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<p>Traditional maize grains, used in human diets and animal feeds, are deficient in methionine (an essential amino acid), which severely affects growth and development. <i>Aspartate kinase2</i> (<i>ask2)</i> gene plays a pivotal role in the accumulation of methionine in maize kernels. Here, we studied the temporal expression dynamics of <i>ask2</i> gene and accumulation of methionine in maize kernel among inbreds with the mutant (<i>ask2</i>) and wild-type (<i>ask2</i>) allele at 20-, 30- and 40-days after pollination (DAP). The inbreds (PMI-PV5-<i>ask2</i> and PMI-PV6-<i>ask2</i>) with mutant <i>ask2</i> gene were developed through marker-assisted introgression into two elite inbreds (PMI-PV5 and PMI-PV6) with wild-type (<i>ask2</i>) allele. An average of 4.30-fold change was observed among <i>ask2</i> mutant inbreds over inbreds possessing the wild-type <i>ask2</i> allele at 20-DAP.. Gene expression of <i>ask2</i> gene showed decreasing pattern with peak expression at 20-DAP (0.255) and decreases towards 30- (0.072) and 40-DAP (0.030). The <i>ask2</i>-based inbreds showed higher methionine (0.370% in flour) over original versions (0.346% in flour) at 20-DAP. DAP contributed the most (77.29%) to total variance for methionine, followed by genotype (17.68%) and genotype × DAP interaction (3.95%). The highest accumulation of methionine was observed at 20-DAP (0.354%) and decreased at 30-DAP (0.255%), with the least at 40-DAP (0.219%). Strong positive correlation (r = 0.763, p &lt; 0.01) was observed between the transcript abundance and methionine accumulation over the kernel growth stages. Results revealed deeper insights into the regulation and accumulation of methionine in maize endosperm. This is the first report on the expression dynamics of <i>ask2</i> gene and its association with accumulation of methionine across developmental stages of maize kernel. The results assume great significance in the pursuit to develop high methionine maize cultivars to alleviate protein energy malnutrition, especially in developing countries.</p>

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Unveiling the Link Between Expression of Aspartate Kinase2 (ask2) Gene and Accumulation of Methionine in Developing Maize Kernels

  • 期刊论文

  • 发表日期：

    2026年3月10日

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  • Hriipulou Duo,
  • Rashmi Chhabra,
  • Rajkumar U. Zunjare,
  • Gaurav Sharma,
  • Subhra J. Mishra,
  • Vignesh Muthusamy,
  • Firoz Hossain

摘要

Traditional maize grains, used in human diets and animal feeds, are deficient in methionine (an essential amino acid), which severely affects growth and development. Aspartate kinase2 (ask2) gene plays a pivotal role in the accumulation of methionine in maize kernels. Here, we studied the temporal expression dynamics of ask2 gene and accumulation of methionine in maize kernel among inbreds with the mutant (ask2) and wild-type (ask2) allele at 20-, 30- and 40-days after pollination (DAP). The inbreds (PMI-PV5-ask2 and PMI-PV6-ask2) with mutant ask2 gene were developed through marker-assisted introgression into two elite inbreds (PMI-PV5 and PMI-PV6) with wild-type (ask2) allele. An average of 4.30-fold change was observed among ask2 mutant inbreds over inbreds possessing the wild-type ask2 allele at 20-DAP.. Gene expression of ask2 gene showed decreasing pattern with peak expression at 20-DAP (0.255) and decreases towards 30- (0.072) and 40-DAP (0.030). The ask2-based inbreds showed higher methionine (0.370% in flour) over original versions (0.346% in flour) at 20-DAP. DAP contributed the most (77.29%) to total variance for methionine, followed by genotype (17.68%) and genotype × DAP interaction (3.95%). The highest accumulation of methionine was observed at 20-DAP (0.354%) and decreased at 30-DAP (0.255%), with the least at 40-DAP (0.219%). Strong positive correlation (r = 0.763, p < 0.01) was observed between the transcript abundance and methionine accumulation over the kernel growth stages. Results revealed deeper insights into the regulation and accumulation of methionine in maize endosperm. This is the first report on the expression dynamics of ask2 gene and its association with accumulation of methionine across developmental stages of maize kernel. The results assume great significance in the pursuit to develop high methionine maize cultivars to alleviate protein energy malnutrition, especially in developing countries.