skip to main content

Attention:

The NSF Public Access Repository (NSF-PAR) system and access will be unavailable from 11:00 PM ET on Thursday, October 10 until 2:00 AM ET on Friday, October 11 due to maintenance. We apologize for the inconvenience.


Title: Enhanced Reproductive Thermotolerance of the Tomato high pigment 2 Mutant Is Associated With Increased Accumulation of Flavonols in Pollen
Climate change has created an environment where heat stress conditions are becoming more frequent as temperatures continue to raise in crop production areas around the world. This situation leads to decreased crop production due to plant sensitivity to heat stress. Reproductive success is critically dependent on plants’ ability to produce functional pollen grains, which are the most thermo-sensitive tissue. Flavonols are plant secondary metabolites known for their potent antioxidative activity, essential for male fertility in several species including tomato, and implicated in heat stress tolerance. Since flavonols are highly abundant in fruits of the tomato high pigment 2 ( hp2 ) mutant, we tested the level of flavonols in pollen of this mutant, under the hypothesis that increased accumulation of flavonols would render pollen more tolerant to heat stress. Indeed, pollen from two alleles of the hp2 mutant was found to have flavonols levels increased by 18 and 280% compared with wild-type (WT) under moderate chronic heat stress (MCHS) conditions. This mutant produced on average 7.8-fold higher levels of viable pollen and displayed better germination competence under heat stress conditions. The percentage of fully seeded fruits and the number of seeds per fruit were maintained in the mutant under heat stress conditions while decreased in wild-type plants. Our results strongly suggest that increased concentrations of pollen flavonols enhance pollen thermotolerance and reproductive success under heat stress conditions. Thus, the high flavonols trait may help frame the model for improving crop resilience to heat stress.  more » « less
Award ID(s):
1656774
NSF-PAR ID:
10390808
Author(s) / Creator(s):
; ; ; ; ;
Date Published:
Journal Name:
Frontiers in Plant Science
Volume:
12
ISSN:
1664-462X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    A combination of drought and heat stress, occurring at the vegetative or reproductive growth phase of many different crops can have a devastating impact on yield. In soybean (Glycine max), a considerable effort has been made to develop genotypes with enhanced yield production under conditions of drought or heat stress. However, how these genotypes perform in terms of growth, physiological responses, and most importantly seed production, under conditions of drought and heat combination is mostly unknown. Here, we studied the impact of water deficit and heat stress combination on the physiology, seed production, and yield per plant of two soybean genotypes, Magellan and Plant Introduction (PI) 548313, that differ in their reproductive responses to heat stress. Our findings reveal that although PI 548313 produced more seeds than Magellan under conditions of heat stress, under conditions of water deficit, and heat stress combination its seed production decreased. Because the number of flowers and pollen germination of PI 548313 remained high under heat or water deficit and heat combination, the reduced seed production exhibited by PI 548313 under the stress combination could be a result of processes that occur at the stigma, ovaries and/or other parts of the flower following pollen germination.

     
    more » « less
  2. In a search for efficient fungal endophytes that can promote crop production and/or increase crop tolerance to abiotic stress, we isolated and tested various species harbored by wild plants. Sixty-seven endophytic fungal isolates were obtained from drought stressed, poor soil habitats, and inland high salt areas. We extensively tested the roles of Ampelomyces sp. and Penicillium sp. isolates in improving tomato growth and yield. Under greenhouse and field trails, Ampelomyces sp. and Penicillium sp. endophytes proved effective in conferring positive benefits to tomatoes placed under stress as well as under normal growing conditions. Ampelomyces sp. conferred tolerance to tomatoes placed under drought stress in addition to enhancing overall plant growth and fruit yield in comparison to non-symbiotic plants under drought stress. Penicillium sp. conferred tolerance to tomatoes placed under 300 mM salinity stress in addition to enhancing root biomass in comparison to non-symbiotic plants. Both endophytes proved efficient in enhancing plant growth, stress tolerance, recovery, and fruit yield under optimal experimental conditions in comparison to non-symbiotic plants. Field testing of tomato yield showed increased yield of symbiotic tomatoes compared to non-symbiotic ones. This data suggests that both Ampelomyces sp. and Penicillium sp. share a promising potential for improving future agricultural production, particularly with the projected changes in climate in the future. 
    more » « less
  3. Summary

