Water is a crucial element for the growth of watermelon plants, making rapid and non-destructive monitoring of plant water content vital for precision irrigation in watermelon farming. While previous research has demonstrated the sensitivity of short-wave infrared (SWIR) bands to plant water content, their high costs limit widespread application. In contrast, visible and near-infrared (VNIR) spectral instruments offer significant advantages in terms of affordability, compactness, and spectral resolution. However, their potential for predicting the leaf water content (LWC) of watermelon plants has yet to be fully investigated. This study aims to assess the efficacy of hyperspectral reflectance measured with VNIR spectral instruments in estimating the LWC of watermelon plants at various leaf layers. Hyperspectral reflectance data (350−1100 nm) were collected from three leaf layers (upper, middle, and lower) under various drought treatments. Models for estimating LWC were developed using both spectral indices and full wavelength data. The results indicated that the middle leaf layer was the most effective for estimating LWC, and using full wavelength data achieved higher accuracy in LWC estimation. Furthermore, compared to the simple regression model, the AdaBoost-based machine learning model demonstrated superior performance, achieving an R2 of 0.9636 in estimating LWC through five-fold cross-validation, which indicates high predictive accuracy. Ensemble learning significantly outperforms traditional methods, providing a substantial improvement in model accuracy. The findings offer important technical assistance for the spectral monitoring of LWC and precision irrigation in watermelon cultivation.

The color of the rind is one of the most crucial agronomic characteristics of watermelon (Citrullus lanatus L.). Its genetic analysis was conducted to provide the identification of genes regulating rind color and improving the quality of watermelon appearance. In this study, a mapping population of 505 F2 plants, derived from a cross between green (CG058) and light-green (CG265) rinds, along with a high-density genetic linkage (average 0.9 cM distance between bin markers), was used to map and identify possible candidate genes. The green rind trait was determined to be regulated by a single Mendelian locus and was precisely located within a 110 kb genomic site on chromosome nine (Chr 9). In the respective region, two potential genes, Cla97C09G175170 and Cla97C09G175180, were substantially downregulated in the light-green rind in comparison to the green rind. Previous studies revealed that Cla97C09G175170, encoding a two-component response regulator-like protein (APRR2), is possibly involved in the green rind trait in watermelon. Virus-induced gene silencing (VIGS) assay confirmed that ClAPRR2 is a key gene responsible for green rind color. Moreover, qRT-PCR analysis revealed that the transcription levels of multiple key genes in the chlorophyll (Chl) biosynthesis pathway were downregulated in the light-green rind relative to the green rind. The current findings have the potential to clarify the regulatory mechanisms that underlie the color of the watermelon rind. These data would provide valuable insights for the targeted molecular design and development of watermelon rinds.

江城1号是湖北省农业科学院经济作物研究所以自交系003CBA作母本,自交系296ACA作父本杂交选育而成的优质有籽西瓜新品种.中熟,春露地栽培果实发育天数32 d左右.易坐果,平均单果质量6～8 kg,每667 m2产量2400～2500 kg.果实椭圆形,果皮浅绿色覆绿色宽虎条,果皮厚1.1 cm左右,不易裂果.瓤色红,中心糖含量12.0％左右,边糖含量9.0％左右,瓜瓤细脆.适宜湖北省平原地区春季露地种植.2023年通过国家非主要农作物品种登记,编号为GPD西瓜(2023)420012.

