘Sorbonne’ bulbs, which were generated on Hiseq Illumina 2000. The results showed that these genes were closely related to lily bulb vernalization and development. Combining gene expression pattern with gene co-expression network, five genes (Contig5669, Contig13319, Contig7715, Contig1420 and Contig87292) were considered to be the most potential signals, and the sucrose transporter gene (SUT) was the focus of this study. Carbohydrate transport pathway and genes’ regulation mechanism were inferred through a physiological and molecular test. SUT seemed to be the sugar sensor that could sense and regulate sugar concentration, which might have effects on other genes, such as FT, LFY and so on. LoSUT2 and LoSUT4 genes were cloned from Oriental hybrid lily ‘Sorbonne’ by RACE, which was the first time for these genes in Oriental hybrid lily ‘Sorbonne’. The physiological properties of these proteins were analyzed such as hydrophobicity and phosphorylation. In addition, secondary and tertiary structures of proteins were predicted, which indicated the two proteins were membrane proteins. Their cellular locations were verified through positioning the experiment of the fluorescent vector. They were highly expressed in cells around phloem, which illustrated the key role of these genes in sugar transport. Furthermore, transient expression assays showed that overexpressed LoSUT2 and LoSUT4 in Arabidopsis thaliana bloomed significantly earlier than the wild type and the expression of FT, SOC1 and LFY were also affected by LoSUT2 and LoSUT4, which indicated that LoSUT2 and LoSUT4 may regulate plants flowering time.

In lily reproduction, the mechanism of formation of bulbs has been a hot topic. However, studies on stem bulblet formation are limited. Stem bulblets, formed in the leaf axils of under- and above-ground stems, provide lilies with a strong capacity for self-propagation. First, we showed that above-ground stem bulblets can be induced by spraying 100 mg/L 6-BA on the LA hybrid lily ‘Aladdin’, with reduced endogenous IAA and GA₄ and a higher relative content of cytokinins. Then, expression patterns of three potential genes (two KNOTTED1-like homeobox (KNOX) and one partial BEL1-like homeobox (BELL)), during stem bulblet formation from our previous study, were determined by RT-qPCR, presenting a down-up trend in KNOXs and a rising tendency in BELL. The partial BELL gene was cloned by RACE from L. ‘Aladdin’ and denoted LaBEL1. Physical interactions of LaKNOX1-LaBEL1 and LaKNOX1-LaKNOX2 were confirmed by yeast two-hybrid and bimolecular fluorescence complementation assays. Furthermore, hormonal regulatory patterns of single LaKNOX1, LaKNOX2, LaBEL1, and their heterodimers, were revealed in transgenic Arabidopsis, suggesting that the massive mRNA accumulations of LaKNOX1, LaKNOX2 and LaBEL1 genes during stem bulblet formation could cause the dramatic relative increase of cytokinins and the decline of GAs and IAA. Taken together, a putative model was proposed that LaKNOX1 interacts with LaKNOX2 and LaBEL1 to regulate multiple phytohormones simultaneously for an appropriate hormonal homeostasis, which suggests their potential role in stem bulblet formation in L. ‘Aladdin’.

Carbohydrates are a primary nutrient for plant growth, and sugar transporter proteins play a crucial role in sugar allocation. In this study, hexose transporter genes encoding in the genome of colored calla lily ‘Jingcai Yangguang’ (Zantedeschia elliottiana cv. Jingcai Yangguang) were identified, and their expression patterns following infection by Pectobacterium carotovora subsp. Carotovora were investigated. Additionally, the transport characteristics of three hexose transporters, ZeSTP7, ZeSTP15, and ZeSTP17, were determined. The results showed that the sugar transporter protein family in Z. elliottiana comprises 18 members, most of which possess 12 transmembrane domains. Phylogenetic analysis revealed that the ZeSTP gene family was divided into five subgroups. Tandem gene duplication events were identified on the 16 chromosomes of Z. elliottiana, with multiple tandemly duplicated genes detected. Comparative analysis of synteny between species identified ZeSTP8 and OsSTP22 as homologous gene pairs, while OsSTP6 (OsMST6) was identified as a homologous gene pair with both ZeSTP14 and ZeSTP17. Following infection by P. carotovora subsp. carotovora, the transcript levels of ZeSTP7, ZeSTP15, and ZeST17 were all significantly elevated. Yeast mutant hexose complementation tests indicated that ZeSTP7 could transport glucose and galactose, whereas ZeSTP15 and ZeSTP17 exhibited limited transport capacity in this respect. This study provides a systematic identification and analysis of hexose transporter genes at the genome-wide level, highlighting the role of ZeSTP genes in the response of colored calla lily to soft rot and laying a theoretical foundation for further understanding the functions of sugar transporter genes.

Here, we present the complete genome sequence of Providencia rettgeri strain ZAPR22R, isolated from the petiole and tuber of calla lily ( Zantedeschia hybrida ), infected with soft rot. The genome consists of a single chromosome (4,528,722 bp) with a G+C content of 41.1%.

The complete genome of Pectobacterium brasiliense WZZ2024, isolated from soft rot-infected petioles and tubers of fast-growing cabbage ( Brassica rapa var. glabra Regel ), comprises a single 4.83 Mb chromosome (GC content: 52.16%).