Exploring natural variation in foliar and non-foliar tissues to improve yield potential in Pisum sativum

As global populations rise exponentially and the impacts of climate change intensify, it is becoming increasingly imperative to increase crop production capable of withstanding future climatic conditions to meet food demands. As genetic approaches have legal restrictions, breeders are focusing on alternative strategies, with natural variation in photosynthetic capacity and stomatal responses remaining an underutilised resource for crop improvements. Studies that have explored natural variation have mainly focused on leaves, however it is becoming increasingly apparent that non-foliar tissues are capable of photosynthesising and are possible compensatory mechanisms for foliar tissues during stress. Although demand for peas are increasing (as an alternative source of protein), their yields are stagnating due to poor conditions. As many different varieties of pea exist, including conventional leafed, semi-leafless and leafless varieties, they provide an ideal model to explore for the identification of beneficial traits in both foliar (leaves and stipules) and non-foliar (pods) tissues. This study utilised IRGA’s, chlorophyll fluorescence and surface impressions to determine that photosynthetic capacity/rates, stomatal characteristics and iWUE naturally varied amongst the pea accessions utilised and between the different types of foliar tissues. The findings demonstrated that variation in foliar tissues existed in the traits mentioned above when pea accessions were subjected to mild drought. Whilst a bespoke Lawson Lab gas exchange chamber was used to highlight that pea pods were photosynthetically active, naturally varied in measured traits across the pea accessions, had functional stomata and that pod photosynthesis potentially acted as a compensatory mechanism under drought stress. Such findings emphasised that natural variation exists even amongst a small population of peas, with potential for future breeding programmes to explore the accessions and traits presented here, for enhanced pea production under future climatic conditions in order to meet demand.