Twenty-four representative melon varieties and six parental cultivars were examined in this study. Among 159 pairs of simple sequence repeat (SSR) primers, 18 SSR core primers with rich polymorphic information, a large number of genotypes, and the ability to distinguish different melon varieties were selected. A total of 113 genotypes were detected among the 30 experimental materials, with an average of 6.28 genotypes for each pair of primers. The polymorphic information content was on average 0.6807, ranging from 0.5618 to 0.7885. Specific bands of the primers for the 30 experimental materials were analyzed, and by combining different primer loci, all 30 varieties were identified. Unique barcodes for molecular identity cards for the 30 experimental materials were established using the fingerprints formed with this SSR marker system. Each variety has a unique identity card that can be applied for the registration of the newly bred varieties, the protection of breeders’ rights, and the authenticity of breeds after promulgation of the new Seed Law of the People’s Republic of China.
Li Li, Xiulan Xu, Ping Wu, Guo Zhang, and Xiaobing Zhang
Jiyu Zhang, Min Wang, Zhenghai Mo, Gang Wang, and Zhongren Guo
The floral homeotic C-function gene AGAMOUS (AG) has been shown to be critical in the determination of stamen and carpel identity in Arabidopsis. In the present study, a new homologue of AGAMOUS gene from pecan [Carya illinoinensis (Wangenh.) K. Koch], denoted by CiAG, was isolated and its function was characterized. The complementary DNA (cDNA) of CiAG contains an open reading frame of 687 base pairs (bp) encoding 227 amino acids. Multiple sequence comparisons revealed that CiAG had the typical MIKC structure. Phylogenetic analysis indicated that CiAG is closely related to C-lineage AG. The expression of CiAG was highly accumulated in the reproductive tissues (staminate flowers, pistillate flowers, and fruitlets) than in vegetative tissues (leaves and current-growth branches). Arabidopsis overexpressing CiAG exhibited earlier flowering. The homeotic transformations of petals into stamen organs were observed in 35S::CiAG transgenic plants. All these results indicated that CiAG plays a key role in the process of flower development of pecan.
Guoting Liang, Junhui Liu, Jingmin Zhang, and Jing Guo
Drought has become an important factor limiting crop yields in China. As an important greenhouse horticultural crop in China, the research of tomato (Solanum lycopersicum L. cv. Jinpeng No.10) is of great theoretical and practical significance. In the study, four different relative soil moisture contents (74% to 80%, 55% to 61%, 47% to 52%, and 25% to 30%) were used to induce drought stress. We investigated changes in photosynthetic gas exchange, chlorophyll fluorescence, and other related physiological parameters in response to different relative soil moisture contents. Drought inhibited the photosynthesis of tomato significantly, as shown by a clear decline in the net photosynthetic rate. Our results indicated stomatal limitation and nonstomatal limitation were responsible for the photosynthesis reduction.
Doudou Guo, Ziyi Chen, Danfeng Huang, and Jingjin Zhang
Water management is one of the most important operations in greenhouse baby leaf production. However, growers mainly irrigate the plants based on experience, which generally leads to yield loss, uneven quality, and low water-use efficiency. This study evaluated four evapotranspiration (ET) models, such as Radsum, Penman methods, FAO Penman-Monteith, and Priestley-Taylor, for irrigation strategy by predicting the ET level of greenhouse baby pakchoi [Brassica rapa L. ssp. chinensis (L.) Hanelt] under different plant densities (72-, 128-, 200-, and 288-plug tray). Among environmental factors, net radiation and photosynthetically active radiation (PAR) had the highest correlation with ET, with R 2 of 0.93 and 0.94, respectively. Plant growth period was divided into different stages according to canopy development and substrate surface coverage. The corresponding crop coefficient (Kc) was introduced into ET prediction models. The result shows overestimation of ETc (crop evapotranspiration) by the Radsum and Penman methods. FAO Penman-Monteith and Priestley-Taylor methods performed the best with R 2 ≈0.7 for all planting densities. These two methods are recommended for greenhouse irrigation scheduling in baby pakchoi production.
