Phenotypic and morphological characterization of the root system architecture in low phytic acid1-1 maize mutant

Phytic acid (PA) represents the major storage form of phosphate (P) in the seeds. It is accumulated as phytate salts with different cations, reducing their bioavailability. Only ruminants can degrade PA, while monogastrics assimilate 10% of phytate in feed and 90% is excreted, contributing to P pollution. Hence, many low phytic acid (lpa) mutants have been isolated in all major crops. The lpa trait can provide several potential benefits to the nutritional quality of foods and feeds and to the environmental P sustainability in agriculture. Among different lpa mutants in maize, lpa1-1 is characterized by a 66% reduction in PA, followed by a proportional increase in inorganic P. PA decrease is often accompanied by negative pleiotropic effects on the seed and on plant performance. One of the agronomic defects observed on lpa1-1 in field conditions is a greater susceptibility to drought stress, which could be caused by an alteration in the root system architecture (RSA). With the aim to assess the effect of drought stress on the mutant, we have compared the RSA of lpa1-1 to a wild phenotype, using hydroponic cultivation and two soil conditions (pots and field). In this work we present the first results obtained in hydroponics tests and pots experiments, which clearly show a variety of morphological changes in the mutant root system. If these alterations will be confirmed in the field (summer 2020), the RSA would play a key role in drought stress sensitivity, thus representing an important objective of lpa genetic improvement programs.