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Summary Starch is synthesized as insoluble, semicrystalline particles within plant chloroplast and amyloplast, which are referred to as starch grains (SGs). The size and morphology of SGs in the cereal endosperm are diverse and species–specific, representing a key determinant of the suitability of starch for industrial applications. However, the molecular mechanisms modulating SG size in cereal endosperm remain elusive. Here, we functionally characterized the rice (Oryza sativa) mutant substandard starch grain7 (ssg7), which exhibits enlarged SGs and defective endosperm development. SSG7 encodes a plant–specific DUF1001 domain‐containing protein homologous to Arabidopsis (Arabidopsis thaliana) CRUMPLED LEAF (AtCRL). SSG7 localizes to the amyloplast membrane in developing endosperm. Several lines of evidence suggest that SSG7 functions together with SSG4 and SSG6, known as two regulators essential for SG development, to control SG size, by interacting with translocon‐associated components, which unveils a molecular link between SG development and protein import. Genetically, SSG7 acts synergistically with SSG4 and appears to be functional redundancy with SSG6 in modulating SG size and endosperm development. Collectively, our findings uncover a multimeric functional protein complex involved in SG development in rice. SSG7 represents a promising target gene for the biotechnological modification of SG size, particularly for breeding programs aimed at improving starch quality.

The site of Qujialing experienced a long, sustained process of the development of Neolithic culture in the Jianghan Plain, with a period of some1600 years. Our previous studies based on macrofossil remains and phytoliths revealed that rice ( Oryza sativa ) from Qujialing was already domesticated, and millet ( Setaria italica and Panicum miliaceum ) had also been spread into the site since the Youziling Culture period (5800-5100 BP). Nevertheless, no direct evidence has been provided regarding the daily consumed plant foods, especially plant foods obtained by gathering, throughout the site occupation. This paper thus examines pottery sherds (n=41) associated with culinary practices from Qujialing with starch grain analysis. Apart from starch grains from rice and millet, the results indicate that job’s tears ( Coix lacryma-jobi ), lotus roots ( Nelumbo nucifera ), tubers possibly from Chinese yam ( Dioscorea panthainca ), acorns ( Quercus sp.), and beans ( Vigna sp. or/and Vicia sp.) were consumed by the ancient Qujialing people, within job’s tears and lotus roots were not discovered before in the macrofossil remains and phytoliths. Combining the starch data and multiple lines of evidence from macrofossil remains and phytoliths, it is suggested that rice was among the most frequently consumed plant foods since the first occupation phase at Qujialing, while acorns could have been gradually replaced by other agricultural products (i.e., rice) and became less important food ingredients, especially when agriculture was more developed in the last occupation phase at Qujialing. These novel findings not only complement our previous research by providing the first line of evidence of paleodiet in the Jianghan Plain from the perspective of starch grain analysis but also delivers a better understanding of the characterized dietary trends and agricultural development in the research region.

Peanut is a world-renowned oilseed and food crop. Improving its biochemical quality is of great significance not only for meeting the demand for edible oil and food, but also for producing clean renewable energy. Identification of peanut genotypes with high and stable oil content in coastal areas is of economic importance, as the high oil trait of peanut bred in inland areas is difficult to fully express in coastal areas. Two peanut genotypes were grown at two sites in the coastal area. One of the genotypes was identified as having high oil and low carbohydrate, while the other had low oil and high carbohydrate. We noticed that number and total area of oil bodies were higher in high oil peanut than in low oil peanut, and that peanut with higher protein content had larger total protein body area. A novel finding of the present study was that number and area of starch grains were higher in peanut with high total soluble sugar (TSS) and sucrose contents than in peanut with low TSS and sucrose. Regarding the ultrastructural properties associated with oil, protein and TSS/sucrose contents, significant and highly positive correlations were detected between total oil body area and number of oil bodies, between total protein area and maximum protein body area, and between total starch grain area and number of starch grains. This study laid the foundation for further exploration of the mechanisms shaping peanut seed biochemical quality.

