BACKGROUND: High temperature stress (HTS) has become a serious threat to rice grain quality and few studies have examined the effects of HTS across multiple stages on rice grain quality. In the present study, we conducted 2 years of HTS treatments under three temperature regimes (32/22 °C, 40/30 °C and 44/34 °C) and HTS durations of 2 days and 4 days at three critical stages: booting, flowering, and a combination of booting and flowering. We employed the heat degree days (HDD) metric, which accounts for both the level and duration of HTS, to quantify the relationships between grain quality traits and HTS.
RESULTS: The results revealed the diverse effects of HTS on rice grain quality at different stages, durations and temperature levels. HTS significantly (P < 0.05) reduced grain quality, with the highest sensitivities (reduction per 1 °C day-1 increase in HDD) observed at the flowering stage, followed by the combined and booting stages treatments under mild HTS treatment (40/30 °C). However, under extreme HTS treatments (44/34 °C) for 4 days, rice grains subjected to combined HTS treatment experienced complete mortality.
CONCLUSIONS: Pre-exposed to HTS at the booting stage within a certain intensity can alleviate the adverse effects of post-flowering HTS on grain quality. This provides valuable insights for assessing the potential impact of multiple HTS events on the grain quality under future climate warming. © 2024 Society of Chemical Industry.

Pitaya, a desert plant, has an underexplored flowering mechanism due to a lack of functional validation assays. This study reveals that the transition from vegetative to generative growth in pitaya is regulated by significant metabolic shift, underscoring the importance of understanding and address the challenging issue pitaya\'s phase change. Lateral buds from 6-years-old \'Guanhuahong\' pitaya (Hylocereus monacanthus) plants were collected on April 8th, 18th, and 28th 2023, representing early, middle, and late stages of phase transition, respectively. Results showed diminished nitrogen levels concurrent with increased carbon levels and carbon-to-nitrogen (C/N) ratios during pitaya phase transition. Transcriptomic analysis identified batches of differentially expressed genes (DEGs) involved in downregulating nitrogen metabolism and upregulating carbon metabolism. These batches of genes play a central role in the metabolic shifts that predominantly regulate the transition to the generative phase in pitaya. This study unveils the intricate regulatory network involving 6 sugar synthesis and transport, 11 photoperiod (e.g., PHY, CRY, PIF) and 6 vernalization (e.g., VIN3) pathways, alongside 11 structural flowering genes (FCA, FLK, LFY, AGL) out of a vast array of potential candidates in pitaya phase change. These findings provide insights into the metabolic pathways involved in pitaya\'s phase transition, offering a theoretical framework for managing flowering, guiding breeding strategies to optimize flowering timing and improve crop yields under varied nitrogen conditions.

Accurate prediction of flowering times is essential for efficient orchard management for kiwifruit, facilitating timely pest and disease control and pollination interventions. In this study, we developed a predictive model for flowering time using weather data and observations of budbreak dynamics for the \'Hayward\' and \'Zesy002\' kiwifruit. We used historic data of untreated plants collected from 32 previous studies conducted between 2007 and 2022 and analyzed budbreak and flowering timing alongside cumulative heat sum (growing degree days, GDDs), chilling unit (CU) accumulation, and other environmental variables using weather data from the weather stations nearest to the study orchards. We trained/parameterized the model with data from 2007 to 2019, and then evaluated the model\'s efficacy using testing data from 2020 to 2022. Regression models identified a hierarchical structure with the accumulation of GDDs at the start of budbreak, one of the key predictors of flowering time. The findings suggest that integrating climatic data with phenological events such as budbreak can enhance the predictability of flowering in kiwifruit vines, offering a valuable tool for kiwifruit orchard management.

暂无摘要。

Cannabis sativa L., one of humanity\'s oldest cultivated crops, has a complex domestication history due to its diverse uses for fibre, seed, oil and drugs, and its wide geographic distribution. This review explores how human selection has shaped the biology of hemp and drug-type Cannabis, focusing on acquisition and utilisation of nitrogen and phosphorus, and how resulting changes in source-sink relations shape their contrasting phenology. Hemp has been optimized for rapid, slender growth and nutrient efficiency, whereas drug-type cultivars have been selected for compact growth with large phytocannabinoid producing female inflorescences. Understanding these nutrient use and ontogenetic differences will enhance our general understanding of resource allocation in plants. Knowledge gained in comparison with other model species, such as tomato, rice or Arabidopsis thaliana can help inform crop improvement and sustainability in the Cannabis industry.

