The ability of a seed to provide high and synchronous germination and seedling establishment under different environmental conditions is an important agronomical trait, ensuring homogenous crop establishment needed for optimal yield. The different seed traits that determine seed vigor are germination speed, primary and secondary dormancy, desiccation tolerance and longevity, i.e. the capacity of the seeds to maintain their vigor during storage. The biotic and abiotic environment during seed production has major impacts on the vigor of progeny seeds. Our team works on providing novel mechanistic insights into regulatory processes during seed development that are required for the resilience of seed vigor in response to the biotic and abiotic environment.

Our research efforts focus on understanding seed quality of tomato and legume seeds, such as Medicago trunctula, pea and soybean. Production of grain legumes, which are an important source of proteins, is strategically and economically important for food security to sustain the increase in meat consumption world-wide. Given their ability to fix atmospheric nitrogen, they are pivotal to the development of European sustainable agriculture. To decrease the European dependence on protein imports, instability of legume seed yield due to environmental fluctuations needs to be reduced, and producing highly vigorous seeds is a key lever to increase crop production efficiency and reduce weed management.

Our research is focused on two axes:

1. Identification of the molecular events controlling environmental responses of seeds during development and imbibition

The acquisition of desiccation tolerance is a key element in the preservation of our genetic ressources and storability of seeds. A better understanding of the genetic and epigenetic regulation of its acquisition and loss, both during seed maturation and in relation to germination will be obtained in the DESWITCH and SEED-REG project, and aid in the creation of more tolerant variaties during the early phases of seedling emergence. In the SOYADAPT project, we aim to identify the genes and molecular pathways implicated in cold tolerance of soybean seeds (avoidance of imbibitional damage, rapid germination under cold conditions) via the use of natural and created genetic diversity. 

SEED, in collaboration with the ImHorPhen team, participates in the ANR-PPR SPECIFICS project, to work on the competitiveness of legumes to weeds by screening for the emergence of pea seedlings under optimal and cold sowing conditions. Phenotyping data will be used to identify marker-phenotype associations to improve crop establishment and yield using GWAS approaches.

Our understanding of seed development and performance has moved from a vision of a highly structured program under predominantly genetic control to a view in which major processes are highly plastic and strongly influenced by environmental cues, which perceived by both the mother plant and zygote can have a dramatic effect on seed quality. Our research focuses on a better understanding of the underlying factors regulating seed quality and heat response of tomato seeds during fruit development and imbibition, and to identify plasticity regulators that are responsible for thermo-tolerant, thermoinhibited and thermodormant phenotypes. This work is carried out in the framework of the PAUSE program with financial support from INRAE.

2. Understanding and improving seed behavior in its biotic environment

Our previous work carried out in collaboration with the Emersys team at IRHS has identified a molecular dialogue between the developing seeds of Medicago truncatula and Xanthomonas, plant pathogenic bacteria transmitted by seeds and causing harmful diseases to crops. The seed is able to perceive the bacteria and respond to its presence by expressing a set of defense genes (Terrasson et al., 2015). In parallel, we have shown that at the end of maturation and in dormant seeds, basal defenses are activated to protect the seed (Bolingue et al., 2020, Righetti et al., 2015). Our current interest is to further understand seed defense.

Within the framework of the PPR SUCSEED project, the SEED team is responsible for WP2: Improvement of seed defenses, one of the three levers of action that the SUCSEED project proposes to identify alternative solutions to pesticides. We will study the molecular pathways of defense stimulation in tomato and common bean seeds via priming of the mother plants to identify intermediate signaling molecules. In parallel, we will characterize the defense mechanisms that are activated in dormant seeds.