{"id":{"repo_id":"milano","oai_identifier":"oai:air.unimi.it:2434/949417"},"canonical_url":"https://search.dev.ndltd.org/etd/milano/oai:air.unimi.it:2434/949417","repository":{"repo_id":"milano","name":"Università degli Studi di Milano","base_url":"https://air.unimi.it/oai/request"},"display":{"title":"LOW-PHYTATE GRAINS TO ENHANCE PHOSPHORUS SUSTAINABILITY IN AGRICULTURE: GENETIC ANALYSIS ON THE LOW PHYTIC ACID1-1 MAIZE MUTANT","abstract":"Background: Phosphorus is an essential component of fertilizers and feed and in recent decades has become one of the main sustainability issues as a non-renewable resource. In plant seeds, the main reserve of phosphorus is phytic acid, a strong anti-nutritional factor for monogastrics and a pollutant of cultivated lands. The reduction of phytic acid in cereal seeds has become a major challenge in breeding programs to increase the nutritional quality of foods and feeds and to improve the environmental phosphorus sustainability in agriculture. In maize (Zea mays L.), four low phytic acid (lpa) mutations have been isolated and lpa1-1 is the most promising. However, the reduction of phytic acid in lpa1-1 leads to many adverse pleiotropic effects on the seed and in general on plant performance. A seed weight reduction and a consequent yield loss were previously described in this mutant. Method: In this work, a field experiment to study seed weight and yield was conducted for two years in two different genetic backgrounds (B73 and B73/Mo17). Furthermore, the greater susceptibility of lpa1-1 to drought stress was also investigated: a dedicated field experiment was set up and measurements were carried out under optimal water conditions and moderate drought stress. Results: From the first experiment it emerges that under high-input conditions, lpa1-1 seems to have comparable or even better seed weight/ear than the relative control. The main problem of this mutant remains the reduced field emergence (~40%). In the study of drought stress it was found that the increased sensitivity in the mutant is mainly caused by an altered stomatal regulation, but not by a less developed root system, as previously reported. When the stress occurred, the parameters measured did not significantly change in the wild-type, while they dropped in the mutant: the net photosynthesis decreased by 58%, the transpiration rate by 63% and the stomatal conductance by 67%. Conclusions: Some possible solutions have been proposed, with the aim of developing a commercial variety, which remains the main goal to exploit the nutritional benefits of low phytic acid mutants.","abstract_html":"Background: Phosphorus is an essential component of fertilizers and feed and in recent decades has become one of the main sustainability issues as a non-renewable resource. In plant seeds, the main reserve of phosphorus is phytic acid, a strong anti-nutritional factor for monogastrics and a pollutant of cultivated lands. The reduction of phytic acid in cereal seeds has become a major challenge in breeding programs to increase the nutritional quality of foods and feeds and to improve the environmental phosphorus sustainability in agriculture. In maize (Zea mays L.), four low phytic acid (lpa) mutations have been isolated and lpa1-1 is the most promising. However, the reduction of phytic acid in lpa1-1 leads to many adverse pleiotropic effects on the seed and in general on plant performance. A seed weight reduction and a consequent yield loss were previously described in this mutant. Method: In this work, a field experiment to study seed weight and yield was conducted for two years in two different genetic backgrounds (B73 and B73/Mo17). Furthermore, the greater susceptibility of lpa1-1 to drought stress was also investigated: a dedicated field experiment was set up and measurements were carried out under optimal water conditions and moderate drought stress. Results: From the first experiment it emerges that under high-input conditions, lpa1-1 seems to have comparable or even better seed weight/ear than the relative control. The main problem of this mutant remains the reduced field emergence (~40%). In the study of drought stress it was found that the increased sensitivity in the mutant is mainly caused by an altered stomatal regulation, but not by a less developed root system, as previously reported. When the stress occurred, the parameters measured did not significantly change in the wild-type, while they dropped in the mutant: the net photosynthesis decreased by 58%, the transpiration rate by 63% and the stomatal conductance by 67%. Conclusions: Some possible solutions have been proposed, with the aim of developing a commercial variety, which remains the main goal to exploit the nutritional benefits of low phytic acid mutants.","abstract_has_math":false,"creators":["COLOMBO, FEDERICO"],"institution":"Università degli Studi di Milano","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["relatore: S. R. Pilu ; supervisori esterni: F. Sparvoli","S. Salvi; coordinatore: P. A. Bianco","F. Colombo","PILU, SALVATORE ROBERTO","BIANCO, PIERO ATTILIO"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-12-19","date_published":"2022-12-19","updated_at":"2026-07-27T20:18:56Z","subjects":["Settore