IntroductionFlesh color is an important trait in watermelon (Citrullus lanatus L.). Several flesh color genes have been identified in watermelon; however, the inheritance of and the molecular basis underlying the white flesh trait remain largely unknown.MethodsIn this study, segregation populations were constructed by crossing the canary yellow flesh line HSH-F with the white flesh line Sanbai to fine-map the white flesh gene in watermelon.ResultsGenetic analysis indicated that the white flesh trait is controlled by a single recessive locus, termed Clwf2. Map-based cloning delimited the Clwf2 locus to a 132.3-kb region on chromosome 6. The candidate region contains 13 putative genes, and four of them—Cla97C06G121860, Cla97C06G121880, Cla97C06G121890, and Cla97C06G121900—were significantly downregulated in the white flesh compared to the canary yellow flesh watermelon fruits. The Cla97C06G121890 gene, which encodes a tetratricopeptide repeat protein, showed almost no expression in the white flesh fruit before maturity, whereas it had a very high expression in the canary yellow flesh fruit at 18 days after pollination. Transmission electron microscopy revealed rounded and regularly shaped chromoplasts in both the canary yellow and white flesh fruits. Further quantitative real-time PCR analysis showed that the expression levels of several key plastid division genes and almost the entire carotenoid biosynthesis pathway genes were downregulated in the white flesh compared to the canary yellow flesh fruits.DiscussionThis study suggests that the proliferation inhibition of chromoplasts and downregulation of the CBP genes block the accumulation of carotenoids in watermelon and lead to white flesh. These findings advance and extend the understanding of the molecular mechanisms underlying white flesh trait formation and carotenoid biosynthesis in watermelon.

Cadmium pollution in agricultural soil is a great threat to crop growth and human health. In this research, with 1%, 3% and 5% biochar applied to control soil cadmium pollution, melon was selected to be the experimental object for physiological detection and transcriptome analysis, through which we explored the mechanism of cadmium tolerance and biochar mitigating cadmium stress in muskmelon. Three set concentrations of biochar have a mitigative effect on muskmelon cadmium stress, and 5% biochar and 3% biochar respectively have the best and the worst alleviative effect. The alleviation of biochar to cadmium stress on muskmelon is primarily in the manner of inhibiting cadmium transfer, while the resistance of muskmelon to cadmium stress is through activating phenylpropanoid pathway and overexpressing stress related genes. Under cadmium treatment, 11 genes of the phenylpropane pathway and 19 stress-related genes including cytochrome P450 family protein genes and WRKY transcription factor genes were up-regulated, while 1%, 3%, 5% biochar addition significantly downregulated 3, 0, 7 phenylpropane pathway genes and 17, 5, 16 stress-related genes, respectively. Genes such as cytochrome P450 protein family genes, WRKY transcription factor genes, and annexin genes may play a key role in muskmelon's resistance to cadmium stress. The results show the key pathways and genes of cadmium stress resistance and the effect of different concentrations of biochar in alleviating cadmium stress, which provide a reference for the research of cadmium stress resistance in crops and the application of biochar in cadmium pollution in agricultural soil.

Cadmium (Cd) pollution is the most dangerous and widespread heavy metal pollution in our country, which seriously affects food safety and human health. It is urgent to study the method and mechanism of alleviating Cd toxicity. In the experiment, we examined the effects of normal growth, Cd stress (400 mg/kg) and a-Fe2O3 nanoparticles (NPs) (50 mg/kg) + Cd stress (400 mg/kg) on muskmelon seedlings through pot experiments. The distribution of Cd in the system and the physiological indicators such as antioxidant enzymes in muskmelon leaves were measured. The transcriptome of muskmelon seedling leaves was sequenced by Illumina sequencing technology. The results showed that a-Fe2O3 NPs could reduce the content of Cd in muskmelon fruits by 52.25% compared with the Cd treatment. In addition, a-Fe2O3 NPs could reduce the activity of superoxide dismutase (SOD) and catalase (CAT) by 24.98% and 29.54%, respectively. The results of transcriptome analysis showed that muskmelon seedlings mainly responded to cadmium stress by up-regulating the expression of 312 differentially expressed genes (DEGs), while the application of a-Fe2O3 NPs mainly responded to Cd stress by down-regulating the expression of DEGs (369 down-regulated genes). After a-Fe2O3 NPs application, the expression of Psb and Psa genes encoding structural proteins of photosystem II and photosystem I increased significantly, protecting the photosynthetic system. a-Fe2O3 NPs protects plants by activating auxin responsive genes, inhibiting the overexpression of abscisic acid (ABA) signal transduction factors, and relieving the inhibition effect of Jasmonate ZIM-domain (JAZ) on jasmonic acid-mediated hormone signal transduction pathways. The enrichment analysis of mitogen-activated protein kinase (MAPK) signal transduction pathway suggested that a-Fe2O3 NPs could improve plant tolerance to Cd by regulating the balance of reactive oxygen species in plants. In conclusion, a-Fe2O3 NPs can alleviate muskmelon Cd toxicity and protect the human body from Cd damage. In this study, the molecular mechanism of a-Fe2O3 NPs alleviating Cd stress in muskmelon was thoroughly investigated, which provides a basis for further application in genetic engineering and phytoremediation. (c) 2023 SAAB. Published by Elsevier B.V. All rights reserved.