Le Luo, Chao Yu, Xuelian Guo, Huitang Pan, and Qixiang Zhang
Rosa laxa is widely distributed in the Xinjiang Uygur Autonomous Region of China and is highly adaptable and rich in variation. In this study, we investigated the morphology, habitats, and palynomorphology of R. laxa botanical varieties from Xinjiang, China. In addition to R. laxa var. laxa, there were three other botanical varieties of R. laxa growing in southern Xinjiang, including var. mollis, var. kaschgarica, and var. tomurensis. Together, these four botanical varieties exhibited morphological variation, mainly in the morphology of prickles and the glandular trichome and in flower color. The pollen grains of the R. laxa botanical varieties, all medium in size (21.77–48.39 μm), came in three shapes: perprolate, prolate, and subspheroidal. Their pollen exine sculptures were characterized by either a striate-perforation pattern or striate pattern, but perforation varied in terms of diameter and density and striae varied in depth and density. Palynomorphological assessment showed that three types of evolution, i.e., primitive, transitive, and evolved, were present among R. laxa botanical varieties, and pollen dimorphism was observed in the same botanical variety. Perprolate pollen with a dense striate pattern was the most evolved type. Based on morphological and palynomorphological investigations, var. tomurensis was considered to be the most evolved one among the studied botanical varieties.
Ji-Yu Zhang, Zhong-Ren Guo, Rui Zhang, Yong-Rong Li, Lin Cao, You-Wang Liang, and Li-Bin Huang
This study examined the ability to vegetatively propagate 1-year-old pecan (Carya illinoinensis) through the rooting of hardwood cuttings. Cuttings were treated with varying concentrations of different auxins and different combinations of media and ambient temperatures. Under different temperature conditions, all auxin treatments induced the rooting of cuttings but did not promote sprouting. The effectiveness of the induction of adventitious roots was as follows: 1-naphthalene acetic acid (NAA) > indole 3-butyric acid > indole 3-acetic acid. The base of the parent shoot treated by NAA at a concentration of 0.09%, planted in substrate with bottom heat was the most effective, with 82% rooting, 8.3 roots/cutting and root lengths of 7.3 cm. These findings suggested that auxin and substrate/air temperature differences are both indispensable in the process of adventitious roots formation in pecan. This study revealed that the propagation of hardwood cuttings derived from branches of 1-year-old pecan is possible.
Haiying Zhang, Jianguang Fan, Shaogui Guo, Yi Ren, Guoyi Gong, Jie Zhang, Yiqun Weng, Angela Davis, and Yong Xu
Watermelon belongs to the genus Citrullus. There have been continuing interests in breeding of watermelon for economic benefits, but information on the scope and utilization of genetic variations in Citrullus is still limited. The present study was conducted in 2012–13, to evaluate the genetic diversity and population structure of the 1197 line watermelon collection maintained by the Beijing Vegetable Research Center (BVRC), which belongs to seven Citrullus species including Citrullus naudinianus, Citrullus colocynthis, Citrullus rehmii, Citrullus ecirrhosus, Citrullus amarus, Citrullus mucosospermus, and Cirullus lanatus subsp. vulgaris. Twenty-three highly informative microsatellite markers evenly distributed in the watermelon genome were used to assess genetic diversity in this collection. The markers detected on an average of 6.05 alleles per locus with the average value of polymorphism information content (PIC) at 0.49. A high level of gene diversity [Nei’s gene diversity index (Nei) = 0.56] and a low observed heterozygosity (H o = 0.10) were revealed within the collection. Structure analysis grouped the 1197 accessions into two main populations (Pop I and Pop II) and an admixture group. Pop I contained 450 accessions from C. lanatus subsp. vulgaris (446) and C. mucosospermus (4). Pop II comprised 465 accessions, 379 of which belonged to C. lanatus subsp. vulgaris and 86 to C. naudinianus (3), C. ecirrhosus (2), C. rehmii (2), C. colocynthis (11), C. amarus (58), and C. mucosospermus (10). The remaining 282 accessions were classified as an admixture group. The two main populations were further subdivided into four subgroups. The groupings were consistent with the estimation of F statistics (F st) and Nei’s genetic distances in collections. We confirmed the distinct genetic backgrounds between American and East Asian ecotypes. Subsequently, we defined a core set consisting of 130 accessions including 47 from Pop I, 68 from Pop II, and 15 from the Admixture group. This core set was able to capture all 133 alleles detected by 23 simple sequence repeats (SSRs) in 1197 accessions. These results will facilitate efficient use of genetic variations in Citrullus in watermelon breeding and help optimization of accessions in genomewide association studies.