AGR/07 - Genetica Agraria"],"languages":["eng"],"rights":["info:eu-repo/semantics/openAccess"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["http://dx.doi.org/10.13130/colombo-federico_phd2022-12-19","10.13130/colombo-federico_phd2022-12-19"],"render_values":[{"text":"http://dx.doi.org/10.13130/colombo-federico_phd2022-12-19","href":"http://dx.doi.org/10.13130/colombo-federico_phd2022-12-19","code":true},{"text":"10.13130/colombo-federico_phd2022-12-19","href":"https://doi.org/10.13130/colombo-federico_phd2022-12-19","code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/2434/949417","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["relatore: S. R. Pilu ; supervisori esterni: F. Sparvoli","S. Salvi; coordinatore: P. A. Bianco","F. Colombo","PILU, SALVATORE ROBERTO","BIANCO, PIERO ATTILIO"]},{"key":"dc:creator","label":"Author","values":["COLOMBO, FEDERICO"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2022-12-19"]},{"key":"dc:publisher","label":"Institution","values":["Università degli Studi di Milano"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Settore AGR/07 - Genetica Agraria"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2434/949417","http://dx.doi.org/10.13130/colombo-federico_phd2022-12-19","10.13130/colombo-federico_phd2022-12-19"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Background: Phosphorus is an essential component of fertilizers and feed and in recent decades has become one of the main sustainability issues as a non-renewable resource. In plant seeds, the main reserve of phosphorus is phytic acid, a strong anti-nutritional factor for monogastrics and a pollutant of cultivated lands. The reduction of phytic acid in cereal seeds has become a major challenge in breeding programs to increase the nutritional quality of foods and feeds and to improve the environmental phosphorus sustainability in agriculture. In maize (Zea mays L.), four low phytic acid (lpa) mutations have been isolated and lpa1-1 is the most promising. However, the reduction of phytic acid in lpa1-1 leads to many adverse pleiotropic effects on the seed and in general on plant performance. A seed weight reduction and a consequent yield loss were previously described in this mutant. Method: In this work, a field experiment to study seed weight and yield was conducted for two years in two different genetic backgrounds (B73 and B73/Mo17). Furthermore, the greater susceptibility of lpa1-1 to drought stress was also investigated: a dedicated field experiment was set up and measurements were carried out under optimal water conditions and moderate drought stress. Results: From the first experiment it emerges that under high-input conditions, lpa1-1 seems to have comparable or even better seed weight/ear than the relative control. The main problem of this mutant remains the reduced field emergence (~40%). In the study of drought stress it was found that the increased sensitivity in the mutant is mainly caused by an altered stomatal regulation, but not by a less developed root system, as previously reported. When the stress occurred, the parameters measured did not significantly change in the wild-type, while they dropped in the mutant: the net photosynthesis decreased by 58%, the transpiration rate by 63% and the stomatal conductance by 67%. Conclusions: Some possible solutions have been proposed, with the aim of developing a commercial variety, which remains the main goal to exploit the nutritional benefits of low phytic acid mutants.","Phytic acid (PA) is a strong anti-nutritional factor with a key antioxidant role in countering ROS accumulation. Despite the potential benefits of low phytic acid mutants, the reduction of PA causes pleiotropic effects, e.g. reduced seed germination and a viability loss related to seed ageing. In this work, using a historical series of naturally aged seeds, we show that lpa1-1 seeds aged faster compared to wild-type seeds. To mimic natural ageing, we set up an accelerated ageing treatment at different temperatures: incubating the seeds at 57 °C for 24 h, the wild-type germinated at 82.4% and lpa1-1 at 40%. We also propose two possible solutions to overcome these problems: i) we used classical breeding to constitute synthetic populations carrying the lpa1-1 mutation with genes encouraging anthocyanin accumulation in the embryo (R-navajo allele). The results showed that the presence of R-navajo gene in lpa1-1 genotype was not able to improve the germinability (-20%), but this approach could be useful to improve the germinability in non-mutant genotypes (+17%); ii) hydropriming was tested on lpa1-1 and wild-type seeds subjected to accelerated ageing: it emerged that germination was improved by 20% in lpa1-1, suggesting a possible role of seed priming in restoring germination, with promising outcomes toward the improvement relevant maize cultivars.","Phytic acid (PA) represents the major storage form of seed phosphate (P). During seed maturation, it accumulates as phytate salts chelating various mineral cations, therefore reducing their bioavailability. During germination, phytase dephosphorylates PA releasing both P and cations which