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Soil remediation for cadmium (Cd) toxicity is essential for successful tobacco cultivation and production. Melatonin application can relieve heavy metal stress and promote plant growth; however, it remains somewhat unclear whether melatonin supplementation can remediate the effects of Cd toxicity on the growth and development of tobacco seedlings. Herein, we evaluated the effect of soil-applied melatonin on Cd accumulation in tobacco seedlings, as well as the responses in growth, physiological and biochemical parameters, and the expression of stress-responsive genes. Our results demonstrate that melatonin application mitigated Cd stress in tobacco, and thus promoted plant growth. It increased root fresh weight, dry weight, shoot fresh weight and dry weight by 58.40%, 163.80%, 34.70% and 84.09%, respectively, compared to the control. Physiological analyses also showed significant differences in photosynthetic rate and pigment formation among the treatments, with the highest improvements recorded for melatonin application. In addition, melatonin application alleviated Cd-induced oxidative damage by reducing MDA content and enhancing the activities of enzymatic antioxidants (CAT, SOD, POD and APX) as well as non-enzymatic antioxidants (GSH and AsA). Moreover, confocal microscopic imaging confirmed the effectiveness of melatonin application in sustaining cell integrity under Cd stress. Scanning Electron Microscopy (SEM) observations illustrated the alleviative role of melatonin on stomata and ultrastructural features under Cd toxicity. The qRT-PCR analysis revealed that melatonin application upregulated the expression of photosynthetic and antioxidant-related genes, including SNtChl, q-NtCSD1, NtPsy2 and QntFSD1, in tobacco leaves. Together, our results suggest that soil-applied melatonin can promote tobacco tolerance to Cd stress by modulating morpho-physiological and biochemical changes, as well as the expression of relevant genes. [ABSTRACT FROM AUTHOR]

Maize is one of the most important food and feed crops in China due to the high demand for its use by both humans and animals. The Huang-Huai-Hai region is a major maize cultivation area in China, and the special cropping rotation system of wheat and maize requires a suitable reproductive period for maize. The AUX/IAA and ARF transcription factors are two key genes that regulate auxin signals in plants, which play an important role during the process of auxin regulation in plant growth and development. In this study, we obtained two overexpressed lines of ZmIAA29 belonging to the AUX/IAA transcription factor family. Compared with the Wide type, the overexpressed strains of ZmIAA29 were significantly regulated in maize during the flowering time and had increased ear weight. Moreover, ZmIAA29 was assayed via the yeast two-hybrid and BiLUC systems for interaction, and the results showed that ZmIAA29 interacted with several ZmARF transcription factors. Furthermore, RNA-seq and DAP-seq analysis revealed that ZmIAA29 regulates maize growth and development by influencing pathways such as those for plant signal transduction and the key genes related to maize flowering. Taken together, our results suggest that ZmIAA29 plays a key role in the development of maize flowering. This study provides new insight for better understanding the combined regulation of the AUX/IAA and ARF transcription factors during flowering time in maize. [ABSTRACT FROM AUTHOR]

Lycium ruthenicum Murr. is one of the most important shrubs grown in northwest China. Healthy buds and leaves of L. ruthenicum Murr. were selected for the present study. Flower development was divided into six stages, namely, flower bud pre-differentiation (I), late flower differentiation (II), squaring stage (III), dew crown period (IV), open stage (V) and senescent stage (VI). Endogenous hormone content and specific value, soluble sugar, sucrose, starch, and soluble protein were measured, and ABA/IAA, ABA/GA3, ZR/IAA, ZR/GA3, and C/N were calculated in buds and leaves at stage VI. The results showed that ABA, GA3, and ZR content of buds significantly increased from flower bud pre-differentiation to late flower differentiation stage. However, ABA, GA3, and ZR content of leaves had the opposite change trend. From open stage to senescent stage, IAA, ABA, and GA3 content of buds and leaves significantly increased in L. ruthenicum Murr. However, ZR content of buds and leaves significantly decreased from open stage to senescent stage. ABA/IAA, ABA/GA3, ZR/IAA, and ZR/GA3 values of buds significantly increased from lower bud pre-differentiation to late flower differentiation stage. However, ABA/IAA, ABA/GA3, ZR/IAA, and ZR/GA3 values of leaves significantly decreased from lower bud pre-differentiation to late flower differentiation stage. ABA/IAA and ABA/GA3 of buds significantly increased from open stage to senescent stage, but ZR/IAA and ZR/GA3 of buds significantly decreased from open to senescent. At this stage, ABA/IAA, ABA/GA3, ZR/IAA, and ZR/GA3 significantly decreased in L. ruthenicum Murr. The higher soluble sugar and sucrose content in the buds and leaves were beneficial to the flower bud differentiation of L. ruthenicum. The increasing of soluble sugar improved the energy basis to florescence and senescent. The carbohydrates metabolism enhanced from open stage to senescent stage and nitrogen metabolism reduced from open stage to senescent stage of L. ruthenicum. [ABSTRACT FROM AUTHOR]

Rice floret number per unit area as one of the key yield structure parameters is directly related to the final yield of rice. Previous studies paid little attention to the effect of the variations in vegetation indices (VIs) caused by rice flowering on rice yield estimation. Unmanned aerial vehicles (UAV) equipped with hyperspectral cameras can provide high spatial and temporal resolution remote sensing data about the rice canopy, providing possibilities for flowering monitoring. In this study, two consecutive years of rice field experiments were conducted to explore the performance of florescence spectral information in improving the accuracy of VIs-based models for yield estimates. First, the florescence ratio reflectance and florescence difference reflectance, as well as their first derivative reflectance, were defined and then their correlations with rice yield were evaluated. It was found that the florescence spectral information at the seventh day of rice flowering showed the highest correlation with the yield. The sensitive bands to yield were centered at 590 nm, 690 nm and 736 nm–748 nm, 760 nm–768 nm for the first derivative florescence difference reflectance, and 704 nm–760 nm for the first derivative florescence ratio reflectance. The florescence ratio index (FRI) and florescence difference index (FDI) were developed and their abilities to improve the estimation accuracy of models basing on vegetation indices at single-, two- and three-growth stages were tested. With the introduction of florescence spectral information, the single-growth VI-based model produced the most obvious improvement in estimation accuracy, with the coefficient of determination (R2) increasing from 0.748 to 0.799, and the mean absolute percentage error (MAPE) and the root mean squared error (RMSE) decreasing by 11.8% and 10.7%, respectively. Optimized by flowering information, the two-growth stage VIs-based model gave the best performance (R2 = 0.869, MAPE = 3.98%, RMSE = 396.02 kg/ha). These results showed that introducing florescence spectral information at the flowering stage into conventional VIs-based yield estimation models is helpful in improving rice yield estimation accuracy. The usefulness of florescence spectral information for yield estimation provides a new idea for the further development and improvement of the crop yield estimation method. [ABSTRACT FROM AUTHOR]