This study examined the potential of using the endophytic bacteria Bacillus subtilis (10-4 and 26D) to enrich hydroponically grown potato seed minitubers (Solanum tuberosum L. cv. Bashkirsky) to improve plant growth, photosynthetic pigments, yield, and quality parameters, including nutritional value (i.e., macro-/microelements, vitamin C, anthocyanins). Potato seed minitubers, obtained from in-vitro-grown microplants in a hydroponic system, were inoculated with endophytic B. subtilis and subsequently grown in pots under controlled conditions. The results demonstrated the successful colonization of seed minitubers by B. subtilis, with subsequent distribution into growing plants (roots, shoots). The endophytes accelerated the plant’s phenological shifts, resulting in earlier emergence of sprouts, budding, and flowering compared with control plants. They also had increased leaf photosynthetic pigments (chlorophyll (Chl) a, Chl b, and carotenoids), total leaf area, and positively influenced leaf proline contents. The height of plants and number of stems per plant did not change significantly upon endophyte treatment, but improved root growth was observed throughout the experiment. As a result of endophyte application, there was an increase in stolon weight, number and size of tubers, and overall tuber yield. There were no significant differences in terms of total dry matter and starch content of the tubers compared to the control group, but the sugar levels decreased and the size of the starch grains was larger in endophyte-treated tubers. Furthermore, endophyte treatment resulted in an increased accumulation of nutrients including N, P, K, Cu, and Fe, as well as vitamin C and anthocyanins in harvested tubers. These findings indicate that colonization of hydroponically grown potato seed minitubers with endophytic B. subtilis (10-4 and 26D) before planting has great potential as an eco-friendly approach to obtain higher-quality seeds and to increase tuber yield and nutritional value in field conditions.

Cold acclimation before winter has been shown to enhance the cold tolerance of evergreen conifers, including Pinus massoniana Lamb., a characteristic heteroblastic foliage tree in the conifer. In the initial growing season of P. massoniana, both primary needle seedlings (PNSs) and secondary needle seedlings (SNSs) are generated. While previous research has highlighted differences in the morphological structure and photosynthetic physiological functions of primary and secondary needles, their response to cold acclimation remains poorly understood. This study aimed to investigate the changes in morpho-anatomical structure, starch grain accumulation, and lignin deposition in the roots, stems, and leaves of PNSs and SNSs during cold acclimation using solid potassium iodide and hydrochloric acid phloroglucinol double-staining techniques. The results revealed that, during cold acclimation, the leaves and stems of PNSs exhibited sensitivity to low-temperature stress, resulting in noticeable shrinkage and fracture of mesophyll and cortical parenchyma cells. Furthermore, the early stages of cold acclimation promoted the accumulation of starch grains and lignin in the seedling tissues. In contrast to PNSs, the leaves and stems of SNSs exhibited a shorter cold acclimation period, attributed to the hydrolysis of starch grains in the epidermal cell walls and the transformation of xylem lignin, which supports cell structure stability and enhances cold resistance. In conclusion, these findings suggest that SNSs displayed a superior cold resistance potential compared to PNSs following cold acclimation, providing a significant theoretical basis for the further screening of cold-tolerant germplasm resources of P. massoniana and the analysis of cold resistance traits in heteroblastic foliage.