in turn can be used for the nutrition of the growing seedling. Animals do not possess phytase, thus monogastric animals assimilate only 10% of the phytate ingested with feed, whilst 90% is excreted and may contribute to cause P pollution of the environment. To overcome this double problem, nutritional and environmental, in the last four decades many low phytic acid (lpa) mutants (most of which affect the PA-MRP transporters) have been isolated and characterized in all major crops, showing that the lpa trait can increase the nutritional quality of foods and feeds and improve P management in agriculture. Nevertheless, these mutations are frequently accompanied by negative pleiotropic effects leading to agronomic defects which may affect either seed viability and germination or plant development or in some cases even increase the resistance to cooking, thus limiting the interest of breeders. Therefore, although some significant results have been reached, the isolation of lpa mutants improved for their nutritional quality and with a good field performance remains a goal so far not fully achieved for many crops. Here, we will summarize the main pleiotropic effects that have been reported to date in lpa mutants affected in PA-MRP transporters in five productive agronomic species, as well as addressing some of the possible challenges to overcome these hurdles and improve the breeding efforts for lpa mutants.","Phytic acid (PA) is an anti-nutritional factor for monogastrics and contributes to phosphorus pollution. The low phytic acid (lpa) trait can provide several benefits to the nutritional quality of foods/feeds and to environmental sustainability. In maize, four lpa1 mutants have been isolated, and lpa1-1 is the most promising. Nevertheless, these mutations are frequently accompanied by many negative pleiotropic effects affecting plant performance. One of these is a greater susceptibility to drought stress, probably caused by an alteration in the root system. In this work, we set up an experiment in hydroponics and two in mesocosms, where pots were built using transparent PVC sheets to better access the roots. The results suggested that neither root architecture nor root depth are limiting factors in mutant plants. In hydroponics, the dry weight of the mutant and the root area per unit of length were twice that of the corresponding wild-type. However, lpa1-1 exhibited a reduced efficiency of photosystem II (Fv/Fm, 0.810 vs. 0.800) and a reduced leaf temperature (−0.5 °C compared to wild-type), probably due to increased water loss. Furthermore, molecular analysis performed on genes involved in root development (rtcs, rtcl, rum1, and BIGE1) revealed the abundance of rtcs transcripts in the mutant, suggesting an alteration in auxin polar transport."]},{"key":"dc:title","label":"Title","values":["LOW-PHYTATE GRAINS TO ENHANCE PHOSPHORUS SUSTAINABILITY IN AGRICULTURE: GENETIC ANALYSIS ON THE LOW PHYTIC ACID1-1 MAIZE MUTANT"]}]}],"canonical_facts":{"dc:contributor":["relatore: S. R. Pilu ; supervisori esterni: F. Sparvoli","S. Salvi; coordinatore: P. A. Bianco","F. Colombo","PILU, SALVATORE ROBERTO","BIANCO, PIERO ATTILIO"],"dc:creator":["COLOMBO, FEDERICO"],"dc:date":["2022-12-19"],"dc:description":["Background: Phosphorus is an essential component of fertilizers and feed and in recent decades has become one of the main sustainability issues as a non-renewable resource. In plant seeds, the main reserve of phosphorus is phytic acid, a strong anti-nutritional factor for monogastrics and a pollutant of cultivated lands. The reduction of phytic acid in cereal seeds has become a major challenge in breeding programs to increase the nutritional quality of foods and feeds and to improve the environmental phosphorus sustainability in agriculture. In maize (Zea mays L.), four low phytic acid (lpa) mutations have been isolated and lpa1-1 is the most promising. However, the reduction of phytic acid in lpa1-1 leads to many adverse pleiotropic effects on the seed and in general on plant performance. A seed weight reduction and a consequent yield loss were previously described in this mutant. Method: In this work, a field experiment to study seed weight and yield was conducted for two years in two different genetic backgrounds (B73 and B73/Mo17). Furthermore, the greater susceptibility of lpa1-1 to drought stress was also investigated: a dedicated field experiment was set up and measurements were carried out under optimal water conditions and moderate drought stress. Results: From the first experiment it emerges that under high-input conditions, lpa1-1 seems to have comparable or even better seed weight/ear than the relative control. The main problem of this mutant remains the reduced field emergence (~40%). In the study of drought stress it was found that the increased sensitivity in the mutant is mainly caused by an altered stomatal regulation, but not by a less developed root system, as previously reported. When the stress occurred, the parameters measured did not significantly change in the wild-type, while they dropped in the mutant: the net photosynthesis decreased by 58%, the transpiration rate by 63% and the stomatal conductance by 