Molecular Horticulture最新文献

Parthenocarpy is an important target trait for the yield and quality of fruit crops. It has been used and selected in cucumber breeding for more than a hundred years, which has led to variation in parthenocarpic ability among different cucumber groups and thus resulted in a complex genetic basis. Here, we performed deep resequencing of 236 cucumbers from six cucumber groups and investigated parthenocarpic phenotypes over three years and six seasons to explore the genetic basis of parthenocarpy in cucumber. Among the 34 loci associated with parthenocarpy identified through a genome-wide association study (GWAS), 17 (50%) were correlated with reported quantitative trait loci (QTLs), and 27 (79.4%) were selected during cucumber domestication. We found that favorable parthenocarpic alleles continuously accumulated in cultivated cucumbers, and our data pinpoint that different favorable alleles were selected in the cucumber groups, leading to variations in parthenocarpic ability among them. To validate the favorable alleles detected by GWAS, we cloned three genes, CsACA10, CsCaM, and CsERT2, and verified their roles in the regulation of parthenocarpy for the first time. Our study elucidated the genetic basis and molecular mechanism of parthenocarpy, providing important germplasms for improving parthenocarpy in cucumber breeding.

Drought stress is a significant environmental threat to global agricultural production and distribution. Plant adaptation to dehydration stress involves intricate biological processes with substantial changes in metabolite composition. In this study, we investigated the role of tricarboxylic acid (TCA) cycle metabolites in drought tolerance in grapevine and Arabidopsis by metabolome, live cell imaging, electrophysiological and pharmacological approaches. Metabolome analysis revealed that amount of malate, citrate, and isocitrate increased over time in detached grapevine leaves. Ca²⁺ imaging and ion channel measurements indicated that fumarate, malate, and α-ketoglutarate induced cytosolic free Ca²⁺ concentration ([Ca²⁺]_cyt) elevation in guard cells and directly activated a guard-cell anion channel SLOW ANION CHANNEL-ASSOCIATED 1 (SLAC1). However, only malate induced stomatal closure, which required increases in [Ca²⁺]_cyt in guard cells and activation of SLAC1. Through pharmacological experiments and reverse genetics analyses, G-proteins were identified as essential components of malate signaling by regulating second messenger production. These results indicate that TCA cycle metabolites are sensed individually by guard cells and that malate plays a key role in connecting metabolic regulation and drought tolerance through G-protein-dependent signal cascades.

Prunus species, also known as stone fruits, include several eye-catching fruits such as cherries, plums, apricots, peaches, nectarines, etc., which have significant economic value and are widely cultivated worldwide. Carotenoids are important secondary metabolites contributing to stone fruits' aesthetic appeal and nutritional value. Carotenoids contribute hues ranging from pastel yellow to rich orange in Prunus fruits. Carotenoids accumulate in Prunus tissues through the action of chromoplasts, particular structures that store and stabilize these pigments, giving rise to their vibrant colors. The diversity in carotenoid types and levels among Prunus species and cultivars leads to diverse tissue colors, reflecting their genetic diversity and evolutionary adaptations. The most important genes related to coloration are PSY, LCYB/E, and BCH1, which are responsible for carotenoid biosynthesis, whereas CCDs and NCEDs are involved in the degradation of carotenoids. PSY leads to increased carotenoid accumulation, providing yellow and orange pigmentation. LCYB involved in β-carotene accumulation results in an orange color. LCYE can lead to lutein biosynthesis and contribute to yellow coloration. BCH1 contributes to yellow pigmentation. CCD4 plays an essential role in the flesh color of the fruit, leading to white flesh in Prunus fruits, especially peaches. NCED is involved in abscisic acid formation by degrading carotenoids. Despite the importance of carotenoids, the connection between carotenoid profiles and the diversity of Prunus fruits has received little attention in the past. This review outlines the present knowledge regarding the molecular diversity mechanisms of the carotenoid biosynthesis pathway in Prunus fruits.