The effects of elevated carbon dioxide concentration on the morphology of leaf blades in two Chinese yam lines under different temperature conditions were determined. Plants were grown under two [CO 2 ] levels, ambient (about 400 µmol mol −1 ) and elevated (ambient + 200 µmol mol −1 ) in the daytime, and two mean air temperature regimes, approximately ambient temperature (22.2°C) and high temperature (25.6°C). The palisade layer was thicker under elevated [CO 2 ] than under ambient [CO 2 ] in both temperature regimes, and the whole yam leaf blade was thicker under elevated [CO 2 ] than under ambient [CO 2 ] in the approximately ambient temperature regime. The numbers of chloroplasts per palisade cell and spongy cell as well as per unit profile area of palisade cell, number of starch grains per chloroplast, profile area of the starch grain, and starch-to-chloroplast area ratio in both palisade and spongy cells were higher under elevated [CO 2 ] than under ambient [CO 2 ] in both temperature regimes. Furthermore, the stomatal density on the abaxial side of the leaf blade in Chinese yam was greater under elevated [CO 2 ] than under ambient [CO 2 ] under both temperature regimes, and stomatal-pore length was higher under elevated [CO 2 ] than under ambient [CO 2 ] in the approximately ambient temperature regime. These results indicate that elevated [CO 2 ] positively affects the photosynthetic apparatus. The results of this study provide information for understanding the response characteristics of the leaf blade under elevated [CO 2 ] and a possible explanation for the positive photosynthetic responses of Chinese yam to elevated [CO 2 ] in our previous study. List of Abbreviations:[CO 2 ]: carbon dioxide concentration

Abstract Golden trumpet, Tabebuia chrysotricha, is a native tree from the Brazilian Atlantic rain forest, with a broad latitudinal distribution. In this study, we investigated the potential effects of short-term changes in micro-weather conditions on structural features, and total protein and carbohydrate content of golden trumpet leaves, using structural and histochemical approaches. Leaves were harvested in four different micro-weather conditions: 1. Afternoon, after a hot, sunny day; 2. at dawn, after a previously hot, sunny day; 3. at noon, of a hot, sunny day; and 4. at noon, of a cold, cloudy day. Leaflets exposed to low light irradiance showed flattened chloroplasts, uniformly distributed within the cells, throughout the palisade parenchyma. Conversely, leaflets exposed to high light irradiance presented flattened and rounded chloroplasts, in the upper and lower palisade parenchyma cells, respectively. The strongest protein staining was found for leaves harvested at the coldest period, whereas the weakest protein staining was found for leaves harvested after a hot, sunny day. The largest and most numerous starch grains were found for leaves harvested in the afternoon, after a hot, sunny day. Conversely, the smallest and less numerous starch grains were found for leaves harvested at dawn. Analysis of the data reported herein suggests that the leaflet responses to transient changes in micro-weather conditions are likely to contribute to the golden trumpet successful establishment in the broad latitudinal distribution in which the species is found. Resumo Ipê amarelo é uma árvore nativa da floresta Atlântica brasileira, encontrada em uma ampla distribuição latitudinal. Neste estudo, nós investigamos os efeitos potenciais de alterações de curto prazo nas condições micro-climáticas sobre características estruturais, proteína e carboidratos histoquimicamente marcados, de folhas de ipê amarelo, usando estratégias de análise estrutural e histoquímicas. As folhas foram marcadas em quatro condições microclimáticas distintas: 1. Tarde, após um dia quente e ensolarado; 2. Amanhecer, após um dia quente e ensolarado; 3. Ao meio-dia, de um dia quente e ensolarado; e 4. Ao meio-dia, de um dia frio e nublado. Folíolos expostos à baixa irradiância luminosa apresentaram cloroplastos achatados, uniformemente distribuídos no interior das células, por todo o parênquima paliçádico, enquanto que folíolos expostos à alta irradiância apresentaram cloroplastos achatados e arredondados, nas células superiores e inferiores do parênquima paliçádico, respectivamente. A marcação mais intensa para proteína foi observada para folhas coletadas no momento mais frio de coleta, enquanto que a marcação mais fraca foi observada para folhas coletadas após um dia quente e ensolarado. Os grãos de amido maiores e mais numerosos foram observados em folhas coletadas durante a tarde de dia quente e ensolarado, enquanto que os menores e menos numerosos grãos de amido foram observados em folhas coletadas ao amanhecer.

