Discovery of SHUKR Gene

Researchers at CSIR-CCMB, Hyderabad, discovered the SHUKR gene that controls pollen development in flowering plants (eudicots). This finding sheds light on the rapid diversification of flowering plants about 125 million years ago, addressing Darwin’s “abominable mystery,” and has implications for improving plant resilience amid climate change.

Understanding the Evolutionary Significance and Agricultural Implications of the SHUKR Gene

• Evolution of Land Plants: Plants evolved from freshwater algae, gradually transitioning from aquatic to terrestrial habitats over 450 million years. This shift altered their life-cycles and reproductive strategies.
  • Early land plants like mosses spend most of their lifecycle as gametophytes (haploid), with motile sperm swimming through water to fertilize eggs.
  • Flowering plants (angiosperms), especially eudicots, have dominant sporophyte (diploid) phases, with enclosed gametophytes. Their male gametophytes develop as pollen, delivered by biotic or abiotic vectors.
• Life-cycle Dynamics:
  • Gametophyte: haploid phase producing gametes (sperm/egg).
  • Sporophyte: diploid phase producing spores.
  • In flowering plants, sporophytes control pollen development, unlike in mosses where gametophyte development is independent.
• Discovery of SHUKR Gene:
  • SHUKR is expressed in the sporophyte phase and regulates development of viable pollen in Arabidopsis thaliana (a model eudicot).
  • Absence of SHUKR results in non-viable pollen, causing reproductive failure.
  • SHUKR modulates F-box genes which manage protein turnover in pollen, essential for pollen maturation.
• Evolutionary Significance:
  • SHUKR appeared about 125 million years ago in eudicots, coinciding with the rapid diversification of flowering plants.
  • SHUKR and pollen-specific F-box genes are rapidly evolving, enabling plants to adapt pollen to diverse environmental stresses (heat, cold, humidity, aridity).
  • This molecular innovation could explain the sudden evolutionary success and habitat expansion of flowering plants, addressing Darwin’s “abominable mystery.”
• Implications for Food Security and Climate Resilience:
  • Flowering plants provide seeds that form the basis of human and animal food (cereals, pulses, oilseeds).
  • Climate change-induced stresses affect pollen viability and plant reproduction, threatening food security.
  • Understanding SHUKR’s role may enable development of crops with better resilience to environmental challenges through natural modulation of pollen traits.