Anthocyanin pigmentation and soluble sugar content are important factors affecting the quality of strawberry fruits, and their accumulation processes are profoundly influenced by light signals. However, the molecular mechanism through which light regulates this process remains to be fully elucidated. Here, we identified two blue light receptors, FvCRY1 and FvCRY2, from woodland strawberry. Functional complementation in Arabidopsis cryptochrome mutant confirmed their photoperceptor roles. Stable overexpression of FvCRYs in cultivated strawberry (Fragaria × ananassa 'Ningyu') significantly enhanced anthocyanin accumulation and soluble sugar content, concomitant with upregulation of key biosynthetic genes. Strikingly, yeast one-hybrid and dual-luciferase assays revealed FvCRYs possess intrinsic transcriptional activation domains that directly bind E-box cis-elements in promoters of anthocyanin synthesis gene FvCHS2, FvDFR2, FvCHI, and sugar metabolism-related genes FvSFP9 and FvINV. This DNA-binding capacity is potentiated by blue light, enabling transcriptional expression of anthocyanin synthesis and sugar metabolism genes. Our findings unveil a non-canonical cryptochrome signaling mechanism involving direct receptor-promoter interaction, redefining our understanding of photoreceptor-mediated frui quality regulation.

Pepper (Capsicum spp.), one of the world's most important vegetable and spice crops, has attracted considerable attention due to its phenotypic diversity, abundant secondary metabolites (particularly capsaicinoids), and substantial economic value. However, current research on the genetic basis and key regulatory genes underlying most traits in pepper is limited. Therefore, in this study, we used two parental lines that presented multiple phenotypic differences-namely, BVRC1 and BVRC25-to generate a recombinant inbred line (RIL) population (F₁₀ generation, 216 lines), after which we performed whole-genome re-sequencing on all lines. Based on a high-resolution bin map, 19 significant loci were identified in association with 13 traits, explaining an average of 26% of the phenotypic variance in the RILs. On the basis of uncovering the major effect locus FL-3.2 (FS-3.1) for fruit shape/fruit length, we constructed new genetic populations to finely map and clone a novel minor-effect regulatory locus FL-10.1 for fruit length. Candidate gene CaSUN29 encoded an IQD protein that was specifically expressed in the early stage of fruit development, affected cell expansion in the pepper pericarp, and subsequently impacted fruit elongation. Virus-induced gene silencing of CaSUN29 in pepper resulted in shorter fruit, while heterologous CaSUN29 overexpression in tomato led to longer fruit. In contrast to the pleiotropic locus FL-3.2, which regulated fruit length, width, and shape simultaneously, FL-10.1 only regulated fruit length. Based on the identified loci, a trait-locus network was constructed to understand the correlations among traits based on the degree of locus linkage. These findings are helpful for our exploration of new genes regulating important traits, providing better understanding of the linkage relationships among complex traits.

Alpinia officinarum Hance, a medicinal and edible plant in the Zingiberaceae family, has applications in pharmaceuticals, food, nutraceuticals, spices, cosmetics, and fruit and vegetable preservation. However, the molecular mechanisms governing the biosynthesis of flavonoids, the primary bioactive compounds in A. officinarum, remain unclear. This study provided the first chromosome-grade genome assembly of A. officinarum, revealing it to be a triploid species with a 2.10-Gb haploid genome. Using integrated transcriptomic and metabolomic analysis, 107 flavonoid compounds selectively accumulated in the rhizome and prospective rhizome-specific flavonoid genes were identified. Gene-metabolite correlation analysis and weighted gene co-expression network analysis suggested that AobHLH94 was imperative to flavonoid biosynthesis regulation in the rhizome. Functional assays confirmed that AobHLH94 was a key regulator in the flavonoid biosynthesis pathway in A. officinarum and enhanced flavonoid accumulation in rice (Oryza sativa). We also discovered that AobHLH94 bound to the e-box elements (-CANNTG-) in the promoters of AoC4H and AoCHI genes, thereby upregulating their expression levels and enhancing flavonoid synthesis. Simultaneously, AobHLH94 indirectly modulated AoCHS. Our research explains the regulatory processes behind rhizome-specific flavonoid accumulation and provides relevant information for future A. officinarum improvement and breeding efforts.