    Increasing populations and temperatures are expected to escalate food demands beyond production capacities, and the development of maize lines with better performance under heat stress is desirable. Here, we report that constitutive ectopic expression of a heterologous glutaredoxin S17 fromArabidopsis thaliana(AtGRXS17) can provide thermotolerance in maize through enhanced chaperone activity and modulation of heat stress‐associated gene expression. The thermotolerant maize lines had increased protection against protein damage and yielded a sixfold increase in grain production in comparison to the non‐transgenic counterparts under heat stress field conditions. The maize lines also displayed thermotolerance in the reproductive stages, resulting in improved pollen germination and the higher fidelity of fertilized ovules under heat stress conditions. Our results present a robust and simple strategy for meeting rising yield demands in maize and, possibly, other crop species in a warming global environment.

     
    more » « less
  4. Abstract

    Domesticated plants can differ from their wild counterparts in the strength and outcome of species interactions, both above‐ and belowground. Plant–soil feedbacks influence plant success, and plant‐associated soil microbial communities can influence plant interactions with herbivores and their natural enemies, yet, it remains unclear if domestication has changed these relationships.

    To determine the effects of domestication on plant–soil interactions, we characterized soil microbial communities associated with various cultivars of domesticated tomato and some of its wild relatives. We measured the strength and direction of plant–soil feedbacks for domesticated and wild tomatoes, and the effects of soil on plant resistance to specialist herbivory byManduca sexta, and the attraction of a parasitoid wasp,Cotesia congregata.

    Domesticated tomatoes and their wild relatives had negative plant–soil feedbacks, as conspecifics cultivated soil that negatively impacted performance of subsequent plants (longer germination time, lower biomass) than if they grew in non‐tomato soils. Significant variation existed among domesticated and wild tomato varieties in the strength of these feedbacks, ranging from neutral to strongly negative. For above‐ground plant biomass, tomato wild relatives were unaffected by growing in tomato‐conditioned soil, whereas domesticated tomatoes grew smaller in tomato soil, indicating effects of plant domestication. Overall, increased microbial biomass within the rhizosphere resulted in progressively less‐negative plant–soil feedbacks.

    Plant cultivars had different levels of resistance to herbivory byM. sexta, but this did not depend on plant domestication or soil type. The parasitoidC. congregatawas primarily attracted to herbivore damaged plants, independent of plant domestication status, and for these damaged plants, wasps preferred some cultivars over others, and wild plants grown in tomato soil over wild plants grown in non‐tomato soil.

    Synthesis.These results indicate that crop tomatoes are more likely to show negative plant–soil feedbacks than wild progenitors, which could partially explain their sensitivity to monocultures in agricultural soils. Furthermore, cultivar‐specific variation in the ability to generate soil microbial biomass, independent of domestication status, appears to buffer the negative consequences of sharing the same soil. Last, soil legacies were relatively absent for herbivores, but not for parasitoid wasps, suggesting trophic level specificity in soil feedbacks on plant–insect interactions.

     
    more » « less
  5. Abstract

    Reactive oxygen species (ROS) contribute to cellular damage in several different contexts, but their role during chilling damage is poorly defined. Chilling sensitivity both limits the distribution of plant species and causes devastating crop losses worldwide. Our screen of chilling-tolerant Arabidopsis (Arabidopsis thaliana) for mutants that suffer chilling damage identified a gene (At4g03410) encoding a chloroplast Mpv17_PMP22 protein, MPD1, with no previous connection to chilling. The chilling-sensitive mpd1-1 mutant is an overexpression allele that we successfully phenocopied by creating transgenic lines with a similar level of MPD1 overexpression. In mammals and yeast, MPD1 homologs are associated with ROS management. In chilling conditions, Arabidopsis overexpressing MPD1 accumulated H2O2 to higher levels than wild-type controls and exhibited stronger induction of ROS response genes. Paraquat application exacerbated chilling damage, confirming that the phenotype occurs due to ROS dysregulation. We conclude that at low temperature increased MPD1 expression results in increased ROS production, causing chilling damage. Our discovery of the effect of MPD1 overexpression on ROS production under chilling stress implies that investigation of the nine other members of the Mpv17_PMP22 family in Arabidopsis may lead to new discoveries regarding ROS signaling and management in plants.

     
    more » « less