Breeding and Bioengineering of Male Sterility in Rice

Abstract

Male sterility has been an important trait for heterosis-based breeding programs. Harnessing hybrid vigor has been a promising approach to tackle the current challenges of increased population and climate change. Recent advancements in understanding the molecular basis of male sterility phenomenon have helped breeders develop desired varieties. The molecular approaches for the generation of male-sterile lines through regulation of phytohormonal biosynthesis in reproductive organs are also under way. The era of omics have enriched the understanding of genes cytoplasm and nuclear communication, and further molecular tools such as DNA markers implicated in hybrid breeding have facilitated further understanding of their interactions. Bioengineering is the application of engineering principles to the fields of biology and health care. Bioengineering of crop plants for improved tetrahydrofolate production is one such example. There are three types of male sterilities, viz., nuclear male sterility (NM), cytoplasmic male sterility (CMS), and the other cytoplasmic genetic male sterility (CGMS). CMS genes may be formed during evolution through gene duplication and multi-recombination, and the corresponding nuclear Rf genes appear to have undergone coevolution. The mitochondrion being a semiautonomous organelle with its own genome encodes genes that control TCA cycle and ATP generation. Until now 28 CMS genes have been identified from 13 crop species. The knowledge obtained about the molecular mechanisms of these nuclear and cytoplasmic genes can be used in hybrid development using bioengineering. Bioengineering in plants such as development of golden rice has been successful as a technology, but it has been facing challenges with respect to its acceptance among the public due to safety issues that need to be resolved at the earliest.