Cadmium pollution in farmland has become a global environmental problem, threatening ecological security and human health. Biochar is effective in remediation of soil pollution. However, high concentrations of biochar can inhibit plant growth, and low concentrations of biochar have limited mitigation effect on cadmium toxicity. Therefore, the combination of low-concentration biochar and other amendments is a promising approach to alleviate cadmium toxicity in plants and improve the safety of edible parts. In this study, muskmelon was selected as the research object, and different concentrations of α-Fe2O3 nanoparticles were used alone or combined with biochar to explore the effects of different treatments on muskmelon plants in cadmium-contaminated soil. The results showed that the combined application of 250 mg/kg α-Fe2O3 nanoparticles and biochar had a good effect on the repair of cadmium toxicity in muskmelon plants. Compared with cadmium treatment, its application increased plant height by 32.53

Cadmium is toxic to plants. The accumulation of cadmium in edible plants such as muskmelon may affect the safe production of crops and result in human health problem. Thus effective measures are urgently needed for soil remediation. This work aims to investigate the effects of nano-ferric oxide and biochar alone or mixture on muskmelon under cadmium stress. The results of growth and physiological indexes showed that compared with the application of cadmium alone, the composite treatment (biochar and nano-ferric oxide) decreased malondialdehyde content by 59.12% and ascorbate peroxidase activity increased by 276.6%. Their addition can increase the stress resistance of plants. The results of soil analysis and cadmium content determination in plants showed that the composite treatment was beneficial to reduce the cadmium content in various parts of muskmelon. In the presence of high concentration of cadmium, the Target Hazard Quotient value of peel and flesh of muskmelon in the composite treatment was less than 1, which means the edible risk was greatly reduced. Furthermore, the addition of composite treatment increased the content of effective components; the contents of polyphenols, flavonoids, and saponins in the flesh of the compound treatment were increased by 99.73%, 143.07%, and 18.78% compared with the cadmium treatment. The results provide a technical reference for the further application of biochar combined with nano-ferric oxide in the field of soil heavy metal remediation, and provide a theoretical basis for further research on reducing the toxicity of cadmium to plants and improving the edible quality of crops.

Tendrils are threadlike organs in vining plants that play essential role in climbing to reach more sunlight and growing space. However, the molecular basis underlying tendril organogenesis has only been studied in a few taxa. Here, a tendril-less watermelon mutant CG149 with determinate inflorescence was identified. Genetic analysis showed that the two traits of tendril-less and determinate inflorescence were co-segregated and were controlled by a single recessive gene, termed as Cltl/df . Bulked segregant sequencing and map-based cloning delimited the Cltl/df locus into a 61.6 kb region in watermelon chromosome 4. Gene sequence and expression analysis revealed that gene Cla97C04G076830 ( ClTFL1 ) encodes a TERMINAL FLOWER 1 protein as the most probable candidate gene for Cltl/df . A single nucleotide mutation from C to A in the fourth exon was identified in ClTFL1 , which resulted in a mutation from alanine to glutamic acid within a conserved motif of the TFL1 protein. Further qRT-PCR analysis showed that the expression level of ClTFL1 was significantly down-regulated in the inflorescence of the tendril-less mutant. The results of this study reveal the pleiotropic effects of ClTFL1 in regulating watermelon architecture and provide molecular mechanism of tendril organogenesis in angiosperms.

