How Rice Gene Mixes Affect Plant Growth and Yield

Greg Howard
9th March, 2024

How Rice Gene Mixes Affect Plant Growth and Yield

Image Source: Natural Science News, 2024

Key Findings

  • In South Korea, scientists found genes that control rice flowering time and other traits
  • Three main genes (Hd1, Hd16, Ghd7) affect when rice flowers and its yield and quality
  • Rice with certain gene combinations can flower earlier without losing yield or quality
Rice is a staple food for more than half of the world's population, and its production is a balancing act of various factors, one of which is the timing of flowering, known as the heading date. The heading date is crucial because it can affect both the grain yield and quality. If rice plants head too early, they may not have enough time to develop fully, leading to reduced yields. Conversely, if they head too late, they may encounter adverse weather conditions that can also impact yield and quality. Therefore, scientists are continuously working to optimize the heading date to ensure the best possible rice crop. At Jeonbuk National University, researchers have made significant strides in understanding how to control the heading date in rice[1]. They focused on a rice population created from the crossbreeding of two rice varieties, Koshihikari and Baegilmi, to identify specific regions in the rice genome, called quantitative trait loci (QTLs), which are associated with the heading date and other important traits like plant height and grain size. The study identified three major QTLs that influence heading date, which involve the genes Hd1, Hd16, and Ghd7. These genes don't work in isolation; they have pleiotropic effects, meaning they can control multiple traits at once. For example, Ghd7 not only affects when the rice heads but also has an impact on the number of panicles (the branches that bear the rice grains) and the size of the grains themselves. The research team discovered that by manipulating the combinations of these genes, they could influence the heading date and other agronomic traits. In particular, they found that rice plants with a nonfunctional version of either hd16 or ghd7, while retaining the functional forms of the other two genes, showed promise for maintaining good yield and quality while also heading earlier. This latest study builds upon previous research that has delved into the genetic mechanisms of heading date regulation in rice. For instance, earlier studies have shown that the Hd1 gene has a dual role in promoting or suppressing flowering depending on the length of the day[2][3]. Under short days, Hd1 promotes heading, but under long days, it can delay heading, especially when combined with other genes like Ghd7 and DTH8[2]. This dual function is essential for rice plants to adapt to different growing environments. Moreover, the study of Korean rice cultivars has shown that different Hd1 alleles can have significant effects on heading dates across various environments[3]. This information is invaluable for rice breeding programs that aim to fine-tune flowering times for specific climates. Another study using CRISPR mutagenesis to create isogenic lines among the core photoperiod sensitivity-flowering genes, including Hd1, Ghd7, and DTH8, has contributed to understanding how these genes interact under different day lengths[4]. This research has helped to clarify the genetic relationships and their effects on the regulation of target genes and photoperiod sensitivity variation. Additionally, the discovery of a novel Ghd7 allele that is important for extremely early flowering in a rice variety adapted to Hokkaido, Japan, highlights the importance of allelic variations for adaptability to different cultivation regions[5]. The findings from Jeonbuk National University's study not only advance our understanding of the genetic regulation of heading date but also provide practical pathways for rice breeders. By selecting specific gene combinations, breeders can develop rice varieties that are better suited to local environments and have optimized yield and grain quality. This research is a step forward in the global effort to ensure food security through improved crop performance.

GeneticsPlant ScienceAgriculture

References

Main Study

1) Allelic combinations of Hd1, Hd16, and Ghd7 exhibit pleiotropic effects on agronomic traits in rice.

Published 6th March, 2024

https://doi.org/10.1093/g3journal/jkad300


Related Studies

2) Hd1, Ghd7, and DTH8 synergistically determine the rice heading date and yield-related agronomic traits.

https://doi.org/10.1016/j.jgg.2022.02.018


3) Hd1 Allele Types and Their Associations with Major Agronomic Traits in Korean Rice Cultivars.

https://doi.org/10.3390/plants10112408


4) Strong photoperiod sensitivity is controlled by cooperation and competition among Hd1, Ghd7 and DTH8 in rice heading.

https://doi.org/10.1111/nph.16946


5) Genetic effect of a new allele for the flowering time locus Ghd7 in rice.

https://doi.org/10.1270/jsbbs.19112



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