In intercropping systems shading conditions significantly impair the seed yield and quality of soybean, and rarely someone investigated the minimum amount of light requirement for soybean growth and development. Therefore, it is an urgent need to determine the threshold light intensity to ensure sustainable soybean production under these systems. An integrated approach combining morphology, physiology, biochemistry and genetic analysis was undertaken to study the light intensity effects on soybean growth and development. A pot experiment was set up in a growth chamber under increasing light intensity treatments of 100 (L ), 200 (L ), 300 (L ), 400 (L ), and 500 (L ) μmol m s . Compared with L , plant height, hypocotyl length, and abaxial leaf petiole angle were decreased, biomass, root:shoot ratio, and stem diameter were increased, extremum was almost observed in L and L Leaf petiole movement and leaf hyponasty in each treatment has presented a tendency to decrease the leaf angle from L to L . In addition, the cytochrome content (Chl a, Chl b, Car), net photosynthetic rate, chlorophyll fluorescence values of / , / , , Φ , and were increased as the light intensity increased, and higher values were noted under L . Leaf microstructure and chloroplast ultrastructure positively improved with increasing light intensity, and leaf-thickness, palisade, and spongy tissues-thickness were increased by 105, 90, and 370%, under L than L . Moreover, the cross-sectional area of chloroplast (C) outer membrane and starch grains (S), and sectional area ratio (S:C) was highest under L and L , respectively. Compared to L , the content of starch granules increased by 35.5, 122.0, 157.6, and 145.5%, respectively in L . The same trends were observed in the enzyme activity of sucrose-synthase, sucrose phosphate synthase, starch synthase, rubisco, phosphoenol pyruvate carboxykinase, and phosphoenol pyruvate phosphatase. Furthermore, sucrose synthesis-related genes were also up-regulated by increasing light intensity, and the highest seed yield and yield related parameters were recorded in the L . Overall, these results suggested that 400 and 500 μmol m s is the optimum light intensity which positively changed the leaf orientation and adjusts leaf angle to perpendicular to coming light, consequently, soybean plants grow well under prevailing conditions.

It is generally understood that foxtail millet and broomcorn millet were initially domesticated in Northern China where they eventually became the dominant plant food crops. The rarity of older archaeological sites and archaeobotanical work in the region, however, renders both the origins of these plants and their processes of domestication poorly understood. Here we present ancient starch grain assemblages recovered from cultural deposits, including carbonized residues adhering to an early pottery sherd as well as grinding stone tools excavated from the sites of Nanzhuangtou (11.5–11.0 cal kyBP) and Donghulin (11.0–9.5 cal kyBP) in the North China Plain. Our data extend the record of millet use in China by nearly 1,000 y, and the record of foxtail millet in the region by at least two millennia. The patterning of starch residues within the samples allow for the formulation of the hypothesis that foxtail millets were cultivated for an extended period of two millennia, during which this crop plant appears to have been undergoing domestication. Future research in the region will help clarify the processes in place.

Main conclusion The changes in the expression of key sugar metabolism enzymes (SPS and SUS), sucrose content and arrangement of chloroplast starch may play a significant role in the cold response in M. giganteus  and maize plants. To understand the mechanism of the chilling-response of two closely-related C 4 plants, we investigated the changes in the expression of sucrose phosphate synthase (SPS) and sucrose synthase (SUS) as well as changes in their potential products: sucrose, cellulose and starch in the leaves of Miscanthus  ×  giganteus and Zea mays . Low temperature (12–14 °C) increased SPS content in Miscanthus (MG) and chilling-sensitive maize line (Zm-S), but not in chilling-tolerant one (Zm-T). In Zm-S line, chilling also caused the higher intensity of labelling of SPS in the cytoplasm of mesophyll cells, as demonstrated by electron microscopy. SUS labelling was also increased by cold stress only in MG plants what was observed in the secondary wall between mesophyll and bundle sheath cells, as well as in the vacuoles of companion cells. Cold led to a marked increase in total starch grain area in the chloroplasts of Zm-S line. In turn, Fourier transform infrared spectroscopy (FTIR) showed a slight shift in the cellulose band position, which may indicate the formation of more compact cellulose arrangement in Zm-T maize line. In conclusion, this work presents new findings supporting diversified cold-response, not only between two C 4 plant species but also within one species of maize.