楚天1号是湖北省农业科学院经济作物研究所以四倍体西瓜自交系4W006CAA作母本、二倍体西瓜自交系2W018CAA作父本杂交选育而成的中熟优质无籽西瓜新品种.其在湖北省春季露地栽培果实发育时间为34 d左右.平均单果重5～7 kg,单产33000～34500 kg/hm2.果实圆形,果皮黑色上覆不规则隐纹,果皮厚1.2 cm左右,不易裂果.瓤色红,中心含糖量12％左右,边部含糖量8％左右,瓜瓤硬度中等,肉质脆.适宜在湖北省平原地区春季露地种植.2021年楚天1号通过国家非主要农作物品种登记.

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.

根肿病现已成为中国十字花科作物的主要病害之一,萝卜等十字花科蔬菜因根肿病的侵害可大量减产甚至绝收.分子标记被广泛应用于标记辅助选择育种领域,本研究在前期定位的5个抗根肿病区间内挖掘抗病基因,并开发分子标记.与参考基因组比对后,进行基因KEGG和KOG_class注释分析,挖掘到注释为抗病(Disease resistance)和具有抗病基因结构域的基因,共计38个,在抗病基因所在的位置开发分子标记,共获得20对SSR标记.多态性鉴定筛选出5对SSR标记,利用F2分离群体的基因型和F2∶3的表型,最终确定SSR标记fold92946_4806与根肿病的抗性关联.重建图谱第九条染色体,对比之前的QTL定位结果,fold92946_4806标记在定位区间RsCr2内,研究认为该标记为QTL位点关联的抗病标记.

Plant male sterility not only has important theoretical value in the study of plant development, but also has important application value in the utilization of heterosis in crops and fruits. However, the molecular mechanism of male sterility in watermelon, especially in artificially created autotetraploid watermelon, is still unclear. In the present study, we performed comparative transcriptome analysis between two normal fertile autotetraploid watermelon W59 and N14 and a male sterile autotetraploid watermelon N14-MS. A total of 1,045 differentially expressed genes (DEGs) related to the male sterility were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment of the DGEs showed that pathways of lipid metabolism and flavonoid biosynthesis were significantly enriched. Moreover, a number of DEGs related to male sterility were identified, including the CER1, FAR, LOX2S, HPL, OPR, CHS and F3H gene. Also, DEGs directly regulate anther cuticle development and pollen wall development were detected, such as the BAHD acyltransferase gene, GDSL esterase/lipase gene, and jasmonic acid-amino synthetase. Furthermore, a number of differentially expressed transcription factors including the MYBs, WRKYs, MADS, and bHLHs were identified. Our research provides a basis for further studies of molecular mechanism of male sterility in watermelon and related cucurbit plants.

凯丽是以自交系2W292作母本,自交系2W293作父本杂交选育而成的优质有籽西瓜新品种.早中熟,春露地栽培果实发育天数32～33 d;易坐果,平均单瓜质量6～8 kg,667 m2产量2300～2500 kg;果实高圆形,果皮深绿色覆墨绿色条带,果皮厚1.2 cm左右,不易裂果;瓤色大红,中心糖含量12.0％左右,边糖含量9.0％左右,瓜瓤硬度中等,肉质细脆;适宜湖北省平原地区春季露地和大棚种植;2019年通过国家非主要农作物品种登记.

