Gain-of-function of the 1-aminocyclopropane-1-carboxylate synthase gene ACS1G induces female flower development in cucumber gynoecy.

Unisexual flowers provide a useful system for studying plant sex determination. In cucumber (Cucumis sativus L.), three major Mendelian loci control unisexual flower development, Female (F), androecious [a; 1-aminocyclopropane-1-carboxylate {ACC} synthase 11, acs11], and Monoecious (M; ACS2), referred to here as the Female, Androecious, Monoecious (FAM) model, in combination with two genes, gynoecious (g, the WIP family C2H2 zinc finger transcription factor gene WIP1) and the ethylene biosynthetic gene ACC oxidase 2 (ACO2). The F locus, conferring gynoecy and the potential for increasing fruit yield, is defined by a 30.2-kb tandem duplication containing three genes. However, the gene that determines the Female phenotype, and its mechanism, remains unknown. Here, we created a set of mutants and revealed that ACS1G is responsible for gynoecy conferred by the F locus. The duplication resulted in ACS1G acquiring a new promoter and expression pattern; in plants carrying the F locus duplication, ACS1G is expressed early in floral bud development, where it functions with ACO2 to generate an ethylene burst. The resulting ethylene represses WIP1 and activates ACS2 to initiate gynoecy. This early ACS1G expression bypasses the need for ACS11 to produce ethylene, thereby establishing a dominant pathway for female floral development. Based on these findings, we propose a model for how these ethylene biosynthesis genes cooperate to control unisexual flower development in cucumber.

An exon skipping in a SEPALLATA-Like gene is associated with perturbed floral and fruits development in cucumber.

We isolated a mutant showing perturbations in the development of male and female floral organs and fruits. Analysis of the single nucleotide polymorphisms from bulked F2 pools identified the causative variant occurring in Csa4G126690. Csa4G126690 shows high homology to Arabidopsis SEPALLATA2 (SEP2) thus being designated CsSEP2. The causative variant was located on the splicing site of CsSEP2, resulting in the skipping of exon 6 and abolishment of the transcriptional activity. Our data suggest that CsSEP2 is involved in the floral organ and fruits development by conferring transcriptional activity.

Fertility restorer gene CaRf and PepperSNP50K provide a promising breeding system for hybrid pepper.

Cytoplasmic male sterility (CMS) is pivotal in plant breeding and widely employed in various crop hybrids, including pepper. However, the functional validation of the restorer of fertility (Rf) gene in pepper has been lacking until now. This study identifies and characterizes CaRf, a single dominant locus crucial for restoring CMS in the pepper strong recovery inbred line Zhangshugang. The CaRf gene encodes a mitochondria-targeted pentatricopeptide repeat protein, validated through the induction of male sterility upon its silencing in hybrid F1 plants. To enhance pepper breeding efficiency, 176 important pepper breeding parent materials were resequenced, and a PepperSNP50K liquid-phase breeding chip was developed, comprising 51 172 markers. Integration of CaRf functional characterization and PepperSNP50K facilitated the development of a high-quality red pepper hybrid. These findings provide significant insights and practical strategies for advancing molecular-designed breeding in peppers.

A multi-omics approach identifies bHLH71-like as a positive regulator of yellowing leaf pepper mutants exposed to high-intensity light.

Light quality and intensity can have a significant impact on plant health and crop productivity. Chlorophylls and carotenoids are classes of plant pigments that are responsible for harvesting light energy and protecting plants from the damaging effects of intense light. Our understanding of the role played by plant pigments in light sensitivity has been aided by light-sensitive mutants that change colors upon exposure to light of variable intensity. In this study, we conducted transcriptomic, metabolomic, and hormone analyses on a novel yellowing mutant of pepper (yl1) to shed light on the molecular mechanism that regulates the transition from green to yellow leaves in this mutant upon exposure to high-intensity light. Our results revealed greater accumulation of the carotenoid precursor phytoene and the carotenoids phytofluene, antheraxanthin, and zeaxanthin in yl1 compared with wild-type plants under high light intensity. A transcriptomic analysis confirmed that enzymes involved in zeaxanthin and antheraxanthin biosynthesis were upregulated in yl1 upon exposure to high-intensity light. We also identified a single basic helix-loop-helix (bHLH) transcription factor, bHLH71-like, that was differentially expressed and positively correlated with light intensity in yl1. Silencing of bHLH71-like in pepper plants suppressed the yellowing phenotype and led to reduced accumulation of zeaxanthin and antheraxanthin. We propose that the yellow phenotype of yl1 induced by high light intensity could be caused by an increase in yellow carotenoid pigments, concurrent with a decrease in chlorophyll accumulation. Our results also suggest that bHLH71-like functions as a positive regulator of carotenoid biosynthesis in pepper.

Eu3+-doped Bi4Si3O12 red phosphor for solid state lighting: microwave synthesis, characterization, photoluminescence properties and thermal quenching mechanisms.

