The remodeling of root architecture is a major developmental response of plants to phosphate （Pi） deficiency and is thought to enhance a plant＇s ability to forage for the available Pi in topsoil. The underlying mec...The remodeling of root architecture is a major developmental response of plants to phosphate （Pi） deficiency and is thought to enhance a plant＇s ability to forage for the available Pi in topsoil. The underlying mechanism controlling this response, however, is poorly understood. In this study, we identified an Arabidopsis mutant, hps 10 （hypersensitive to Pi starvation 10）, which is morphologically normal under Pi sufficient condition but shows increased inhibition of primary root growth and enhanced production of lateral roots under Pi defi- ciency, hpslO is a previously identified allele （als3-3） of the ALUMINUM SENSITIVE3 （ALS3） gene, which is involved in plant tolerance to aluminum toxicity. Our results show that ALS3 and its interacting protein AtSTAR1 form an ABC transporter complex in the tonoplast. This protein complex mediates a highly electro- genic transport in Xenopus oocytes. Under Pi deficiency, als3 accumulates higher levels of Fe3＋ in its roots than the wild type does. In Arabidopsis, LPR1 （LOW PHOSPHATE ROOT1） and LPR2 encode ferroxidases, which when mutated, reduce Fe3＋ accumulation in roots and cause root growth to be insensitive to Pi defi- ciency. Here, we provide compelling evidence showing that ALS3 cooperates with LPR1/2 to regulate Pi deficiency-induced remodeling of root architecture by modulating Fe homeostasis in roots.展开更多
Many differentiated plant organs have the ability to regenerate into a new plant after detachment via de novo organogenesis. During de novo root organogenesis from Arabidopsis thaliana leaf explants, wounding first in...Many differentiated plant organs have the ability to regenerate into a new plant after detachment via de novo organogenesis. During de novo root organogenesis from Arabidopsis thaliana leaf explants, wounding first induces endogenous auxin production in mesophyll cells. Auxin is then polar transported to, and accumulates in, regenerationcompetent cells near the wound to trigger the cell-fate transition. The TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS(TAA) family proteins and the YUCCA(YUC) family proteins catalyze two successive biochemical steps in auxin biogenesis, and YUCs have been shown to be involved in auxin production in mesophyll cells during de novo root organogenesis. In thisstudy, we show that the TAA family is also required for adventitious rooting. Inhibition of TAA blocked adventitious root formation from leaf explants. Intriguingly,whereas YUC1 and YUC4 have been shown to be highly induced by wounding, TAA genes retained consistent expression levels before and after leaf detachment.Therefore, we suggest that TAAs and YUCs are both required for auxin biogenesis in leaf explants, but they play different roles in regeneration. While YUC1 and YUC4 function in response to wounding to catalyze the ratelimiting step in auxin biosynthesis, TAAs probably serve as abiding and basal enzymes during de novo root organogenesis from leaf explants.展开更多
文摘The remodeling of root architecture is a major developmental response of plants to phosphate （Pi） deficiency and is thought to enhance a plant＇s ability to forage for the available Pi in topsoil. The underlying mechanism controlling this response, however, is poorly understood. In this study, we identified an Arabidopsis mutant, hps 10 （hypersensitive to Pi starvation 10）, which is morphologically normal under Pi sufficient condition but shows increased inhibition of primary root growth and enhanced production of lateral roots under Pi defi- ciency, hpslO is a previously identified allele （als3-3） of the ALUMINUM SENSITIVE3 （ALS3） gene, which is involved in plant tolerance to aluminum toxicity. Our results show that ALS3 and its interacting protein AtSTAR1 form an ABC transporter complex in the tonoplast. This protein complex mediates a highly electro- genic transport in Xenopus oocytes. Under Pi deficiency, als3 accumulates higher levels of Fe3＋ in its roots than the wild type does. In Arabidopsis, LPR1 （LOW PHOSPHATE ROOT1） and LPR2 encode ferroxidases, which when mutated, reduce Fe3＋ accumulation in roots and cause root growth to be insensitive to Pi defi- ciency. Here, we provide compelling evidence showing that ALS3 cooperates with LPR1/2 to regulate Pi deficiency-induced remodeling of root architecture by modulating Fe homeostasis in roots.
基金supported by the National Basic Research Program of China (973 Program,2014CB943500/2012CB910503)the National Natural Science Foundation of China (91419302/31422005)Youth Innovation Promotion Association CAS
文摘Many differentiated plant organs have the ability to regenerate into a new plant after detachment via de novo organogenesis. During de novo root organogenesis from Arabidopsis thaliana leaf explants, wounding first induces endogenous auxin production in mesophyll cells. Auxin is then polar transported to, and accumulates in, regenerationcompetent cells near the wound to trigger the cell-fate transition. The TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS(TAA) family proteins and the YUCCA(YUC) family proteins catalyze two successive biochemical steps in auxin biogenesis, and YUCs have been shown to be involved in auxin production in mesophyll cells during de novo root organogenesis. In thisstudy, we show that the TAA family is also required for adventitious rooting. Inhibition of TAA blocked adventitious root formation from leaf explants. Intriguingly,whereas YUC1 and YUC4 have been shown to be highly induced by wounding, TAA genes retained consistent expression levels before and after leaf detachment.Therefore, we suggest that TAAs and YUCs are both required for auxin biogenesis in leaf explants, but they play different roles in regeneration. While YUC1 and YUC4 function in response to wounding to catalyze the ratelimiting step in auxin biosynthesis, TAAs probably serve as abiding and basal enzymes during de novo root organogenesis from leaf explants.