Cadmium (Cd) contamination is the most serious and largest heavy metal pollution of China. It is necessary to explore the mechanism of Cd poisoning and the mechanism of resistance to Cd stress in crops. In the study, Illumina sequencing technology was used for transcriptome high-throughput sequencing. The molecular mechanism of Cd stress in muskmelon was investigated using gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis. In addition, through the detection of physiological indexes of muskmelon leaves, it was found that chlorophyll content and POD activity were considerably reduced. In addition, the related genes were significantly up-regulated exposed to Cd. In the study, the main pathways and genes of muskmelon response to Cd stress were analysed, providing a theoretical foundation for future research into the mechanism of Cd stress response.

西瓜是湖北省重要的经济作物,2020年种植面积104.3万亩(6.95万hm2),全省可分为三大西瓜产区,分别是鄂东南早熟西瓜区、鄂西北中晚熟西瓜区和江汉平原无籽西瓜区.湖北省属北亚热带季风气候,降水丰沛,雨热同季,早春潮湿寡照,病虫害多发,且西瓜种植习惯与大田作物一样,大水大肥,重化肥轻有机肥,且化肥、农药滥用、乱用、过量使用现象时有发生,带来的直接影响就是产品安全无法保障,环境面源污染加重,西瓜生产过程中的化肥农药减施已迫在眉睫.集成和优化适合湖北省西瓜化肥农药减施增效生产技术是为了规范湖北省西瓜主产区合理、科学施用化肥和农药,推动西瓜产业向安全、健康方向发展,同时促进湖北省生态环境保护.

病害是西瓜生产中导致产量和品质下降的关键因素.利用已报道的西瓜抗枯萎病、炭疽病和白粉病分子标记对230份西瓜种质资源进行抗病性鉴定,分别筛选出相应的抗性种质60份、20份和35份,其中兼抗枯萎病和炭疽病的资源6份,兼抗枯萎病和白粉病的资源8份,兼抗炭疽病和白粉病的资源6份.对其中23份种质进行抗枯萎病人工接种鉴定,筛选出8份高抗西瓜种质,为西瓜抗病育种提供了宝贵的种质资源.

楚金1号是以高代自交系TH607为母本,以高代自交系TH605为父本配制而成的中晚熟厚皮甜瓜一代杂种,全生育期103 d(天)左右,果实发育期42～45 d(天).植株生长势强,分枝能力中等,叶色绿,以子蔓结瓜为主.果实圆形,果皮黄色覆深绿色斑块,单果质量1.5 kg左右,果肉白色,果肉厚3.7 cm左右,肉质软,中心可溶性固形物含量16％左右,品质优良,口感风味好.田间对白粉病、霜霉病的抗性与对照伊丽莎白相当,大棚吊蔓栽培产量2500 kg·(667 m2)-1左右,适宜长江中下游地区春秋季设施栽培.

种质资源遗传背景狭窄是当前西瓜育种面临的一大瓶颈.利用449个SNP标记对64份西瓜材料进行遗传多样性分析,结果表明,平均多态性信息含量(PIC)为0.229,平均Nei's多样性指数(H)为0.28,平均Shannon多样性指数(I)为0.43,平均期望杂合度(He)为0.282;64份材料的最优群体结构数为4,各亚群材料的地理来源与遗传关系没有显著相关性;材料之间的平均遗传距离为0.175.农艺性状统计分析表明,4个亚群在首雌花节位、坐果节位和果皮厚度3个性状之间存在显著差异.本研究将为西瓜种质资源创制、杂交育种的亲本选择和培育优异、适应性强的西瓜新品种提供理论依据.

病毒病是为害萝卜的主要病害之一.基于核酸检测的植物病毒病检测技术,因其检测范围广、灵敏度高、适合大批量检测而得以广泛应用.本试验利用小RNA高通量测序方法鉴定萝卜病毒病的种类,并调查分析了264份萝卜核心种质资源及育种品系对病毒病的抗性.结果表明:萝卜病毒病的主要病原为芜菁花叶病毒(TuMV).参试的核心种质资源和品系多数表现出较好的抗性,且不同品系姊妹系间抗性表现基本趋于一致.田间抗病性调查结果显示:抗病材料有103份,高抗材料有64份,且有25份材料达到免疫.