Sheng Chen, Zhenchang Wang, Zhanyu Zhang, Xiangping Guo, Mengyang Wu, Ghulam Rasool, Rangjian Qiu, and Xiaojun Wang
Soil salinity influences plant growth and crop yield significantly. Former studies indicated that uneven salt distribution in the root zone could relieve salt stress. But, how uneven salt distribution influences Na+ and Ca2+ concentration in the stem, leaf, and fruit and whether this influence would bring effects on fruit blossom-end rot (BER) still needs to be further studied. Under consideration of this, pot experiment with four treatments, T1:1, T1:5, T2:4, and T3:3, was conducted by setting the upper soil layer salinity at 1‰, 1‰, 2‰, and 3‰ and the lower soil layer at salinities of 1‰, 5‰, 4‰, and 3‰, respectively. Compared with the uniform salt concentration in the root zone (T3:3 treatment), the incidence of BER in the T1:5 and T2:4 treatments decreased by 60% and 35%, respectively. The fruit Na+ concentration and Na+/Ca2+ ratio were positively correlated with the incidence of BER. The value of the upper-root selective absorption Ca2+ over Na+ (SCa/Na(upper root)) for T1:5 was 0.8 times more than that of T1:1. The results showed that the incidence of BER was positively correlated with root dry matter and SCa/Na(root) weighted mean salinity. The overall results suggested that uneven salt distribution in the root zone could promote the Ca2+ absorption, Ca2+/Na+ ratio, and selective absorption Ca2+ over Na+ and consequently decrease the incidence of BER in tomato fruit.
Yumei Zhang, Runfang Hu, Huawei Li, Haisheng Zhu, Jinming Zhao, Na Guo, Han Xing, and Guoqiang Lin
Vegetable soybean is an important economic and nutritious crop. In this study, 48 differentially expressed proteins were identified from filling seeds of soybean (Glycine max) cv. Mindou 6 by using two-dimensional electrophoresis (2-DE) combined with liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Among them, 25% were related to protein destination and storage, 42% to energy and metabolism, 15% to disease/defense, 6% to transporters, 4% to secondary metabolism, 4% to transcription, 2% to protein synthesis, and 2% to cell growth/division. Along with the maturity of seeds, the number of unchanged abundance proteins decreased, while that of both upregulated and downregulated proteins increased. Both downregulated expression of caffeic acid O-methyltransferase (COMT) and upregulated expression of sucrose-binding protein (SBP) 2 precursor may contribute to increase in digestibility, nutritional value, and eating quality of vegetative seeds at suitable picking period. The pattern of unchanged proteins during the whole seed-filling stage may be also beneficial to the quality of vegetable soybean.
Liu Yang, Zhongkui Xie, Zhijiang Wu, Yajun Wang, Zhihong Guo, Yubao Zhang, and Ruoyu Wang
The oriental hybrid lily (Lilium oriental cv. Sorbonne) is an economically important flower noted for its pink petals. Flower quality is determined by plant height, number of flowers per plant, and flower diameter. The commercial value can be increased by improving flower quality through cultural practices such as exogenous application of hormones; however, information on this practice is unavailable for this lily hybrid. In the present study, we soaked lily bulbs for 24 hours in one of four concentrations of abscisic acid (ABA) or one of three concentrations of the ABA biosynthesis inhibitor fluridone before subjecting the bulbs to a cold storage treatment at 4 °C. During cold storage, bulbs were sampled and buds were collected every 10 days for 80 days (that is, lasting eight times). The ABA and gibberellic acid 3 (GA3) contents of buds of treatments that showed a significant difference with the control were measured in a 10-day interval. Greenhouse experiments with different cold storage durations of bulbs that measured height, flower number per plant, and flower diameter were conducted. The interaction of hormone treatments and cold storage duration played nonsignificant roles in parameters of flower quality. Exogenous fluridone application to bulbs at 12 mg·L−1 improved flower quality: height and flower number increased significantly compared with the control, but flower diameter did not change. ABA had no effect on flower quality. Because the fluctuation of endogenous GA3 is more remarkable than ABA after the application of fluridone that led to the improvement of flower quality, it can be inferred that this influence on flower quality is achieved through fluridone’s regulation on the content of endogenous GA3. A low endogenous GA3/ABA ratio was associated with improved flower quality: 12 mg·L−1 fluridone decreased the GA3/ABA ratio in most times of the cold treatment. In addition, cold storage duration affected flower quality; the 50-day cold storage can achieve the highest height, the most flower number, and bigger flower diameter simultaneously. The results of the present study suggest that soaking bulbs in 12 mg·L−1 fluridone before cold treatment followed by 50 days of cold storage before planting will increase plant height and flower number per plant.