Kent J. Bradford

Plant genetic transformation is a powerful tool for crop improvement and functional genomics, yet many economically important species remain recalcitrant to current methodologies. To address this limitation, we screened nine developmental regulatory genes (DRs) and sixteen DR combinations, identifying the combination of PLETHORA5 (PLT5) and GROWTH-REGULATING FACTOR 4/GRF-INTERACTING FACTOR 1 (GRF4/GIF1) (labeled as PLT5-GRFs combo) as a potent enhancer of regeneration and transformation efficiency. PLT5-GRFs combination was effective across diverse plant species, including petunia (Petunia hybrida), tomato (Solanum lycopersicum), lettuce (Lactuca sativa), ornamental eggplant (Solanum aethiopicum), and recalcitrant species such as chili pepper (Capsicum annuum), begonia (Begonia semperflorens), bahiagrass (Paspalum notatum Flügge), and blueberry (Vaccinium corymbosum). Moreover, it enhanced in planta transformation in Gloxinia (Sinningia speciosa). Transcriptional profiling revealed that PLT5-GRFs synergistically regulates key pathways in development, hormone signaling, epigenetic modifications, and cell fate reprogramming. Our findings establish PLT5-GRFs as a universal tool for plant genetic modification, offering a broadly applicable platform in plant biotechnology with profound implications for basic research, crop improvement, and sustainable agriculture.

Athelia rolfsii, causal agent of ‘southern blight’ disease, is a soil-borne fungal pathogen with a wide host range of more than 500 species. This study's objectives were to: (i) quantify the effect...

In the coming decades, maintaining a steady food supply for the increasing world population will require high-yielding crop plants which can be productive under increasingly variable conditions. Maintaining high yields will require the successful and uniform establishment of plants in the field under altered environmental conditions. Seed vigor, a complex agronomic trait that includes seed longevity, germination speed, seedling growth, and early stress tolerance, determines the duration and success of this establishment period. Elevated temperature during early seed development can decrease seed size, number, and fertility, delay germination and reduce seed vigor in crops such as cereals, legumes, and vegetable crops. Heat stress in mature seeds can reduce seed vigor in crops such as lettuce, oat, and chickpea. Warming trends and increasing temperature variability can increase seed dormancy and reduce germination rates, especially in crops that require lower temperatures for germination and seedling establishment. To improve seed germination speed and success, much research has focused on selecting quality seeds for replanting, priming seeds before sowing, and breeding varieties with improved seed performance. Recent strides in understanding the genetic basis of variation in seed vigor have used genomics and transcriptomics to identify candidate genes for improving germination, and several studies have explored the potential impact of climate change on the percentage and timing of germination. In this review, we discuss these recent advances in the genetic underpinnings of seed performance as well as how climate change is expected to affect vigor in current varieties of staple, vegetable, and other crops.

Key message: Bet-hedging is a complex evolutionary strategy involving morphological, eco-physiological, (epi)genetic and population dynamics aspects. We review these aspects in flowering plants and propose further research needed for this topic. Bet-hedging is an evolutionary strategy that reduces the temporal variance in fitness at the expense of a lowered arithmetic mean fitness. It has evolved in organisms subjected to variable cues from the external environment, be they abiotic or biotic stresses such as irregular rainfall or predation. In flowering plants, bet-hedging is exhibited by hundreds of species and is mainly exerted by reproductive organs, in particular seeds but also embryos and fruits. The main example of bet-hedging in angiosperms is diaspore heteromorphism in which the same individual produces different seed/fruit morphs in terms of morphology, dormancy, eco-physiology and/or tolerance to biotic and abiotic stresses in order to ‘hedge its bets’ in unpredictable environments. The objective of this review is to provide a comprehensive overview of the ecological, genetic, epigenetic and physiological aspects involved in shaping bet-hedging strategies, and how these can affect population dynamics. We identify several open research questions about bet-hedging strategies in plants: 1) understanding ecological trade-offs among different traits; 2) producing more comprehensive phylogenetic analyses to understand the diffusion and evolutionary implications of this strategy; 3) clarifying epigenetic mechanisms related to bet-hedging and plant responses to environmental cues; and 4) applying multi-omics approaches to study bet-hedging at different levels of detail. Clarifying those aspects of bet-hedging will deepen our understanding of this fascinating evolutionary strategy.

Seed germination is a critical developmental phase for seedling establishment and crop production. Increasing salinity stress associated with climatic change can pose a challenge for seed germination and stand establishment of many crops including lettuce. Here, we show that water soluble carbon nanoparticles (CNPs) can significantly promote seed germination without affecting seedling growth. Twenty-seven varieties of lettuce (Lactuca sativa) were screened for sensitivity to germination in 150 and 200 mM NaCl, and six salt-sensitive varieties (Little Gem, Parris Island, Breen, Butter Crunch, Muir, and Jericho) were selected and primed with 0.3% soluble carbon nanoparticles. Pretreatment with CNPs significantly improved seed germination under 150 mM NaCl and high temperature. CNP treatment slightly inhibited the elongation of primary roots but promoted lateral root growth and accumulation of chlorophyll content of seedlings grown under salt stress. Despite different lettuce varieties exhibiting a distinct response to nanoparticle treatments, results from this study indicate that soluble nanoparticles can significantly improve lettuce seed germination under salinity stress, which provide fundamental evidence on the potential of nanoparticles in agricultural application to improve crop yield and quality under stressful conditions.