Europium-doped bismuth silicate (Bi4Si3O12) phosphor has been prepared by microwave irradiation method and its crystal structure is determined using Rietveld method. As-prepared phosphor consists of spherical, monodispersed particles with few agglomeration, high crystallinity, and narrow grain size distribution. The phosphor can be efficiently excited in the wavelength range of 260-400 nm, which matched well with the emission wavelengths of NUV LED chips. The photoluminescence spectra exhibit the highest emission peak at 703 nm originating from 5D0 → 7F4 transition of Eu3+ under NUV excitation. The luminescence lifetime for Bi4Si3O12: 2 at% Eu3+ phosphor decreases from 2.11 to 1.86 ms with increasing temperature from 10 to 498 K. This behavior of decays is discussed in terms of radiative and nonradiative decays dependence on temperature. The thermal quenching mechanism of 5D0 emission of Eu3+ in Bi4Si3O12 phosphor is a crossover process from the 5D0 level of Eu3+ to a ligand-to-europium (O2- → Eu3+) charge transfer state. The quantum efficiency of the phosphor under 393 nm excitation is found to be 14.5%, which is higher than that of the commercial red phosphors Y2O3: Eu3+, Y2O2S: Eu3+. The temperature effect on CIE coordinate was discussed in order to further investigate the potential applications.

An ACC Oxidase Gene Essential for Cucumber Carpel Development.

Sex determination in plants gives rise to unisexual flowers that facilitate outcrossing and enhance genetic diversity. In cucumber and melon, ethylene promotes carpel development and arrests stamen development. Five sex-determination genes have been identified, including four encoding 1-aminocyclopropane-1-carboxylate (ACC) synthase that catalyzes the rate-limiting step in ethylene biosynthesis, and a transcription factor gene CmWIP1 that corresponds to the Mendelian locus gynoecious in melon and is a negative regulator of femaleness. ACC oxidase (ACO) converts ACC into ethylene; however, it remains elusive which ACO gene in the cucumber genome is critical for sex determination and how CmWIP1 represses development of female flowers. In this study, we discovered that mutation in an ACO gene, CsACO2, confers androecy in cucumber that bears only male flowers. The mutation disrupts the enzymatic activity of CsACO2, resulting in 50% less ethylene emission from shoot tips. CsACO2 was expressed in the carpel primordia and its expression overlapped with that of CsACS11 in female flowers at key stages for sex determination, presumably providing sufficient ethylene required for proper CsACS2 expression. CmACO3, the ortholog of CsACO2, showed a similar expression pattern in the carpel region, suggesting a conserved function of CsACO2/CmACO3. We demonstrated that CsWIP1, the ortholog of CmWIP1, could directly bind the promoter of CsACO2 and repress its expression. Taken together, we propose a presumably conserved regulatory module consisting of WIP1 transcription factor and ACO controls unisexual flower development in cucumber and melon.

[Effects of yikunning on the expressions of bcl-2 and bax in rat ovaries during perimenopausal period].

OBJECTIVE: To investigate the effects of Yikunning (YKN, Chinese Traditional Medicine) on the expressions of bcl-2 and bax in rat ovaries during perimenopausal period. METHODS: Thirty female Wistar rats during perimenopausal period were selected by unforced aging. Then the rats were divided into 3 groups randomly: YKN group, Livial control group and Aged control group. Ten young female Wistar rats were selected as young control group. Intragastric administrations were conducted for 4 weeks once daily continuously. The expressions of Bcl-2 Bax mRNAs and proteins in rat ovaries were detected by RT-PCR and Western blot. RESULTS: The levels of Bcl-2, Bax mRNAs and proteins in rat ovaries in YKN group were higher than those in Aged control group, which showed differences among them (P < 0.01). The Bcl-2/Bax mRNA rate and protein rate in rat ovaries in YKN group were higher than those in Aged control group, which showed differences among them (P < 0.05 or P < 0.01). CONCLUSION: YKN could increase the expressions of Bcl-2, Bax mRNAs and proteins and up-regulate the Bcl-2/Bax mRNA rate, protein rate in rat ovaries during perimenopausal period, which might be one of the molecular mechanisms of YKN postponed the ovarian failure and cured perimenopausal syndrome.

[Effects of Yikunning on the apoptotic rate and expression of caspase-3 in rat ovaries during perimenopausal period].

OBJECTIVE: To investigate the effects of Yikunning (compound of Chinese traditional Medicine, YKN) on the apoptotic rate and expression of caspase-3 in rat ovaries during perimenopausal period. METHODS: Thirty female Wistar rats during perimenopausal period were selected by unforced aging. Then the rats were divided into 3 groups randomly: YKN group, livial control group and aged control group. Ten young female rats were selected as young control group. Intragastric administrations were conducted for 4 weeks once daily continuously. The apoptotic rate in rat ovaries were detected by TUNEL. The expression of caspase-3 mRNA and protein in rat ovaries were detected by RT-PCR and Western blot, respectively. RESULTS: The apoptotic rate in rat ovaries in YKN group was lower than that in aged control group, which showed difference between them (P < 0.01). The levels of caspase-3 mRNA and protein in rat ovaries in YKN group were lower than those in aged control group, which showed differences among them (P < 0.01). CONCLUSION: YKN can decrease the apoptotic rate and down-regulate the expression of caspase-3 mRNA and protein in rat ovaries of during perimenopausal period. It may be one of the molecular mechanisms of YKN postponed the ovarian failure and cured perimenopausal syndrome.