暂无摘要。

OBJECTIVE: Changing precipitation regimes can influence terrestrial plants and ecosystems. However, plant phenological responses to changing precipitation temporal patterns and the underlying mechanisms are largely unclear. This study was conducted to explore the effects of seasonal precipitation redistribution on plant reproductive phenology in a temperate steppe.
METHODS: A field experiment with control (C), advanced (AP) and delayed (DP) growing-season precipitation peaks, and the combination of AP and DP (ADP) were employed. Seven dominant plant species were selected and divided into two functional groups (early- vs. middle-flowering species, shallow- vs. deep-rooted species) to monitor reproductive phenology including budding, flowering, and fruiting date, as well as reproductive duration for four growing seasons from 2015 to 2017, and 2022.
RESULTS: The AP, but not DP treatment advanced the phenological (i.e., budding, flowering, and fruiting) dates and lengthened the reproductive duration across the 4 growing seasons and 7 monitored species. In addition, the phenological responses showed divergent patterns among different plant functional groups, which could be attributed to shifts in soil moisture and its variability in different months and soil depths. Moreover, species with lengthened reproductive duration increased phenological overlap with other species, which could have a negative impact on their dominance under the AP treatment.
CONCLUSIONS: Our findings reveal that changing precipitation seasonality could have considerable impacts on plant phenology by affecting soil water availability and variability. Incorporating these two factors simultaneously in the phenology models will help us understand the response of plant phenology under intensified changing precipitation scenarios. In addition, the observations of decreased dominance for the species with lengthened reproductive duration suggest that changing reproductive phenology can have a potential to affect community composition in grasslands under global change.

The intracellular localization of the florigen FLOWERING LOCUS T (FT) is important for its long-distance transport toward the shoot apical meristem. However, the mechanisms regulating the FT localization remain poorly understood. Here, we discovered that in Arabidopsis thaliana, the chloroplast-localized protein THYLAKOID FORMATION 1 (THF1) physically interacts with FT, sequestering FT in the outer chloroplast envelope. Loss of THF1 function led to temperature-insensitive flowering, resulting in early flowering, especially under low ambient temperatures. THF1 mainly acts in the leaf vasculature and shoot apex to prevent flowering. Mutation of CONSTANS or FT completely suppressed the early flowering of thf1-1 mutants. FT and THF1 interact via their anion binding pocket and coiled-coil domain (CCD), respectively. Deletion of the CCD in THF1 by gene editing caused temperature-insensitive early flowering similar to that observed in the thf1-1 mutant. FT levels in the outer chloroplast envelope decreased in the thf1-1 mutant, suggesting that THF1 is important for sequestering FT. Furthermore, THF1 protein levels decreased in seedlings grown at high ambient temperature, suggesting an explanation for its role in plant responses to ambient temperature. A thf1-1 phosphatidylglycerolphosphate synthase 1 (pgp1) double mutant exhibited additive acceleration of flowering at 23 and 16°C, compared to the single mutants, indicating that THF1 and phosphatidylglycerol (PG) act as independent but synergistic regulators of temperature-responsive flowering. Collectively, our results provide an understanding of the genetic pathway involving THF1 and its role in temperature-responsive flowering and reveal a previously unappreciated additive interplay between THF1 and PG in temperature-responsive flowering.

Most of the studied MADS box members are linked to flowering and fruit traits. However, higher volumes of studies on type II of the two types so far suggest that the florigenic effect of the gene members could just be the tip of the iceberg. In the current study, we used a systematic approach to obtain a general overview of the MADS box members\' cross-trait and multifactor associations, and their pleiotropic potentials, based on a manually curated local reference database. While doing so, we screened for the co-occurrence of terms of interest within the title or abstract of each reference, with a threshold of three hits. The analysis results showed that our approach can retrieve multi-faceted information on the subject of study (MADS box gene members in the current case), which could otherwise have been skewed depending on the authors\' expertise and/or volume of the literature reference base. Overall, our study discusses the roles of MADS box members in association with plant organs and trait-linked factors among plant species. Our assessment showed that plants with most of the MADS box member studies included tomato, apple, and rice after Arabidopsis. Furthermore, based on the degree of their multi-trait associations, FLC, SVP, and SOC1 are suggested to have relatively higher pleiotropic potential among others in plant growth, development, and flowering processes. The approach devised in this study is expected to be applicable for a basic understanding of any study subject of interest, regardless of the depth of prior knowledge.

Heat stress represents a significant environmental challenge that adversely impacts the growth, physiology, and productivity of wheat. In order to determine the response to high temperatures of the wheat varieties developed mostly in the Pannonian environmental zone, as well as varietal differences, we subjected seven varieties from Serbia, one from Australia, and one from the UK to thermal stress during anthesis and mid-grain filling and combined stress during both of these periods. The changes in chlorophyll fluorescence and index, leaf temperature, and main agronomic traits of nine winter wheat varieties were investigated under high temperatures. Heat stress negatively affected leaf temperature, chlorophyll fluorescence, and the chlorophyll index during different growth stages. Compared to the control, stress at anthesis, mid-grain filling, and combined stress resulted in yield reductions of 32%, 46%, and 59%, respectively. Single treatment at anthesis had a more severe effect on the number of grains per plant, causing a 38% reduction compared to the control. Moreover, single treatment during mid-grain filling resulted in the greatest decline in grain weight, with a 29% reduction compared to the control. There was a significant varietal variation in heat tolerance, highlighting Avangarda and NS 40s as the most tolerant varieties that should be included in regular breeding programs as valuable sources of heat tolerance. Understanding the genetic and physiological mechanisms of heat tolerance in these promising varieties should be the primary focus of future research and help develop targeted breeding strategies and agronomic practices to mitigate the adverse effects of heat stress on wheat production.