67%. Conclusions: Some possible solutions have been proposed, with the aim of developing a commercial variety, which remains the main goal to exploit the nutritional benefits of low phytic acid mutants.","Phytic acid (PA) is a strong anti-nutritional factor with a key antioxidant role in countering ROS accumulation. Despite the potential benefits of low phytic acid mutants, the reduction of PA causes pleiotropic effects, e.g. reduced seed germination and a viability loss related to seed ageing. In this work, using a historical series of naturally aged seeds, we show that lpa1-1 seeds aged faster compared to wild-type seeds. To mimic natural ageing, we set up an accelerated ageing treatment at different temperatures: incubating the seeds at 57 °C for 24 h, the wild-type germinated at 82.4% and lpa1-1 at 40%. We also propose two possible solutions to overcome these problems: i) we used classical breeding to constitute synthetic populations carrying the lpa1-1 mutation with genes encouraging anthocyanin accumulation in the embryo (R-navajo allele). The results showed that the presence of R-navajo gene in lpa1-1 genotype was not able to improve the germinability (-20%), but this approach could be useful to improve the germinability in non-mutant genotypes (+17%); ii) hydropriming was tested on lpa1-1 and wild-type seeds subjected to accelerated ageing: it emerged that germination was improved by 20% in lpa1-1, suggesting a possible role of seed priming in restoring germination, with promising outcomes toward the improvement relevant maize cultivars.","Phytic acid (PA) represents the major storage form of seed phosphate (P). During seed maturation, it accumulates as phytate salts chelating various mineral cations, therefore reducing their bioavailability. During germination, phytase dephosphorylates PA releasing both P and cations which in turn can be used for the nutrition of the growing seedling. Animals do not possess phytase, thus monogastric animals assimilate only 10% of the phytate ingested with feed, whilst 90% is excreted and may contribute to cause P pollution of the environment. To overcome this double problem, nutritional and environmental, in the last four decades many low phytic acid (lpa) mutants (most of which affect the PA-MRP transporters) have been isolated and characterized in all major crops, showing that the lpa trait can increase the nutritional quality of foods and feeds and improve P management in agriculture. Nevertheless, these mutations are frequently accompanied by negative pleiotropic effects leading to agronomic defects which may affect either seed viability and germination or plant development or in some cases even increase the resistance to cooking, thus limiting the interest of breeders. Therefore, although some significant results have been reached, the isolation of lpa mutants improved for their nutritional quality and with a good field performance remains a goal so far not fully achieved for many crops. Here, we will summarize the main pleiotropic effects that have been reported to date in lpa mutants affected in PA-MRP transporters in five productive agronomic species, as well as addressing some of the possible challenges to overcome these hurdles and improve the breeding efforts for lpa mutants.","Phytic acid (PA) is an anti-nutritional factor for monogastrics and contributes to phosphorus pollution. The low phytic acid (lpa) trait can provide several benefits to the nutritional quality of foods/feeds and to environmental sustainability. In maize, four lpa1 mutants have been isolated, and lpa1-1 is the most promising. Nevertheless, these mutations are frequently accompanied by many negative pleiotropic effects affecting plant performance. One of these is a greater susceptibility to drought stress, probably caused by an alteration in the root system. In this work, we set up an experiment in hydroponics and two in mesocosms, where pots were built using transparent PVC sheets to better access the roots. The results suggested that neither root architecture nor root depth are limiting factors in mutant plants. In hydroponics, the dry weight of the mutant and the root area per unit of length were twice that of the corresponding wild-type. However, lpa1-1 exhibited a reduced efficiency of photosystem II (Fv/Fm, 0.810 vs. 0.800) and a reduced leaf temperature (−0.5 °C compared to wild-type), probably due to increased water loss. Furthermore, molecular analysis performed on genes involved in root development (rtcs, rtcl, rum1, and BIGE1) revealed the abundance of rtcs transcripts in the mutant, suggesting an alteration in auxin polar transport."],"dc:identifier":["https://hdl.handle.net/2434/949417","http://dx.doi.org/10.13130/colombo-federico_phd2022-12-19","10.13130/colombo-federico_phd2022-12-19"],"dc:language":["eng"],"dc:publisher":["Università degli Studi di Milano"],"dc:rights":["info:eu-repo/semantics/openAccess"],"dc:subject":["Settore AGR/07 - Genetica Agraria"],"dc:title":["LOW-PHYTATE GRAINS TO ENHANCE PHOSPHORUS SUSTAINABILITY IN AGRICULTURE: GENETIC ANALYSIS ON THE LOW PHYTIC ACID1-1 MAIZE MUTANT"],"dc:type":["info:eu-repo/semantics/doctoralThesis"]},"updated_at":"2026-07-27T20:18:56Z"}